POPULAR WIRELESS WEEKLY, June 2nd, 1923. REGISTERED AL THE G.P.O. AS A NEWSPAPER. CONSTRUCTION & CALIBRATION OF GRID LEAKS. PopularWireless

No. 53.Vol. III. SCIENTIFIC ADVISER: SIR OLIVER LODCE, F.R.S., D.Sc. June 2nd, 1923.

LORD GAINFORD, CHAIR- MAN OF THE B.B.C., WITH HIS CABINET SET.

FEATURESIN THIS ISSUE. Tackling the Dead -End Problem. Easily Made Boxes for Panel Mounting. A Crystal Adapter. An Improvised Winder. Some More Practical Ideas. Timed Spark for C.W. Transmission. And interesting articles by Sir Oliver Lodge, F.R.S., D.Sc., Dr. N. W. McLachlan, M.I.E.E., and P. J. Risdon, F.R.S.A. POPULAR WIRELESS WEEKLY. June 2nd, 1023. The" BROWN "- LOUD SPEAKERS EDISWAN with new improved Curved Horns THE requisites of a Loud Speaker are pure tone, clear articulation, and good volume of sound. The VALVES BROWN Loud Speaker possesses all these qualities in a marked degree. Type H. 2 has been designed to meet home requirements, both as to volume of sound and price. PRICES H. 2 (Small). Low Resistance. H.2 120 ohms, height 12 in. £3 0 0 (small H. I (Large), Low Resistance. 120 size). ohms, height 21 in. £6 5 0 Height1-ligh Reitstauces for either size, 2:6 to 5, -extra, 12 in. THE BROWN MICROPHONE Noiseless AMPLIFIER. This amplifier gives a magnification macS greater than that obtained from a two -valve amplithr Prices Illustrated Catalogue of Head- Low Resistance (tze ohms input)£6 0 0 Sensitive phones,Loud Speakers and High Resistance (z,ono ohms input) £6 2 6 Amplifiers, post free. Obtainable from All Wireless Dealers. Sole Manufacturers : Robust S. G. BROWN, Ltd., There is no better valve for wireless work than London Showrooms (Retail only): the Ediswan Type A.R.Itissilent working, 19, NIORTIMER STREET, LONDON, W.1. sensitive,andessentiallystrong. Itgives Head Office and Works (Trade Only), Victoria Road, North Acton, W.3. high amplification, is verycompact, and extremely economical incurrent consumption. This Valve-made by the makers of the world- R 1 famous Ediswan Electric Lamps-has been specially designed for operation on low plate voltages and HULLO !!! C.Q. WILL DAY CALLING 1 isparticularly recommended for amateur work. TO ANNOUNCE SOME RARE BARGAINS I READY FOR THE OPERA BROADCASTING

We have had very considerableexperience inthe it development and manufacture of the Thernzionic Valve. BIJOU CRYSTAL RECEIVING SET in The first experiments in connection with the investigation imitation Morocco, wave -length 600 of the" Edzson Effect," on which the working of a valve : metres, stamped B.B.C.Price, inc:ud- depends, were carried out at our Ponders End Works ing fee ...... 20;- each : by Prof. J. A. Fleming, who was then in our employ A THOROUGHLY RELIABLE PAIR OF

HEADPHONES, stamped B.B.C... 20'- par pair 100 feet 7, 25 Stranded Copper Aerial Wire 1 / 1 0 per coil

PRICE 15s. HAVING PURCHASED THE WHOLE OF A MANU- DESCRIPTIVE LEAFLETS FREE ON REQUEST. FACTURER'S STOCK OF GUARANTEED 7,22 HARD

Also manufacturers of complete Receiving Sets, Accessories, DRAWN AERIAL WIRE IN 100 FT. HANKS, WE ARE . and H.T. and L.T. Batteries. ABLE TO OFFER THIS AT THE LOW PRICE OF Ask your usual Dealer, and if unable to supply send us 2 2 PER HANK OR 2. FOR 50 HANKS AND UP. a post card with his name and address. Sheet Ebonite, Grade A, cut to any size THE Every requisite in Stock for Wireless TRADE SUPPLIED. These are only a few of our bargains.Do not fail to send EDISON SWAN ELECTRIC for our Price List gluing the lowest prices for the best CO , LTD., quality goods.Postage on all goods extra. Contractors to H.M. Admiralty, War Office, Royal Air Force Write for our new Catalozue,now ready. 123/5, Queen Victoria St., E.C.4, Do not fail to try the NEW "DAYZITE," Regd. The super marvel Crystal with Silver Detector Point at and 71, Victoria Street, S. W.1 2,6 each, or mounted in Brass cup, 2;10, Postage 3d. extra. WORKS: PONDERS END, MIDDLESEX. Branches in all Principal towns WILL DAY, .LTD., 1 9, Lisle St.,Leicester Sq., London,W.C.2 ELECTRIC COLIDMIIIIIIIk 'Phone: Regent 1577. Telegrams : Titles, Westrand, London.

- -. . ..noW-614 Popular Wireless Weekly, June 2nd, 1923 SI 7 POPULAR WIRELESS

June 2nd, 1923. SCIENTIFIC ADVISER, SIR OLIVER LODGE, F.R.S.,D.Sc. [Every Friday. TOPICAL NOTES AND NEWS. The " Rev." Uncle. microphone of the new studio." I want Hungry Uncles. ACCORDING to a notice in. a daily to come again," he remarked, " and to say TBELIEVE the " uncles" enjoy them- paper Uncle Rex has taken " Holy more to the listeners -in ;you have to get 'selves as much as the kiddies when Orders," and should now bead- used to it." children's story -time arrives.The other dressed as the Rev. Rex Palmer. Un- day Icaught Uncle" Cactus "busily doubtedly we must expect a new class of OUR COMPANION PAPER engaged with some cream buns while Uncle Sunday concert. " WIRELESS REVIEW AND SCIENCE Jeff was in the studio telling the tales. * WEEKLY " (3c1. fromall bookstalls and newsagents), is proving to be more greatly Not True. in demand thanwas anticipated, and Tea or Tales ? SPEAKING to Mr. Palmer-I mean the to prevent disappointment, copies should be ordered in advance.No. 2, out on Tuesday, UNCLE JEFF was not going to be left " Rev." Uncle-about this, he indig- June 5th,will contain, among many other out of it for long, however, and he nantly denied that he had taken such interesting features, articles by Dr. Lee de Forest, Sir William Noble, Sir Oliver Lodge, soon called out for ,Uncle " Cactus." a step, and pointed out that the " x " in F.R.S., and many other well-known scientists. The remainder of the children's hour was Rex had been misprinted as a " v." ORDER YOUR COPYNOW! spent in a competition between the uncles! as to who should tell the tale, and who Uncle Arthur Chased. Wireless Racing. should have the tea.After all,I don't IWAS surprised the other afternoon to see FURTHER attempts at joekeyless horse - think we can blame them, for they both Uncle Arthur rushing breathlessly past racing are being made in France.The work very hard all day, to say nothing of, thestudio lookingveryperturbed. horses are to be fitted with small frame the evening. "What's the matter?" * * I asked." There's a NovelDemonstration man after me," he Van. said, and pushed me TT is difficult to give into the studio. 1 demonstrations * * in r3mote country Ill -health . Due to villages, but Messrs. Broadcasting. WirelessService, SAFELY inside, this by rigging up a uncleunfolded special van.It con- his tale of a man sists -ofatouring who had chased him motor -car, the body that morning, and of which has been how a policeman had camouflaged to look to be called to take like a small country him away."The cottage.A short yet man's possessed with efficientaerialhas the idea that I am the been erected on the cause of the wireless roof, and the interior waves interfering isequipped with a with his health. I only Gecophone two -valve got in by the skin of receiving set and loud my teeth - through speakerequipment. the back door." Some very successful * tours have been made New Uncle. in the country dis- IHEAR that Mr. tricts within 100 miles Page hasbeen of London, arid the promoted to the This studio, that of the London Broadcasting Station, may become the central studio for all the British van has visited several position of " Uncle broadcasting stations, should the " group " system materialise. Note the " blanketing," the microphone, market townsand at 2 L 0.Though his and, on the right, the famous tubular bells. given demonstrations full title has not yet in the market -places. been designated, he often takes the part of aerials and loud speakers in conjunction with announcer. receiving sets on their saddles. Each horse Better Transmission. * * will be " tuned -in " to its own particular T AM told by the B.B.C. that they are Lord Mayor at 2 L 0. wave -length, and it, is hoped will respond to 1experimenting with a view to eliminate THE Lord Mayor appeared to be quite the instructions from its jockey in the the " rushing " noises that are heard at home in front of the microphone grand stand. when a land line is used. when he spoke at 2 L 0 some days * * * * * * ago.He told me that he was the first man Brighter Tennis. A New Code. to speak on the telephone in the days of ACERTAIN lawn tennis clubclaim TAM told of a new alphabet for use in Edison and Bell. better and brighter tennissince a 1wireless telegraphy which will enable * * wireless installation and loud speaker transmissionstotakeplacenearly " Have to Get Used To It." has been installed.The club has prepared twice as quickly as at present.Tests have HE was very pleased withhisfirst an open-air dance ground for the use of been made in America and at the G.P.O., experience of broadcasting and was members during Saturday afternoons, when London,andgoodresultshavebeen proud of the fact that he should be the proposed dance programmes will be obtained. the first Lord Mayor to speak through the broadcast. (Continued on page 578.) 578 Popular Wireless Weekly, June 2nd, 1923. NOTES AND NEWS. Broadcasting and Theatres. mendous welcome among our readers - THE effect of the broadcasting of The Quite a number of bookstalls told me that (Continued from page 577.) Marionette Players, from the Scala they were sold out very quickly and that someeveningsago,was,instan- many people were disappointed.After all, Clear the Ether. taneous. The very next day seats were even it is not very remarkable, for " W. R. THE inventor, General Squier, said that more rapidly booked up than usual, the 'contains such a host of wonderful articles the proposed improvement in sending first bookers being listeners -in who had from the pens of the foremost scientists messages would not only make it heard the play the evening before.This of the day that an increaSing demand is seems to me -to -point very strongly -to the inevitable. possible to send them faster, but would also * * * help to clear the ether of disturbances over effect broadcasting has on the theatres. a wide range of frequencies. Virtue Rewarded. The Causes of " Fading." IMMEDIATE rewardfollowed2 L 0's AMATEURS are invited by the Radio recent explanation to thekiddies of Research Board, through the Radio how to clean their teeth, for on the

. Society of Great Britain, to assist in following morning each " Uncle " received the investigation into the cause of " fading " a neat little present in the form of a tube and similar irregularities in the strength of tooth paste.Evidently some enterpris- of signals.Those who wish to assist should ingmanufacturerbelievesinstriking communicate with the Secretary, Dept. of while the iron is hot. Scientificand IndustrialResearch(for * Radio Research Board),16, Old Queen Success of Operas. Street, S.W. 1.If this address is used, no stamp will be necessary. A form will then LISTENING to the "Magic Flute" the be forwarded, which should be filled up other evening, I was agreeably sur- and returned after observations have been prised by the clearness of the trans- made. mission ;the B.B.C. are to be congratu- * . * lated on the progress made since the last operaseason.I.. have receivedseveral Opera at 5 W A. I HEAR that the Welsh station is to have letters from our readers stating that they an opera broadcast in the near future. were pleased with the improvement. The opera, composed by Major Corbett - * * Smith, the station director, is to be per- The Prince of Wales. formed and broadcast- from the studio. OVER50listeners -infromLondon This will be the first time that an opera -will Calling the ttnnis players by radio atHurlingham. and the neighbouring districts have have been both performed and broadcast - sent a letter to Messrs. Chappell & In Use for Eighty Years. from the station itself.I am told that this Co.condemning the latters'decision to TT is interesting to note that the inter- particular opera was written in 1913 for prohibit the broadcasting of the Prince of '.national code perfected by Professor the London Coliseum, under the title of Wales' speech from the Queen's Hall on Morse was first used 80 years ago. " Elizabeth." Whit Sunday.Thisshowsthestrong * * public feeling that has arisen owing to What Next I' Broadcasting a Battle. action of thetheatresand musio THE following message has been sent to AN inventionissaid to have been publishers with regard to theB.B.C. artistes who singat the Sunday perfected in America to transmit photos by wireless. The inventor, Mr. Back to the Crystal. concerts organised by Reginald Mills, Francis Jenkins, suggests that it will soon the controller of the Sunday League, who be possible for an admiral to witness a MANY of the American " fans " are have broadcast: battle at sea or a general to watch the returning to the crystal as a detector' " As we notice you have recently sung at movements of troops miles away.Further, and remarkable results are reported. a wireless concert, and as the British Broad- it is claimed that it will be possible to have High - grade crystal sets have been con- casting Company only pay you a guinea, if motion pictures by the same method. structed that do away with the usual dead- anything, we shall not be able to pay you a * * end losses, basket coils being used for tuning. larger fee than a guinea at any concert at Ranges offrom100 to 500 miles Are which you appear for us." New Form of Dull Emitter. AM given to understand that in the nothing unusual.It must be remembered No comment is necessary. States the amateurs are adopting a that some of the American broadcasting * * * stations use more power than do ours. The Sheffield Station. type of dull emitter valve known as the W.D.-11, which operates on a filament ARIEL. is hoped thatthe relay station at current of only 1.1 ITSheffield will be opened within about volts which may be a month from now. supplied by an or- dinary dry -cell bat- 2 L 0 " Testing." tery of volts.It REX tells me that hiswife certainly eliminates UNCLElistens -intoMrs.Peel's, cooking the accumulator recipes every evening,andoften - troubles and charg- when Uncle returns, a dish from one or ing difficulties that other of them is ready for him to sample. harass many ama- teurs.' -This class of New Stations. valve,however,is IAM told thatinJune a high -power little used in t hi s 1 stationwill ' beopenedatBuenOS Country, thoughit Aires ;two other stations will be ready has-beenon the in South America later in the year.These marketfor some stations will be in direct communication time now andis with the French station at Saint AssiSe, really, most, efficient. with Nauen in Germany, and with Long * * Island in U.S.A.If South America desires " Sold Out." to communicate bywireleSswiththis OU R companion country, she will have to send her message paper," Wire- via France, owing to the Post Office not less Review and yet having granted a licence for the erection Science Weekly," of a station in this country. has had atre- An interesting view of the double doors leading into 2 L 0's studio. Popular Wireless Weekly, June 2nd, 1923. 579 TO ESTIMATE THE CAPACITY OF AN AERIAL. By SIR OLIVER LODGE, F.R.S., D.Sc. (Scientific Adviser to POPULAR WIRELESS). In this article our scientific adviser deals with an important subject, which generally involves most advanced mathematics, in a manner well within the understanding of the amateur.

AERIALS can be made in innumerable I have said that all the above fractions will material. Assuming that the wires are two shapes. But the original Marconi depend to some extent on the thickness of or three feet apart, the combined capacity aerial of a single vertical, or nearly the wire, but they change only very slowly will be roughly between two and a half and vertical, wire, suspended from a high post with that thickness, and if the length and two and three-quarters that of each wire by an insulator, is one that is very likely tothickness of the wire increased together, so separately ;and, by using a factor like be used, with slight modifications, by an that if one was doubled the other was that, some useful notionis obtained of amateur, and in its simplicity it has advan-doubled too, no change would be made in what capacity to expect in a given case. tages.To estimate the capacity of suchthese fractions.They may be taken as Before leaving the subject, however, we an aerial, the simplest plan is to take it as roughly correct for a wire 5 metres in length had better write down the formulae which one -twentieth of its length.It may be ex- and izoth of a millimetre in diameter.If have enabled us to make the above rough pressed in centimetres, or feet, or any units the length is made 50 metres and the estimates. But no simple formula like this of length you please.It is unfortunately thickness 1millimetre, the fractions will can take account of all the varied circum- rather customary to specify it in micro- remain the same-that is to say, still .21,1,th stances associated with an aerial, for its microfarads, which are not a convenientof the length will be a rough approximation capacity depends upon not only itself but unit, though they are approximately of the of the capacity for an isolated vertical wire, upon everything in the neighbourhood.It order of a centimetre.Accurately, eachija-th of the length for an isolated hori- is pretty easy to calculate the self-induction micromiorofarad is .9 of a centimetre-that zontal wire, and T',,,th of the length for a of a given wire, because that depends on its is, 10 micromicrofarads equal 9 centimetres wire isolated in a large room. length,thickness, and shape. But its -which is just near enough to be confusing. If the isolated vertical wireis much capacity is another matter.That depends Besides, centimetres are so much -handier to thicker, say ten times as thick, so that the on all those things, too, but it depends on work with. To convert a capacity expressed 5 -metre- length is a millimetre thick, then other things in addition.Still, a rough in micromicrofarads into centimetres, you instead of taking 5 per cent.. of the length, estimate can be made, and the estimate is only have to multiply it by .9. That is to say, we must take 6 per cent.That is the kind often quite sufficiently near for a knowledge subtract about 10 per cent. of its numerical of difference made by a tenfold increase in of the wave -length to be expected when a value-a centimetre being the larger unit of the thickness. , given capacity is connected to a given the two, and therefore a given capacity being self-induction. expressed by a smaller number in centi- Multiple Wire Aerials. metres. Very often an aerial, instead of being a A Rough Estimate. single wire, is a pair of wires in parallel, I say, then, that the first rough esti- kept apart by distance pieces, say, a foot or CATALOGUES. mate of a vertical wire is Bath of its length. two or a yard apart. In that case we might It will depend a little on the thickness of the expect the capacity to be doubled. It is not wire, and still more on how near objects, quite doubled ;it is about one and three- ANEW wireless map of Great Britain has such as buildings, are to it.These always quarters what we should estimate for each been published by Philips'. It has been tend to increase itscapacity. And ,..fluth wire separately.Professor Fleming has compiled from information supplied of its length will therefore be an under- made experiments on the actual capacity of by the Wireless Press, Ltd., and measures. estimate.Fleming finds that it is well tomultiple wires, and his treatise must be 36 in. by 48 in., with a scale of 12 miles to add ten per cent. to the calculated value, referred to if more exact details are wanted. the inch, showing at a glance all transmitting in order to allow for the effect of the earth, But really the capacity of an aerial ought stations with their call signs. Broadcasting, which is inevitably not very far away fromto be measured by experiment, since that Commercial, Avis,' ion, Amateur, and Admir- a part of the wire. This comes to the samewould takeallthecircumstancesinto altystationsare allincluded. There is thingasmeasuringitinmicromicro- account. It is impossible to calculate them a complete index to all amateur and ex- farads and then calling them centimetres, all, and not worth while. But it.is useful to perimental stations, the origin of a call without reduction.In practice, it will be be able to make a rough estimate of what sign . being at once located by means of found that a wire suspended from any build- the capacity will be. numbered squares.Diagrams with com- ing, such as a chimney, although stretched Another common formisfour wires pass bearings show the direction of impor.. quite free from it, but hanging down near it, arranged at the corners of a square, being tent overseas stations in relation to different will have a capacity not much less than 6 kept apart by a cross -piece of wood or other portions of the map. per cent. of its length, instead of 5 per cent. as above estimated for a fairly free wire. If , a wire, instead of being vertical,is horizontal, the influence of the ground is more marked ;and, at any height likely to be adopted inpractice,-?,th ofits length, or 6 per cent., is not a bad rough estimate. Usual Type of Aerial. If, however, any part of the wire is in a building, isolated in a moderate -sized room forinstance,7_thofthat partofits length would be a fair guess at its capacity. Hence, if an aerial has three portions, one part in a building, one part nearly vertical, and one part horizontal, we might take firth ofthe, lengthforthehorizontal, nth of the length for the vertical, and --k,th of the length for the internal portion, and add them together for the total capacity. Any wire coming through an earthed tube will have a greater capacity, and to estimate that the size of the tube and of the wire must be more accurately known. One of the huge high -frequency generators at the German station Eilvese. 580 Popular Wireless Weekly; June 2nd, 1923.

As Mr. Enilyn Jones stated in his speech, it is the duty of ea cry man and everywoman' to take keen interest in their country's CRYSTAL ADAPTER. welfare; and that could be done properly by, A faithful adherence to one or other of the This handy little device will prove very useful when a valve burns out, or great political parties. Party adherence, in' when the battery unexpectedly runs down. fact, formed the really adequate vehicle of expression in state affairs.In the present welterofconflictingconditions no one THE adapter about to be described was inserted in one end, and 1 in. of same in the could afford to be disinterested. Parliament designed upon an occasion when the other, or if any amateur possess a lathe heis the organised opinion of the nation ; that writer was unfortunate enough to may be able to turn this all in one. opinion is best organised when Parliament, break both his valves when he wished to A piece of ebonite may be used to make through its members, is -representative of the receive a certain conrzrt ;thus, its origin a handle to fit on the 1 in. rod, and on theentire body of voters. arose from a necessity. other piece of rod the cat's -whisker should The 'lime Limit. It consists of a crystal detector mounted be soldered.The ball should be put into Dealingwithhispersonalopinions, on four valve legs.The base consists of a placebefore the two arms are riveted Mr. Emlyn Jones Affirmed that his politics piece of ebonite, 31 in. by 1 in. by in. were a form of religion to him. He believed Thefourvalvelegs,terminal,crystal absolutely in the tolerance of all views, (Hertzite), and a crystal cup, were pur- providing they were of national utility. He chased from a local dealer for 2s. was at one with Voltaire in that, although The ebonite was trimmed up to size with many were bound to disagree with himself a file and the holes drilled for the valve in political faith, he would fight for the right legs, the filament legs being 1in. from the of his opponents to hold and to prosecute end and the grid and plate legs being set at their own views. the irrespective distances on either side of I had a chat with Mr. Jones during the these.The crystal cup -fixing screw was usual half-hour recess, and as a matter of 2 B.A., so a hole No. 11 was drilled in. course I wanted first to learn how he had from the grid leg. felt while speaking into the 'phone. Another hole was drilled in. from the " I missed," he said, " the inspiration of crystal cup, with a No. 11 drill, to take the a seen audience, but Sir William Graham terminal. Three-quarter inch from the oppo- has just telephoned to say I did very well, site end a hole of the same diameter was so I suppose I ought to be satisfied.As drilled to take the nut and bolt for clamping you know, I have been reading from type- down the cat's -whisker adjustment arm. script to -night, whereas I never use notes The ball or socket arm was made from when delivering a speech." a piece of brass, 41 in. by z in. by in.A I remarked that Welsh speakers, as a hole in. from one end was drilled No. together, and when the arm is finished, it should appear as in the diagram. rule, do not need notes when speaking. 11 to take a nut and bolt, at the other end " Quite so," replied Mr. Jones ; but I a hole I in. diameter and 1 in. from the end Wiring Up. had a time limit, and also had to be careful was drilled. After assembling, a lead was taken fromto keep within the rule laid down by Major Two and one -eighth in. from this hole was the terminal to the crystal cup, and another Corbett -Smith as to controversial matter. drilled another hole to take a 1 -in. rivet. from the adjustment arm clamping screw But speaking from notes is not conducive to Another piece of brass, 2 in. byin. byin., to the plate leg ;this wiring should be done inspiration, although it may be safer. It is, was used for the lower arm, and 37 in. from on the underside of the adapter.For usehowever; just as well I took the precaution the adapter should be inserted in the de-of writing my speech, because of the time tector valve socket of the valve set. limit.I had no idea of the passage of time A lead is taken from the aerial terminal while at the 'phone." on the set to the terminal on the adapter. I pointed out that most people lost the The H.T. and L.T.is removed and the sense of time while broadcasting. terminals shorted with short pieces of wire. Mr. Jones was interested to learn he had The tuningis done with the condenserbeen listened -in to from all parts of the and coils on the original set. country-London, the Midlands, and the North. Great Educational Value. POLITICAL NIGHT" "Broadcasting is a wonderful thing," he went on; " and Isee in it a means of AT 5 W A. education such as we have not had before' By our Cardiff Correspondent. nor thought possible. People will be listening - in to subjects which up to now have hardly AS already announced in our interviewinterested them.' Science Night' will come with Major Corbett -Smith, the along, with an address about something' directorof CardiffBroadcasting almost unknown to the average man.It Station, Saturday is known as " Politicalis quite possible he willseethatthat Night." something isof fundamental importance' Accordingly, learning one end a hole to take a sin. rivet was drilled, that Mr.J.E. to human welfare. He will probably go Emlyn Jones, the well-known shipownerto a library to read up the subject.He while at the other end a holein. in diameter and Liberal M.P. for North Dorset, would will feel an incentive to educate himself and in. from the end was made. be broadcasting his views on the 7th inst., along that line.I say this, if broadcasting Universal ,Adjustment. I wended my way to the studio and had the does not lead to more than that it will still The piece of brass, 5* in. hang, was bent pleasure of hearing an admirably concise havejustifieditself.But thereisthe at right angles, 2 in. from the end in which and broadly based statement of that gentle. musical side as well. The music given at the the in. hole was situated.The opposite man's political faith. Cardiff station is an education in itself." end was bent at right angles,in. from the In the first place, it must be understood " Yes," I remarked, " the station in its end, only in the opposite direction, thus that controversial matter is not allowed toambitious programmes is representative of the piece of brass formed Z shape. The be broadcast. There will be political debatesthe Cardiff spirit of progress." smaller length of brass was bent at right later on, but even then the discussions will Mr. Jones agreed, and concluded with the angles, T74in. from the end, in which the notbeofan electioneeringcharacter. expression of his belief that the city is rivet hole was drilled. " Political Nightis, without doubt, a bold indebtedtoMajorCorbett -Smithfor The ball isTs'', in. in diameter, and was conception ;already has it been justified;enabling Cardiff to add substantially to its made in brass with ,1 in. of a in. brass rod it will continue to be justified. already immense importance. Popular Wireless Weekly, June 2nd, 1923. 58!

A TIMED SPARK FOR C.W. TRANSMISSION. By B. H. J. KYNASTON. This system is interesting, inasmuch as it is one that is well within the scope of the average experimenter possessed of a transmitting licence and the simple apparatus involved.

ALMOST every amateur who transmits have died out, the power in the aerial circuit foiland photoplates,and theactual on C.W. uses the valve as a generator is radiated in the form of continuous waves, capacity of these condensers is not im- of high -frequency oscillations.This as shown by Fig. 2. portant, since they do not affect the wave- article, which describes an entirely different length.Six sheets of tin foil, 3 by 4 in., method of C.W. transmission, should prove Construction of Disc. should give a large enough capacity. of interest to those amateurs who want to The actual number of studs on the try other methods. Also those who require trigger disc is not shown in Fig. 1, but in to alter existing spark sets intoC.W. the set made by the author this disc was transmitters. made from a wooden wheel 4 in. in diameter, A few years ago I made a transmitter of with forty copper nails driven in the rim, the timed Spark type, which transmitted on and all connected together by copper wire. about 81 watts, and had a normal range of The actual number of studs used is not approximately thirtymiles,using three important, however, to obtain good results valves at the receiving station.Although over thirty should be used. This discharger the range obtained was not as good as that was driven by a ten -volt motor driven from obtained by valve transmitters, the set had the 250 -volt mains by placing a resistance one decided advantage, which was the cost of 80 ohms in series with the motor.This of maintenance.As the current used was resistance consisted of two 50 -candle -power taken from the250 -voltelectriclight lamps in parallel. Since the lamps con- mains, and there were no accumulators or sumed two amperes each,thecurrent valves, the running costs were very small. flowing through themotorcouldnot exceed four amperes.However, to make The circuit used is shown in Fig. 1, and is sure no damage to the motor could be done, slightly different from the circuit employed a five -ampere fuse was inserted in circuit. by the Marconi station at Carnarvon. The This fuse consisted of one strand of No. 38 principle upon which the transmitter works copper wire. is as follows. The trigger spark gap TS in The induction coil was worked from the The coil, A, consists of 30 turns of No. 28 Fig. 1, is revolved at a high speed by means mains in exactly the same manner, and a d.c.c. wire on a 3 -in. former, and the coil, C, of a small motor. which is wound over the top of A, consists of 150 turns of the same wire. The coils, F and Two Primary Circuits. 0, are of the same size. Upon pressing the transmitting key K the induction coil causes a spark to pass About 8.5 Watts. between the gap, B. As the coil, A, is in this The condensers, K1 and K2, each consist circuit, a high-tension current is induced in of 10 sheets of tin foil, 2 by 3 in., separated the coil, C, and the two small condensers in by mica, and the coils, L, were each com- the circuit discharge across D and Q. posed of 20 turns of No. 20 rubber -covered The spark which passes the gap, Q, is wire wound on a cardboard former of 2 in. ionised, and as the condenser, K, is charged, diameter.The aerial coil, M, was wound owing to it being connected direct to the upon the same former, but between the two 250 -volt mains it will discharge as soon as coils, and consisted of 60 turns.However, the ionised spark jumps the gap, Q. When the number of turns in the aerial coil will the trigger disc has turned so that El and vary with differentaerialsinorder to obtain a wave -length of 1,000 m. E2 are opposite, the induction coil will spark fuse also inserted in that circuit.Iron wire between these electrodes instead of the resistances instead of lamps can be used if In Fig.1 a milliammeter is shown in the previous ones. The transformer F -G being desired, the amount of wire needed depend- 250 -volt circuit, this was used to find the now in circuit, the circuit containing K2 ing upon the size of wire used. power in the primary circuit.The reading now discharges. Fig. 3 shows how the various parts were obtained was -0362 amperes, and since It will be seen that owing to the trigger made. It will be noticed that ordinary watts = volts x amperes it will be seen disc revolving rapidly the two primary brass wood screws were used for the fixed that the power supplied to this circuit was circuits will oscillate alternately. The coils, electrodes of the trigger disc and spark approximately 8-5 watts. This milliammeter, L, induce these oscillations into the aerial. gap, D. When making the trigger disc, care however, is not necessary for transmission. coil, M, and as the aerial circuit oscillates must be taken so that when one,screw is op- after the oscillations in the primary circuits posite a moving electrode, the other screw is hall -way between two. Four Spark Gaps Necessary. The distancebetween theelectrodes should be very small in both gaps, is of inch, or smaller.The quenched gaps con- sisted of two gaps in series, and consisted of three circular copper discs, 1 in. in diameter. These discs are for cooling the gap. On either side of these are small silver- plated discs of about I -in. diameter, and these are separated from each other by means of 1 -in. mica washers having a-in. hole in the centre through which the spark 9igurei. passes. Two quenched gaps and two fixed gaps are necessary.The four small con- densers shown in Fig. 1 were made from tin Morse class in the 8th Liverpool Y.M.C.A. Scouts. :582 Pp'lulu). Wireless 'Weekly, June. 2nd, 1923.

claim full recognition for knowing all about the pathway down which you ensnared the TACKLING THE " DEAD-END " mystery.You will explain it to all who will listen, drawing diagrams that show your PROBLEM: chimney, your window, and your garden, for all and sundry to see and to admire. By introducing this simple mechanically operatedbreak," greater efficiency For to -day wireless has descended from on 'a " tapped " coil will be ensured. the austere heights of pure science, passed along home-made aerials, through insulating tubes, traversed bedrooms and bathrooms, SOONER, or later,the amateur using This done, the loop from the coil to the and: has demonstrated itself, without fear toils for the long wave -lengths will be usual contact stud is broken on one sideof contradiction, by shouting jazz music confronted with the disadvantage of only (D), and the ends soldered one to eachat you across your own hearthstone. the wasteful and weakening effects of the of the bottoms of the studs (B B).Thus it "dead end that part of a coil (often a will be seen that as the normal finger of the Crystals No Good. considerablelength) not inactualuse. switch -arm reaches the stud under treat- Having done so it goes to " earth"-not Where a con is tuned by the familiar slide ment (E), the extension of the arm closesusing that word inits planetary sense, method the writer has found that by con- the circuit and puts in use just that length vaguely, but in the most local, tangible, and necting the- end -of the coil to the earth of coil needed. Inversely, in switching back familiar form that you know it-the form terminal an imprOvement has resulted. a definite break is made, cutting out the in which you plant potatoes. - portion of coil not required.The method As I said, this is the day of Wireless in the Simple in Action. described is entirely automatic in action, asHome, but it was not always thus. I - It is, however, in relation to coils from remember when wireless poles were so rare which tappings -are taken to contact studs that one used to knock at the house where that I wish to deal, and by the method de- they appeared, and calmly ask if it was scribed below it is possible to disconnect convenient to have a look at the set --more- entirely that part of the coil not in use, by over, one was welcomed !Devotees were automatically opening and closing a " break few, but they had infinitely more in common in the tapping loops by the rotation of the than is 'now the case, when skill in pushing switch -arm. round shop -windows, or mere patience in In the first place it is necessary to solder standing, will gain a glimp-se of the shining on to the laminated part of ordinary instruments. switch -arm a piece of brass or copper form- In those days crystals were handled almost ing a second finger aboutin. beyond the reverently, in pill -box and cotton -wool, and finger provided, as shown in Fig. 1.This nobody foresaw the time when they would extension will not be needed to act as a be piled in little heaps as part of a window- contact arm, but to actuate a movable arm dressing scheme, labelled, and, worse still, or pawl. libelled !Only yesterday I heard a young lady assistant at a counter, in tones of Automatic " Cut Out." authority,judiciallyandwithfinality, The other items needed are three small informahesitatingyoung man that contact studs and a small piece of sheet " Crystals are no good, really.You want a brass or copper shaped as in Fig. 2, the size TAPPING LOOP valve."She almost smiled afterwards, but depending largely on the space between the FROM COIL I did not smile, for I was thinking of my ordinary contact studs and the length of the first piece of crystal, and my awe at its soldered extension to the switch -arm. Such perfection. a piece is easily fashioned from an old clock the movement of the switch -arm in one wheel with the aid of a file.This latter is directionleaves the moving portionin Wireless Thrills. position for the return journey. To -day you hear in trains and buses Although.it is possible to use this system snatches of conversation about " conden- 5/OE VIEW Of 5WITCHAAW with regard to each contact stud, itwill sers " and " insulators," and as you try to SOLDEREDEXTENSION usually be found quite useful if fitted to read in the newspaper what " Our Wireless every third or fourth stud, to suit individualExpert " says, you have difficulty in follow- 11111=11E1111 requirements, and correspondingly the parts ing that gentleman's lucid explanations, need not be on so small a scale. because of the strap -hanger explaining to the man on your right how he first suspected, then logically traced, and finally gloriously FIG. I overcame a faulty connection in his earth - lead. WIRELESS AT HOME. Then there is the man who devours every By a Wireless Operator. word that appears on wireless, no matter in FIG.2. FIG.5. what paper, and proceeds to put all this knowledge to the test, in spite of the fact THIS is essentially the day of Wireless in that the " evidence " of different writers is the Home, and from a hazy admiration oftencontradictory, and then wonders now soldered to the top of one of the small of this latest science the public haswhy he has so many failures and mishaps contact studs as shown in Fig.3. The passed to a practical insight into its work- with his set.In criss-crossing the world diagram (Fig. 4) should now be consulted. ing.We operators have lost our monopoly, anywhere between Montreal and Vladi- This shows clearly the position of the two and I find that you laymen either look overvostok I gained the universal sense and small contact studs (B B) and the -stud your fence and envy the aerial of your feel of wireless.I saw it serenely inde- with the shaped top piece (C) in relation neighbour, or you make an " earth 'in pendent over merelocality,indifferent to the particular tapping and contact stud your own garden,interrogate the highwhether theaerial swung beneath the under treatment. Washer and nuts should heavens by a questioning wire (the chimney" Great Bear " or showed as a black tracery fix the moving piece (C) so that it does not and clothes post aiding you), and, havingagainst the stars that look down on Table rotate too freely. The tops of the two studs thus tapped the illimitable ether, you haveBay.Probably there was only one place ( B B).should be slightly rounded to obviate broughtWireless, that latest marvel ofwhere I should have been surprised at the moving piece catching and jamming man's ingenuity," from out of the intangiblewireless penetration, and that is where I when switching to the right. By means of realms where it hovered almost beyondhave found it now-" Wireless at Home," the switch -arm make sure that the moving imagination, right down on to your own.gatheredinthe back garden, welcomed piece functions in the way desired, -and that sideboard. through a window,discoursinginthe the two studs are properly disconnected when You will admit that you do not under- drawing -room, and buried, in your flower - switching to the left stand the full theory of wireless ;but youbed! Popular Wireless Weekly, June 2nd, 1923. 58.3

EVERYTHING FOR WIRELESS Adjoining the luxurious Wireless Lounge where, amid quiet surroundings, Here everything can be obtained by the wireless amateur for wireless programmes can be heard free every day during, broadcastingbuilding sets and conducting experiments, and wireless experts hours, Harrods have now opened a fully equipped Accessory Section.are always inattendance to give advice and information. k:orla WirelessDept. ,`4,-`&3.kss.`k\iSsisils SecondFloor LEADING -IN VERNIER ADJUSTMENT SLIDER, TUBES with Rack and Pinion movement. Makes exception- ally fine tuning possible. Finest quality ob- Each4/6 tainable Various lengths. From40

FILAMENT RESISTANCES Speciaily modefor PHOSFER BRONZE panel mountine Each AERIAL WIRE 4/6 and 3/6 DOUBLE POLE, DOUBLE Excellent quality. SERIES PARALLEL THROW KNIFE SWITCH, Per Coil of too fem. SWITCHtS 3/6 Mounted on Ebonite mounted on china. abnibuosatrr Heavy copper clips and INTERVALVE REACTION UNIT VARIABLE INTERVALVE REACTION UNIT blade. Insulated 4/6 handle. Each 11// Made from finestquatity This Unit will enormously ado to the efficiency tion. Each D.P. one way. Q/6- materials,this short range of your instrument and may be safely_used48/(,_ Unmounted.0 fia Each 10 Unit is highly efficient Each /- during the hours of Broadcasting Earls / Write to -day for detailed Catalogue of Wireless Accessories HARRODS LTD KNIGHTSBRIDGE LONDON SW1

The Hall -mark GenuineWire- ofQualityfor less Components UNIVERSAL ELECTRIC SUPPLY CO., LTD, 4, BROWN STREET, Estab. 1892. Box No. G.P.O. 519. OUR NEW TYPE OURTYPENo. 2. MANCHEST ER, No. 1. AsSembled complete for Send for our, fully illustrated and Assembled complete for Panel Mounting, includ- descriptive Catalogue of Wire- Panel Mounting (or can We Specialise in ing Ivorine Scale, Pointer less Broadcast Receiving Sets be used as separate Sup- unit). Variable Condensers. and Knob.Unassembled and All Radio Mounted on four legs, less scale plies.post free 2d. and complete with special and end solid Ebonite Knob and ass. plates. Engraved Dial 0-180. .001 121- 7/- CapacityNo.ofPrice .00075 111- 6/- Plates. .0005 101- 419 .001 57 13 /6 .0003 7/63/6 .00075 43 12/6 .0002 6/62/9 .0005 29 11/6 .0001 516 2/3 .0003 19 9 / Vernier 5/- 21 - .0002 13 El .0001 7 7/ Instructions to assemble Filament Rheostats Vernier 3 616 sent with every set. VARIO- These Condensersenclosed Circular Ebonite End. METER in superiorMahogany plates. 1/6 a pair. Case or Dust proof Permits Celluloid Mounting Add Ebonite Dial 0-180, 113. extreme( y 7/6 to above prices Type.0005. Ivorino Scale, 0-180, 6d. close Tun- W.B.C. CRYSTAL DETECTORS. W.B.C. Switch Arms ing. Type L (Dustproof) Vertical W.B.C. FilamentResistance3/6 Mounted or Horizontal Mounting 4/6 W.B.C. FilamentResistance on sub- Type 2.(Dustproof) Vertical Dials 1/3 stantial From 3 3.Fitted Mounting only W.B.C. Valve Holders 1/3 Ebonite wills Engraved Type 3.Open, for Panel W.B.C.Fixed Condensers, Panel, Mal, as illustrated, withEbon- 49Post Free. Mounting 2/- guaranteed capacities, .0003 iteKnob W.B.C. Telephone Board to.006 1/6 mat En - (6 pairs), in series 10/6 W.B.C. Leading -in Tubes: gravid Dial. W.B.C. Basket Coils, set of 12 in., 1/4; 6 in. PriceDA 7, 300-3,000 metres 4/6 W.B.C. WoundInductance Post Free. Fit te d W.B.C. Solid Ebonite Knobs, Tubes: 12x 4, 3/3; 6 x 31, withDetectorand DOUBLE tapped 2 B.A. Gd. 2/3; 5 x 4 2/. Crystal, as illustrated, KAI) All W.B.0 Componentsare Guaranteed and the 20,- Post Free. RECEIVERS. same distinctive EboniteKnob is used on all parts. CRYSTAL DETECTOR. LAMINATED British Unde. SWITCH ARM. SEND FOR OUR PRICE LIST. Remit ample postage-balance refunded. We recommend TA LITE Crystal, for use with our Detectors, 2/- each. LARGE SUPPLIES of only the best Quality Component Parts in Stock. WHITESIDE, BLOOMFIELD & CO., LTD., i& 2, Ham Yard, Great Windmill St., Piccadilly Circus, London, W.1. Phone: REGENT 3749. Cables: TITMOUSE, LONDON Radius in. CITY RETAIL BRANCH : 31, MEREDITH ST., ST. JOHN'S ST.. E.C.1. Single Pole 2/- 4,000 f.,hins. Complete Monntecl on Ebonite Base, Double Pole with cor Is, 2:1/8 Post Free. 'Phone:Clerkenwell 5884 2 /9 Post Free. 3/3,Post Free. Including B.B.G. stamp. 581 Popular Wireless Weekly; June 2nd, 1923:-

-A4'":4-esults really marvellous -" " -..RESULTS WERE REALLY MARVELLOUS. We read L 0 with two pairscalfAihones on This letter is typical of many we receive from users of table, at 3 ft. distance. our valve sets all over the country. Heardsongs clearly at horn) ft.distance. Some clients get the U.S. concerts consistently.You Ithinkitiswell see, the secret of this big -distance reception is that we worth trying my Loud Speaker after results build our sets with the very utmost reaction allowed by on two pairs of the P.M.G.Valve users know what that means. 'phonesasabove." I Extractfrom & Scottish letter on reception in north These valve sets are so simply made that a novice can Britain. operate one in half an hour.Complete from aerial to 'phones £20, carriage paid. Write to -night for lists giving particulars of our crystal sets and famous 'phones. The British L. M. Ericsson Mfg. Co., Ltd., International Buildings, 67.73, Kingsway, W.C.2.

WARNING When you ask for Ericsson 'Phones look for the name ERICSSON BEES TON stamped thereon Don't accept Continental" 2 IritIAVE stuff as Ericsson's RECEIVER

Areyou a" Pirate " ? THE P.M.G. has now begun to grant a large number of Experimenters' Licences. If your earlier application for one has been Radio turned down, we advise you totry again. Press Many keen amateurs-although possessingthe AMERICAN TYPE VARIOMETERS. requisite amount of wireless knowledge-have been Series refused because they did not conform to the Post The mostsuccessfuldesignon the market for Fine Tuning, Smooth Action, Best Make. No. 11. Office requirements. The object of this book is to show you exactly " A " Range 300-450 Metres .-.. 12/6.Post 4d. what you should know before you can be granted "B" 700-1,000 Metres 14/6.Post 4d. this Licence. WE ALSO SUPPLY THE STATORS, ROTOR, CrRemember the Experimenter's Licence will AND FORMER UNWOUND AS ILLUSTRATED give you much greater freedom than the "A" Range 4/.. "B" Range 4/6.Post 3d. Constructor's Licence (even if the latter is issued) and your position is legalised once and for all. 10' 1Rabio 9/.16, VALVES from 7/6, CRYSTAL SETS from 15/, Devereux Court, STRAND, W.C.2.

YOU CANNOT AFFORD TO BE WITHOUT OUR 100 PAGE Frontall book. CATALOGUE, WITH OVER 1,200 ILLUSTRATIONS. sellers or post POST 3d. FREE. free direct, 131 GRAFTON ELECTRIC GRAFTON 'ELECTRIC COMPANY, CAMOCLIE 54, GRAFTON STREET, (Opposite Maples,) TOTTENHAM COURT RD., LONDON, W.1, Wireless Licences Telephone: -----MUSEUM 241. Works: SLOUGH. How to obtainthem MANUFACTURERS OF WIRELESS GOODS FOR OVER 16 YEARS. By E Redpath Popular Wireless Weekly, June 2nd,1023. 5S5 MISS ELLEN TERRY LISTENS By " ARIEL" England's greatest actress listens -infer the first time on the "Popular Wirciess " Marconi portable reciev.

I HAD the privilege of demonstrating the Shortly afterthe next number com- been sent out by ether waves from Marconi six -valve portable set built specially menced, I thought I detected a smile of House, and how the sensitive instrument for POPULAR WIRELESS by the Mar- recognition in Miss Terry's face." Who before her picked up those waves by means coni Co. to Miss Ellen Terry on the even- is it now ? " she asked, much interested. of the aerial. ingofHarrods'All -Starconcert.Miss On her daughter replying that it was Laddie " I am afraid I should never understand Terry and her daughter-Miss Edith Craig- Cliffsinging " Don't Scrap theBritish it properly," she said, smiling." I am and a distinguished audience of well-known Navy," the great English tragedienne re- just like a child in these matters.What will artistes and musical critics were present on marked': " Oh, yes ; I have heard him sing it they invent next ? " this the first occasion on which England's before."It undoubtedly caused her much It is impossible to say," I rejoined. greatest actress had listened -in.She was amusement, for she laughed many times. " Wirelessisonlyinitsinfancy,and full of enthusiasm for the novel experience already it has caused consternation among and took the keenest interest throughout A Non -Technical Explanation, theatre managers."I then pointed out to the. concert.Almost immediately I got But when Miss Jose Collins sang " Ciga- Miss Terry the dispute between theatre in touch with 2 L 0, announcing a perform- rette," Miss Terry was carried away in ad- managers and the B.B.C. in the broadcasting ance of the band of H.M. Irish Guards. miration of this idol of musical comedy. of plays, and the intention of the B.B.C. to Miss Ellen Terry seized a pair of 'phones " Splendid !Splendid ! " she cried ;and produce their own plays if necessary. with feverish interest.I then gave the jumped to her feet again in ecstacy when Miss Collins reached her top note. Preferred the Singing. " Oh, what a grand thing to be able to " I hope," said Miss Terry, " that the sing like that, and to be heard by so many play will not be neglected by wireless." people at once ! " she exclaimed." The " Of course, it must seem a little strange very thought thrills one as only music can. for an actress to have to rely entirely on her It brings to my mind those immortal lines voice for effects.It is just the opposite with of Shakespeare,' If music be the food of film acting.There it is not the voice, but love, play on, give me excess of it !' " the acting which is wanted." I do not know whether Miss Collins could " Would youliketo broadcast,Miss .have heard this charaCteristic quotation of Terry ? " I asked. the great actress, but she certainly did sing " I should enjoy the novelty very much," on-though without giving excess of it- she answered. And then, with a smile: "I when she followed with the popular song of have been asked this question so often that " The Last Waltz." I feel I must have a try." At length when 2 L 0 announced the news' Miss Terry then took up the earphones, bulletin, Miss Terry felt a little tired and' and listened to the rest of the programme. rested awhile. When the concert was over I asked Miss " You must forgive my ignorance," said Terry whether she considered the vocal Mu Ellen Terry. Miss Terry when the telephones were re- or instrumental items the more distinct. moved from her head, " but I am as much " With theexceptionoftheviolin, remaining pairs of 'phones to the company mystified as to how, or from where, this which I think the most realistic, I liked the present, and contented myself with watch- wonderful music comes as I am enchanted singing best.But it was all very good, ing the enraptured expression of Miss Ellen by the great pleasure it has given me." and I enjoyed the concert immensely.In Terry at the rousing music which I knew I then explained to Miss Terry in non- fact, after to -night, I believe I shall become was coming through. technical language how the concert had a confirmed listener -in." " Itiswonderful ! "exclaimedMiss Terry, jumping to her feet, regardless of the limits of the length of 'phone cord. "Who Is It Now?" " Where does it come from ? " she asked. I told her it came from Marconi House in the Strand.She could hardly believeit,as she said it was so distinct-in fact, just a little too loud.At her request, I promptly reduced the volume. " That's much nicer,"she remarked. " What a blessing this will be for those poor people who cannot get out and about to hear good music and plays."Several times Miss Terry alluded to the great boon of wireless for the sick, and it is characteristic of her sympathy towards the suffering that she considered them first in her appreciation of the advantages of wireless. After this number had concluded and 2 L 0 gave out that there would be a short interval, Miss Terry wanted to know the other items of the programme. I read to her the whole list of the attractions, and my mention of the children's stories caused her to remark on the great educational value of broadcasting for the young mind." What a help it would have been to me in my young days," she said." The children must Mr. F. S. Wright, of " Tiverton," King's Road, Clacton -on -Sea, listening -in on his neatly arrangei simply delight in it." receiving station. 5Se Popular Wireless Weakly, June 2nd, 1923. WIRELESS TELE-VISION. By P. J. RISDON, F.R.S.A. The problem of wireless tele-vision is one that is engaging the attention of a vast number of scientists both amateur and advanced. A further stimulus to research in this direction has been given by the magnificent offer of £500 made by our companion paper, " Wireless Review and Science Weekly," as a prize in connection with practical discoveries in this branch of wireless.The competition is open to all, and in the following article Mr. Risdon briefly indicates the simple nature of a new line of research worth investigating.

PrHE suggestion that some day it would The electro-mignetic waves, hugging the point there must be ether waves correspond- IL be possible to see a person at a clistance earth, pass round or partly round it, branded, ing more or less to both types.No doubt whilst conversing with him on 'theso to speak, with the etherial equivalentfrom the sun we receive such intermediate telephone is by no means a new one. When of the original air waves.Striking other waves, and probably we ourselves produce it was first proposed I do not know, but itaerials, they set up_ in each one a feeblethem, without being able to isolate and must have been well over a quarter of aelectric current, the flow of which bearsemploy them for a definite purpose.An century ago that I first heard it put forwardthe imprint, as it were, of the ether waveexamination of a chart of the spectrum, as a serious proposition. modulations. however, discloses the fact that, in. between One thing seems certain-namely, that This faint current, in turn, imparts itslight and electro-magnetic waves,there the solution of the problem of tele-visionrhythm to a stronger current which obe-occur heat waves, so that it appears dotibt- lies at least as much in the field of wireless diently speeds away, and finally produces ful whether the discovery of any other in- endeavour as in any other. in the telephone receiver or loud speakertermediate waves would be of assistance in air waves of exactly the same pitch as thethe matter of tele-vision. Properties of Light. Original sound waves. When we see an object, it is because light At each stage there is -a complete severance A Possible Solution. rays directed on to it are reflected by it to of the proceedings, although, of course, there The position, in so far as tele-vision is our eyes.These rays travel, to all intents is a continuous wire and ether connectionconcerned, is that although we can produce and purposes, in straight lines.That is between the speaker and the listener.inci- sound (air) waves, and translate them into why we can only view objects up to a cer- dentally,it must not be forgotten thatthe language ofelectro-magnetic (ether) tain distance at sea, owing to the curvature electro-magnetic waves can be directed inwaves, and vice versa-a marvellous pro- of the earth's surface.If light rays in- beams-/ike searchlight beams exceptthat ceeding when you come to thinkit out- stead of travelling in straight lines followed they follow the curvature of the earth. and although we can produce electromag- the curvature of the earth, as electro-mag- netic and light waves separately, we have netic waves do, there would be no such Types of Ether Waves. not yet ascertained how to convert one thing as a horizon,and, given a clear Now let us consider what can be and istype of ether wave into the other, although enough atmosphere, good enough eyesight, done with light waves. We can reflect they are so closely allied. and a sufficiently powerful telescope, one them in any direction, up or down or round The need for such conversion forthe would be able to view the back of one's head corners.We can focusthem,disperse purpose of tele-vision is fairly obvious.In round the world.This curious suggestionthem, and polarise them, which means de- addition to the earth's curvature, atmo- is intended to convey a serious and not apriving them of their undulations in all spheric conditions constitute an effective humorous meaning,which a little con-except a given plane. We can reflect them barrier to the transmission of light over sideration will make clear-namely, that and split them up into their individual com- great distances, even without intervening vision-the act of seeing-is the result ofponent colour waves.In fact, we can do objects.It appears, then, that in the trans- reflected light rays travelling in straight almostanything withlightwavesexcept mission of light rays reflected from an object lines. bend them.Perhaps some day we shallsuch conditions presentaninsuperable Let us next consider what we mean by learn how to do, that. difficulty. Not so, however, in the case tele-vision.In the simplest and fewest A searchlight beam is itself imperceptible, of electro-magnetic waves which, although possible words, it means seeing the image of and only becomes apparent when there isnot entirely independentofatmospheric a distant object, so placed that we could not moisture, smoke or dust in the air.In a conditions,pursuetheircoursefor the possibly viewitintheordinary way, perfectly clear atmosphere, or in a. vacuum, most part unhindered by such obstacle's. either by reason of distance-i.e., due to the beam would be invisible and we should In such a discovery appears to lie- a -pos- curvature of the earth's surface-fog, oronly be aware of it by light rays reflected sible solution of the problem of tele-vision; solidinterveningobstructionssuchas from an object interposed in its path. in the conversion of light waves, reflected bricks and mortar.In so far as wireless is The similarity between light and electro- fromanobject,intoelectro-magnetie concerned, it implies the transmission, of magnetic waves is too well known to need waves.These, at the receiving station, an image by means ofether waves so detailed explanation here.The essentialwould be converted back again to light that we see it exactly as it is-not as a difference is that of wave -length and periodwaves, which, on a screen, would faithfulty reproduction made up of dots or lines. of vibration which, so far as we know, ac- reproduce the original image.And, with counts for the difference in their behaviour the aid of colour photography, we should Wireless Telephony. and effect.According to their properties not only be able to see, but should be able Before we can usefully discuss the pos-and their relative positions in the spectrum, to photograph in colour a person, object, or sibility of such a thing as tele-vision,it it would appear that at some intermediate scene thousands of miles away. behoves us to consider what can already be done with waves. Let us begin with wire-. less telephony, in which the procedure is briefly as follows. First we produce air waves by speaking, -singing,or playing musical instruments. By means of suitable apparatus these.waves cause variationin the flow of electric cur- rent along the wire, and immediately we have finished with the sound waves, which die away.The electric current actuates cer- tain instruments by which it is caused to im- part its variations to another and far more powerful current oscillating in an aerial, and this current sets up electro-magnetic waves in the ether, .which are next -of -kin to light waves. A further view of the Neutrodyne receiver, showing the lay -out of the Panel. Popular Wireless Weekly, June 2nd, 1923 587 DISTINGUISHED EXPERTS who are writing for OUR GREAT NEW COMPANION PAPER

Sanatory Marconi. and ScienceWeekly

Sir OLIVER LODGE,F.R.S., D.Sc. (Scientific Adviser in Chief)

Senatore Marconi Dr. J. A. Fleming,F R.S. Dr. N. W. McLachlan,M.I.E.E. ho will act as Wireless Engineering Consultant. Professor J. Arthur Professor A. M. Low, D.Sc., A.C.G.I. Thomson, M.A., LL.D. Sir Oliver Lodge, F.R.S. Who will act as General Engineering Adviser M.I.E.E. Professor A. 0. Rankine, Sir Wm. Noble, Imperial SchoolofTechnology and Science. Chairman, B.B.C. Committee. E. Blake,A.M.I.E.E. P. J. Risdon,F.R.S.A. Who will act as Physical Science Consultant. Who willact as SpecialResearchEditor.

Readers of POPULAR WIRELESS who are anxious to pursue the study of wireless more fully than amateurs will find our new companion paper, " Wireless Review and Science Weekly," an invaluable guide to every new radio development. Accurate, reliable and absolutely authoritative, this new weekly magazine will deal fully with the technical side of wireless work-both theoretical and practical- giving explanatory articles by the leading experts only, and being exceptionally well illustrated by photographs and diagrams. It is a paper rather more for the student than the " listener -in," and no expense Sir Wrn. Noble, M.I.E.E. will be spared to make it of definite practical value and importance.With POPULAR WIRELESS and " Wireless Review " every aspect of wirelessis now covered completely, and purchasers of these papers can rely upon all the latest authentic information from every source.

WHAT IS YOUR IDEAL £500 BROADCASTING PROGRAMME? OFFERED TO EXPERIMENTERS £500 In order to encourage experiment along a IN PRIZES new and very fascinating line of wireless enquiry, " Wireless Review " offers a sum are offeredina novel competitionfor Prof. A. M. Low, D.Sc. of £500 to the first British subject who, in the selectionofanidealbroadcasting the opinion of a body of experts to be programme. No technical knowledge appointed, best demonstrates the practical is necessaryandevery listener -in possibilityofWirelessTelevision-i.e., shouldcompete. No EntranceFees. seem, by means of wireless an object or First Prize £300 oLs invisible, by reason of distance or intervening obstruction, to normal vision. Second £ 100 and 100 prizes of £ 1 each. Rules governing this offer will be found in No.I. Full particulars in No. I. Quito OOOOO aA

"WIRELESS REVIEW " will be published every Tuesday andwillbeonsaleatallnewsagentsandbookstalls.

P. J. Risc'on, N° 1 ON SALE NOW Price W. Popular Wireless Weekly, June 2nd, 1923. Buildyour oin setwith BURNDEPT Components.

F,BRANCHES': 14,

LEEDS! The leado. Avow. Haat 13691 Rem NEWCASTLE-ON.TYNE7 St. A,&.,.. Boldett W.76 BURNDEPT RADIO CLIPS C6166665. CARDIFF 670.x. Sant are invaluableaidstothe amateur 711d HEAD DISTRIBUTING SERVICE DEPOTS. BURNDEPT COILS, experimenter.There are innumerable uses owing to their patented form of construction for them.Trying out new circuits, testing BIRMINGHAM CS Beyete6 133 176.2566.1. and wrapping (Patent Nos.168249), these for faults, etc.Splendid time savers and so MANCHESTER W. C 136616615. 61 Bodge SRC. BRICKION j GA..,32 St Jen,. S.... coils have a minimum self -capacity and are easy to use. NOTTINGHAM Peen. Bees. 54 L66 Row the most efficient on the market for every

YEOVIL . Weeten Celane Elertneel Pt . No kit is complete without RADIO CLIPS - Eagtneeeme Gee purpose. (.66666 Hose. Pelmet StreeL Concert Coils for broadcast reception, each 5 0 BRISTOL lbs a C.. Western Elettex Waal, Price per dozen - - 5/. Puk Multi -layer Coils, wave -length range, 750- S OOTLAND. 25,000 metres.Price (according to GLASGOW, W A. C. Sew& L61.93 Hoke 56671, wave -length) - - from 5 236 Atesle Sze, IRELAND. BELFAST R. ea S Suet BURN DEPT Kineacoart. RHEOSTATS, DUBLIN, Dam 11. 1166666k II S5,S SL BURNDEPT EIWAORAN orneira. VALVE HOLDERS, a moulded' blockofheat - 172 Rog S..,. WVI. Tore.. of solid ebonite and fixed to the resisting composition with 62VICEDEPOTS IN ALL LOCALITIES panel by means of a screw. ebonite knob. Allfear of short circuitingis No.270.7 ohms, 1 amp. 4 0 eliminated,and capacity effects No. 275. Same,but in Write for Catalogue of Components. reduced to a minimum. walnut box- - 12 6 No.241 - - - 2 0 Also supplied: All trade enquiries to be addressed to the Factory. No. 280. Mounted on No. 271.3 ohms, 2 amps. 5 0 ebonite panel and cased106 No. 272.14 ohms, 3 amps. 5 0 No. 284. Completede- BURNDEPT tector unit - - Ei 0 0 London Office City Depot: 79, Mark Lane, E.C. BURNDEPT LTD and Showrooms: Aerial and Eastnor Works: Blackheath, S.E. 15, Bedford St., Strand, W.C.2. 'Phone: Gerrard 7794. 'Phone: Lee Green 2101 (seven lines).

IMPORTANT

NOTICETO THETRADE& PUBLIC. S.I.D.P.E. HEADPHONES THE PREMIER TELEPHONECO., :.`.(L- p.6:10:41411Dffi 62, Oxford Street, W.1., beg to inform the trade that they are the RulliaRresfacifalzs SOLE DISTRIBUTING AGENTS cou, for the S.I.D.P.E..Headphones and Wireless 1. Wireless forAll -/6 Apparatus and Accessories tothe trade. John Scott -Taggart, F.Inst.P. you want to un- 2. Simplified Wireless 1/r derstand- Wireless, John Scott -Taggart, F.Inst.P. IFthen you need good, 3. How to Make Your Broadcast Receiver 1 / 6 dependable ,Books on John Scott -Taggart, F.Inst.P. WARNING. thesubject.Those 4. How toErect Your Wireless publishedby Radio Aerial 1 /- Press Ltd.-and obtain- B. Mitten, A.M.I.E.E. IT HAS BEEN BROUGHT TO OUR NOTICE able at any Bookseller- 5. TheConstructionofWireless that there are many types of arcproduced byan Receiving Apparatus 1 / 6 P.D. Tyers. organisation.devoted 7. How to Make a " Unit " SUPPLIES Headphones being offered that exclusively to Wireless WirelessReceiver 2/8 are NOT GENUINE S.I.D.P.E. E. Redpath. Literature. You may" 9. Wireless Valves Simply GUARANTEED 'Phones. be sure. therefore, that Explained 2 / 6 all Radio Press Books John Scott -Taggart, F.Inst .1'. AU genuineS.I.D.P.E. are thoroughly reliable 10. Practical Wireless Valve Circuits 2/ 6- FROM 'Phones must bear the John Scott -Taggart, F.Inst.P. . and essential to every 11. Wireless Licences and How marks S.I.D.P.E. and P.T.C. manwho is taking more to Obtain Them 1 / STOCK. than a superficial Those printed in heavy type have been We wish to NOTIFY WIRE- interest in Wireless. All published within the past few days. 'Phones Guaranteed LESS DEALERS thattrade Postage :Pol. per Book extra. inquiries should be sentdirect to-

TrOS 0 THE PREMIER TELEPHONE CO., C- PUBLISHERS OrAUTHORITATIVE WIRELESS LITERATURE 62, OXFORD STREET, LONDON, W.I. Popular Wireless Weekly, June2nd, 1923. THE CONSTRUCTION AND CALIBRATION OF GRID LEAKS. This article covers far more ground than its title would at first indicate. It includes full constructional details of the apparatus required for correctly gauging the resistance of grid leaks-such apparatus can, of course, be employed for other useful purposes-and briefly outlines the theory and practice of the " Wheatstone )Bridge."

MOST readers are aware that the high I. Knob tapped for 2 B.A. screw.(Fig. The resistance to the flow of current resistance orgrid leak used in a 3). along a circuit depends upoli three things : detector valve circuit should have 2. A flat -headed 2 B.A. screw. (a) Length of conductor. a value somewhere in the region of two 3. A thin brass washer dished spherical (b) Area of cross section of conductor. megohms, but the best working value will of with the ball pane of a hammer. (c) The nature of the material of the course vary with the characteristics of the 4. Brass arm and 2 B.A. nut.(Details conductor. Fig. 4). 5. A brass washer aboutin. diameter. Cut put a pieceof T,12: in.brassto dimensions shown in Fig. 4, denting the end, E, to give good contact on the studs. To strengthen the arm the piece can be slightly dented along its length as in section C, D. Then carefully solder the 2 B.A. nut on the top side, taking care that the holes are in correct position.Place the parts as shown, screwing the arm down until fairly tight.The knob can then be used to lock the nut in its place on the screw.The other components of the set, so that it is a dished washer will act as a spring, enabling great advantage to have a leak which is the arm to turn without working loose. roughly adjustable within the limits required. 9idure 5. This article gives directions for the making and calibration of such a resistance, varying by steps of about 100,000 ohms from one Copper and silver offer very little resist- to three megohms. (See Fig. 1.) ance, but with carbon or graphite it is very Firstly, cut out a piece of I -in. ebonite large, so that the few inches painted as above, as shown in Fig. 2.Having drawn the part may amount toseveralmillion ohms. circle centre A, mark off the positions of the Obviously the longer the conductor the studs by starting at B and marking each greater the resistance, but the greater the way ten steps in. apart.Lightly clot - thickness the less the resistance. punch these points, drill and tap them for You will thus see that, assuming your 6 B.A. flat -headed screws.The hole at A line is not the correct resistance at first,

A short wire soldered between the washer 0 0 A and terminal D will complete the construction -13 of the, top portion of the leak. The resistance may now be placed on the under surface of the ebonite.Prepare a mixture of powdered graphite and Indian 2%" ink, and paint the lines as shown in Fig. 5. It is hardly possible to tell the reader the 3/J6 hale amount of graphite to use, he must dis- 0A cover this for himself by experiment. For 0I the benefit, therefore, of those unfamiliar : 0 withelectrical calculations,a littlein- 0 04 formation dealing with resistance will not 9igurez . be out of place.

should be drilled i r in., clearing hole for a 2 B.A. screw, and the holes C, D, drilled and tapped for terminals. Four 4 -in. brass wood screws are required to fix the ebonite to a wooden base, so drill and countersink for these in the corners. The two stops E, F, must also be arranged kisszs01 for. Section on Next rub both surfaces of the ebonite on a. b. a piece of fine emery cloth until all trace of casssm the shiny surface has been removed. Then Section or? screw the studs and terminal C into position, c. d. filing away all metal projecting from the lower surface.Now screw in terminal D, allowing itto project underneath about the method of rectifying it must be by ziS in. altering the thickness of the line.It is The knob and adjustable annext claim better to have it too thick, as when dry it our attention.It consists of the following can easily be scraped thinner. parts : (Continnedonpage 590.) 590 Popularid 'ireless Weekly, June 2nd, 1923:

plane as the mirror, and with the mirror as near the centre of the coil as possible. CONSTRUCTION & CALI- The magnetic effect due to sending a current through the coil will, of course, BRATION OF GRID LEAKS. tend to turn the mirror, but the movement (Continued from page 589.) may be so small that one cannot see the movement. To detect these small deflections,

therefore, we cast a beam of light on the 1[111111111111111111111111111111 Paint plenty of liquid over the contact mirror, and watch its reflection on a screen. points, and when perfectly dry test each stud for flow of current by connecting the Use of the "Bridge." terminals of the instrument in series with Fig. 7will explain how this can be a battery, switch, and telephone.The re- managed. A is a small aperture with a lens ohms.Test for current at this spot by sistance may be roughly tested by noticing placed on the opposite side of the screen to pressing down switch. Notice the direction the loudness of click for the length of line the coil, and the same height as the centre in which spot of light moves. you intend to be two megohms, and then of the mirror.A camera with plate attach- Now test another position of slider.If insertingin place of the instrument a ment removed would answer admirably for the light moves in,the opposite direction you bought leak (which, of course, you must the lens.Place a small flash lamp, as shown, will know that the position for no current to take for granted to be two megohms), and shift it about until its reflection from flow through the galvanometer is somewhere noticing if the click in the 'phones is louder the mirror can be seen on the screen. The in between.When the correct place has or softer. distance the light should be from the screen been found, common sense will tell you The calibration of the leak is rather a can soon be found by trial.This sensitive whether the resistance is too large or too tedious undertaking, but its accomplish- galvanometer can then be tested by passing small, so that you must scrape away, or add ment will give great satisfaction to those a very small current through the coil, and on graphite accordingly, and proceed again desiringpracticeinexperimental work. observing the movement of the spot of with the test until correct. The circuit needed for the tests issown in reflected light. Fig. 9, and depends on the principle that if Final Adjustments. four resistances are connected as in Fig. 8, and if their values are in proportion-i.e. Having corrected the one megohm line, set Circuit for testing the arm of the instrument at stud B, Fig. 2, A Cthen when a current is sent along Resistance and in correcting after a test, scrape or add B D, x equally the ten spaces between the studs. them no part of it will flow between x and y. 8 Obviously for this resistance the potentio- If we, therefore, in our test make B the un- meter slider should be in the middle: known resistance which we wish to measure. and A the two megohm grid leak, by having Lastly, check the total length of line a high resistance potentiometer the slider of which will be correct when the ratio C: D is which can. be made to vary the ratio C: D 2 : 3-i.e. C ist and D isof length of until no current flows through a delicate 9ii172 re 8 potentiometer. galvanometer placed between x and y, we The base can be made from a solid piece of wood about I in. thick, scooped out with can by measuring the lengths C and D find the a- gouge so that when screwed to the leak ratio A : B. Having set up the circuit, Fig. 9, with the only wood and ebonite make contact. B can then be found from the equation galvanometer described above placed be- x D I might 'mention, in conclusion, that if the B -A tween x and the slider of potentiometer, reader has not a potentiometer, he could use proceed to test the line you intend to be a long piece of thin high -resistance wire C and D are not, of course, the actual one megohm. The correct position should, stretched quite straight between two ter- resistances of the two parts of the potentio- C meter, but are proportional to them assum- of course,be because A is two meg- minals fixedto a board with a sliding ing that, the wire is the same thickness D terminal for y. throughout the instrument.

Reflected .Ray LtGITT V --. 4- mirror AtLENS&

Nun? 7

D Our next difficulty is the gabianometel and it must be capable of detecting the very small amount of current flowing when the potentiometer is near the critical -point, y.

An Improvised Galvanometer. First obtain a piece- of -watch spring about 4_ in. long, and magnetise it.Next. procure a piece of silvered glass aboutin. square, the_thinner the better.Stick the magnet on thp_back of the mirror and cover with stout brown paper: When dry suspend the wholeby a silk thread, as shown in Fig. 6. It will, of course, set itself north and south. Now place a duolateral or similar coil up. against the thread with its face in the same The " aunt " and " uncles " of 2 L 0 singing a chorus during the kiddies' hour. Popular Wireless Weekly, June 2nd, 1923. 591

DISTORTION DUE TO MICROPHONE DIAPHRAGMS. By Dr. N. W. McLACHLAN, M.I.E.E. (of the Marconi Research Works, Chelmsford) . It will be remembered that Dr. McLachlan is the inventor of a wonderful new wireless recording device, and that his last article gave a full description of his invention.In this, and a further article that will appear shortly, Dr. McLachlan discusses the more common causes of the distortion arising in telephonic transmission.

THE majority of microphones have some the same frequencies as the diaphragmtones (sum and difference) and tones of form of vibrating system, usually a when tapped lightly by hand.In general, double frequency, the strengths -of which circular .diaphragm securedatits however, with speech and non -percussive are proportional to the squares of the in- periphery.Unless the diaphragm is very instrumental music, the damping of thetensities of the primary tones from which thick or under considerable radial tension, diaphragm, or rate at which it comes tothey originate.Thus, under favourable its fundamental or natural frequency of rest when left alone, is such that the effectsconditions, the alien tones can easily eclipse vibration willliewell within the audio are not so pronounced as might be anti- the pure tones. frequency range-i.e., between 600 and cipated.In some cases the diaphragm has With a complex musical sound there are 1,500 cycles per second.The maximum ceased to vibrate appreciably before the many tones, and if their amplitudes are of displacement of the diaphragm from its termination of a sound-e.g., the sustained sufficient magnitude, the resultant vibration centralor normal positionwill,fora tone from the pianoforte. of the diaphragm will bear little resemblance uniformly varying force impressed on it The next phase of the subject is one in to that of the original sounds-i.e., there will due to vibrations of the air, alter with the which the displacement or movement ofbe considerable distortion.Now, a micro- frequency, the relationship between these the diaphragm from its central position,phone diaphragm will exhibit this effect if two quantities being in the form of a for varying intensities of the sound, will be the movement of its diaphragm is too large, resonance or selectivity curve. contemplated.If the diaphragm is trulyand therefore arrangements must be made so that this does not occur. Simple Musical Sounds. elastic, the displacement will be propor- tional to the- impressed force for small Four Causes of Distortion. Thus,ifa musical scaleof uniform movements.For large movements this is intensity is played on a violoncello, the no longer true, and the law of linearity It has been shown hitherto that -a circular microphone currents corresponding to the is violated. diaphragm, rigidly clamped at its circum- various notes will have different magni- ference, causes distortion for the following tudes. Considering,therefore,a steady We can assume for the sake of example cardinalreasons :(1)Therelationship musical sound, which consists of numerous that the relationship between force and between amplitude and frequency of vibra- simple harmonic or sine wave vibrations of displacement is represented by a parabolic tion for impressed forces, due to the.motion unequal amplitudes, if the relative intensi- curve or square law, i.e., the displacement of the air in front of the diaphragm, the ties of these vibrations are altered, due to the increases more rapidlythantheforce forces all having the same strength, is in the resonance or selectivity characteristic of the causing it, and if the force is doubled the form of a resonance or selectivity curve, microphone diaphragm, distortion of the displacement is quadrupled.Under such whereas for zero distortion the relationship original sounds will ensue.Assuming the circumstances we will endeavour to describe ought to be a horizontal line.' '(2) The effect fundamental frequency of the diaphragm what hapPens when the system (a circular of a sudden or impulsive sound into set the to be 1;000 periods per second, the micro - diaphragm in this case) is subjected to.diaphragm vibrating at its natural frequency phonic currents Aose frequencies are in impressed vibratory forces due to the motion and this is always accompanied by a series excess or in default of this figure will suffer of the air in front of the diaphragm. of overtones.These overtones constitute reduction in amplitude. what is known as an enharmonic series, Now, in speech the frequency ranges Original Tones Destroyed. since their frequency relationships to the from 100- to 5,000and the major portion A system of this nature is said to befundamental or natural vibration are not in of the energy is conveyed by frequencies asymmetric or unsymmetrical. If a steady,the ratios of 2, 3, 4, etc.(3), The damping less than 1,000 ; but the essential charac- pure tone-devoid of upper partials-is or rate at which the natural vibration decays teristicswhich determineinterpretation impressed on the system, the resultingwhen the diaphragm is oscillating freely- are carried by frequencies greater than 1,060. vibrationofthe diaphragm contains a i.e.,at the termination of a sound, is It ,folloWs, therefore, that a system Which family of overtones, and a fundamental different from that of the sound.(4) For robs speech of a portion of its energy and of whose pitch Is slightly different from thatlarge amplitudes of vibration a single pure itsinterpretationalqualitiescausesdis- of the -pure tone.An interesting case istone is transformed into a different tone tortion. Hitherto, we have dealt with that of two pure tones impressed upon awith its family of overtones, and a multi- sounds whose electricalequivalentisa system which is aSymmetric-i.e., of theplicity of pure tones such as make up a steady alternating current, but in speech above nature.If. the tones are of sufficient steady musical sound, yield combination and music there is another important con- intensity there are created combinationtones and tones of double frequency. dition with which we are concerned, namely, the transient state.This state is obtained at the initiation or termination of a spoken or musical sound, and varies in degree according to the particular characteristics of the sound and the person or instrument from which it is emitted. Effect of Forced Vibrations. One of the most common examples is a note struck on the piano ;it commences very quickly and dies away quietly. When any vibratory system receives an impulse, it oscillates in its own natural way, and thus, at the initiation of a sound, the micro- phone diaphragm superposes on the original sound its own natural frequencies.This yieldsthe well-known forced and free vibrations. The forced vibrations are those in which the diaphragm follows the motion of the air in front of it, and the free vibrations, are those due to the impulse or shock, and have A handsome two -valvesetconstructedby Mr. C. W, Sharp, 22, Princes Road, Wishech, Cambs. Poputo; .Tr2!,/,19;3..

conclusively with tile atomic theory, and the main details of the electron theory as applied to electro-magnetic forces and EASILY MADE BOXES FOR wireless in general.The book is crowded with illustrations, both photographic and MOUNTING PANELS diagrammatic, there being hardly a page Quite an original note is struck in this article, but the resultant on which some useful figure does not appear. appearanceofpanelsmounted upon suchboxesisvery Containing only seven chapters, the last pleasing three being devoted to the production of electric waves from the practical side of wireless telephony, both transmission and reception,itis indeed amazing that so FIGURE 1 shows how a variable grid be finished by staining and polishing, or much explanatory detail has been crowded leak was mounted, andthe con- it will look very well if given two coats of into so few pages.Dr. Fleming has filled struction of such a box is very simple. shellac varnish. a long -felt gap in the literature of wireless,' Narrow plain wood photo -frame moulding If ebonite isused for the panel and every earnest radio student would be of a section as shown in Fig. 2 can be pur-it will no doubt project -slightly above the well advised to make a thorough study of chased quite cheaply, and a length of this rebate, and it adds to the appearance if the this most excellent work. will make several small boxes. The first thing is to make a frame of the moulding, as in Fig. 3, of such a size that the rebate opening just takes the ebonite CUTTING -OUT VALVES panel to be mounted. A Great Adyantage TO wireless amateurs who have three, The making of the frame should not four,or more, valve wirelesssets, present any difficulties-the corners are it is often Only necessary, and some- mitred, which can be easily done by using a times preferable, to be able- to listen -in block of wood in which a saw cut has been on a less number of valves.This can be made at an angle of forty-five degrees, as a guide for the saw when cutting the moulding. edges of the ebonite have a slight bevel ;this FROM PLATE Of aio MLYE The corners are then glued or seccotined and can be easily done by drawing (not cutting) AFTER RASS/NG THROUGH a knife edge along it. REACTANCE COIL AND the four pieces put in a cramp-made of FROM PLATE OF PR/AMIRT F/RT L. four pieces of wood and a length of cord One great advantage of mounting a 3. VALVE AFTER TRAmsrag5meR PA.55/NG THROUGH (see Fig. 4)-until the glue has set. panel in this way is that it can be lifted out PR/mARY 2m, L.E of the rebate if necessary to get at the TRANSFORMER underside, without the trouble of undoing screws as when mounted in the usual way. Another Method FROM PzAre- OF ,4 MALYE As an alternative to using the mitred I joint for the corners of the frame, they can be butted by cutting the moulding square ELTON/TE PANEL TO HT 17.4 and removing the rebate, as shown by dotted a line in Fig. 5, at each end of two of the side effected without the necessity of switches pieces. or plugs and jacks at very little cost in the following simple manner, referring to the

above diagram : Terminals A areusual telephone ter- BOOKS, CATALOGUES, minals ; B and C are extra terminals for ETC. cutting out unnecessary valves.For two valvestheleadsfrom highresistance When taken out of the cramp the corners telephones are placed in terminals C.For can be further secured by four thin wire Q GUITERMAN & CO. have just intro- three valves the leads from high resistance nails ;when knocking these nails in, keep duced a new type of hydrometer, telephones are placed in terminals B, but the frame flat on the table with the oppositean instrument essentially for those wireless terminals C must then be strapped across. side resting against something solid. enthusiasts who wish to keep their accu- For four valves the leads from high Pieces of thin wood (fretwood or f -in. mulators in good condition. The instrument resistance telephones are placed in terminals three-ply being very suitable) of the proper iasimple to use, and cannot be broken A, and both sets of terminals B and C must length and depth can now be screwed by owing to the stout carton in which itis then be strapped across.Filaments of means of 1 -in. screws to the outside of thepacked, hence the name " Break Not."By valves not in use are switched out by frame as shown in Fig. 1.For the bottom using one of these hydrometers one can means of the rheostats. a piece of 1 -in. or 1 -in. wood, of the same tell at a glance the state of the accumulators. size as the outside of the frame, can be fixed by small screws. * * * " Electrons, Electric Waves, and Wireless Telephony,"byJ.A.Fleming,M.A., D.Sc.,F.R.S. (The Wireless Press, Ltd., 7s. 6. net). A very interesting and useful little book has been brought out by Dr. J. A. Fleming, in which he amplifies upon the subjects dealtwithinhiscourseof Christmas lectures which he gave at the Royal In- stitution of Great Britain during December, Should the sides project beyond the ends 1921,to January,1922.Ittakes the they can be made flush, and neatly finished reader through the whole theory of wave with a rasp. production, and is written in such a way It will be found that although the sidesas to make it equally interesting both to of the box are only made of thin wood, thebeginnerandthemore advanced Wireless in a nutshell. Mr. A. Watson, 168, the frame top and the bottom make it a student of wireless.Leaving the subject Burbage Road, Dulwich, S.E., claims to receive, signalsupon this miniature set with as great very strong and serviceable box, and it canof waves, the book deals concisely and strength as on a crystal set of more orthodox size:. Pepeler WirelessVeekly, Jame 2nd, 1923. AN EASILY CONSTRUCTED CRYSTAL SET. This article describes the construction of a complete crystal set suitable for broadcast reception.The methods of dealing with those parts, such as the contact slider, etc., which are invariably purchased, is both ingenious and simple. By A. W. DR ANSFIELD.

" set " about to be describedis with various parts of the crystal to select The coil should be mounted at one end, to THEfor the benefit of the absolutebe- the sensitive spot.The holder for the allow room for the detector. A method has ginner, and it will work quite wellcrystal is usually in the form of a cup, the to be now arranged that will allow selection and at the same time is so simple to con- bottom having a belt that goes through of the coil at any turn desired for tuning. struct that the veriest amateur need havethe base to hold it down, and this may be no fear that it will be labour lost. made from a piece of thin tubing, such as Additional Insulation A receiving set consists of tuning coil, an old piece of cycle pump tuing.If There are several ways of accomplishing detector, aerial and earth, and a pair of soldering presents difficulties, cut out a star - this, but perhaps the easiest way will be to telephones.That is the simplest form ofshaped piece of thin sheet brass and make cut a strip of fairly thick sheet brass that receiver, but there are several little extrasa hole in the centre to take the " holding will reach from end to end as shown.If this that may also be added that will assist in down " bolt ;then turn up all the points to presents any difficulty, use two pieces of giving better results.However, the' first brass wire and form a slider out ofthin step will be to make the simplest set and sheet brass (Fig. 2).If itis possible to add to it later. solder an old plungerfrom an electric The tuning coil will be the first thing to lamp holder it will make a goodslider, construct.Procure a piece of cardboard but the springy brass slider will do.The tube 4in. or 5 in. diameter and 6 in. long. copper wire on the coil must be scraped This should be of fair thickness, as the wire clean of all insulation at the point where has to be wound on it, and consequently the slider engages, so that good contact is there will always be a slight pressure on it. made. It is now only necessary to add the termi- Winding the Coil nals and connect up, and the method of Dry this tube, and then shellac varnish doing this is shown in the diagram (Fig. 2). it, inside and out.It may be well waxed Fig. 2. A good plan when mounting the terminals instead, with paraffin wax ; but if treated in make a setting for the crystal (Fig 1).Before is to drill the holes slightly larger than the this manner the whole coil should be warmed mounting the crystal, put the bolt throughthickness of the terminal, then wax a strip in front of the fire and then wiped offthe hole, then press the point on to theof paper the width of the thickness of the smooth with a piece of rag.Drill or piercecrystal until it is firmly held in its mounting. base -board, and before passing the terminals a small hole about in. from each end ;The selector portion may be made in the through, wrap a little of the paper round the these holes are for the ends of the wire --the " cat's -whisker " form, which consists of a terminal.Then place a well -waxed card- commencement and the finish.The wire piece of thin springy brass, German silver, board washer -on the top and on the under- required will . be 20 gauge for the 5 in. or copper wire twisted into a spiral with neath side. diameter, and 22 -gauge if the smaller tube a loop als one end, to is used. it is as well here to mention, for the screw it down with, guidance of the amateur, that the higherand a point at the the number of the gauge, the thinner the other end to rest on wire will be. Hence 22 or 24 gauge would be the crystal. These two fittings thinner wire than 20 gauge. Commence would be better mounted on a small strip of ebonite ; dry wood will do, but is not so good. The inductance when ready for finishing off should be attended to.Cut two pieces of wood 4-in. thick to shape shown, nailing a strip of wood Fig. 1. on the inside of these winding the wire on the tube by passingtwo ends to take the it through one of the holes, leaving about coil, which will be held 2 in. over to be used for connecting purposes in its place when later on. Then wind along the tube, keeping mounted on the base- the wire close and uniform until the other board.The base- hole is reached. board is a piece of a in. or / in. wood, 10 Construction of the Detector in. by 6 in.Fasten Cut the wire off the reel. and pass the end the ends in the coil by thrOugh the last hole, plugging it with a means of a small screw piece of matchstick. If the tube wasat each end, then shellacked, shellac it again, as this will hold stand it on the base- the wire tightly to the tube. If the tube wasboard and mark the waxed, well warm it again, and the wire will position. settle down and adhere to the wax. Drill a hole at each The detector is rather an important pieceof the marks, so that of the apparatus. It consists of a cup or fixing screws passed up to hold the crystal, and an arrangement to through the underside engage it with a point that will be allowed of the base -board will The interior of the Levallois-Perret Station from, which the Radiola concerts to move about so that -contact may be made screw into both ends. are broadcast, 191 Popular Wireless Weekly, June 2nd, 1923.

Bromwich,St.Inglebert,LeBourget, Brussels,Rotterdam,Amsterdam, and occasionally Konigswusterhausen, all these stations in connection with the aeroplane AN IMPROVISED WINDER. overseas service, and from 2 o'clock (French By T. MURRAY, A.M.I.Mech.E. time) till 3 o'clock there is generally an ex- -, ceedingly good concert from Paris ; and then from 3 o'clock tillabout 5.30 p.m. an excellent concert from The Hague ;and at THE two supports, S, together with the One end of the transformer wire is then6.20 we have still another concert from bottom piece, B, which are secured secured to the former and led over theParis, and at 8.30, of course, the usual together by means of wood screws, jockey pulley, the reel of wire either being B.B.C. concert; and then again, at 8.45 were made of hard wood i in. thick, two held in the hand, or on a mall spindle, with(French time), another concert from Paris pieces of brass tubing being used for the just sufficient pressure to keep the wireuntil about 11 o'clock.Surely this should spindle bushes, these latter beinggiven taut. satisfy the most enthusiastic listener -in. a coat of shellac on the outside before being The details can, of course, be modified to I do not, for one moment, wish you to driven into the supportEi. The spindle, suit various parts that one may have bythink that I do not appreciate the B.B.C. either of hardwood, brass or steel, must, of them, also, the bottom piece, B, made toconcerts, but at the same time, being a resident within about ten, miles of 2 L 0, it is a pleasure sometimes not always to have to listen to them or receive their interrup- tion, and I should very much like to see, as far as 2 L 0 are concerned, for every night of the week at least half an hour interval, say from 8.30 to 9, in order that those who arecapableofreceivingotherstations should have the opportunity of doing so; and I hope that this remark may come before, the eyes of the people interested for their consideration. Yours truly, - London, W. W. PRATT.

The Editor, POPULAR WIRELESS. RADIO SOCIETIES. Dear Sir,-In view of the impending issue of the new form of wireless licence, making it possible for amateurs and experimenters throughout the country, without previous knowledge, to make up their own wireless receiving sets -from parts and accessories, may I draw your readers' attention to the advantages gained, particularly by those who have at present little or no wireless knowledge, by joining one of the many radio societies in London and the provinces ? The Radio Society of Great Britain has affiliated to it now upwards of some 250 such radio societies throughout the country. Practically all these radio societies are giving weekly or monthly lectures to their members, Scale of Arrangement- Half Size and those of your readers just commencing Details - Full Size. this interesting new science would do well ag,Ada.. to get in touch with their local society. 9(2.4/ If for no other reason, it is of the utmost importance that those making up their own course, be a tight fit in the ebonite or fibre suit the particular sewing -machine that thesets should- be educated in how -they may former ; but, if found to be too slack, a strip arrangement is to be fitted to.The same make such sets and use them without risk of glasspaper pasted around it will hold the idea can be used for winding telephone ear-of interference to their neighbours by re - former tight and prevent slipping. piece bobbins, bell and buzzer bobbins, etc. radiation from their aerials.The Radio The pulley used was found in the scrap - Society of Great Britain has, since broad - box, the bore being altered to suit, and Casting commenced, formed a new class of pinned to the spindle; the washer, W, is members known as associates.No previous also pinned to prevent lateraL movement CORRESPONDENCE. knowledge of wireless is necessary to join of the spindle between the supports.The this class, the subscription is a nominal grooved jockey pulley, aboutin. diameter, one of 5s., and there is no entrance fee. is mounted on ain. diameter spindle, and The Editor, POPULAR WIRELESS. Special elementary lectures are arranged is free to rotate and also to slide along the Dear Sir,-I was very interested to readeach month for associates. spindle. the communication from your correspon- If any of your readers are in doubt as to dent in your issue of May 5th last, butthe nearest radio society in their district, A Useful Accessory. cannot help expressing my surprise when he I shall be pleased to give them the neces- When assembled, itis screwed to the asks the question: " Why Sunday is suchsary information if they will kindly enclose base of the sewing -machine, as shown in an ' empty day ' for ' listeners -in ' ?" stamped addressed envelope ;or to those Figs. 1 and 2, care being taken to line up In my opinion, Sunday is one of the mostwho desire to join the Radio Society of the large pulley with the belt pulley on the interesting days which I have on my radio Great Britain, application forms and full machine, and a short piece ofin. diameter set, and I can, practically from 10 o'clockparticulars of the different grades of mem- belting used for driving purposes. The in the morning till 11 o'clock at night, in- bership will be sent. stitching mechanism is put out of gear by terest myself and friends the whole of this Yours faithfully, the means provided and the handwheel used time.Surely one does not want to hear L. McMimAxL, Hon. Sec. in the Same manner as when filling the thread anything more interesting than Croydon, 32, Quex Road, spools. Lympne,Fulham, Manchester, Castle West Hampstead, London, N.W.6. Popular Wireless Weekly, June 2nd, 1923: 595

Users of valve receiving sets will do well to realizethat the efficiency of their outfitis largely dependent upon their choice of valves.It's the valve that counts ! You will positively ensure the best reception of vocal and musical items by using

1WRC919 osRAmvAiYfES

Made with the same scrupulous care that has always character- ised the manufacturing operations of the famous Osram factory. MADE TO LAST. Sold by leading Electrical Contractors, Wireless Dealers and Stores. (Wholesale only) The General Electric Co., Ltd., Magnet House, Kingsway, London, W.C. 2. Branches throughouttheUnited Kingdom and inallthe principal markets of theWorld. Popular Wireless Weekly, June 2nd, 1923 596

BROADCASTING TRANSMISSIONS.

GREATBRITAIN. Wave -length Hours of Items Transmitted. Remarks. Station. Call Sign. Transmission. in Metres. London 2 L 0 11.30-12.30 (B.S.T.) Music . 369 ..Every week day. tt 5 p.m. ... Women's " Hour" IP ft 5.30-6.15 p.m. ..Children's Stories If PP ft 7 and 9.45 p.m. ..News... tt vl ft ft 8-10.30 p.m. Music and various ft 8.30-10.30 p.m. ..News and music Sundays. Newcastle 5 . 11.30-12.30 p.m...Music .. 400 Every week day. Usually 5.0-10 p.m. Music, News, etc. PI f Sundays, 8.30-10 p.m... Music and News Manchester 2ZY 11.30-12.30.. Music .. '385 Every week day. It . Usually 5.0-10 p.m. Music, News, etc. to If .6 . 8.30-10 p.m..,. Music and News.. Sundays. 425 Every week day. Birmingham .. 5IT 11.30-12.30 . Music .. t Usually 5.30-10 p.m.Music, News, etc. 8.30-10 p.m... Music and News:. Sundays. Glasgow 5 'g C . Usually 5-10 p.m. Music, News, etc. 415 Every week day. , . 8.30-10 p.m... Music Sundays. Cardiff.. 5 iN A 11.30-12.30 Music .. 353 Every week day. Usually 5.0-10 p.m. Music, News, etc. /I PP Sundays. . 8.30-10 p.m... Music and News Croydon .G E D .Throughout day..Aeroplane Traffic 000

BELGIUM

Brussels (1) . ... Brussels 12 noon (G.M.T.) Weather report ...1100 ..Working days. 4.50 p.m.... Aeroplane traffic _ 1100...When necessary 6 p.m. - Concert ... 1300..Sunday, Tuesday '' andThursday. HOLLAND

The Hague... PCGG 3-5 p.m. (G.M.T.) Concert 1050 Sunday. 8.40-9.40 p.m. ...Concert 1050 'Monday & Thursday The Hague .. PCUU 7.45-10 p.m..,. Concert 1050 .Tuesday. (Laboratorium Heussen) 9.40-10.40 a.m. .. 1050 'Sunday. The Hague (Velthuyzen) PCKK 8.40-11.40 p.m. ... Various 1050 'Friday. Ymuiden (Middelraad) PCMM 8.40-11.40 p.m. ..Concert .. 1050 Saturday. Amsterdam ... P A 5 8.10-11.10 p.m. ..Concert and News 1050 Wednesday.

FRANCE

Levallois-Perret (Radiola) SFR 2-3 p.m. (B.S.T.) Music.. .. 1780 Sunday. 5 p.m. .. Stock Exchange News ... 1780 Every day.

5.15-6.15 p.m. Instrumental music .. 1780 ,

8.45 p.m. .. General News.. 1780 f 9-10.30 p.m. .. Vocal and instrumental concert 1780 Paris (2) (Eiffel Tower) F L 6.40 a.m..... Weather Forecast 2600 11.15 a.m. .. Weather Forecast.. .2600 PP 3.30 p.m. .. Stock Exchange News .e 2000 PP 6.20 p.m... Weather Forecast, Concert .. 2600

10.10 p.m. .. Weather Forecast.. 2600.. Ecole Superieure des P.T.T. 7.45-10 p.m. Radio Concerts .. 450 Tuesday, Thursday, Radio -Riviera (Nice) 2.30-7.30 p.m. Radio Conferences 450f Saturday. 11 a.m. News, Concert, tzigane 460..Every day.

5-6 p.m... News, instrumental Concert.. 460 9-10 p.m. .. Latest News, Concert. .. 460..

GERMANY, CZECHO-SLOVAKIA, AND SWITZERLAND Berlin.. L P 6-7 (G.M.T.) Financial News, etc. 2800 Every day. (Konigswusterhausen) 11-12.30 4-5.30 p.m.....Financial News, etc. 2800 If 1800 Prague P R G 711 a.m. and 3 p.m.Weather News, General News.. VI -9-2 p.m. and 9 p.m.Concert .. 4500

Geneva .,. H B 6-7 p.m... ..Concert .. 1200 PP (1) If, at the indicated times, a station has to receive or transmit service communications, the weather transmission will take place after these communications.Tuesday :Operatic selection on the gramophone.Thursday :Various on gramophone.Sundays :Various by artistes. (2) Special concerts given during the evening are announced in the course of the preceding transmissions. See Notes and News page for later details or alterations, if any, to hand. Popular Wireless Weekly, June 2nd, 1923. 597

`TURRET" WIRELESS MASTS AND "True MusiC., AERIAL EQUIPMENT T.M.C. LOUD SPEAKER COMPETITION. as supplied to H.M. KING OF ITALY. Designed by Naval Ex- perts like a ship's mast. THEenormous number of en- Columbian pine, painted 3 coats.500 inuse. No current jump or steel tries we have received for torust. Unbreakable and easy to fix. Rigged by ex -seamen. this competition testifies to the Light,rigidandsent complete, no extras. Fixings for any roof or very great interest the Public are confined space. taking in all matters relating to " TURRET" TWO 27 ft.As Photo. Wireless Broadcasting, andwe 37/6 Complete. 28 ft. "Turret " Super, have much pleasure inannounc- 59 6 36 ft.Complete, ing the names of the successful 79,6 42 ft. With Telescopic competitors : top pole,89;6 56 ft.In 4 sections, FIRST PRIZE:100 GNS. T.M.C. extra guys, and Tele- SUPERB CABINET "DE LUXE." scopic top poles, L6-18.6 W.R.MILNER, SIMPSON & BLYTHE, 8-9, SherwoodStreet, Piccadilly, LONDON, W.1. 4, MEATH ROAD, and most Wireless Stores.'Phone :2650 Gerrard. ILFORD, ESSEX. .11111IMININEnt,

" TrueMusiC." SOLDER OR SORROW WHICH :sit to be? SECOND PRIZE: £30: 0 : 0 T.M.C. 3 -VALVE The Wireless aspirant who issatisfiedinleaving RECEIVING SET WITH LOUD SPEAKER. the connections of his aerials andsetterminalstolook W. GREENWALD, afterthemselvesbyjust 3a, BEECHWOOD ROAD, twistingthemtogetheris asking for trouble. Apart HORNSEY, N.8. from the untidy appearance, careless connections are going whose entry was thefirstsubmitting the word to lower the efficiency of the finestreceivingsetinthe world. SOLDERING will make doubly sure of them, and, incidentally, " TruMusiC." FLUXITE will make sure of the soldering.Soldering ischild's play when you've a tin of FLUXITE at hand to help you, or, better still, a complete Soldering Set that we have had specially prepared for the con- venience of customers.Ask your Ironmonger or Hardware Dealer to " True -Music" aptly describes all show you the neat little we claim for ourLoud Speaker. 11F`X.411:TME1OIrIE Every note of music reproduced SOLDERING SET Reduced Itisperfectly simple to use, and Price from the Broadcasting Stations will last for years in constant use. It contains a special " small -space 716 rings true, and really is music. Solderingiron,with non -heating metal handle, a Pocket Blowlamp, FLUXITE, Solder,etc., and full WRITE FOR FULL PARTICULARS. instructions.Price 7/6 sample Set, post paid, United Kingdom. THE FLUXITE TELEPHONE MANUFACTURING Co.,Ltd. SIMPLIFIES SOLDERING London Showrooms: 69, Newman St.. W.I. Telephone: Museum 5581 All Hardware and Ironmongery Stores sell FLUXITE in tins, price 8d., 1,4, & 2,11. Felcne cool -kitof your car or HOLLINGSWORTH WORKS, WEST DULWICH, S.E.21 Buy a Tin To -day. motor -cycle,orany soldering lobs about the home. E.P.S. 82. FLUXITE LTD.. 324 Bevinaon St., Bermondsey, En4land. Popular Wireless Weekly, June 2nd, 1923. No Boundary in the Ether World

Radio Signals travel at the rate of 186.000 miles a second. to users of Naturally, signals got weaker the farther they travel: Ifa signal istoo feeble do operate the .Del eeter Valve,It could never be heard, no matter how many stages of amplification were used after rectification. Rot the LISSEN REACTANCE (P. PATENT)METHOD BUILDS UPWAVEENERGYbefore passing it on to the Detector Valve, and so makes easily heard signals that would otherwise be in - LISSEN .audible. Use the LOSSES REACTANCE (P. PATENT) Method of H.F. amplification, and so build with your own hands a receiver that shall be capable of spanning great. distances. Reactance LISSEN REGENERATIVE -REACTANCE PRICE (P. PATENT). Complete_ Makesareceiversosensitivethatunder many conditions bothaerialand cai ih (P. Patent). connections may be dispensed with. Provides fully variable non -radiating reaction in highly efileicnt form. Self -tuned; but (lie use of a new LISSEN Vernier ConSenser is recommended.(Price £2 .12.6 12/6, barely 1in. diameter.) Blue print and LOSSES one -hole ilxing-fitted in a few minutes. instructions One knob controls tuning and reaction. sent with each. Still Range, 150 to 4,000 metres-WITS! RECENERATION OVER THE WHOLE RANGE. AMATEURS-Counterfeits may be offered you.Take no sub- DEALERS-Order throughfactor, stitute.If your dealerisnot equipped toserve yen, send send direct.Apply on trade head, to be direct to factory, post free. for list. used LISSEN REACTANCE (prov. Pat.) LISSEN COMPANY Range 150 to 600 metres(6 tap- pings) complete 2716 8-16, Woodger Rd., Coldhawk Range 150 to 10,000 metros (11 tappings)complete - 32/6 Woe print shows easy connections. Shepherd's Bush, London, W.12. Lissen one -hole fining. To be used for one or two stages H.F. (livesgreatamplificatonevenonloud 'PHONE 1072 HAMMERSMITH. signals.For great range and power turn 14.".1 6c1. to using LISSEN REACTANCE. N.B.-Woodger Road is close to Goldhawk Road Met. Rly. Station. LissenApparatus : Well thought out-then well made.

ACCUMULATORS SPECIAL OFFER AT REDUCED PRICES Post Free Orders Popular Type. Clear Celluloid Cases. Volt-Ignition A. A.II. Price age. Amps. Cap - Erin ALL HEADPHONES 1 4 71 8 9 11 1310 4 20 10 12 11 ; 16 Double Receivers, FEDERAL, 4,000 ohms ....23'6 131' 4 ' 30 15 1411) WIRELESS 1320 4 40 20 ERICSSON B.B.C., 4,000 ohms21/- 1330 4 60 30 22AI 2/3 ACCES- .. ., BRUNET (French) 22,6 1340 4 80 40 29'-

E P R FELLOWS B.B.C. 1420 6 40 20 27/6 t 2/8 SORIES ,, SIDPE (French) 19,'6 ACCUMULATORS 1430 6 60 30 3391 1440 80 40 39 6 STERLING B.B.C. 32'- cite KEPT 1450 6 I Single Receivers, BRUNET (French), 2,000 ohms10/6 20 YEARS' 100 50 45 6

BRUNET (French), 4,000 ohms12'6 REPUTATION IN T.S.F. (French), 4,000 ohms .. 10i- RICHFORD & Co., Of 1'I IL ftir,lIllthe' STOCK. FELLOWS B.B.C., 2,000 ohms15:6 pi,mi,s(lay and 153,FLEET ST., LONDON, E.C.4. night . Telephone ::Holborn 5120. listab. 1876.

ACCESSORIES Finest Quality L.F. Transformers (5 I Guar- SECURE anteed) 12/6 Swi tell Arms (Best quality) 1/- Perfect Tone Reception Filament Resistances (rst Quality) .. 2/6 By using Rotax Accumulators, 4v. 4o amps.). not sent 16/- 6v. 4o amps./ by post k 25/- Ebonite Dials, o -18o, bored in centre.. 1/- " IGRANIC" Valve Holders, 1st Quality .. 11 - GIMBAL TUNING SYSTEM. (Patent Applied for) Gimbolder Tuning Stand (Palen! appli:d for) FOWLER & BRIGDEN Write for Leaflet Z 58 130, EUSTON ROAD, LONDON, N.W.I. 147, Queen Victoria Street, Tel.: ------Museum 4827 LONDON. GRANIC Works :Elstow Road, ELECTRIC Co_ Ltd. BEDFORD. Popular Wireless Weekly, June 2nd,1923. :T,99

SOME MORE PRACTICALIDEAS.

last stud on each row of contact studs, COIL WINDER. use two studs which stand about * in. above the others, and file about two-thirds A SIMPLE LIGHTNING THIS coilwinder may be made out of the head down as per sketch. This will ARRESTER. of a few odds and ends.The cone leave an upright edge for the switch arm ends may be made from two wooden to engage with, and so act as a stop. barrel -bungs. The spindles are made from The same idea can be utilised where simple QUITE a good lightning arrester can be two pieces of-'in.iron wire, flattened on -and -off switches are in use. These.switches made from old half -watt electric globes. out and driven into the centre of the bungs. can be purchased very cheaply, and when The glass globe A, Fig. 1, is first removed, The handle end, of course, hasa threadthe wood base is removed, can be fixed care being taken not to leave any glass in direct on to the panel, using two ordinary the collar, A, or a nasty cut may result. studs for contacts filed down as above. The glass rod B and filament supports Bl SERRATIONS TO and B2 are next taken out, leaving the MAKE TUBE GRIP. SPIRAL SPRING TO KEEP TENSION UPRIGHT EXTENSION filament leads, C, Fig.2, and glass tube, Cl. HANDLES.

EVERYONE who has had any experience at all with valve receiving sets knows something about the capacity effect set up by the hand when placed upon the WIRE IN FORM adjusting knob of a tuning condenser, and OF STAPLE. will readily appreciate a device that will obviate most of this. By the introduction of an upright extension handle fitted to an to fasten the crank on. The crank is made out of a piece of sheet brass 2 in. long, with a hole at each end ; one hole should be4in., the other only large enough to rivet the intended handle in. The wood uprights are 4 in. long, 1in. wide, andiri. thick ; the base -board is 1 ft. long, 21 in. wide, and 1 in. thick.The base- board is slotted to take the uprights, and Two copper or brass plates, Dl and D2, it will be seen that the slot is extended about half inch square, are soldered to at one end to accommodate varying lengths the filament leads as in Fig.2 .The filament of tube ;the taper also allows of differ- leads are now' bent as shown- in Fig. 3, so ent diameter tubes being wound.The that the plates Dl and D2 are parallel. The plugs should have small serrations scratched distance between the plates can be altered lengthwise to make the tubes grip.The by bending the leads C. The arrester is now dotted lines show a tube in position ready completeand only requiresfixinginto for winding. The spindles should fit fairly a holder. This is an ordinary electric lamp tight in their holes, so that there will be holder which -can be screwed on to a panel or no slip when winding.The dimensions baseboard. may easily be altered to suit the particular coil to be wound, or it is very easy to have cones on spindles interchangeable so that they may be placed in the uprights at will. NOVEL SPIDER COIL It will be noticed ,that a spiral spring is placed between the handle -end bung and FORMERS. the upright ;this will keep a tension and keep the tube central. adjustable portion of a valve set the caphcity TAKE apieceof round, hard wood effect is practically nil, giving the advantage (Fig. 1), cut according to size of coil. SWITCH ARM STOPS. of permitting much finer tuning, thus adding Space round the wood to the amount greatly to the efficiency of the set. of spokes required, and then bore a * in. The extension handles shown inthe hole at each space. Take some cycle spoke TO avoid the expense and trouble of diagrams hardly need any explanation, and nipples and drive one in each hole.To fitting stops to switch arms, and also the making of them is simplicity. itself.I drillingthe necessary holes in thehave draWn two diagrams which show at a panel, the following tipwillbefound glance how they are constructed. In Fig. 1 efficient,especially where a numberof the handle is fitted to a condenser, whereas switch arms are in use.For the first andFig. 2 shows the handle in sections. All that is required to make one handle is ORDINARY a piece of ebonite tube, 5 in. long by * in. 'ON' & 'OW SWITCH sivirep in diameter with A- in. bore, also 1 in. of ARM No. 2 B.A. screwed rod. Thread both ends STUD FILE!) DOWN 517.106 of the tube with a 2 B.A. tap, the latter can RIZEDDOWN be made by filing to a taper a piece of No. '2 prevent damaging the tapered hole in the flu'-a. B.A. screwed rod, then unscrew knob from nipple, a piece of metal (Fig. 2) with , art the condenser, and fit it to one end -of the in. drill will overcome the- difficulty. When / AZY ASV kV ebonite tube by means of the 1 in. of screwed all the nipples have been driven in, screw Awn, roc,ran1e2xt fitting the rod as -shown in Figs. the spokes into the nipples and the formei is 1 and ready for use. Popular Wireless Weekly, June 2nd, 1923. 600 It was decided that the society should accept the offer of the directors and hold their future meetings and demonstrations in the Central WIRELESS CLUB REPORTS. Liberal Club.The conditions for reception of The Editor will be pleased to publish concise reports of meetings of Wireless clubsand radio concerts, etc., are distinctly more favour. associations, reserving the right to curtail the report if necessary.Hon. secretaries are able than at their present rooms in Church Reports sent Street. reminded that reports should be sent in as soon after a meeting as possible. The members also decided to hold several field in cannot appear in this paper in less than ten days after receipt of same.An Asterisk days during the summer. denotes affiliation with the Radio Society of Great Britain. Hon. sec., F. Gomersall, 1, Ashworth Terrace, Dewsbury. SwanseaandDistrictRadio Experimental Leyton and District Wireless Club. Society.* A very successful meeting of the above was At a large gatheringof members of the held at headquarters on Monday, May 7th, Swansea Radio Society recently held at their when, after the usual Morse, etc., classes, a very headquarters, the Y.M.C.A., a lecture was given interesting lecture and demonstration was given by MrMcNamara,entitled" Elementary by one of the members, Mr. P. J. Slade, on WIRELESS - Principles of Wave Motions," Mr. A. T. Sage valves. presiding. At the close of the lecture, the chairman, Mr. IN SUMMERTIME The lecturer compared in a simple manner W. Bassett, very successfully operated his three - the differences between waves in water, air, valve set. COMPETITION. and ether, which was eagerly followed by, those Meetings are held fortnightly, and the secre- present. tary will be glad to hear froni any interested The chief aim of the lecturer was to cater for persons. (A selection from the hundreds of postcards the non -technical man, and the lecture proved Hon. sec., W. G. Peacocke, 73, Frith Road, to be of exceptional interest to the experi- Leytonstone, E. 11. sent in by competitors in the " Summertime " menter. competition.The result and the name of the A further series of elementary lectures will " Wireless Review and Science prizewinner will appear very shortly.) he given at a future date, and all beginners in wireless theory are cordially invited to attend. Weekly." In our new companion journalwillbe Hon. sec., H. Morgan, Esq.,218, Oxford found full details for a MAO award in cash MR. W.J. DAVIES, of 86, Corporation Street, Swansea. prizes for readers. Street, Stafford : £600 is offered for In invention, and £500 " To keep up a steady interest during Walthamstovi Amateur Radio Society.* for an Ideal BroadcastingProgramme. On Thursday, April 26th, a large audience Someof the greatestliving writers con- the summer months, I suggest the issue gathered to witness a wireless demonstration tribute tb WIRELESS REVIEW AND of a' supplementary' licence to prevent held at the Hut, Church Hill.Mr. A. Kruse, SCIENCE WEEKLY-Senatore Marconi,Sir licence: holders allowing them to use their 51.111., was in the chair.The demonstration Oliver Lodge, Dr.J.A.Fleming, Professor J. A.Thomson,Dr. Lee de Forest-to sets portably. The wireless man could then was held for the purpose of providing funds for mention only a few names. theY.M.C.A.,inwhose grounds the Hut The fascination of popular science is also take his set out in his motor -car, side -car, stands, and was given by, the Radio Association clearly demonstrated in the science articles etc., or even carry it. What would be more in co-operation with the Walthamstow Amateur appearing in this new journalevery Week. enjoyable to the town -dwelling wireless Radio Society.Prof. A. M. Low, D.Sc., de- " Making the Cinema Talk "is the theme enthusiast than to take his set into rural monstrated his audiometer, and many. of the round which Dr. Lee de Forest has written, audience had the pleasure of seeing their voice in along article inNo. 2 of the new journal, surroundings and receive the concerts with andinwhich he describeshisinvention, the aid of an improvised aerial, etc. 1 Even on the screen.Prof. Baker, B.Sc., then told whiohhasatlastmadethe " movies "- the audience how wireless was made possible; vocal. the humblecrystaluser would derive and the theory of the wireless wave.Major pleasure in testing his set under varying Raymond Phillips then showedhiswireless The Radio Society of Highgate.* conditions of distance and surroundings. controlled train, and proved how easy wireless Mr. H. Andrews, B.Sc., continued his series of controlofmechanismwas.Capt.Drury lectures on Friday, May 4th, by giving a lecture The fee for the licence would have to be Coleman addressed the audience, and told how on " C.W. Transmission."He explained that small, say 2s. 6d. to 5s. for three or four the Radio Association was anxious to helpa C.W. heterodyne was really a low -power months (half to G.P.O. and half to B.B.C.). the amateur.Many well-known local amateurs transmitter, ordinary transmitting sets differing Amateur wireless clubs with transmitting -whiSse call -signs are usually to be heard, and therefrom only in the matter of the amount of licences would be able to supply additional in some cases have been picked up at Nice-power dealt with.Receiving valves of the were seen on the platform.The meeting ended' ordinary type may be used, a range of 50 miles " fare " for the members to pick up when with a hearty vote of thanks to the Radio having been accomplished by means of an " R " out with their sets." Association, and the Y.M.C.A. funds will be valve;but in such cases itis necessary to considerablyincreased,the whole of the overrun the filaments, thereby- reducing the life Mae. W. A. COOMBS, of 20, Norfolk Street, proceeds being handed over for that purpose. - of the valves.Various examples of British, Sec.,Mr. R. H. Cook, Y.M.C.A.,Church French, and German transmitting valves were Mile End, E. 1: Hill, Walthamstow, E.17. exhibited, and their characteristic features ex- " With reference to broadcasting during plained.The usual methods of obtaining the the summer, I suggest that programmes TreharrisandDistrictRadioandScientific necessary high voltage direct current supply for should be of a light character, similar to Society. transmitting purposes were described, and the what one would hear at the seaside, such as A radio society has been formed at the above lecturer then went on to describe in what respects place.. The informal meeting was held at Mr. the inductances used differ from those used in good bands and concert parties, chats about Dan Osborne's Studio,PerrottStreet,Tre- receiving sets.Transmitting condensers were the various holiday resorts and tours, etc., harris, who has very kindly given the society also dealt with, it being mentioned that the with news regarding the various sports. the use of his studio as the society's head- capacity of an ordinary variable condenser can " One's imagination could be carried a quarters, which offer was greatly appreeiated. be approximately doubled by immersing it in long way listening -in to a good concert or It was decided to hold two meetings weekly,good quality insulatingoil. Various trans- on Tuesday'and Thursday, at 6.30 p.m.Tues- band whilst lounging on the lawn, or in the mitting circuits were then drawn on the board, day will be devoted to construction of members' special mention being made of the Colpitt back garden during the warm weather." sets and parts ;Thursday will be devoted to Circuit.This circuit hails from America, and lectures and discussion.All intending members in the experience of the lecturer is very efficient, MR.T. A. SCRUBY, of 17, Castleton Road, will be given every assistance and welcome. and easy to adjust. Using an input of 10 watts, E. 17. Hon.Sec.,DavidD.Richards,Mametz an output of 1 amp. in the aerial had been ob- House, Bontnewydd Terrace, Trelewis, Glam. tained.Methods of keying and modulation " Wireless could be made very popular in wore then dealt with, and the lecturer con- Bumpier time if the B.B.C. were to broad- The Southampton and District Radio Society. cluded with a few remarks on the subject of cast some good musical and dance items The first meeting of the Southampton and microphones and speech amplifiers. say from 4 to 7 and 8 to 10.30 p.m. on District Radio Society at the new headquarters, Hon. sec.,J.F. Stanley,B.Sc., A.C.G.I., Y.M.C.A., Ogle Road, was held on Thursday, F.R.A., 49, Cholmeley Park, Highgate, N. 6. Saturdays, so that Sports Clubs could install May 3rd, when, after the business items were a loud speaker set (not an expensive item disposed of, Mr. Bateman gave a very instructive Dewsbury and District Wireless Society. where the membership is 100 or more) and lecture on the interesting topic of dual amplifica- The Dewsbury and District Wireless Society entertainment would thus be available for tion.He dealt with various circuits, and gave recently had a meeting at the Central Liberal musical teas and dancing on the lawn in the his audience the benefit of a description of a Club, Bond Street, Dewsbury.It was their dual amplification circuit which he has devised, first " difficulties " night, and several members twilight. and with which excellent results have been ob- brought up radio troubles for discussion, and " Also, if the weather should turn out tained. He concluded his discourse by a practical an interesting hour or so was spent. A tempo- wet, this suggestion provides a means of demonstration of this circuit in a set of his own rary aerial had been erected, and the prograinme keeping the club pavilion always popular on construction.Mr. Bateman also described the from Manchester, and part of that from London, a wet evening. -Also members waiting construction of a novel form of potentiometer. was afterwards received.The 'receiving sets New members will be welcomed. used were lent by Mr. F. Dransfield (a, three - their turn for a game would find interest in Hon. sec., Mr. P. Sawyer, 55, Waterloo Road, valve home-made set) and Mr, J. T. Foggo wireless. Adaptations of this would naturally Southampton. (Gecophone and two -valve note magnifier). suggest themselves." Popular Wireless Weekly, June 2nd, 1923. 601 Advertisement issued by Peto-Scott Co., Ltd. My home -assembled Set the interesting experiences ofan Amateur's first steps in Wireless

ALWAYS being fond of mechanics-in a crystal set-with the Detector Unit (N.). 4),by- separating . the coils..and .adjusting the mild sort of way-I fell an easy victim alone.Having bought the complete set ofcondensers-to cut out all interference from to the fascination of wireless.After parts for the modest sum of 17s. bd., and near -by stations. reading one or two little books on the sub- followed the directions contained in a six - ject I made up my mind to build up my own page illustrated instruction folder, a couple set.A timely article in a wireless paper of hours' work gave me a complete valve Every Broadcasting Station describing a simple crystal set seemed to unit. There were no holes to drill ;all I heard on this Set me to show just the instrument which hadtodo I was now on .the high road to success. would fill the bill. wastoin- These three units enabled me to pick up sertthe all the broadcasting stations with ease from A Crystal Set parts as London to New- shown. castle,aswell It was simple and consisted of few parts Although as the splendid -a, great advantage to a novice-and could my valve Eiffel Tower con- be constructed for a few shillings.I well now gave certs from Paris. remember the thrill experienced when I me much In due course heard my first telephony on it-the excite- better re- --and as funds ment of other members of the household Lt sults than Ipermitted - I hearing this " music through the air." But had ever addedahigh this set, good though it was, later on began been able frequency ampli- to pall.My interest seemed to wane ;I to obtain fyingunit(at wanted to hear more than the nearest broad- The Detector Unit with my the moderate casting station and the few amateurs in my crystalset, cost of but 13S. neighbourhood.In short,I had tired of I found that my primitive tuning arrange- 6d.) enabling me thiS crystal set and wanted a more ambitious ments had very serious drawbacks, there- to pick up the valve receiver. fore I decided that my next step would be Hague,anda L.F. Unit After looking around I found that to buy to invest in a- proper tuner. low frequency unit which gave me the a ready-made instrument was far beyond necessary strength to use my headphones my means, and constructional articles in the attached to an old gramophone horn as a wireless papers seemed hard to understand A Tuner for all Wavelengths loud speaker. and to require rather more skill in the use An outlay of E,3 9s. 6d., therefore, pro- of tools than I possessed. cured for me all the requisite parts for aBuilding the Set into an old really first-class tuner in two units suitable A Unit Valve Receiver in sets for all wavelengths.The tuner unit itself Bureau is most ingenious. Besides a three -coil You willobservethatIhavesaid of parts holder it had two rotary switches ;one is nothing about cabinets.Although I could There seemed no alternative until by for putting the condenser in series or inhave purchased suitable mahogany ones chance I discovered just the type of receiv- parallel with the primary coil, and the other fromPeto-Scott,Ltd.,foraslittleas lig set I had in mind.It was in units-is for " Stand by " or "Tune."The ad- 3s. 6d. each,. I did not do so ;instead I :hat is to say, it could be made to expand vantages of the former are probably very botight at a local and more valves could be added just as well known to you, but the latter may be as auctionsalea oftenasone'spursepermitted,until new to you as it was to me. fine old bureau eventuallyasuper -sensitivemulti -valve which I am now receiver is converting as a obtained. suitablerecep- Justlikea tacle for all certain ex- these five units. panding Theresultof bookcase, in my efforts,I fact, " al- amconvinced, ways com- will be a three - plete, yet valve set worthy never fin- of any home,and ished." And one which would the greatest havecostme H.F. Unit advantage of probably three times as much had I bought all, perhaps, it ready made.It will certainly be an in- The Condenser Unit was that it Tuner Unit vestment I shall never regret.E. R. G. was supplied in complete sets of parts all ready to as- It operates like this : When the switch is PRICE LIST OF SETS OF semble at home. PARTS at " Stand by " the tuning is done on one a Wepleased are always to The manufacturers and designers of this coil only-the other one for the time being receive from our (Complete for Home Assembling) clever set were the Peto-Scott Co., Ltd., of customers similar is not in use at all.The result is that the interesting ex-No. r Tuner Unit-- - - 27 6 64, High Holborn, London, W.C.1, and tuning is quite " broad " and non -selective. periences. AnyNo. 2 Condenser Unit - - 42 - having found that they issue a little six- photographs of No. 3 H.F. Amplifying Unit 13 6 This has advantages :for instance, if you Pete -Scott UnitsNo. 4 Detector Unit - - 17 6 penny booklet describing the whole system are searching for a station you can find it built into specialNo. 5 L.F. Amplifying Unit 33 6 -as well as giving an interesting descrip- cabinetsorinto so much quicker on a non -selective circuit. articles of furni-Cabinets for r, 3, 4 and 5 - 3 6 tion of the whole principles of wireless-I Also, if you are listening to a couple of tare will be fiberCabinets for No. 2 - - 7 - lost no time in getting a copy and studying ally paid for uponCatalogue of all Radio Com- amateurs talking to one another, you can acceptance. ponents, 32 pp. - - 3d. it. hear them both without having to re -tune Postage gd. per Unit extra, but each time, supposing they are not exactly paid on all Orders of 1:2 or over Making a start with one Valve on the same wavelength. Advertisement issued by: I found that I could make an excellent When the switch is at " Tune " you are PETO-SCOTT CO., LTC., start-using the tuning coils from my old operating two circuits at once and arc able- Featherstone House, 64, High Holborn,w.r.i. 602 Popular Wireless Weekly, June 2nd, 1923.

sense connections hold, the second slider going tc the detector. RADIOTORIAL. S. E. D. (Thorpe Bay).-What is the method used to test a crystal with a buzzer ?What AllEditorial Communications to be addressed The Editor, POPULAR voltage is required for the buzzer, and do you advise any special make ? .WIRELESS, The Fleetway House, Farringdon Street, London, E.C.4.

I hope by now that the majority of POPULAR recent developmentsintheRadioworld, WIRELESS readers have seen a copy of our new some ofthe arrangements and specialities companion paper-" Wireless Review andScience described may bethesubjectofLetters Weekly." It is not often that such excellent value for 3d. is Patent, and the amateur and trader would published :readers have only to glance at the con- be well advised to obtain permission of the tents of the first issue to get an idea of the enormous patentees to use the patents before doing so. cost of production. But" WirelessReview andScienceWeekly " meets a long felt want. POPULAR WIRELESS has laid out foritself a S. I. D. (Ely).-Will you give a diagram of a definite policy-a policy to please a very large public ; double -pole, double -throw switch for connect- KEY on in " Wireless Review and Science Weekly "the aim SWi TEN is to cater more extensively, elaborately and techni- ing the aerial tuning condenser in series or cally for those desirous of taking a deeper interest in parallel with the aerial inductance for short or wireless and popular science.To that end some of long wave reception ? - BATTERY the greatest living scientists and experts have been Raked to contribute, and the result is a publication unique in the history ofBritish journalism.The Popular appeal isnot lacking in the new journal. Many of the articles are of universal interest, and ZI can be easily understood even by the non -technical .511A14. BUL2ER reader ,and the offer of £500 in cash prizes for an idealBroadcasting Programme should prove more COIL than popular.To allreaders who have supported POPULAR WIRELESS I earnestly recommend them to purchase a copy of our companion paper, so that they can see for themselves the excellent value offered for the low price of 3d. weekly. THE EDITOR.

The above diagram of a crystal with buzzer teste will be quite satisfactory.You will notice that the buzzer circuitis only inductively coupled to the crystal circuit and is not connected mechanically. The small coil can be of the spider -wound type, and is made as follows.Wind about twenty turns of No. 28 S.W.G. D.C.C. on a cardboard former one inch Owingtothe enormousnumberofqueries in diameter.A 41 -volt dry battery will be suitable received for the buzzer.Any buzzer will do.An old bell daily from readers of POPULAR snakes a good buzzer as long as it is still in working WIRELESS, I have temporarily decided to limit the number of questions sent in by one reader to order.Remove the gong and saw off the hammer, three.Readers are asked to keep their questions and a useful buzzer results, the note of the buzzer as short and as concise as possible in order that being varied by the adjustable contact screw.For the minimum of delay can be exercised in answer- crystal adjustment a high-pitched note from the ing queries.Until further notice three questions buzzer Is most suitable.To adjust crystal press from me reader will be the limit for one letter. key while moving cat's -whisker until loudest signals All questions should be addressed to POPULAR a'e obtained in 'phones.It does not matter where WIRELESS Queries Department, Room 138, Fleet - AEW t ie slider is placed as long as it makes contact with way House, Farringdon Street, London, E.C.4. the coil. Readers are requestedto send thenecessary Above is a suitable diagram.When the switch postage for reply. Isin left-hand position, the condenser is in series with the A.T.I. and aerial.When in the right-hand G. B. C. (Enfield).-I have some wire the The Editor desires to direct the attention of position the condenser is in. parallel.In the dia- diameters of which are millimetres, .25 milli- gram a honeycomb coil is shown.With an ordinary metres, and .4 millimetres. Which of these wilt his readers to the fact that, as much of the in- slider inductance connect earth stud to end of the formation given in the columns of this paper coil and the top middle terminal of the switch to be most satisfactory for an inductance to tulle is of a technical nature and concerns the most the slider.In the case of a double -slidecoil the (Continued on page 604.) HOW 2 L O's DANCE ITEMS WERE RECEIVED ON THE RIVER. Popular li-lreless- Weekly-, June 2n41, 1923 MARCONI'S LATEST NewPopularMarconiphoneBrings ALL Broadcasting Stationswithin Range A new and improved Two -ValveMarconiphonehasbeen perfected and is now on sale. With it, no matter what part of the country you live in, you can listen -in with perfect results to all the British Broadcasting stations from Glasgow to Cardiff. Price Reduced Owing to the enormous demand created for this instrument, it has been found possibleto economise largely in overhead charges. The public is given the benefit of these economies, and the New Marconiphone V2 is on sale everywhere at

£16 3 6 without accessories-or S2,1 complete

oOne `the Vrtumphof theaCaster THE NEW MARCONIEHONE VS. Ask your local dealer al once about the New Marconiphone V2. All orders are 7i77 dealt with in strict rotation. MARCONI'S WIRELESS TELEGRAPH COMPANY LIMITED Marconiphone Department, Marconi House, Strand, London, W.C. 2

SUPREME TO ANY r---.DEPENDABLE-46-1 OF THEIR TYPE AT THE PRICE. RADIO SERVICE HEADPHONES PRECISION VARIABLE CONDENSERS 4,000 ohms Best French ZO 17 6

11 " Brunet " 1 2 6 THE ACME OF SIDPE 1 00 PERFECTION. 8,000 11 SIDPE 1 26

GrUA Ft/LP7TEEEI 4,000 Single with NOT UNDER STATED CAPACITY. .. Accurately and completely assembled. Handles, BBC 012 0 INCLUDING KNOB AND DIAL. 4,000 ohms Double Head- Large metal to metal Bearings. One band, BBC .. 1 0 0 hole only required for fixing to Panel. 8,000DittodittoBBC 1 2 6 British made throughout, FREE PRICELIST therefore best:: VALVES OF MERIT Bard Dutch Valves for Amplification ..11 6 Soft Dutch Valves (Excellent Rectifiers) ..10 6 Full Guarantee given with each '001 ---8/6 Telefunken Valves (Noiseless Amplifiers)..12,6 Instrument. '0005 - COIL HOLDERS For Duo -Lateral Coils Packing and postage extra, '0003 - Best Ebonite 2 -Way .. 6/6 - 59 3 -Way .. One only,9d. - Two,1'-. 8/6 Vernier-47. 1d 16d.for Postage DELIVERY BY RETURN. BASKET COILS setof six 170-2,000 Metres (By Post3/0 2,6 Obtainable through your Dealer or direct from :- THE "VARIOPHONE"Crystal Receiving Set, comprising :-Variometer, Crystal Detector, etc., mounted on Polished Oak.Complete, Assembled, JACKSON BROS. 10 Unassembled, 7 - 1.(1,11/.for Postag, Condenser Specialists WATERLOO ELECTRIC Co. lc 8, POLAND STREET, OXFORD STREET 129, Waterloo Rd., London, S.E.1 LONDON, W.I. TRADE ENQUIRIES INVITED. 'PHONE I HOP 5649. OPEN TILL 9 O'CLOCK SATURDAY llifulynowwftesk".'Phone: Gerrard 6187 hownwetotstea 60; Popular Wireless Weekly, June 2nd,1923. RADIOTORIAL HERE'S A QUESTIONS AND ANSWERS. CABLE - '''''1111111:11111111111i, (Continued from page 602.) SCOTT BATTERY Varionieters woundforwave- up to 3,000 metres ? How many turns, etc.? length 300 750 TESTER What are the gaugesofeach ? metres. 7 mm. =22 S.W.G., *25 tom. =32 S.W.G., '4 mm. 10/- Each that won't Made with ebonite 28 S.W.G. For a coil to tune up to 3.000 metres stator and turned break. wind 500 turns of No. 32 S.W.G. on a former I inches rotor, they are just ill dialnetgr. the ideal thing for perfect reception No. 31287. POLARITY (Huddersfield).-Please will you for amateurs who The arebuildingtheir give me details of a cheap " polarity" indicator? ownCrystal or 76 "Break -not." Valve Sets.Cable. Procure about threepennyworth of sodium sul- SCO tt Variometer phate from a chemist and -threepennyworthof tuning, with single phenolphthalein. Put as much of the former as will knob, gives 20 per cent. better re- THE cover a five -shilling piece into a cup half full of warm sultsthansliders tiur water and as much phenolphthalein as will cover a orstuds and can farthing.Stir until dissolved. To test this mixture, be mounted on Or with wiring diagram-only place leads Into it about If inches apart, when the under panel. crystals and terminals re - " BREAK -NOT" negative leadwill turn the surrounding liquid a Post10/6Free quired to complete set. reddish colour.Shaking the liquid will make the HYDROMETER colour disappear.To make a container, obtain a C. F. CABLE.SCOTT, glass tube about 3 in. long, and two rubber stoppers 141, Dalmally Road, CROYDON. to fit.Terminals should be fitted tightly through is a necessity to every one wishing stoppers protruding about in. on the inside.Fill to take proper care of their wireless the tube with the liquid, leaving a small air space. equipment. Tellsata glanceif * HAVE YOU accumulators are fully charged, half " PAs "(Ealing).-I am puttingup a charged, or discharged, and being double aerial, 30 ft. long. What size spreaders -THE do I need, and what wood ?Using a crystal packed m unbreakable carton, can set, am I likely to get any telephony, except be placed in tool -box without fear. from the London Broadcasting Station, if my Your localdealer can supply you, inductance coil is large enough ?My aerial but it you have any difficulty send is about 26 ft. high.. us your order and we will arrange The spreaders should not be less than four feet long, for same to be executed. and six feet would probably be most satisfactory. Use a light wood for the spreaders, such as bamboo or For Trade Terms write ash, -though this latter is on the heavy side. You will probably get telephony from Croydon which fre- ONE IS WAITING FOR YOU. quently transmits to aeroplanes throughout the day, It is just what you want.Covers Units S. GUITERMAN & CO.,Ltd., and you should also get any local amateur trans- and Sets in parts for home assembly. How 55/6, ALDERMANBURY, LONDON, E,C.2 mitters.Otherwise we are afraid that 2 L 0 will be to extend the range of your Set. Reac- the only station from which you will be able to hear tance apparatus at small cost.And the telephony. whole range of components and sundries. CRY" S.T11.1....5.. RADIAX, LTD., 10, Radio House, Percy Hertaite, Electronite, Permanite, Talite, * * * Street, Tottenham Court Road, London, Zincite, Copper -Pyrites, Galena, Bornite, V.C.L.(Berwick).-Is there any real W.1.Ilrit.eurt. 490, -THESilicon, AMAX etc. Wholesale CRYSTAL only. Delivery CO., Iron]Red stock.Lion advantage in a variable grid leak, as I wish to House, Red Lion Court, Fleet Street, E.C.4. have one put in my new set in place of one of TO WIRELESS EXPERIMENTERS. PATENT YOUR the fixed type ? INVENTIONS. For long distance work a variable grid leak is very ELECTRADIX RADIOS They may prove very valuable. Particulars and consulta- useful, and should always be incorporated in a set, tionsfree. BROWNE &CO..PatentAgents, especially if the valves are being constantly changed, Immediate Delivery 9, Warwick Court, Holborn, London, W.C.1.Estab- as very often a valve will give very poor results on lished 1840. Telephone: Chancery 7547. a leak that may be highly satisfactory when working from our Huge Stocks. with another valve.For short distance work, or on a B.D.C. set, they are not so necessary. Everything from a Wave Meter to TELEPHONES (Continued on page 606.) an Earth Clip. NOTE MYPRICE The beat equipped City depot. ER I CSSON (Continental) COME AND SEE US. E.V. (B.B.C.) - - - 19,6 9, Colonial Avenue is first opening on C.E S. Silk wound to 4,000 ohms " ENSENITE" leftinthe Minories,nearAldgate THE SUPER CRYSTAL. guaranteed.Perfect reception, Station, Metropolitan Railway. superior finish - -21'- Extremely sensitive and reliable, no better Crystal obtainable. Price

LESLIE DIXON&Co. AveLe.1.60 FRENCH, 4,000 - - - 156 per piece 1/6 each with special 9, Colonial Avenue, London, E.I. Delivery at once.No waiting.Cash with Order. contact wire. We guarantee to return your money if you are not POSTAGE entirely satisfied. We aresole

distributersof Ensenite and can 1 pair, 9d.2 pairs, 1.1- 4 pairs, 1.'3

offer special terms to the trade. ROBT. DEANE, THE ENSIGN RADIO CO., 15, STRAND, W.0.2. 01' .1 Ch., StUt,0.) \64.137, EnglefieldRd., London, N.1 'Plume.GERILI III)67e,

.'11111111111111111I1111111illli111111_,,,

ELEcTRoNITE .,..-= When replying The WORLD'S MOST FAMOUS CRYSTAL Eto Advertisers be sure to RHYME No. 1. My Crystal is Electronita, My Wire is Tordinodium, mention Fin getting all my signals right, My Set is in good °ileum "POPULAR TRADE SUPPLIED WIRELESS WEEKLY"P- RADIO SUPPLIES E" AshleyWireless 234,HIGH HOLBORN LONDON. to ensure Telephone Co.Ltd. 'Phone: HOLBORN 2188. ::prompt:: 69Renshaw St. Liverpool Sole Agents for Lancashire and Cheshire : Messrs. HENRY HOLLINGDRAKE & SON, LTD., attention. == Sole AVerits PRINCES STREET, STOCKPORT. '11111111111i11111111f11111111111111i;. Popular Wireless Weekly, June2nd, 1923. 695 <\.,7%VkNONNKii. '''ANKAWININKANKAWli, ''''''ANK,N/AWAK"'i', ''''AWAN!!" MAKW%,\ -.4

CS1

--_<

--_._<'

WE shall be glad to supply one of these illustrated showcardsto all bona -fide wireless dealers, complete with strip to pasteacross, reading :" IN STOCK - ALL COMPONENTS FOR MAKING THE B.D.V. ' WIRELESSSET." This is a great opportunity for the live traderto reap the benefits of our extensive advertising campaign now being launched. The demand for these cards is very great, andwe urge you, in your own interest,to apply at once. To the Wireless Enthusiast :- The complete series of cards now being issued with thefamous " B.D.V." Cigarettes tells you in simple language how to construct your own set -efficiently and inexpensively. With this set working and a packet of " B.D.V.' " your evening will be one long round of enjoyment and satisfaction.Start collecting to -day.

20for111D. (.) The King of Cigarettes AllaPPiicalzon,to,choloCaras should omadeo :- " B.D.V." Publicity Dept., Albion House, 59-61, New Oxford Street, London, W.C.1. gllUn ,0\ ,WASatiarAiWidoiceurAscelpii, 'due "Ill'. "1 WleC'UelIZ'aAWAW,% billIll ahAdlMIN d1!1' ffA

WIRELESS !WIRELESS !WIRELESS !and EVERYTHINC for it. We insistonbeing the DON'T PAY MORE ! Cheapest in Great Britain. NOTE. We areexclusively WIRELESSNOT DABBLERS! Reliable goods at less than so-called Wholesale Prices (to the Public) " DON'T BE BLUFFED." " ERPCSSON " HEADPHONES (Co.,- STOPS, with nuts and washers per doz.7d. SLIDER KNOB each 2d. tinental). Our price,stamped B.B.C., TERMINALS, withnut & Washers, SWITCHES ON EBONITE, S.P Sl per pair 15 / 3 each 1d., ltd. & 2d. (quality the best) each " SUPER " FRENCH HEADPHONES. EBONITE KNOBS, 2 B.A., with nut & SWITCHES ON EBONITE, .S.P D.T.. Brand new. 4,000 ohms, and guaranteed washers each 2d., 3d. & 4d. (quality the best) each 1/11 each pair tested per pair 15/9 SPACING WASHERS, large per doz.21d. SWITCHES ON EBONITE, D.P D.T. L.F. TRANSFORMERS, Ratio 5 to1. SPACING WASHERS, small per doz.11d. (quality the best) each 2 / 9 All guaranteed.(Postage 1/-) each 11/3 CRYSTAL CUPS, 2 screw eachld. CONDENSER SPINDLES, allsizesin CRYSTAL DETECTORS, Adjustable 1/61 CRYSTAL CUPS, 4 screw each 2d. stock, from each11d. CRYSTAL DETECTORS, enclosedin FIXED CONDENSERS,allcapacities,each 111d. SCREWED ROD, 2B.A., 12 in.long, Celluloid unbreakablecase...... 2/3 EBONITE, cut to any size by machinery each 3d. SWITCH ARMS, best makes 113 & 100. while you wait per lb.4/ - SCREWED ROD.. 4 B.A.,12 in.long, AERIAL WIRE, 7/22, guaranteed hard- TELEPHONE TERMINALS, nuts & each 21(1. drawn copper, 100 ft.(postage 1/-) 2/. washer, each 111:1 per doz.1/4 RUBBER -INSULATED LEADING -IN CONDENSER VANES, fixed or moving, W. 0. TERMINALS, nuts& washer, WIRE per yard 2d. Reer doz 31 each '2d per doz.1/9p INSULATORS, white reel,2in.,each Gold Cat's Whiskers each 2d.d. PANEL BUSHES, drilled,eachlid., lid. per doz. 1/4 Real Silver Cat's Whiskers eachld. per doz. 1/4 INSULATORS, whiteEgg,each2d., CONDENSER SCALES, 0 to 180...each 31d. TOP CONDENSER, bushes,each ld.; per doz. 2/9 IVORINE LABEL SET, 12 different per doz. 11d. SPECIALHERTZITE CRYSTAL, r iadin s theset 81d. BOTTOM CONDENSER, bushes,each large piece earls 101d. NUTS, 2 B.A per doz.21d. Id per doz.9d. WOUND INDUCTION COILS(post- NUTS, 4, 5, 6 & 8 B.A per doz.2d. VALVE LEGS, nut & washer, each Id.; age Id.). WASHERS, 4 B.A per doz.ld. per doz 10d. 12 x 4 9 x 48 x 21 6 x 36 x 2 WASHERS. 2 B.A per doz.ltd. VALVE PINS, nut & washer, each 1cl.; 2/8 2/5 2/2 1/11 1/8 FILAMENT RESISTANCES,smooth per doz. 9d. TAPPED INDUCTANCE -COILS, 20 action, marvellous value 1/101d. & 2/. PLUNGER SPRINGS, complete each 11d. tappings wound to 1,600 metres each 2 / 11 CONTACTSTUDS,with nuts, and SLIDER ROD, brass,13 in.long, 1in. VARIOMETERS (TubeType)complete washers per doz.5d. square, drilled each 4d. with knob 4 / 6 Please remit ample postage. iiELKAY WIRELESS CON,225, Bishopsgate, London, E.C.2. Trade Supplied --Accumulators charged on premises. Open Sunday: 11-2.30. Telephone: Bishopsgate 2292. CO3 Popular Wireless Weekly, June 2nd, 1923. RADIOTORIAL QUESTIONS AND ANSWERS. (Continued from page 601.)

F.S. (Melrose).-Whatismeant by a " characteristic curve " This is the relation between two variables.For a valve, characteristic curves may be plotted between volts on grid and current in anode -filament circuit, or between current in anode and volts applied to anode -filament circuit.

A. W. (Langley).-I wish to make a high- tension batteryof small accumulator cells. How is the paste on the positive plates made ? It is not advi4able to attempt the formation of accumulator plates. as itis a very tedious under- taking to get the piste to remain in the holes for any length of time, owing to the tendency of the materials to crumble away.The paste is made of oxide of lead, usually red lead or litharee, and some extra substance such as potassium silicate, and sulpluiric acid.The plates are dried after being carefully filled with this paste, and then placed in a bath of dilute sulphuric acid with some pure lead plates as negative electrodes, and a very gentle current of about one half of an ampere is passed through.After a few days the paste on the positive plate should have undergone theValveyou a change, the lead oxide having been still further oxidised to lead peroxide, and they will then be of a dark brown colour.The plates are then said to be will eventuallyuse. " formed." A better plan would be to cut up some old accumulator plates and use those for your battery. * * * THE efficiency of any three -elec- W. R. (Bourne End).-What is meant by trode Valve-whether rectifying " parallel resonance "? How many watts are or amplifying-depends on the there in one horse -power ? The condition of parallel resonance is said to exist quantity of the electrons given off by in a circuit when it is tuned to the same frequency the filament and usefully employed. as that of the-electro-motive force introduced across it.In this condition an oscillating current, is caused to circulate in the circuit of such a value as to pro- The COSSOR Valve is so wonder- duce across the circuit an oscillating voltage, equal at every instant to the electro-motive force intro- fully efficient because practically all the duced across it. The current flowing to the circuit from the source of eleetro-motive force will depend electrons given off by its curved filament upon the resistance of the circuit.There are 746 are caught by the hood -shaped Anode watts in one horse -Dower. and Grid-none can escape wastefully * * to the sides of the glass. "JoNITio).1" (Epping).-A friend told me that a great deal of those so-called " atmo- No matter whether your Receiving spherics" may be waves sent out -by the Set is of your own construction thousands of magnetos on moving vehicles. For detecting or a Is this at all possible ? or amplifying handsome Cabinet inperiod style- It is quite true that magnetos used for ignition whether it uses one Valve or six-you in petrol engines act as small transmitters.In fact, one hears the magneto " transmission " from the want the best results. powerful engines used on an aeroplane if one is passing close overhead when tuning for telephony.But the To make sure that your Valve is above waves so radiated are very damped and very short, so that they do not travel far.The range. of dis- suspicion, use a COSSOR-for general turbance caused by an ordinary magneto would be all-round dependability, distortionless but a few yards. 15 speech, freedom from microphonic noises whetherdetectingoramplifyingat -NowReady-. From all Dealers in high or low frequency, and for long life Foyle's Revised Listof Books on wireless components you'll find it hard to beat. WirelessTelegraphy andTelephony. Sent FREE of charge on receipt of a postcard mentioningList 120 (Wireless.) COSSOR VALVE CO., LTD.-HIGHBURY GROVE,N.5. FOYLES,121, Charing Cross Road, London. 1,,rmense Stock (Second-hand nod New) on all subjects. WIRELESS. Agents wantedbywell-known London manufacturer to sell wireless sets to private persons.Good commission.Give references, age, and experience.Anyone having spare time may apply.Agents must be prepared topurchasedemonstratingsetatvery special- low price.Write for particulars to Box 366, W. S. CRAWFORD, Ltd. 233, HIGH - HOLBORN, W.C.1' PHONESREWOUND 4/6 You can have that low resistance phone rewound. We have rewound -thousands, let us rewind yours. Single 2,000 ohms, 4/6.Single 4,000 ohms,5/9each. Pair 2,000 ohms, each8/6.Pair 4,000 ohms, each 10/3. Every Phone istested and satisfactionis guaranteed. Gilbert Ad. Any make Phones rewound and repaired SEND AT ONCE. AND SAVE DELAY H. SALT, 111, Harbut Rd., Clapham June., S.W.11 Popular Wireless Weekly, June 2nd, 1923. C07

Ka l' 154 EVERYBODY-wo

ALL GOODS ORDERED BY POST VARIABLE CONDENSERSmust be accompanied by the Correct ASSEMBLED AS ILLUSTRATED Post Prices marked on each article. Drilled Ebonite Ends to fix yourself 1 /- per pair extra The quality and value given do not permit of them being sent otherwise. Approx. Cap. No. of in Mfd. Plates Price Norubbishy catch lines here. All realvalue for money. PLEASE NOTE. '001 57.6/6 Rubber Lead-in Wire (good), 12 yd. 1/9.Bypost,2/6. Bell Wire, 12 ytt. 8d.By post,1/.. '0005 29 Twin Flex,' I2 yd. 1/9.By post,2/.. - 4/6 Switch Arms, 10d 1/-,1)3;1/6. Post, 6d. each extra. Rotax Accumulators, 4 v.40, amp., 171-. Carriage, 2/ - each. '0003 19 Fixed Condenserg. Good value. 11d.,1/3. Post,6d. 3/13 - each extra. , H.T. Batteries, 60 volt, 9/-.Carriage, 2/- each. H.T. Batteries, 15 volt, 2/6:Carriage, 1/- each. Ebonite Valve Holders,10d.,1/-,1/3. Post, 6d. each '0002 13 2/6 extra, Basket Coils, " Oojah,"setof 7, 5/-.By post,6/- set. Basket Coils, 2)8 and 3/6.set.Post, 6d. extra. Insulated Sleeving, 5d. and 6d. length. '0001 7 2/3 Crystals (Mounted), Ilertzite, 1/..By post, 1/6. Crystal Detectors, on ebonite, 1/5.By post, V, Vernier... 31/9 Detectors,Perikon enclosed with2 crystals, 2/4.By Perikon Detectors,suit expensive set,3/9. Bypost,4/S. Enclosed Detectors,1/8; -2/9,3/6,3/9. Post,1/- each extra. Valve Pins, slotted,7d. doz.By post, 1/... Aluminium Vanes, 22 gauge, Id. doz.By post, sd. doz. COMPLETELY ASSEMBLEDAS SHOWN TappedCoilson Ebonite,10 tappings, broadcasting. ,ixe. price 2/6.Post, 1/- each extra. -vs 001+.000 8/- S.P.D.T. Switches on Ebonite, 1/9, 2/6 each.

D.P.D.T. 11 2/6, 3/6 each. Series Parallel Switches on Ebonite, 3/6, 4/- each. 5/11 All 1/- each extra by post. Accumulators, 6v.60 a.,absolutelythe best,35/.. - .0003 4/11 Carriage, 2/- extra. Slider Knob andPlunger,3d. Bypost,7d. .0002 3/11 Terminals,\V.O., Telephone, P.O.andallpatterns, including nuts and washers, not junk, 2 for 34d. 0001 3/6 1/6 doz.By post, 1/- doz. extra. Aerial Wire, 100 ft., 7x22, 2/11.By post, 9/3. IntervalveTransformers, very best,25/-. Also12)6 Vernier 3/3 each, 16/-,20/- each.Post, 1)- each extra. Knobs, hushed 2 B.A. (best), 3d. each.By post, 7d. 3 Way Coil Holders, Ebonite and brassfittings,7/6. ALL ORDERS BY POST MUST BE Post, 1/ extra. ACCOMPANIED by1/3perset EXTRA. Radio Instruments Transformers, 25/,Post, 1/6. - OTHERWISE NOT EXECUTED - Dubilier Condensers, at usual prices. Telephone Transformers (R.I.),20/.Post,1/6. H.T. Batteries, 30 volt, 4/6; 36 volt, 5/-.Post, 1/- each extra. Telephone Leads, long,1/..Post, 6d. extra. Filament Resistances,1/6,1/8,2/-,2/6,3/-Post,9d. BRUNET " FRENCH PHONES extra. 4,000 ohms (different headbands) . . . . 22/6 and 25,' - French Phones, leather headband, 4,000 ohms . 15/6 and 17/6 B.B.C. Phones, best quality 1 7/- and 19/6TO CALLERS ! T.M.C., 4,000 ohms, stamped B.B.C.. . . . 24/6 pair. (Phones supplied by T.M.C. themselves, taken from expensive sets to clear.) rinlier.,I sell everything you want for your home - madeSets. No junk. No MUZZLEPHONE " CRYSTAL SETScheap job ,inesAll low in price, in handsome polished case.B.B.C. Royalty paid,r40 Post 2/6 but first-class quality. or with pair of 4,000 ohm phones, aerialwire, etc.,50 -I-. /- TRADE SUPPLIED TRADE SUPPLIED

i111111111111111111111111111111111E = E Right Opposite a- Phone: GERRARD 4637 DALY'S E M. RAYMOND -OPEN 9 to 8-a7 .= E GalleryDoor = Saturdays -9 to 6 p.m. =- 27, LISLE STREET, W.C.2 == :11111111MIH1111111111111111J

154154154154154154155154 h4aBxsiIL44 x 4bh 4 4154 415.415415.41541581545.4154b.4154 154154154154154 154154 608 Pcp:ila: Trii-Jess Weekly, June 2nd, 1923.

TELEPHONES -BUY OF THE MAKERS - The Finest 'Phone Offer Ever Made. RECENT WIRELESS 2Crystal -Valve SetsSets, fitted with our patent £71 155 0o 1 -Valve Amplifier 2 10 0 Pair of brandnewEnglishHeadphone 2 -Valve Amplifier 5 0 0 Receivers, Brown's 6 -ft.headCordsand INVENTIONS. Headphones, 4,000 French 17 0 Headphones. 4,000 B.9.0 1 5 0 Tags, Twin Aluminium Headbands, at half The following abstracts are specially con- L.P. Transformers (Best) 14 6 cost; 10/- per set.Postage 6d. extra.Cash Detectors, mounted 2 0 with order.Guaranteed onCrystalSets tributed by Mr.Harold C. Forrester, Detectors, Vertical, enclosed...... 3 6 If you Filament Resistance 2 6 within 20 miles of B.B.C. Station. Fellow of the Chartered Institute of Patent Switch Arms 1 3 do not like the 'phones afterthree days' Agents, 88-90, Chancery Lane, W.C.2. Nuts, Washers, Contact Studs, trial, money returned.We know that these Terminals, &c. 'phones cost double the price, and as the Complete parts for making up given Valve & Crystals Sets. number islimited preference will be Genuine Nertaite, 9d., 15. 6d., and 25. to callers.Sullivan Headphones, L.R., 12/, Grant of the following Patents can be Sheet Ebonite. French, 2,000 ohms, with cords, 16/9. opposed and printedcopies of the full Trade Supplied.Agencies open. specifications purchased. Write for our List.Post Orders by return. LESLIE DIXON & CO., Cash With Order. 9, Colonial Avenue,Minories,E.1 (first turning on left down Minories). 193,060.-E, PFIFFNER.-CONDEN- G. H. TURNER & CO. LTD., Can and inspect our huge stocks of wire and 9, Cross St., Hatton Garden, E.C.I. Wireless Apparatus. SERS. - Discharges from the edges of plates separated by an insulating dielec- Telephone:Holborn 2045. ABSOLUTELY INCOMPARABLE PRICES tric are prevented by providing the plates L. F. Transformers (Ratio 5 to I) . ..11/3 each with a high -resistance border such as a very Switch Arms ..1.0i ea.SliderKnollswith Filament Resistance Plunger....lid. thin layer of conducting material applied to FOLLOW THE CROWD 100 & V.., '001, .002, & '093 fixed Genuine HertziteNI. Condensers..6d. the insulator by chemical precipitation or BOUND EACH DAY FOR Gold Cat's -whiskers Ed 2 -Valve Set, less Valves. suitable for Loud Speaker, by heat, or powdered graphite and a binder. Price One Guinea 193,092. -BRITISH THOMSON- Send for our Bargain List. Traci; Suppitrit. SPENCER'S STORES P. laceraltic Wireless Supplies HOUSTON CO., LTD. -PRODUCING 4-5, MASON'S AVENUE, 308; High Road, Lee,9.E.13. OSCILLATIONS. -Ina thermionic nega- RAS1NGHALL STREET, ...... -..."...'phone :Lee Green 1110. -ssinstrss/%4 tive resistance device the electrode emitting LONDON, E.O. 2 : Reactance on the Anode will the secondary electrons or " dynatrons " is bringinthe distant stations SPECIAL OFFER. and double your amplification. maintained at an average negative potential. Our principle is approved F.M.G. is FRENCH PHONES -Guaranteed -16S, and doesn't radiate. In one arrangement the load circuit PRICE LIST POST FREE. RADIAX Regd.VariableRe- coupled to the plate circuit of a valve and actance Coil forallwave- lengths,10 / -.TunedAnode is given a high positive potential (300-1,000 Coilforsame,topluginto any H.F. Transformer SOckets, volts) by a direct current source. The grid THE NEWTONIA WIRELESS FACTORY 350-500 metres, 5/6. FOR ALL WIRELESS PARTS AT FACTORY PRICES If you haven't is connected to the usual oscillatory (induc- H P. add our Unit. 13/15, WHITCOMB ST., W.C.2. H.F.Unit,inOak tance capacity) circuit, but is maintained at Regent 5489. LONDON. Case, 26 / 6. a negative potential by a battery.Oscilla- Var" ableCondenser .0003forgenie,in RAD/Ax tion is started by giving a momentary posi- case, 14 / 6. ACCUMULATORS, ETC. /RADIAX LTD., 10, Radio House illIMIL tive charge to the grid. . NEW AND GUARANTEED. PercyStreet, Tottenham Court 4 -Volt, 25 -Amp Celluloid 11/3.Postage 1/-. Road,London,W.1 Museum 490 WE SATISFY YOU 194,836.-E.POLLOCK. TRANS- 4 - Volt, 40 - Amp.. 17/6 6 - Volt, 40 - Amp., 25/6 MISSION.- In transmittingspeechorb 4 60 .,21/3 6 60 4 SO 27/-6 80 :: 36/--

spark signals the output circuit, controlled 4 . ., . 100 331- 6 100 45/- RECEIVERS RE -WOUND. as described in No. 194,765, is inductively B.T.H."R"Packing 1 Valve/ 6 extra. Packing 2 / - extra. TELEPHONE RECEIVERS RE -WOUND up to 2,000 coupled indirectly to the aerial inductance 36 -Volt. H.T. Battery Relies= 8/6. Postage 1 I -. ohms each Receiver. 3/6. Send Bobbins only. 60 14/-. 1/-. MAKE TOUR OWN. TRANSFORMER? Wire, Bob- bin, and full instructions,2/..Steel Headbands. which is also inductively coupled to the Cash with order. Goods despatched per return. 1/6 pair.Resistance spools, 1,000 ohms. No. 42 plate circuit of a triode valve, the grid circuit LOWKB & RON% LTD., NORTHAMPTON. SilkWire,9d.each.Headphones,4,000 ohms, 15/6 pair.Odd Receivers fitted with Head -band, of which is shunt coupled to the microphone 3/- pair. Allpostfree. or key.Thus current variations in the TO THE TRADE. A. ROBERTS & CO.. TELEPHONES. VARIABLE CONDENSERS. INSULATORS. la, OLDRIDGE ROAD, BALHAM, S.W.12. microphone or key circuit cause modulated FILAMENT RHEOSTATS. DIALS. TRANSFORMERS, etc. energy to be transmitted by the aerial.In DELIVERY EX STOCK. SEND FOR LIST AND SAMPLES, another arrangement, use is made of a EBONITE SHEET. PANELS. TUBES. EBONITE. COPPER WIRE, Enamelled, Cotton or Silk Covered combined generating and modulating valve. Cables & ElectricalSupplies, Mica House, Finest quality, i,3 in. andin.thick, 194,864.-L. G. PRESTON & G. OffordSt.,CaledonianRd.,London,N.1. 4d. per square inch.Squared and SHEARING. -TRANSMISSION. - Telephone: North 310(5. ground accurately tosize,Id. per Sparking and other troubles due to cutting square inch. Holes marked off and ---,Beginners Guide to Wireless-. drilled 1d. each extra. All post free. out portions of the grid coupling coil when Explain-, in plain everyday language, everything power you wish to know about Wireless Telegraphy. D.EPT.WEPT 2H3A14TLYEOPROKOLR. OAD:. reducing the wave -length in high SCOTT'S, . are HOW TO ERECT, CONNECT, AND MAKE sets prevented by splitting up the the apparatus required, and fullinstructions coil into several sections arranged equally for making coils, tuners, and complete valve -- WIRELESS INVENTORS,.....'" on each side of the exciting coil.Mutual and crystal sets.Instructions and diagrams Patents and Trade. Marks, Advice Hand -book for a two -valve receiver are alone worth four and Cons. free. -B. T. KING, Regd. Patent coupling between thesections and the times cost of the book.112 pages, price is., Agent (G.B. & U.S.A.), 146a, Queen Victoria sparking potentials of th6 tapping points postfree. -SAXONRADIO CO.(Dept.14), St., E,C.4.'Phone: Central 682.38 yrs. refs. are thereby reduced. South Shore, Blackpool SensationalReductions 400 BEST CONTINENTAL SUPER -SENSITIVE FEATHERWEIGHT4,000 OHMS DOUBLEHEADPHONES,easilydetachable 'LaminatedPoleShoes, PAIRS Aluminium Ear -pieces, Ebonite Caps, and self-adjusting Headband; 17/- ERICSSON per pair, postage 6d. Ditto, Adjustable, 22/6 per pair, post 6d. 3000 Ohms Basket Inductances, 150-4,000 metres, per set of C,,.2/6; per set of 7, 3/6; post 3ii.Complete with 8 diagrams mid calibrations. Pair of Coils, for broadcast wave -length, 1/3 per pair. GENUINE H.F.Transformers, for use with above coils, 1/3 each. PHONES Variable Condensers (Circular), in Celluloid Dustproof Case,.001,15/6 each, post 6c1. NOT THE GERMAN IMITATION Laminated Switch Arms, complete with knob, boss, bush, spring, and spindle, each.Switch Arms only, 3d. each. " Sensitone," the super -sensitive Crystal, 6d. per specimen. This offer cannot be repeated dia. Stalloy Diaphragms, 4d. each. 5/ 47 S.W.G. D.S.C. Wire, sufficient to wind one H.R. Ear -piece, 1/- per bobbin. Ex-Arnly Single Ear -pieces, 150 w., 2/9 each, post 3d. STAMPED B.B.O. Send for Bargain List. POSTAGE 6d. Scientific Supply Stores, PUGH BROS 95-101, HOLLOWAY ROAD, "I:: LONDON, : n2: 717i.126, Newington Causeway, London, S.E.1. Arne 2nd, 1923. POPULAR WIRELESS WEEKLY. iii

NOTICE To All Engagedin ENGINEERING FREE WRITE FOR -or

PART 1 I1;11 al TO -DAY THE BENNETTCOLLEGE ENCYCLOPAEDIC ILLUSTRATED DICTIONARY OF ) ENGINEERING kerik CIVIL. MECHANICAL, ELEcTRICAL,MOTOR, ETC, ETC., PART 1

SHEFFIELD. To extend the name of The THE BENNETT COLLEGE Bennett College to everyone $1111111.01 engagedin thedifferent

branches of Engineering, We are publishing an . Illustrated Dictionary of Engineering in about 24 Monthly Parts. You can have each monthly part as it comes out FREE -3d. Postage only to pay. SUPER THE CONDITIONS ARE THAT YOU send your name and address, your age and occupation, with three penny stamps (to cover postage), writing your name and address very clearly. We shall then place your name on our Free List, and send you Part 1 at once. The others will be forwarded as THIS isahigh- issued.Address your appli- cation to gradeCrystal (Do not fail to give the par- Detector es- ticulars re4uired, and use this full address.) pecially designed for Department DlOg receivingbroadcast- ing,andcomplies The ideal withallregulations. Beautifully pure clear INSULATING VARNISH speech and music are received, and as many as threepairs of HARDICOL Fellows 4,000 ohms double headphones SHELLAC INSULATING can be simultaneously used. :: VARNISH CEMENT The " FELLOCRYST SUPER " is mounted in a Guaranteed made from pure Shellac, A saturated highly polished oak cabinet and is sent out complete solution in the cold.Perfect for all insulation work. with 100 ft. coil of 7;22 stranded copper aerial wire, Enquiries invited from the trade. twoshellinsulatorsand onepair4,000 ohms ad.and 1/- Bottles.Also in BULK. double headphones, and is British Made Through. H ARDICOL IS OBTAINABLE FROM THE out.Fully approved by the Postmaster -General and USUAL DEALERS AND THE MAKERS: the British Broadcasting Company. A. F. HARDING & CO., LTD., EXMOUTH ST., STEPNEY, E. PRICE COMPLETE -- £4 - 15 - 6. inclusive of all taxes. Postage 21- each. GOSSAMER AdditionalDouble Headphones - 21 "SENSIFONES' (4,000 ohms) inclusive of all taxes. are the Latest and Best thing in Head- phones, and to convince you ofthis we FELLOWS MAGNETO Co., Ltd. offer them to you on a LONDON, N.W.10. SEVEN DAYS' FREE TRIAL Telephone: Telegrams: WILLESDEN 1100-1 "QUIX-711AO." PHONE. LONDON after which period, if you are not satisfied, your money will be immediately returned. EXTRA LONG CORDS.DO NOT BUY CHEAP FOREICN 'PHONES. Itisbettertobe safe than sorry. Fitted with Magnets made from aspecially prepared SEND FOIL FREE LIST. yooct and expensivesteel,and scientifically arranged and jo-eey adjustedtogivea loud,TOWNSHENDS, ITO., ERNEST ST., clear no to without distortion. ' BIRMINGHAM. a REDUCTION IN PRICES OF THE

"MAGNAVOX" LOUD SPEAKER O O The Reproducer Supreme

0 JUNIOR MODEL SENIOR MODEL

The ideal instrument for The instrument for extreme the home, or when extreme volume ; specially designed volumeisnotrequired. for large audiences.

No. R.1293,complete with No. R 1282,as No. R. 1293, but step-downTransformerand black with 18 -inch Horn and switch for

enamelled spun copper I4 -inch Horn. breaking field current. eo £8-0-_O £15-10-0 .j;

4,2C

R 1293. si" HORN.

, - Will enable you to derive the greatest possible pleasure from "listening -in" to GRAND OPERA AT COVENT GARDEN

andwillintroduce youto' one of the highestformsofmusicalart. You will then be more than ever anxious to hear the actual performances.

Photo by Swains. Photo by Swains. Miss Edna Thornton, as Amneris in RADIO BRINGS IT Miss Florence Austral, as Elizabeth " Aida." in " Tannhau.ser." Reproduced by exclusive permission of MAGNAVOX TELLS IT Reproduced by exclusive permission of the British National Opera Cu.,I Id. the British National Opera Co.; Ltd. To be obtained of all dealers or direct from: STERLING TELEPHONE 'AND ELECTRIC CO.;' TELEPHONE HOUSE, 210-212, TOTTENHAM COURT ROAD, LONDON, W,1. Telephone: Museum 4144 (7lines). Telegrams:" Cucumis, Wesdo, London." BIRMINGHAM: ' CARDIFF: MANCHESTER: NEWCASTLE ON -TINE: WORKS: 150, Edmund Street. so, Park Place. 54, St. Peter's Square. 9, Clavering Place. Dagenham, Essex. The above instruments bear the B.B.C. Seal.

Printed and published every Friday by the proprietors, The Amalgamated Press (194), Ltd., The Fleetway House, Farringdon Street, London, E.C.4. Ac1vertisowent .0fliees: Messrs.l-a. 11.Lile, Ltd., 4, Ludgate Circus, London,E.C.4,Registered as a newspaper and for transmission by Canadian Magazine Yost.Subscription rates: Inland and Abroad, 17/4 per annum, 8/8 for six months.Sole agents for South Africa: The Central News Agency, Ltd.Sole agents for Australia and New Zealand: Messrs. GordonHach, Ltd.; end for Canada: The hsyerial News Co. (Canada), Ltd.53414day, June 2nd1923.

RI4 POPULAR WIRELESS WEEKLY, June 9th, 1923. REGISTERED AT THE G.P.O. AS A NEWSPAPER CONSTRUCTION OF A SINGLE -VALVE RECEIVER PopularVireless

No. 54.Vol. III. SCIENTIFIC ADVISER: SIR OLIVER LODGE, F.R.S., D.Sc. June 9th, 1923.

FEATURES IN THIS ISSUE. Pictorial Four -Valve Circuits. Low -Frequency Amplifiers. Hints on Metal -Working. Further Practical Ideas. Scouting and Wireless. Wireless in the Midlands. Methods of Measuring the Properties of Valves. POPULAR WIRELESS WEEKLY.

esre.."4.

L

i HULLO !!! C.Q. WILL DAY CALLING TO ANNOUNCE SOME RARE BARGAINS EDISWAN READY FOR THE OPERA BROADCASTING THE LATEST MARVEL,apairof VALVES Midget Headphones, weigh under 4 ounces, 4,000 ohms.Call and test these at our showrooms.. ..Price21,'-per pair A THOROUGHLY RELIABLE PAIR OF p COMPACT HEADPHONES, stamped B.B.C...20'.per pair ECONOMICAL RELIABLE 100 feet 7 25 Stranded Copper Aerial Wire 1 1 0 per coil HAYING PURCHASED THE WHOLE OF A MANU- FACTURER'S STOCK OF GUARANTEED 7,22 HARD DRAWN AERIAL WIRE IN 100 FT. HANKS, WE ARE ABLE TO OFFER THIS AT THE LOW PRICE OF 2.2PER HANK OR 2!. FOR 50 HANKS AND UP. Sheet Ebonite, Grade A, cut to any size Every requisite in Stock for WirelessTRADE SUPPLIED. These are only a few of our bargains.Do not fail to send for our Price List giving the lowest prices for the best quality goods.Postage on all goods extra. 1 Write for our new Catalozue, now ready. Do not fail to try the NEW "DAYZITE," Regd. The super marvel Crystal with Silver Detector Point at SENSITIVE 2,6 each, or mounted in Brass cup, 2,10, Postage 3d. extra. SILENT ROBUST WILL DAY,LT D., EDISWAN 199 Lisle St.,Leicester Sq., Loridon,W.C.2 Phone : Regent 15;7. Telegrams :Titles, Westrand, London. MEANS THE BEST VALVE JEARY "SENSIFONES" Actual performance has proved beyondall Including B.B.C. Every set tested question the superiority of the Ediswan Valve for TRADE MARK. and guaranteed. wireless work. Every day adds to its reputation. 4,000 97/6 TYPE AR. TYPE R. Ohms driw Bnit isk Hake. 15,'- 17/6 Compare and test these with any other make, you will be conPincel of their \\'e have unique experience in the development highquality.Lightweight,easily and mann facture of the Thermionic Valve. The first adjusted, highly sensitive, detachable experiments in connection with the itive,-tigation receivers. 1 NI EDIATE DELIVERY. (.4 the " Flison Effect " ,on which the working of Send your order NOW. a valve depends were carried out at our Ponders Wholesale Agents for Igranic Radio Dev.ces. Eel Workii by Prof. -\ Fleming, \-i`,was the The JEARY ELECTRICAL Co., Ltd. onitittro 'sScientific A d __,S,Lambeth Hill, & 97, Queen Victoria St., E.C. Also at GLASGOW, BIRMINGHAM, &c. Alsomanufacturersof complete ReceivingSets, Accessories and H.T. and L.T. Batteries.Dealers should write at onceforparticulars and terms. Descriptive leaflets free on request. ACCUMULATORS SPECIAL OFFER AT THE ACCUMULATORS4110 REDUCED PRICES EDISON SWAN ELECTRIC Popular Type. Clear Celluloid Cases. Veit- IgnitionAct.A.H.1,,icec,,,r. CO., LTD., -nue.(*an. Amps.Cap. ' Extra ALL ContractorsIsH.11. Adriraliy, War Office, Royal Air Force. 1000, 4 71 8 9'111 4v ZI)A 1310 4 20 10 12 11 ,1/6 123 5, Queen VictoriaStreet,EC. 4. 131, 4 30 15 14 113 WIRELESS and71, Victoria Street, S.W.1. 1320 4 40 20 16 11 II 1334.1 4 60 30 22 6 -2/3 ACCES- WORKS PONDERS END, MIDDLESEX. E P R 1340 4 80 40 29'- J LI anCileS in all I i20 6 40 20 27/6I 2/6 SORIES Principal t0w111 ACCUMULATORS iiati6 60 30 33/9 J

\ 1140 6 80 40 39,6 I 3,6 10 KEPT 20 YEARS' 1;50 6 100 456 I REPUTATION RICHFORD & Co., IN STOCK. . ;11,1 153, FLEET ST., LONDON, E.C.4

. 1-plaTate : illi,ilierir 5126. Est al,. 1,76. 6o9 Popular Wireless Weekly, June 911i,1923. POPULAR WIRELESS

June 9th, 1923. SCIENTIFIC ADVISER, SIR OLIVER LODGE, F.R.S., D.Sc. [Every Friday. TOPICAL NOTES AND NEWS. Royal Wireless Station. series will be one dealing with the simple "Twelfth Night." HE King of Italy, a correspondent tells mathematics met with in calculations ofTrt was a pleasant change to hearShake- Ime, is having all British goods in con- capacity, inductance, and similar electrical speare's " Twelfth Night "broadcast nection with his wireless set, and is problems. 'from the London stationlast week favouringMessrs. Burndepts'receivers, although _thegeneral programmes from while the aerial is tobe supported by a this station do not lack interest, and there high. WIRELESS REVIEW AND SCIENCE " Turret " mast 56 ft. supplied by WEEKLY "isTHE journalofwireless, is plenty of variety in them.I am sure Messrs. Simpson and Blythe. electrical, and general science.Authorita- that a fairly regular transmission of this * * tive, yet written in such a way that even type of feature would prove popular to the veriestamateur will finditintensely Less Blanketing. interesting, it possesses a universal appeal, a vast number .ofbroad-catchers." IAM gladthat the blanketing round and shouldfind a placein thehome of everyone desirous of following the romantic 2 L O'sstudioistobe reduced. trend of advancementin science. Voices Well -Balanced. The tremendous amount ofcanvas No. 3 on sale Tuesday, June 12th, price 3d., CATHLEEN NESBIT, who tookthe at present used quite spoils the otherwise from all bookstalls and newsagents. partsofSebastian and Viola, the perfecttransmissions. A little" echo ORDER YOUR COPY NOW! twin brother and sister, has a good effect " is necessary in order to give the broadcasting voice and came through very voices andinstru- well indeed. On the ments theirnatural whole, the transmis- tone. sion was agreat * * * success,andthe Howling. artistes must have THOSE who suffer beenplacedvery from "noisy" carefullyin the setswillfind studioso that nc that a very useful drowning effects hint is to place the were caused by a set on a steel plate strong voice being whichis earthed. placed nearer to th( This will practically microphonethan eliminate body capa- one not so powerful. city, and the tuning * * will be more stable. Complete Set ls. I believe that IT seems that the " tables "for.this order of the -day is purpose are already to endeavour to on the market. establish a record in * * * the " cheapness " of Gramophones. " complete "sets. gramophone A section of one of the efficient workshops in the factory operated by Radio Instruments, Ltd. but "complete' THEcompanies,I does not generally am told, are obtaining increased business " Amateur's Day." cover such indispensableitems astele- through the medium of the B.B.C.,:because T DO not know how many readers of phones, aerial wire, etc.However, a corre- listeners -in who possess gramophones desire 1 POPULAR WIRELESS listen -in on Sunday, spondent informs me thathehasen- to -hear broadcast tunes'again. but personally I find it by far the most deavoured to break all preceding records interesting day of the week.All our old with a set., the total cost of which did not The King's Set. friends, the amateurs, who have been com- exceed Is. complete. IT is probable that by the time the King paratively silent since broadcasting began, and Queen arrive at Balmoral for their reappear during the morning, and lately Some Detector. autumn holiday, towards the end of 2 0 M has been very busy. THE inductance was wound and the aerial August, a special wireless set will be in- * * * erected with " disposals " wire pur- stalled. " 2 L 0 Testing." chased in a length of 25 yards from * * * THIS well-known station is still steadily a " junk " stall for 6d., old bottles forming A Secret Code. improving, and indeed will soon rival the insulators. A low -resistance earpiece was THIS will bring the Royal Scottish resi- 2 L 0 in its transmission.The latter picked up for another 6d., and the detector dence into much closer communica- also very often does a great deal of " etherconstructed from the veriest of scrap. The tion with the Government, butit shaking 'during Sunday, and a week or so latter included a piece of iron pyrites found will be necessary to inaugurate a new code age gave a very prolonged test during the in the household coal, and an ordinary pin. so that it cannot be understood by listeners - afternoon and early evening. in. -- I am given to understand that the * * Quite So! transmissionofmessagestoand from The New Paper. THE coil, by the way, was wound on a Balmoral will notaffectbroadcasting or GoING up to town the other day I cocoa tin.My correspondent claims the usual traffic. noticedthat quite a lot of people quite good results on this peculiar in thetrain were reading the newset, but adds that he is but a mile or -so Articles for "Popular Wireless." paper. As one man put it."Wireless from the broadcasting station. A technical THE Editor tells me that he has arranged Review ' is just what was wanted, a magazinefriend tells me that although interesting, for several useful series of articles to that will go withP.W.,' and carry you stillthe idea is not original, and that he has appear shortly in POPULAR WIRE- further into those realms which that paper himselftriedout aset,constructed on LESS. Among theseavery interesting opens up:" (Continued on page 610.) (110 Popular Wireless Weekly; June 9th, 1923.

B.B.C, Operas. NOTES AND NEWS. THE company intend not only to con- (Continued from page 609.), tinue their local stations, but to send operatic and musical companies on similar lines with quite fair results." With tour so that the concerts at provincial H.R. 'phones, a good detector, and finer stations may be on the same high level as tuning,results would have been much those of 2 L 0. better, " was his intelligent comment. Music Traders and B.B.C. * * * MR. FERGUSON, of the National As- Silent Periods. sociationofRadio Manufacturers, READERS owning multi -valve sets will gave an address to the Music In- begladto learnthat the, various dustries Convention at Buxton. He said that broadcastingstationsareto close broadcasting had come tosstay, and advised down for half an hour each evening.This them to push the sales of wireless sets, and will enable long-distance reception to be that the listeners -in in England would soon carriedout withoutinterference. The be as big aforce asin America, where " silent " periods are : 2 L 0, 7.30 to 8 p.m. ; 3,000,000 homes were fitted with receiving 2 Z Y and 5 S C, 7.45 to 8.15 p.m. ; 5 W A sets, providing entertainment to 10,000,000 and 5 N 0, 8.0 to 8.30 p.m. ; 5 1 T, 8.15 to out of a population of 166,000,000. 8.45 p.m. * * * * " Pirates." Stop Howling. HE went on to say that there have been IHOPE' 2 X ?, catches the " gentleman " eighty thousand licencesissued in at Wimbledon who caused him to England, and more than 200,006 closedownhisteststhe other " pirates 'who had not secured licences evening owing to the latter's efforts on a were being entertained. Multi -valve reaction set. * - * * Plays Broadcast Regularly. Wireless in the Open. rAPT. LEWIS tells me that over 300 THE annual charity fair at Eastcote, %...4 letterscommenting on. the Shake- Middlesex, on June 9th, is arranging an speareNight havebeenreceived extensive programme for listeners -in. A Royal Aerial. A 56 ft. " Turret " Wireless Mast for His Majesty the King of Italy. by the B.B.C., and only four of these were The Marconi Co. have promised to give offering any adverse criticism.In view demonstrations, and to exhibit some of of this 2 L 0 hopes to make this type of their latest receivingsets, while 2 L 0 will despatchedtothepointswherethey evening a fortnightly feature. provide the music.A large open-air dance are needed. * * floor has been laid and altogether the fair * " The Merchant of Venice." should be a great attraction. THE second play to be broadcast from Local Stations to Remain. 1 2 L 0 willbe" The Merchantof Restriction on Plays. EVERAL of ourreaders have been Venice," to be performed on June 12th. AT a meeting of the Society of Authors, k../ asking me if the B.B.C. intend to link The story of the play will be found on Playwriters, and Composers, it was up the whole of the B.B.C.'s stations page 628. unanimously passed that no member with land lines and have only one pro- of the society should permit his works to gramme transmitted.I can assure them Broadcasting Committee. be broadcast without a fee, and that the thatthisisnot to be thecase.The rr HE committee under thechairman - rocietyshould benotifiedthe amount B.B.C.aregoingtocontinuedistrict 1 ship of Major -General Sir Frederick offered. broadcasting and they are still going for- Sykes, which was appointed by Sir * * ward with the erection of new stations in WilliamJoynson-Hickstoconsider the The Largest Aerial in the World. thedistrictsnotadequatelyservedat agreement between thePostOffice and ANEW and powerful station is to be present. theBritishBroadcasting Company and built in Ger- thefutureof many, and I broadcasting, is now am toldthat the meeting three times station will have for a week. A consider- the aerial masts two able amount of evi- mountains 5,680 ft. dence has been given and 3,083 ft.high by representatives of respectively, a n d the Post Office, the nearlytwo'miles British Broadcasting apart. Company, and the manufacturing and trading interests Wireless and t h e concerned. Derby. * IAM givento * 1 understand that A Lonely Station. wireless will ASMALL island, againbe usedto near Iceland, control trafficat uninhabitable Epsom Races. A except for asmall special transmitting wirelessstation, is set will be installed to be let for hunt- in the Grand Stand, ing.The operator and to a number must have a cheer- ofcars. Ifthe fultime,as the traffic is unduly island is notedfor congestedatany blue fox and polar point messages bears. will be sent round andcarswillbe Cadetsat Sandhurst undergoing training infieldwireless work. ARIEL POPULI/' Ft7if.:'; (ii E ANNOUNCER'S DAY. By CAPT. C. A, LEWIS. This is a sketch of those hectic days a few months ago when the Broadcasting Company was just formed, when the day was too short to dream of getting through the work that lay before one.It is not, however, the state of affairs at present, and the writer will be excused, no doubt, if he has coloured his picture a little too highly. Much remains to be done in the organisation of our programmes, but our Staff is now able to cope with the work. In the glorious days of old it was not ---but that was half the fun.

One Side: tions will be held by the programme staff- theannouncing and supervision ofthe ABOUT seven -thirtyany evening in a suggested enlargement and improvement evening programme. Then his day's work is perhaps20,000homesormore of some part of the programme, the best only just beginning. crystals are being adjusted, .valves way to circumvent some barrier placed in He has then to scrape in a little food- are being turned on, condensers twirled, as the company's way-and there are many -- fuel -to keep the engines running-between the innumerable Mr. Jones and Mr. Smiths by an organisation whose interests six -fifteen and seven.There is no time for wait forthe opening chimes from -the supposedly conflict with our own. thehalf -an -hour digestiveperiod ! He Broadcasting Station. It is a wild rush. A fight, with at spice of digestsas hereads the news bulletin. " Two minutespastthehalf,"says adventure init,seeing that every day (Now you know why his voice is a bit Mr. Jones." They ought to be on by now. brings fresh problems, fresh difficulties, and " down," Mr. Brown !) Then at seven -thirty I wonder if there's anything wrong with the fresh obstacles that must be overcome. the night's work begins in earnest.The orchestra arrives, the first item is announced, set ? "And he commences to twirl the Lunch-time comes in a flash.Tea -time condensers more vigorously than ever. seems to be about three o'clock, and before off we go. What do you think the announcer " Five minutes late again ! " says Mr. he knows that the day has passedthe does while they are playing ? He rushes off Smith, pulling out his Ingersoll. " I do wish to another part of the building and listens to they would get a decent clock at the station ; them. " That trombone is playing too loud," nothing is more irritating than to sit and--,-- shouts the engineer ; " cut him down a bit." ah ! there they are ! "-and he sits down to The announcer forthwith attempts to do so. enjoy or criticise the concert. Then Miss X. has lost one of her songs, and wishes to change her items.By this time The Tired "Voice." the orchestra has finished and the next item " Idon'tknowwho'sannouncing has to be announced.No sooner is this to -night,"says Mr. Brown to his wife. started than someone rings up to complain " He sounds as if he were going to sleep. of fearful oscillation in the Belfast district, As if we weren't all tired and depressed and while the announcer is advising him to enough in the evening without having to buy a set of direction finders, the orchestra listen to a voice droning away like that ! stops again. I shall write up to them and complain.It, End of a Trying Day. must be easy enough to get a cheery fellow to talk in the evening.Why, I beliei-e I " I do hate these waits between each could do it better myself." item !" says Mr. Smith. " Why can't they " Who does the announcing ?Do you announce the items as soon as they are over, know, dear ? " asks his wife. instead of waiting like this 7" While Mr. Smithissayingthis,the Oh, one of those chaps who arranges announcer is doubling down the passage to the programmes,Ithink,"repliesher the microphone in the studio, using the most spouse. " But there'snothing in this unpardonable language about the gentle. announcing, anyway, and it ought to be man from Belfast. done properly ! " And so on. And so it goes on. Ten -thirty comes, and The Other Side: after hisfinal" Good -night," our much. - c ri ticised- announcer emerges into the Strand. just for the sake of argument, then, let He gets on a 'bus and goes rolling down to us look at the other side of the picture. CharingCross. Theelectricsignsare About a quarter to nine the " announcer," glitteringeverywhere,and - thehappy as he is known to the general public, boards 2 L O'spopularannouncer, Uncle Cactus," crowds are just emerging from the theatres. his train or 'bus and leaves for the office. Capt. C. A. Lewis. And so as Big Ben tolls out eleven, the He turns over in his mind, as the 'bus jolts 'bus, bearing its precious burden, kilts on along, the long list of things that he had " announcer," who is among other things through the depths of London. no time to do yesterday, and doubts if he an " uncle," leaps for his hat and dashes A fourteen -hour day, Mr. Jones !Four- will find thne,to do to -day.Arrived at the off to the " Children's Hour." teen hours!Trying to give you and your office about nine -thirty, the rush begins. family and your children an evening's A hundred letters from his beloved nephews A Frantic Rush. pleasure.I admit I was a bit off-colour to- and nieces await him. Each separate little night, but now, this is strictly between our- letter, sometimes so carefully written that Here, for the moment, he will forget his he knows it must have taken an hour of worries and troubles.The hour must be a selves-would you care to tackle it, seven patient toil to form the letters, has to be jolly and a happy one. His remaining energy days a week ? goes to the accomplishment of this.He There is one thing about it ; you don't considered and answered. He lingers, need rocking to sleep on this job ! perhaps, longer over these than he should. trusts to the personality of his colleagues pileofmanuscripts :Lectures, and his own imagination to carry the thing Next a through. The secretof success of the irtieles,children'sstories,followedby " Children's Hour "-if it is a success-lies mother heap of criticisms and suggestions. in the fact that the " uncles " themselves Z1,000 in Prizes. Day Too Short. love their work and the children, too. For full details of this magnificent As he attempts to wade through these, At six -fifteen the hour is over and, if our offer,seeNo. 3of" Wireless the telephone hardly ever stops ringing. " announcer" is lucky, he has nothing more Review and Science Weekly," out There are future engagements that must be to do than go back to the office and sign up on Tuesday, June 12th, and obtain- made, confirmationsofothers, and the the day'S mail he has dictated and go home. He may be away by seven. able at all Newsagents' and Book- hundred -and -one things that crop up in a price 3d. young, rapidly -growing organisation. But suppose for a minute that he happens stalls ; In the middle of all this, hurried consulta- to be " on ',that night-i.e. entrusted with 612 Pupillar Wireless Weekly, June 9th, 1923. SCOUTING AND WIRELESS. By H. RUSSELL JONES. Wireless is becoming one of the most popular features of scout work, and no more interesting or instructive subject could be chosen.This article recounts the progress made in this direction by one of the first troops to introduce it into their programme of summer activities.Doubtless scores of other troops will follow this splendid example during the coming months, and wireless will become an indispensable feature of camping and field operations.

HOW eagerly did certain members of a the detector (carborundum and steel With a and the trek cart loaded with" aerial North Wales Troop- of Boy Scoutspotentiometer) signals began to" come masts " (tent poles), etc., and off we went, await the day (in .1919) when thethrough." It was our (now) old friend F L looking like a mixture of an anarchist gang war -time W/T restrictions would be re- with his weather report, and .prese,ntly on and a crowd of rag and bone merchants. moved.Waiting -for broadcasting to begingoing doWn to 600 metres Seaforth (G L V) What a glorious week we had !There was wasn't in it !For months and months had and several ships were heard.Words failed hardly time to eat or sleep, and if it had we practised Morse, and made strenuousto express our delight, and after a period -of lasted much longer it is very doubtful if efforts to master the art of " iddy umpty." listening -in until we were nearly frozen, we some of us would have survived.One of Sheets of paper had been used in, drawingreturned to the club -room.The aerial and the boys, when wearied out, was heard to diagrams and sketches of the apparatus toearth mat i(a roll of wire netting) were left say," After all, one must make sacrifices in be constructed " as soon as these bloomin' in position on the mountain. the cause ofscience " !Onedifficulty, restrictions are removed." Soon the news of our success spread however, slightly marred our joy, and that around, and the scoffers scoffed a little less, was our inability to receive C.W. stations A Primitive Set. and the enthusiasm of the troop was good above a thousand metres.Try as we would At last the great day dawned, and in wentto see.When could we go again ?That only spark stations (natural note) could we our application for a crystal set licence. was the great question., get above this wave -length.The set would After a week or two of impatient waiting the not oscillate above this. imposing O.H.M.S. letter arrived, and we New Use for Aerial. Imagine bow we felt during the Marconi were free to get on .with the making. of our Two of us.being, free on the following Wed- speech tests, which lasted for three weeks. apparatus and to erect an aerial.Thennesday, it was decided to hike up again on Not one single word did we hear.At last our troubles started.There was no place that day.After wearily dragging the set the " mystery " was solved.The reaction suitable for the erection of an aerial tofor many miles imagine our dismay, on coil was not large enough to cause the set to enable us to get decent signals on a crystal aniving at the scene of our former labours, oscillate above a thousand metres, and we set, and, of course, we didn't dream ofto find that an enterprising fanner had used couldn't find the carrier wave to enable us spending what was, to us, a small fortune on the aerial to repair a broken fence, and the to make a critical adjustment for speech. valve apparatus. Soon all was well and we received C.W. on After much solemn discussionit was all' wave -lengths. decided to make a portable set, and after having had the licence amended we pro- ceeded to do this.Mothers were besieged And So It Goes On. for cardboard jam containers for inductance Then the event occurred.Dame Melba tubes, old electric bells were stripped in order was to sing from the Chelmsford. Marconi to obtain wire for coils, and many money- station._ The dayof preparation for the making schemes evolved in an attempt to 1.,.ception of that concert will live long in raise the necessary for a pair of high-resist- my memory.The accumulator was freshly erre 'phones.Eventually we were able to charged, a new H.T. battery made up, new buy a re -wound singleBrown " earpiece. insulators fixed to the aerial,all connec- At last all was ready and a weird -looking tions tested, and everything looked to that would assist our chances of a successful crystal set, mounted in a Tate sugar box, iThis photograph shows the simple nature of the made its appearance in the club -room. The components of a variometer tuned crystal set. reception of the music and speech. " non-scientific " members ofthe troop Just before 8 p.m. (the time of the con- were highly amused at our amateur efforts. cert) one or two long -wave C.W. stations A test aerial, about 15 feet high and 12 feetearth mat in the construction of a home for were tuned in as a final test.Then as we long, was erected, but in spite of all adjust-a happy crowdofchickens !However, came down to 2,800 metres Chelmsford's ments and tuning not a signal was received. minor setbacks of this nature didn't upset carrier wave was heard, and the set was then The " scoffers " scoffed more than ever,us much, and our enthusiasm still ran high. kept just off oscillation point (" radiators " and the noble band of " scientists " were In a month or two the novelty of listening of 1922 please note !).Soon the music came very depressed.It was then decided that in to the longer wave European spark through, and on this single -valve set at a the aerial arrangements were far from satis-stations and ship stations began to die away distance of 200 mites from Chelmsford the factory, and that we must get an aerial and we longed for a valve. . It was ever thus concert wasclearlyreceived.In these high up " and not screened." Only get among WiT amateurs !Give 'em a crystal days of improved circuits and apparatus as high as you can and all will be well,"set and they want a valve.Give 'em a (for great strides have been made since quoth a wise one.So the next Saturdayvalve and they soon want two, and so the 1919) such a result is quite ordinary, and afternoon we bought a hank of galvanisedgame goes on, until a. 6 -valve receiver, loud with a crudely made set and at the first iron wire and set out far the Cambrianspeaker, and a transmitting set doesn't attempt I can assure you we felt very proud heights. satisfy 'em !Still,to get on with the of ourselves. " story." The next move was to obtain transmitting True Enthusiasm. licences, and a kindly P.M.G. granted us After climbing to a height of about 2,000 Joys of a Valve Set. permission to use two portable10 -watt feet two very high trees were discovered, The financial position of some of the inter- spark sets on a wave -length of 180 metres. and soon we had a decent aerial erected.Iested members began to improve and a Many interesting experiments were carried shouldmention that it was a winter's after- valve was purchased.The usual accessories out with these Sets, and the calls of 2D A and noon, with the snow lying thickly on thewere gathered from the junk heaps of older 2 D B were often to be heard.However, ground. We were in shorts and had our scientific friends. The day ofbasket " shortly after this the wireless enthusiasts sleeves rolled up.But minor details likeandslab " coils had arrived, and soon the were parted, and so ends the story of a the snow and icy blast were forgotten in the valve set was ready. troop's W/T activities. effort to obtain signals. The Easter holidays were now at hand, To -day as I " listen -in" on a " posh " four - Soon all was ready, and the earth mat ,and four of us had the good fortune to secure valve set with loud speaker, those earlier buried in the snow." Telephones " were the loan of a hut, on the sea -shore, for a efforts and experiments seem very, primitive, pift on, and after very careful adjustment of week.Blankets and grub were got ready but the experience gained was worth it all. l'opnfai frirelevs Weekly; June 9/b, 1923. THE CONSTRUCTION OF A SINGLE -VALVE RECEIVER. By H. G. HERSEY. This set differs from those previously described by the author in POPULAR WIRELESS not in efficiency, but in type and wave -length range.It is worthy of note that every piece of apparatus detailed by Mr. Hersey has actually been constructed, tested and plioved to be satisfactory before being written up for POPULAR WIRELESS.

THE valve receiver I am about to describe ably upon a piece of ebonite strip). These A piece of wood 1 in. thick is cut as per isto be more of an experimental are lettered A, B, and R 1and R 2. A Fig. 6:in the position shown a circular nature and to cover from 150 metres second piece of wood, half an inch or thicker, piece of wood 14 in. in diameter is screwed. to 4,000. metres.. This receiver when built is now cut, 31 in. by 5 in.., and screwed It is over this the coils are to be placed.At will be ideal for the reception of broad- firmly in the shaded portion X.This is the end a strip of ebonite is screwed, and casting, and at the same time enable the the back support for the coils.Upon this to this two pins (valve legs) are screwed reader to reach the longer wave -lengths pt piece of wood two coil holders are mounted; 11 in, apart, so as to plug into the tuning present employed by aircraft, Dutch con- one fixed, and the other upon a hinge so stand holders.Thisis shown better in as to open like a book. The holders should Fig. 7.As many of these as possible should, s" be constructed according to' Fig. 3 from a be constructed ;if possible, one for each , piece ofin. wood, and a strip of ebonite mounted in the position shown. x®R.1 Winding the Coils. R.27* Upon the ebonite two valve sockets are Z mounted 11 in.apart.The fixedholder 17C2 A1 should be mounted in the position Z, and .8 the swinging holder should be mounted in ymm.my., 7 FIG. I. the position Y upon a hinge, the holders being aboutin. apart. Two short lengths MEP= E E ZafffWifilii i rildiffin. of flex are now connected to the terminals 7' and the sockets by connecting A and B to the fixed holder and R 1 and B 2 to the coil, and -tilelatter could then be per certs, and Paris transmissions ;also by manently fixed in the holder, connections going down below 200 metres it will enable from the inner and outer ends going to the the reader to hear some of the excellent two pins. amateur transmissions.From the above it will be understood that one tuning coil The Detector Panel. can hardly be expected to fulfilallthese It should here be well noted that the purposes efficiently ;therefore a number of connections of the coils to the pins should basket coils are to be constructed, each be the same throughout the set-i.e., always ha ;Mg its particular range of wave -lengths. connect the inside end to the lower pin, or vice versa, and always place the coil upon, The Coil Holders. the holder in the same way-i.e., the winding The tuner will be dealt With first.For from the centre clockwise or anti -clockwise. this a piece of wood is cut about.5 in. by 7 in. . If this is done, when the reader connects (Fig.1) ;on the right, in the position up he may have to reverse a pair of leads. shown, four terminals are mounted (prefer - and the set is then ready for all times and for any of the coils, otherwise he may have noving holder.This completes the coil to reverse certain connections for every holder so far, and we can proceed to make other coil he may plug in circuit. the coils. A A piece of wood 11 in. in diameter is cut - (Continued on page 014.) ZBON/TE as per Fig. 5, and 11 knitting -needles are STR/P placed around the circumference, each 21 in. long. Now wind up the coils basket fashion. The first five coils are wound with No. 26 S + D.C.C. wire, the turns being 25, 30, 38, 50, 67 ;after winding, each coil is waxed and the spokes removed.The second range of VALVE coils should be wound with No. 32 D.C.C. SOCKETS wire with the following turns, 90, 115. 148, 185, 220, in the same manner as the previous coils, giving us the following table of coils and approximate wave -lengths With -0005 variable condenser :

Coil No. ofAerial CondenserAerial Condenser No. Turns. Series. Parallel. 1 25 140- 250 350- 395 2 30 160- 260 380- 450 3 38 180- 300 430- 550 4 50 215- 360 540- 700 5 67 300- 485. 670.- .925

6 90 385- 640 - 900-- 1,200 7 1l:;490- 800 1,100-1.530 F10.3. 8 I4-640- 1,050 1,470- 2,000 9 185 825- 1,325 1.900- 2,500 10 220 940- 1,530 2,200- 3,300 -4- Having constructed the coils, we next 4, require a holder.This is made as follows : 614 Popular Wireless Weekly, June 9th, 1923. portion of the slate should now be lightly four valves ?If so, a 6 volt 40 amp. or rubbed with -ordinary lead pencil.The two 6 volt 60,amp. accumulator should be pur- THE CONSTRUCTION ends of the slate covered -with copying lead chased ;but if a single valve is to be the are now bound with fine wire, so as to make limit, a 4 volt 20 amp. accumulator will be OF A SINGLE -VALVE good connection- with the pencilling. found to suffice.The telephones and valve RECEIVER_ The two ends of wire are now connected are the two final items that we cannot make between the grid condenser terminals.Tlin ourselves. For the 'phones the reader (Continued from page 613.) grid condenser and leak are to be seen in should purchase as good a pair as his means the diagram (Fig. 11) between the switch will allow, of about 2,000 or 4,000 ohms and valve panel. The series parallel switch resistance. The valve should be of the hard The valve panel may now be considered, is the next component, its function being.or R type, purchased at about 15s: or and, seeing that the set is to be- of an to place the aerial tuning condenser either 17s. 6c1. in series or parallel with the aerial tuning experimental nature, should consist of a The Final Lay -out. valve holder and filament resistance only, inductance.The switch may be made as together with the necessary terminals. per Fig. 10, or, if purchased, it is known as With all the components purchased or The panel itself may consist of a piece a reversing switch.It should be connected built, the reader should wire the set up as of ebonite for preference, 6 in. by 4 in., as shown. per Fig.11, and it should resemble the mounted upon a suitable base or box about For the aerial tuning condenser the reader photograph.Place a largecoilinthe 2 in. deep.The valve holder may consist is advised to purchase a .0005 mfd. variable fixed holder and a size smaller in the moving of four valve sockets purchased at 2d. each, condenser, and ifpossible an extension holder; now advance the moving coil to handle should be fitted so the fixed coil and adjust or turn the variable as toreducecapacity condenser.Chirps should now be heard. effects when the hand is If- not, reverse the connections upon R 1 placed near for tuning. A and R 2 terminals of tuning panel, and the .0005condenserwillbe set should oscillate.If by approaching the foundconvenientlylarge reaction coil the set breaks into,a howl, use enough to give each coil a a smaller reaction coil.When using the fair range of wave -lengths, smallest coils in the A.T.I., a size larger and not too large so as to Will, usually be required for reaction. render tuning difficult upon 7 The reader when using .this apparatus short waves. for the reception of broadcasting should The condenser shown in adhere to the regulations regarding reaction Thisphotograph shows the finished partsand lap-ont of the eingle- Fig. 11 is of larger capacity, and cut it out.This is done by removing valve receiver. and used merely for illustra- the reaction coil and shorting tither R 1 tion purposes, the writer's and R 2 terminals of the tuner or detector and mounted in 'the position shown ;or a .0005 being enclosed in a wooden cabinet., panel.. With a set so constructed, my reader mouldedebonitevalveholdercanbe should make an effort to learn the Morse employed. A filament resistance suitable Choosing the Batteries. code, andhe will then spend many a for panel mounting is now obtained, and For the high-tension battery the reader pleasant evening listening to the various mounted as shown in Fig. 8.Ten terminals is advised to buy flash -lamp batteries and ContinentalstationssuchasGibraltar; are next mounted upon the panel as per connect them up in series ;ten to twelve Malta, Berlin, Warsaw, Nauen, Karlsborg, Fig. 8, and lettered accordingly. batterieswillbe found sufficient. The Paris, and Rome, only to mention a few, For the panel wiring connect the filament batteriei for preference should be housed in a 11 of which are easily received upon a single- circuit first, using well -insulated wire of \ al\ e receiver using reaction. No. 20 or 22 gauge ;connect L.T. - to left-hand filament socket and L.T. + to £1,000 IN CASH PRIZES. filament resistance ;from the centre of Itis not too late to submit entries for the latterconnecttoright-handfilament splendid competitionsinrespectof which our companion paper, " Wireless Review and socket ;connect -F to left-hand socket and Science Weekly,"is offering prizes totalling 0 to grid socket. to £1,000in cash.For full particulars see No. 3, on sale Tuesday,12th inst.,and Now connect H.T. + to R 1 and R 2 obtainable fromall newsagentsand book- to plate socket.From H.T. - connect to stalls, price 3d.Apart from the question of P1 and P2 to L.T. competitions, " W ireless Review and Science Weekly "isinitself aprizewellworth securing,and themodest outlayrequired Construction of Condensers. willplaceatthepurchaser'sdisposal a a suitable box with two terminals upon group of articlesfromcontributorsthat We next require two small fixed con- the front or side, and labelled and - hithertona periodicalofthis nature can densers of about .0003 mfd.These are boast of securing.Sir Oliver Lodge, F.R.S., For the accumulator the reader should Dr. Leede Forest,Sir William Noble, constructed by cutting eight pieces of tin- first consider the size of his pocket.By M.I.E.E.,Dr.J.A.Fleming,F.R.S.,Prof. foil or copperfoil 3 in. by 14 in., and several this I mean not to consider the cost of J. Arthur Thomson, M.A., LL.D.. Prof. A. O. pieces of well -waxed notepaper 21 in. by Rankine, O.B.E., D.Sc., constitute but a few various makes, but to think how far his ofthe great scientists who are supporting 2 in.Four pieces of foil are used for each wireless activities are going to take him. WirelessReview and ScienceWeekly," condenser,asper Fig.9,the overlap Is he going to stop at one valve, or build mostly in both in advisory and contributory being bent over and a short piece of flex up a set, a little later with three or perhaps capacities. soldered to each end. The condensers assembled, they should be bound between two pieces of cardboard with thread and the whole well waxed. One condenser is connected inside the panel between the 'phone terminals.This con- denser istoby-pass the high -frequency currents set up in the plate circuit. The second condenser is to be the grid condenser, and should be connected between two terminals mounted upon a piece of wood 31 in. by 21 in. by 4 in.The wood should be recessed upon the underside for about 1 in. and the condenser let in, finally being sealed with wax. For the grid leak a piece of slate pencil is obtained 2 in. long; the ends of the slate for aboutin. to 1 in. should be well rubbed with copying lead all round ;the centre Pnptil Ti'ireless Tree!,.1y, June 9th, 1923.

Choosing Head -phones for Broadcasting. muchdependsupontheefficiencyandcomfortofyour AShead -phones,adiscriminateselection isof vitalimportance. GECoPHONE

Head-phones-specially designedto meet Broadcasting requirements-are thelast word inefficiency,comfort,andfinish, andembodythefollowingspecialfeatures :-- (I) They are contained in aluminium(2) By means o' two steel wires,which slide(3) The connecting Cord, which is of cases connected by a single leatherinside the leather head -band, and whichthe best possible quality, and which testoffive times the head -bandoffinestpig -skin,thisare connected to the Receivers by ball -willpass a joints " GECoPHONE Head -phonesstandard strength test required by the arrangement having been found toreadily adjust themselves to comfortableG.P.O. specification,is fixed at the adaptitselfto thehead withthedimensions, and are particularly suitablesidesothatitwillnotbecome greatest comfort. for ladies as they do not 'catch' in the hair.entangled with anything when in use. Comi5lete with 6 ft. cord and tags. Prices : (120 ohms) 29;'6 each ;(2,000 ohms) 31,'- each ; (1,000 ohms) 32;'- each ; (6,000 ohms) 40/- each. Sold by principal Electricians, Stores Wireless and Musical Dealers.

Sole SellingAgents forthe Music TradersinGreatBritain and befall Columhia GraphophaacCo.,Ltd.,102-103,arkc.,rudi Road, E.C. (Manufacturers and Wholesale only) THE GENERAL ELECTRIC CO., LTD., Head Office :Kingsway, London, W.C.2 616 Popular Wireless Weekly; June 9th, 1923. No Boundary in the Ether World

Radio Signals travel at the rate of 186.000 miles a second. Naturally, signals get weaker the farther they travel: to users of couldnever If a signalistoo feeble. to operate the Di ector Valve, it be heard, no -matter -how many stages of ainplifteatten; wore used after rectification. But the LISSEN REACTANCE (P. PATENT) .31E7'110D- BUILDS VP WAVE ENERGY before passing it on to -the Detector- Valvri, antiad makes easily heard signals that would otherwise be in- audible. ririr. LISSEN N Visethe LISSEN REACTANCE (P. PATENT) Method of H.F. -.amplification, and so build with your own hands a receiver that shall be capable of spanning great distances. - LISSEN REGENERATIVE -REACTANCE PRICE Reactance (P. PATENT). Complete Makes a receiversosensitivethat under many conditions both aerial and earth (P. Patent). connections may be dispensed with. Provides fully variable nou-radiating reaction in highly efficient form. Self -tuned; but the use of a new LISSEN Vernier Tondenser is recommended. (Price £2.12.6 1216, barely 1in. diameter.) LISSEN one -hole fixing-fitted in a few minutes. Blue print and One knob controls tuning and reaction. instructions Range, 150 to 4,000 metres-WITH REGENERATION OVER THE WHOLE RANGE. sent with each. AMATEURS-Counterfeits may be offered you. Take no sub- DEALERS-Order through factor,or stitute.Ifyour dealeris not equippedtoserve you, send send direct.Apply on trade beading direct tofactory,post free. fur list.

LISSEN REACTANCE (Prov. Pat.) LISSEN COMPANY Range 150 to 600 metres (6 tap- pings) complete 27/6 8-16, Woodger Rd., Goldhawk Rd., Range 150 to 10,000 metres (11 tappings)complete 32/6 Blueprintshows easyconnections. Shepherd's Bush, London, W.12. Lissen one -hole fixing. To be used for one or two stages H.F. Gives greatarnplifleatonevenonlotid 'PHONE 1072 HAMMERSMITH. signals.For great' range and power turn List to using LISSEN REACTANCE. N.B.-Woodger Roadis close to Goldhawk Road 1111.=1==1. Met. Rly. Station. Lissen Apparatus :Well thought out-then well made.

ow...... 00w...0"%ftwoomlasotoo"%i Get Better Results Perfect results from your Crystal Set by using with IndoorAerial GAMAGES for World-Famous Crystal " PERMANITE " 1-126 This Super -sensitive Crystal can be used in any type of "Cat's -Whisker ". detector. The Ceebee No. 3. Sensitivepoints can be quickly found, without any trouble." Permanite " gives THIS highlyefficient instrumentis given a most thorough test before CLEARER RECEPTION of music and speech with greater volume TRADE dispatch, and is guaranteed to give than any other crystal yet offered.It perfectreceptionoverabroadcasting lasts longer in use, and we guarantee it to SUPPLIED rarge of 25 mi!es. Wonderful results give satisfaction. can be heard at our Showrooms on this identical set attached to an Indoor Aerial. " Permanite " is Writeforour DEMONSTRATED Price 11:12 : 6 including Royalties WIRELESS CATA- dailyin our wire- LOGUE,postfree lessSalonduring on request. f Broadcasting hours. FOWLER & BRIGDEN PER PIECE, POST FREE. 130, Euston Road, King's Cross, London, N.W.1. 'Phone .MUSEUM 4827. Popular Wiretes's Weekly, June 9th, 1923. 617

SOME PICTORIAL FOUR -VALVE CIRCUITS. By OSWALD J. RANKIN. The author prefaces his description of four -valve circuits with a few remarks on the application of knowledge and experi- ence, and the necessity for the possession of at least a fair amount of both, before the construction of multi -valve wireless sets can be successfully attempted.

BY this time no doubt our valve enthu- The thing not to do is to rush into the job the erection of aerials, this being a job siasts have become more or less expert without knowing how to tackle it, and then, which calls for brute strength rather than in the gentle art of knob turning. on being disappointed, place the blame on brains. Those who have arrived at this stage have the diagram, book, tools, or materials. Our naturally " been through the mill," and con- friend A will make a few mistakes at first, A Short Cut. sequently have acquired that knowledge but he should be consoled by the thought that Practical knowledge is gained by actual that only comes through practical experience. the man who never makes a mistake never experience, and to acquire the necessary It will, therefore, not be necessary to enter makes anything.With regard to the aerial, theoretical knowledge I can think of no into a lengthy discussion on the operation it seems that the one who gets the highest bettersuggestion than theQ.and A. of valve circuits.It has already been said polewins.Apart fromtheinsulation columns of POPULAR WIRELESS.Each week that the success of any valve receiver will problem, there is nothing very intricate in (Continued on page 618.) depend almost entirely on experiments, and it may also be well to consider the individ- ual ability to carry out those experiments. One enthusiast, whom we will call A, may not have known how to drive a nail into a piece of wood before he decided to take up wireless, while another, whom we will call B,isperhaps already a fullyqualified mechanic.It naturally follows that B has the advantage over A, who must embody his first term of apprenticeship with his first attempt at making areceiver.B will know many little dodges of which A isignorant, and consequently be should turn out the best job. T Speaking from Experience. The idea which press on the reader's mind is this :At the present moment there is a prevailing notion amongst the younger enthusiasts that anyone can construct a Wireless receiver out of any old material, whether they be butchers, bakers,orcandlestick makers, and no matter if the material is purchased or dug up from the garden. A would-be listener -in A T I may first acquire some authoritative or un- authoritative information on the subject., and then begin to hunt around for a screw- H T ? driver.Being no screwdriver,nailsare next considered, and in the absence of a hammer these are often driven home by a brick. Soldering is quite out of the question, and RV' there are a hundred and one other little C things, all of the greatest importance, which are entirely ignored.This is no exagger- ation, but a true page from life. The writer AO having a practice as a " wireless doctor," 0- meets many cases such as this, and if he described them allit would necessitate writing a book.When motor -carsfirst began to boom, everybody did not rush home P and make their own cars, for the simple reason that they had no knowledge of -FI mechanical engineering.

Mx Essentials. OP s OP Os 10 Why, therefore, should anyone attempt to build an elaborate valve set if he has no idea of (1) the underlying principlesof telephonic transmission and reception, (2) electricalinduction,(3)insulationpro- perties,(4)high -frequency currents,(5) O capacity effects, and (6) combining theory with practice.We are told that if a job is A T I Worth doing at all it is worth doing properly. In other words, if we cannot do it properly, C.) L T ? 0H T we had better leave it alone until we have r4.1 learned how to do it. D L C18 Popular Wireless Weekly, June 9th, 1923.

headphones.If high -resistance 'phones are The tuning will be very critical, and it will used they are connected direct to the plate probably be necessary to shunt the second- SOME PICTORIAL FOUR - of the last valve and the H.T. positive. -- ary sides of both H.F. transformers with A 1 or 2 mfd. fixed condenser D is shunted .0002 mfd, variable condensers. B and D VALVE CIRCUITS. across the high-tension battery: correspond with the condensers in Fig. 2. (Continued from page 617.) A Frame Aerjal Set. Allthesecircuitsaresuitablefor Diagram 3 depicts a rather more compli- operating loud speakers within reasonable cated circuit employing the first two valves distances from thebroadcasting station numerous questions are answered by experts as H.F. amplifiers, the third as a detector, although obviously four valves would not and it is a good plan to clip them out week and the fourth as a L.F. amplifier. Variable be necessary in cases when the distance by week, and paste them in alphabetical R.F.transformers are used assuitable was but a few miles. order in a scrapbook.In a very short coupling devices, but this may be replaced Finally, it must be remembered that in time the book becomes almost priceless. A by plug-in transformers or anodecoils multi -valve circuits the greatest care and polytechnicinstitutionwouldprobably ifdesired.This circuit is to be recom- attention must be paid to the wiring, in charge a fee of 5s. and upwards for the same mended where signals require strengthening order to avoid capacity effects, leakage and amount of information contained in these such as in the case of frame aerial reception. risks of " shorting." columns each week, and if we consider that this is real expert advice for the modest sum of threepence weekly, we should certainly be rather foolish if we did not take advantage of it.Select a question which you would B like to ask an expert. Study the accompany- ing reply, imagine the expert in front of you answering your question-and you have learned something.This is undoubtedly the shortest cut to a thoroughly reliable theoreticaltuition. An H.F. Stage. Fig. 1 represents a 'good all-round four - valve receiving circuit, employing the first valveasahigh-frequency amplifier, the second as a detector, and the third and fourth as low -frequency amplifiers.The H.F. valve is coupled to the detector by means of a simple plug-in air core transformer, and this should have a .0002 mfd. variable condenser shunted across the primary winding. A and B are 001 mfd. fixed condensers in shunt with the primary_windings of the L.F. transformers, and C is a fixed condenser of .01 mfd. capacity connected in shunt with A T I the 'phones and the high-tension battery. If low resistance 'phones are used it will of H T course be necessary to include a telephone E transformer as shown in Figs. 2 and 3. ojs High -resistance 'Phoneswillgivegood results on this circuit.The input terminals from the aerial tuning inductance are in- dicated by the initialletters A.T.I:, the aerial side of which will be connected to grid and the earth side to L.T. negative. Tuned Anode Coupling. rQo Fig. 2 shows a. circuit in which the valves are similarly arranged-i.e. one H.F., one detector, and two L.F., but instead of em- ploying the transformer, a tuned anode couplingisprovided.Reactionisalso arranged on the anode coil, this being per- missible on the broadcasting wave -lengths. A represents the connections for the anode coil, and R the connections for the reactance coil.A suggested tuning circuit suitable for a receiver of this description is shown in Fig. 4.The terminals R, A, and A.T.I. are connected to the corresponding terminals on the valve receiver. A '0002 mfd. variable condenser should be shunted across the anode coil.An alternative method is to construct two small cylindrical inductances arranged on similar lines to a loose coupler. Full details of such a coupling were given in POPULAR WIRELESS, No. 41. B is a .001 mfd. fixed condenser connected in shunt with the primary winding of thefirst L.F. trans- former, and C isanother of the same capacity similarly connected to the primary sideof the telephone transformer.This, 1111111.111111111101110141 of course, is a step down transformer, having - more turns of wire on the primary than on the secondary, for use with low -resistance Popular Wireless TVeekly, June 9th, 1923. tW)

omivAmpLION NH 11111 11111 IT

fl1i®

In 1887.. Mr. Alfred Graham demonstrated the ediroe first practical Loud Speaker. In 1893.. GRAHAM LoudSpeakers placed upon the market. In 1894.. FirstusedintheBritishNavy. Transmitters applied to Phonographs -the reason why the AMPLION for Loud Speaker reproduction. is undeniably the finest Radio Loud Demonstrations by Prof. Mc Kendrick Speaker,and recognisedasthe at the Royal Society. World's Standard. in 1896.. NavalTelephonesdevelopedand It will be seen that the AMPLION adopted by the Admiralty. is not merely produced to meet a In 1898 ..Watertight Loud Speakers patented. sudden demand butisthe result Fitted on board many War Ships and of years of experiencein Loud Mercantile Vessels.Telephonic Sub- Speaker design and construction. marine Signalling System devised. In 1902 ..Complete Loud Speaker installations on centralbattery planerected on War Ships as sole means of com- munication. Ask for Folder In 1906 .. The most extensive naval installation to dateincluding exchange system fitted to H.M.S. Dreadnought. ALFRED GRAHAM & CO., St.Andrew'sWorks, :: Onwards..Graham Loud Speakers applied to CroftonPark,London,S.E. 4. all sorts and conditions of service at home and abroad, ashore and afloat. Sy denham 2820-1-2Navathada. Catgreen. London SCOTI, IND To 1919-No less than 12,000 ship installations Mr. F. Milligan,25-, Renfrew Street, Glasgow. carried out. JIIEI.1 .V1 In 1920.." AMPLION " Loud Speakers pro- Mr. A R Monday, 41, Chichester Street, Belfast. duced for Wireless and "AMPLION " Trade Mark registered. In 1922.." AMPLION " standardised by lead- ing manufacturers of radio apparatus.

Detnonstrations at our Showroom : THE ALGRAPHONE SALON, 25 6, Savile Row, Regent Street, London, W.1 'Phone : REGENT 1075

:11--71 IIRion Immomom v MEE 620 Popular Wireless Weekly, June 9th, 1923.

Progress -and Improvement are the features of the age-nothing stands still.Every month that passes something fresh- a new idea is introduced to improve our famous " DESKOPHONE "Sets. Thisalso applies to our well-known Accessories.

The H.R.C. High -Tension Battery. Have you seen our latest patented High -Tension Battery ? This is invaluable to all amateurs, as it permits of r 1, 3, and 4.4- volt variations.Trade inquiries specially invited.

PRICES : 36 -volt unit 8/- 63.:Volt unit - 13/6 126 -volt unit : 7 : 0 Double Pole Sterling Headphones. The new type Double Pole Sterling Headphones, sold at the old price, are equal in efficiency to any 'phones on the market. Trade inquiries are specially invited for these 'phones. PRICE £1 : 12 : 0. Writefor ILLUSTR.4TED CATALOGUE. Price 3d. post free. THE DESKOPHONE TWO -VALVE SET (P.O. No. solo.) Two -Valve Set, Tuner, High -Frequency Amplifier and Detector, complete with Accessories, including Headphones, H.T. Battery, THE HOLBORN RADIO CO., LTD., Accumulator, Aerial, Lead-in Wire, and Insulators. 267, HIGH 'HOLBORN, LONDON, W.C.1. PRICE COMPLETE g12 : 17 : 6 . PRICE WITHOUT ACCESSORIES89 : 17 : 6 'Phone HOLBORN 2368. .. The Trade Supplied. Royalties, £3 : o : o extra. Valves, extra.

IIII IIII I I III I III I IIII I II IIII I III I IIII i I II alI I I t I I I I I IIIIIIIII I III I I I III I II I I II III IIIIII I I 1I lIIIIIIIII I lr- Provision is made for adding other Units to Amplify. e "ritons".04.04."ranowave"raokw".","etow...... -..."4,0) SUPREME TO ANY OF THEIR TYPE ---DEPENDABLE AT THE PRICE. RADIO SERVICE J B HEADPHONES PRECISION VARIABLE CONDENSERS 4,000 ohms Best French £0176

"Brunet" . 1 THE ACME OF 26 SIDPE . 1 00 PERFECTION. 8,000 SIDPE 1 26 TJ /V Ft A. 1%1 T E E 13 4,000 , NOT UNDER STATED CAPACITY. Single with Accurately and completely assembled. Handles, BBC.. 0120 INCLUDING KNOB AND DIAL. 4,000 ohms Double Head- Large metal to metal Bearings. One band, BBC 1 00 hole only required for fixing to Panel. 8,000DittodittoBBC 1 26 British made throughout, ::therefore best:: VALVES OF MERIT Hard Dutch Valves for Amplification 11 6 Soft Dutch Valves (Excellent Rectifiers) 106 Telefunken Valves (Noiseless Amplifiers) 12 6 Full Guarantee given with each '001 - 8/6 COIL HOLDERS For Duo -LateralCoils Instrument. '0005 - 7/. Best Ebonite 2 -Way .. 6 6 3 -Way .. 0 8 6 Packing and postage extra, '0003 Add6d, forPostage' One only,9d. - Two, 5/9 Vernier-4/ - BASKET COILS Set of Six DELIVERY BY RETURN. 170-2,000 Metres ..(By Post 3/.) 26 0 THE VAIRIOPHONE " Crystal Receiving Obtainable through your Dealer or direct from :- Set, comprising :-Variometer, Crystal Detector, etc., mounted on Polished Oak.Complete, Assembled, 10 -; Unassembled, 7 - Add 1/.for Postage JACKSON BROS. FREE PRICE LIST Condenser Specialists WATERLOO ELECTRIC CO. 8, POLAND STREET, OXFORD STREET 129, Waterloo Rd., London, S.E.1 1LONDON, W.I. TRADE ENQUIRIES INVITED. 'PHONE (frywitiftrit"ow'Phone: Gerrard 6187 0 b"04ftow~ 4 HOP 5649. OPEN TILL 9 O'CLOCK SATURDAY Popular Wireless Weel.7y, Jtcre 9th, 1923. 621

METHODS OF MEASURING THE PROPERTIES OF VALVES. AU serious experimenters should devote a little time to the study of characteristic curves, as these can almost be styled the link between theory and practice. Much valuable knowledge can be gained by plotting the behaviour of a valveon test, and in this article the writer clearly shows the various comparatively simple methods of enabling the required measurements to be carried out.

THE properties of a thermionic valve and voltage being given by It and E, respec- dealing with valves which are somewhat which determineitsbehaviour and tively.It should be noticed that the fila- " soft. the uses to which it can be put are ment voltmeter, Et, is connected across the The operations necessary for taking a best studied from a characteristic curve, filament and the ammeter ;in consequence characteristic curve are as follows, reference and the .method of obtaining these curves, we are actually measuring the voltage drop being made to both Figs. 1 and 2. as described below, is what is generally along the filament, plus the drop across the known as the step-by-step method. ammeter.Were the voltmeter connected A Universal Principle. The most important curves to be deter- straight across the filament terminals the mined are : voltage drop in the ammeter would be dis The filament voltage and current having been adjusted to a requiredvalue,as indicated by It and E1, sufficient negative potential is applied to the grid, via Bg, the change -over switches being at Y andYt, The latter changes over the voltmeter con- Fa nections, but itis not required when a central zero instrument is used.The de- sired plate potential measured by E. is applied through X and X,: Ifthefullcharacteristicisrequired, negative potential is applied to the grid until -theplate milliammeter reading is reduced to zero. The grid potential is then BEATE reduced, step by step, for each setting of BATTERY SO which the grid and anode current is re- corded. When zero grid potential has been reached poSitive potentialis applied by and the readings continued as before. Care should be taken to keep the anode voltage constant throughout the test, and a FIG. slight adjustment of the anode potentio- meter may be required from time to time. It is also advisable, before commencing to FILAMENT 111111111 take readings, to allow the valve a moment d/ATT-HRY Of :RID BATTERY or so to become steady in operation. ®9 So far sufficient data has been obtained to plot one curve.The anode potential may now be increased to some higher valtieand The relation (1) between anode current pensed with ; but in this case the ammeter the whole operation repeated, each setting and grid volts. would register the current flowing through of anode potential providing brie curVe.. (2) The relation between grid current the voltmeter in addition to the filament Here,then, we hive the method of arid grid volts. current.Since the former method intro- obtaining characteristic curves, whether the :(3) The filament emission. duces the lesser error it is to be -preferred, valve is a power tube capable of, dealing :The lay -out for a complete testing tableand the circuits are usually connected in with several kilowatts; or whether it is a by which the properties of a valve can bethat way.I,, is the plate ammeter and E. tiny receiving tube.The only difference is measured is shown in Fig. 1, but for sim- the plate voltmeter, the former remarksin the magnitude of the constants and regarding the filament voltmeter applying consequently the measuring instruments. also in this case. (Continued on page 6224 Regulation of Plate Voltage. The anode battery, B, should, where possible,consistofsmallaccumulators, 40001 QM M. VOI., C...4 ,,,,, WM connection thereto being made by means of a " wander " clip.If this is not possible, II00Em small dry cells may be used.With 4 -volt cells it is difficult to get the exact voltage 3 in= required, as a certain tapping may be too low while the next may be too high.This onSI plicity,diagrammatic sketches are given may be overcome by connecting one cell indicating the circuit utilised for any par- across a potentiometer, as shown. This . rim tiCular test. method is preferable to shunting the whole

Readings for the anode current grid volts battery with a potentiometer. Grid eurrent- o zi and grid current grid volts curves can be is read either on a sensitive galvanometer ii. obtained simultaneously, and Fig. 2 shows or on a milliammeter Ig,provisionbeing . the circuit employed. The filament energy made so that the galvanometer may read _...... is regulated by a variable resistance R in current in either direction, though this CA. OvEnv., series with the filament battery, the current latter expedient is necessary only when 0 NKL3 622 Pcpular Wireless Weekiy, June 9th, 1923.

anode circuit, and this somewhat alters thezero, and read the anode current. This shape of the curve. .If a resistance of, say, proves to be 2 milliamperes.For. a general METHODS OF MEASURING 100,000 ohms isinserted in the anode case call this a. The plate potential is then PROPERTIES OF VALVES circuit and a characteristic plotted, it willincreased to 80 volts, and with the grid still (C'ontinued from page 621.) be found that the curve is flattened out ; at zero potential the anode current ,is again that is to say, its slope is not so steep. rIt is read off.It has now increased to 2.8 milli- easy to see the reason for this. As the currentamperes, which for a general case we will call For a power valve the anode battery is through the valve increases the current b.The plate impedance is at once given by replaced by a dynamo or other means of - through the resistance will also increase. dividing the change of anode voltage by the obtaining high voltages, and the instrument In effect, we are reducing the anode voltage change in anode current, that is (80 - 60) ÷- for measuring the plate current should be for each increased value of grid potential, (2.8 -2-0)- 20 ÷ (0.8x 10-3) = 25,000 ohms. capable of measurement up to at least one which obviously causes the characteristic to Calling the initial anode voltage E, and the second voltage, greater than the initial, E2, ampere. From the readings obtained a rise less steeply. series of curves can be plotted as in. Fig. 3, Another important seriesof curves iswe have for a general case, in= (E2 - E1) which gives the characteristics for a certain that showing the relationbetween. the (b-a). type of receiving valve. filamenttemperatureandtheelectron Two very important properties of a valve emission.In order to determine the total The Magnification Factor. emission from the filament the grid and One more reading is required in order anode are connected together (switch S to to determine the magnification factor. With the left in Fig. 1) and are in consequence at60 volts on the plate the anode current was the same potential. Having set the filament 2.0milliamperes,and when theplate at any required wattage, the potential onvoltage was increased to 80 the anode the cold electrodes is increased in steps from '7 4.5 v current increased to 2.8. milliamperes. We zero to such a value that no further increase 6 now apply a negative potential to the grid in emission is obtained.This is the satura- until the anode current is again reduced to 5 tion current for that particular setting of 2.0 milliamperes.In this particular case i4 filament energy. this occurs when the negative potential is 13 Plate Impedance. 2.5. We thus have the magnification factor, The diagrammatic scheme of connections which, equal to the ratio of the change in a shown in Fig. 4. anode volts to the change in grid volts, now The filament wattage may now be in- becomes 20 ±2.5 =8. The foregoing de- z creased to some other value and the opera- scribes a rapid method of dealing with any number of valves of the same type, once it is Z 9 tion repeated. For each setting of the 0 filament a different valueof saturationknown at which part of the curve the current will be obtained (Fig. 5).Since a measurements are required. 4 0V valve should always be operated at the lowest possible value of filament energy this characteristic is of great use in deter-

4 mining this factor. When the constants of a number of valves 3 3 5 v are required the process of drawing charac- teristics for each one is a long and laborious _50V task; but there is, however, a quick method which gives fairly accurate results. Making S 10 15 QO QS 30 3.5 40 4630 use once more of Fig. 3, and requiring the 1-I.TVot.rs magnification factor and resistance at the FIG 5 EM ICS .ON CA/W./FS same point as before, the work can be very much abbreviated. Having adjusted the filament current to are readily determined from the charac- the correct value, we apply a potential of teristic. These are the Magnification Factor 60 volts to the plate, the grid potential being and the Anode Impedance. Static Characteristics.

The magnification factor of a valve is the ratio of the change in anode volts to the change in grid volts for the same current value. In Fig. 3 the change in anode volts is 80 - 60 = 20, and requiring the magnification factor at, say, 2 milliamperes anode current, we find the change in grid current to be XY. which measured along the grid axis is 2.5, volts. The magnification factor at this point is therefore 20 = 2.5 = 8. The anode impedance is the ratio of the change in anode, volts to the change in anode current ' for some definite value of grid potential. The change in anode volts is, as before, 80 - 60 -.20, and the change in anode current is given by YX, which measured along the current axis is equal to 0.8 milli- ampere. The plate impedance is therefore 20 divided by 0.0008 (since the current must be stated in amperes), which .gives. 25,000 ohms. These two properties of the valve are of groat importance in the design of a circuit for which a particular valve is to be used. The curves described above are known as " static characteristics."In practice, re- Prof. Hazeltine (left) examining one of his neutrodyne receivers.Enormous ranges without re -radiation sistancesaregenerally includedinthe are claimed for this wonderful instrument. Popular Wireless Weekly, June sta, 1923. 623 Don't measure the length of your aerial from chimney to pole.Measune, from insu- HINTS ON METAL WORKING. lator to insulator.Otherwise you will find By ALBERT BULL. that you have overestimated the length to The following hints will assist the amateur constructor of wireless apparatus the extent of three or four feet, owing to the to a very considerable extent in turning out the metal parts of a set. size of pulleys, insulators, rope, etc. ' Don't use rope for stays and guys if wire is available.Rope has the disadvantage of being at the mercy of the weather, and is TT cannot be impressed upon the amateur When soldering heavier work, such ascontinually stretching or shrinking. Itoo strongly that patience is a virtue, brass rod or sheet, do not overlook the fact Don't wear a long apron when working and that in all classes of delicate work that acertain amount of time is necessary on a roof ;it is apt to get under one's feet. it must be exercised, otherwise disastrous for the transference of heat from your Don't take an aerial over a street if it can results may follow. copper bit to the work and that, in conse- be avoided. Even if permission is obtained, The very first thing to do when about to quence, the bit should be held perfectly stillIt will cause endless trouble if it falls among work upon metals is to memorise the fol- until the solder commences to run from traffic. underneath it.In most amateur cases im- lowing saying : Don't Spare Insulators. Oil on copper, not on brass, patience is the cause of imperfection, so Don't despair if a 20 ft. pole to be attached spare a little time, and note the improve- to a wall seems expensive. Use two clothes Oil on wrought, but not on cast. ment. A very familiar quotationforall who props bolted together. This makes an excel- have to handle metals of this description. lent pole at the cost of about 2s., and is quite When drilling metal, ebonite, or vulcanite rigid when used with back and side stays, be sure that a flat bed is made for your Don't attach a down lead anywhere, work to rest upon. except to the end or the exact centre of the -When tapping a hole do not endeavour to horizontalwire. Thisisimportant for force the tap through directly, but ease it efficient working of the aerial. backwards a little after each turn ;this will Don't let kinks appear in the wire while allow the cuttings to clear. erecting. Even when removed they will be Ofttimes it is desired to use up a few odd - found to have taken the twist out of the sized screws, for which perhaps no taps are stranded wires. at hand; a tap can be improvised from one In securing wires between nuts and ter Don't spare the insulators, especially if of the screws themselves, if it is for vulcanite minals, the ends in all cases should pass of the cheap variety Two at each end should or ebonite by simply filing a slot across the round the stem in the same direction as thatbe the minimum. threads similar to the ordinary tap and with in which you turn the nut or terminal head. Don't erect an aerial without having at ordinary care will last for quite a long while. See Fig. 3. least one pulley. If a pulley is not available, Never allow the end of the wire to. over- a substitute can be made by using a reel Soldering Fine Wires. ride the main wire underneath the nut ortype insulator, the pulley rope being taken Filing flat surfaces is only accomplished terminal head, as it is liable to fracture and over the groove in the insulator which is by practice, and is probably one of the most cause very trying faults. loosely fastened to the top of the pole. difficultproblemsthatconfrontsthe Sometimes difficulty is experienced with Don't commence the roof work until all amateur. A piece of ebonite can quite silk and cotton -covered wires through the the ground work has been completed, such easily be held between two straight edges of insulation " running back."An effectiveas the erection of the pole, completion of wood and filed down until level orparallel. preventiveisbeeswax. Meltthe waxspreaders, soldering of down lead, and fixing See Fig. 1, A.If, on the other hand, it is and dip the wire in, afterwards wipe with a of insulators. desired to file a round corner, do not endea- clean duster.This will be found a most Don't erect the pole until the pulley, vour to follow with the file, in the direction excellent insulator, and incidentally a per - pulley, rope, and all the guy ropes are affixed, feet binder. as a 35 ft. pole is rather an unwieldy object of the required radius, but against it, as it to take down, when a little foresight would were.See Fig.1, B.In pushing the file forward, rock it radially, and it will be Rust Prevention. have eliminated the necessity of doing so. found that a round corner can be filed per- Brasswork that has been lacquered is Don't attach aerial ropes to chimney fectly in this way in a very short time, and best cleaned by means of ordinary lubrica- pots.They are often not as safe -as they will be void of those amateurish -looking ting oil rubbed over with a duster, then look.A rope or wire sound the chimney " flats " when finished. wiped off as dry as possible. stack is much safer. A piece of stiff brown paper will be found Don't have the down lead so tight as to a splendid cover for your bench, and cancause a strain on the horizontal portion of be secured by means of drawing pins. the aerial. Renew when torn. Don't hurry any part of the job. Remem- Small cigar boxes make good receptaclesber it is the- most likely part of the installa- for spare parts, screws, small tools, -etc. tion to receive the least attention, and the If you are not likely to use certain toolsstrength of an aerial depends upon the for some little time, do not forget that a time devoted upon its erection. smear of oil will prevent them from rusting.

If your brass rod or sheet is very brittle, DON'TS.1 heat it to blood red and immerse quickly in A FEW AERIAL cold water ;this will soften it and render it pliable. DON'T contemplate erecting the aerial Do not attempt to bend brass in the vice until the following points have been without first covering the jaws with lead considered, and a rough plan drawn sheet, thus avoiding fractures at the bending up showing type to be used, length, height, paint. length of wire and number of insulators When soldering fine wires such as are required, position of down lead, pulleys and used in winding HR 'phones, thegreat guy ropes. " secret " is in the flux, copper bit, and the Don't make numerous journeys up and softness of the solder.Firstly,usesoft down a ladder when one would do. Try to solder with a little powdered resin as a flux, remember all that will be required, and take and a very small copper bit.A full-size 'as many requisites as can be conveniently sketch is shown, in Fig. 2, of the writer's carried. copper bit used for the work mentioned.It Don't forget to wear rubber shoes for The operator at the London Broadcasting Station .can be quickly heated in an ordinary candle sealing roofs.They are less liable to slip signallingto the studio through the window flame. than ordinary boots. provided for that purpose. 624 Popular Wireless Weekly, June 9th, 1923.. WIRELESS IN THE MIDLANDS BY OUR SPECIAL CORRESPONDENT. An article of particular interest to all readers within range of the Birmingham Broadcasting Station.

ON November 16th, last year, broad- successful, while there still remains another Recently, the station staff were afforded casting was commenced from 5 I T- find to be made. an illustration of the importance of wireless the Birmingham station-which was 5 I T's ac rials will shortly vanish from to ruraldom by the news received from a thus among the first three stations of the Witton. Instead they will appear extended little village in the heart of Leicestershire. British Broadcasting Company to transmit. between two high chimney stacks at theWell off the beaten track its villagers were The station had been dismantled in London, Summer Lane power station, one of theenthusiastic in praise of 5 I T because it set up in three days at Witton, on premises city's electric power stations, situated awas theirprivilegethrough the instru- belonging to the General Electric Company, very few minutes' walk from the Town mentality of the squire to listen -in whenever and on the 16th inst. power was put on Hall,theCouncilHouse,theTheatre the night was one of favourable. weather. the aerial for the first time.The same Royal, the Prince of Wales' Theatre, theFrom the great house the multi -valve set, evening a concert programme was broadcast Empire and Grand Variety halls, as well mounted on a wheel -barrow, was conveyed and from that day onwards 5 I T has been as the University and Midland Institutesdown the drive and at about a distance of broadcasting without break. Prom its position it would be a comparatively 120 yards from the house an aerial was set up simple and inexpensive business to effectand Birmingham was tuned in on a loud. connection by land -line with any one ofspeaker.The people of the village fore- these places-and it is at them that 95 pergathered in the, drive, and added their cent of the most important events in the life interest to the mighty flood which daily of the industrial centre of England takes place. grows throughout the kingdom. At these works, the B.B.C. are to. build, at their own expense, a small room to A Novel Experience. house the transmitting gear, and the move will be made immediately a position for the It is a curious claim by the 5 I T station, central studio can be decided upon.It is in and one which should be of interest to this respect that there has been difficulty,.amateurs, that Bristol appears to tune -in but it is likely to be shortly solved. veryfrequentlyindeedto Birmingham rather than to Cardiff.This may be due to certain consideration of local conditions. Big Belt Interrupts. On one occasion recentlythis provided Finding a place for a broadcasting studiothe staff at 5 1 T, which,' by the way, at the is no easy matter, as any wireless thinker present time consists of Mr. Percy Edgar, will realise.For example, in seeking a new the station director ;Mr. F. H. Amis, the location for 5 I- T's studio it was thoughtengineer ; and Mr. Charles Black, the assis- by the station officials that the ideal placetant engineer, with the opportunityof had been found in a suite of rooms particu- hearing that unheard-of thing, so far as larly well placed, and in all respects ad- radio work is concerned-applause.The mirable.The discussion was nearinga inmates of the Bristol Institution for the business ending when thereoccurred a Blind had been listening -in, and were so totally unexpected interruption.Birming- enthusiastic at thepleasure of the new ham's Big Ben sounded the hours, and thus experience that cheers were given for 5 I T. with the first note of the clock the suita-.The enthusiasm was deemed sufficiently bility of the site became a myth, and theimportant to communicate with the station A single -valve cabinet set assembled. by Mr. F. Bourne, search commenced once again. immediately, and a telephone call being put of 281, Wimbledon Park Road, Soutinields, S.W. When the central studio is put in hand, itsthrough to 5 I T, the stationstaff and But, and this is a fact which has affected design will be as far as possible upon the lines artistes were thanked even while the sound of 5 I T very much and made its difficulties ftS'of 2 L 0, and include all its improvements. the blind audience's applause could be heard. great, if not greater, than any other station, With this new central the very situation of the station has mili- studio5I T willbe tated against itscompletesuccess.Its enabled when .opportu- transmissions have always been perfect- nity offers to engage the it has been picked up over as great distances services of anygreat as any of the stations and only recently a artistewho may be listener -infromtheothersideofthe temporarily in the city, Atlantic claimed to have heard 5 I T. or even to induce some But its distance from the city has made public personage,passing the question of the laying oflandlines throughthecity,to almost impossible, even had the theatrical broadcast his message to managements been inclined to permit their the world of radio.In a productions to be broadcast. word, with a studio so Far 5 I T , however, the future in this close to theheartof, direction is now far more promising and things 5 I T's greatest there has just been brought about between problem will have been the Birmingham station and the muni- solved. cipal authority an arrangement which is In the meantime, to their mutual advantage. while the plans for the change -over have been Search for New Site. perfecting a land -line is The search of the company for a snore being carried from the accessible site than Witton has been long Wittonsiteto a and arduous. Even when broadcasting placeofentertain- first commenced from Birmingham we were ment close at hand, and warned that it was only a temporary site, thus the broadcast pro- but nevertheless it has only been within grammes willbe aug- the past few weeks that the search has been mented. A souvenir of Messines.A German portable wireless set. Popular Wireless Weekly, June 9th, 1923. 625 LONATFREQUENCY AMPLIFIERS. A few notes and suggestions intended to assist the amateur in obtaining silentand efficient results when employing stages of low -frequency amplification.

IN order to obtain good results with anthe value of which depends upon the make the amplifier to the battery.Frying noises 1. amplifier, it must be carefully built,of the transformer.If the amplifier has a and intermittent faint whistling sounds are and all the connections soldered.Thetendency to howl, it may be stabilised by generally caused by bad or run-down cells transformers should be placed far enough of the N.T. battery.Poor amplification is from each other to prevent induction effect generally caused by an interruption in one which produces in the telephones a char- of the grid circuits, either in the connection acteristic roar. from the transformer secondary to the As itis desirable to obtain maximum filament or in the secondary of the trans- amplificationwithoutdistortion,trans- former ;ifa grid - isentirely insulated, formers having different ratios should be howling is heard, which shows an interrup- usedinthedifferentstages,otherwise tion in one of these circuits.When no distortion is most likely to occur when a signals at all are heard, the trouble generally high plate voltage is applied to the valves lies in one of the plate circuits, and the to operate a loud speaker at full -volume. transformers should be verified .for con- tinuity, either with a milliammetcr and a Tendency to "Howl." battery, or by changing their positions in This effect is more marked in a three -stage the amplifier, trying the different trans- amplifier, and it is best to experiment with formers in only one stage' of amplification. various makes of transformers to obtain maximum amplification with the valves in Question of Design. use. The gridpotential must alsobe adjusted when highvoltagesareused. Almost any noise in an amplifier may be For voltages below 100, a potentiometer -eliminated by methodic and careful search, connected across the filament battery and and it will generally be found that the having its slider connected to the secondary cheaper types of transformers; give much of thetransformersprovidessufficient more trouble than the better types designed variation ;but above this voltage a grid and built by experienced firms.One of the battery is often necessary.Its voltage may detailsof construction which should be vary from two to forty-five, according to the looked for -by the buyer is the assembling plate voltage used.To supply a loud and size of the iron cotes, which, if too speaker which is designed for great volume, small, become saturated easily and produce the last stage of the amplifier should con- distortion when usedinamulti -stage sist of a five -watt power valve, with 200 amplifier. to 400 volts on the plate.It is not neces- It is hoped that the little information and sary to use transmitting valves in all of few suggestions given in this article will be the stages. Another form of timepiece that gives simultaneously of some use to those who contemplate the different times of different longitudes. making an amplifier for their receiving set, connecting fixed condensers between the and, to conclude, we would say that for best grid and filaments of the valves.Another results it is necessary to use good materials, good precaution to prevent noisesis tofor, as the saying goes, "the cheapest is connect the iron cores of the transformers, the most expensive in the long run." and other metallic parts, to the positive of the plate battery, so that no differenceofpotential, existsbetweenthese parts.A high -capacity condenser should be con- nected across the plate batteries of the amplifier for the purpose of pro- viding a pathof low resistance for the oscilla- tions,which are con- siderably damped when theresistanceofthe plate battery increases with age, if this conden- ser is not used. The noises which are heard on an amplifier, especially of the audio frequency type, are of various kinds. When One of the " polytopt.: " watches employed by the larger wireless stations to indicate the time in any intermittentcrackling, part of the world at any moment. waichsoundslikea discharge, is heard, the To minimise the possibilities of distortion, trouble should be sought if more than one stage of power amplifica- in the batteries, espec- tion is used, it is best not to connect theially the filament bat- transformersbetween high the tension tery.There may be a This wonderful clock is of German manufacture.The map is lit from behind, souroe and the plate, but to use a choke - bad contact in one of and a moving shadow indicates that part of the world where itis night. Similarly, the.secondary of the trans- the sockets or the rheo- An arrow is drawn from each station's position on the map.Thus it is possible to gauge the time and whether light or darkness reigns at any of the large formers should be shunted by a grid leak, stat or in the leads from wireless stations in the world at a glance. 6-26 Popular Wireless Weekly, June 9th, 1923. AN AMERICAN VIEW. An extract from the questions answered by Mr. M. C. Rypinski, Vice -President and Director of the Canadian Brandes Ltd., and Chairman of the Radio Associated Manufacturers of Electrical Supplies, concerning broadcasting in Great Britain and America, at the offices of the B.B.C.

DID the broadcasting companies begin I believe you have a much better plan narrow view of broadcasting, assuming that voluntarily or by arrangement with in America, and one which we may have it would hurt their business; but now it is the Government ? to approximate to if we are to solve our fairlywellrecognisedasanexcellent Broadcasting began spontaneously with interference difficulties and provide a per- advertising medium and the more progres- the broadcasters, and almost before the manent source of revenue for broadcasting. sive managers are permitting a single act or Government realised the situation it had As you may know, the expense of broad- parts -of an act to be broadcast, and are ex- got out of hand, due, however, entirely casting now falls in part upon a few of the periencing quicker general recognition of the to lack of discretionary power under the larger radio manufacturers who write a small merits of a production. existing laws. part of it off against the profits from the sale of radio apparatus, while the greater part is Boycotting Not Permitted. Considerable Chaos. charged off to advertising.In the case of Do they allow theatreartistesto broad- How Many broadcasting stations are there the newspapers, the department stores and cast from the various studios ? in America ? others, all of it is borne as an indirect ex- Yes. These are about 700 licensed broadcasting pense charged off probably to advertising. Whatfees are the artistes paid ? stations and about 3,000,000 unlicensed I cannot avoid, however, commenting un- None; but it is usual to provide suitable receivingstations.Thelatter transportation and dinner, as the figure is, however,onlyan case may be. estimate as no exact datais Is there any attempt on the available. part of the entertainment world As data bearing on this point, inAmericatoboycottbroad- I offer the information that my casting ? company,CanadianBrandes, No. The boycott is in bad Ltd., of London, Toronto, and order in America as our laws New York, which is only one do not permit it in most cases. of about twenty makers of radio Doyouthinkthatbroad- head telephones supplying that casting will prejudice the enter- country's demands, has put out tainment industry? -in America over 500,000tele- Does the production of phones since broadcasting started gramophonerecordsinterfere there. It is estimated that the with Grand Operaormusic average receiving set includes two publishing ? Grand Opera be- pairs of heid telephoneseven came popular in America only where a loud speakerisalso after the greatartisteswere installed. permittedtosing forrecord Isita fact that two broad- purposes. casting stations may exist in the same block on thesame wave- Question of Copyrights. length and functioningatthe So broadcasting will serve tci same time ? popularisestill furtherthe Unhappily, yes, as there is no entertainment industry, and to regulatory control over the prox- encourage the peopleisolated' imity of broadcasting stations. in their homes to make further FosteredbytheDepartment tribute to this industry as new ofCommerce,however,steps featuresare brought to their have been taken to get the broad- attention by radio broadcasting. casters in a given area of in- What is the attitude of terference to agree on an alloca- American music publishersto- tion of broadcasting. hours.This wards broadcasting? prevents absolute chaos, but it Recently -they decided that has the disadvantage that small they would attempt to collect 5 to 50 watt stations are -given againsttheircopyrightfor recognition equal to 500 watt broadcasting rights.The broad- stations,andgive inadequate The handsome cabinet set assembled by Mr. F. Dewhurst of 52, Goldsmith Rd., caster denied their request and' broadcasting over the area when Kingsbury, N. W.9. for a time eliminated copyrighted they are operating. music from their programme. A Have the broadcastingconditionsin favourably on the fact that your plan, as at vigorous protest was made by the public, and America produced chaos? present carried out, does not appear to pro- my latest information is that the association To a degree, yes, although the public tect the unsuspecting public from being has decided to permit the free broadcasting spirit of the broadcasters and the influence offeredmerchandisewhichcannotbe of copyrighted music for the present. of pending legislation are controlling in some legally used, because it has not met with the Whatistheattitudeof theAmerican measure to give passable, though by no approval of the Postmaster -General. I Society of Authors towards broadcasting ? means perfect, broadcasting.Interference refer particularly to the poorly made, and I do not know definitely what action, if due to re -radiation, or reaction, as you call no doubt inferior. merchandise of foreign any, has been taken by them ; but I am in- it here, makes reception difficult in certain make which appears in such quantities in the clined to think they are awaiting the result localities and at times ;but the public is dealers' windows. of the music publishers' request which has being educated up to the operation of their only just been announced. sets so as to minimise this effect, and the Regarding the Theatres. Do you approve of the formation of a single manufacturers are striving to eliminate re - Whatistheattitudeofthe theatre Broadcasting Authority ?- radiationpossibilitiesthrough improved managers of America to broadcasting, and I do, and I am sure that we will welcome design. do they allow extracts from their plays to be the day in America when the Secretary of What do you think of the British system broadcast ? Commerce may be made such an authority of .broadcasting ? Originally some of the managers took a as the pending legislation proposes. PopWlar Wireless Weekly, June 9th, 1923. 627 Opera by Wireless! THE London Broadcasting Stationare broadcasting opera from Covent Garden during the presentseason, and tens of thou- sands of wireless owners living anywhere neara broadcasting station arefinding impossible to listen-in to their favourite works, except during the short intervals in which their local station closes down, as with the ordinarynon -selective receivingset the trans- mission of the near -by station drowns all other signals within a wide radius.

The owner of an R.F.H. Reaction set is untroubled The Orpheus Radio Telephony Company, by an unwanted station, even if only two or three of Silloth, write : miles away, and by means of this wonderful set he " Glasgow opera came -through very nicely receives perfect telephony from any British Broad- on your2 -valvereactanceset,type' B. casting station as well as the principal Continental We are satisfied that this setis thoroughly concerts,. such as The Hague, Paris,Berlin,&c. efficient, andfully bearsout your adver- Such a set is used under the ordinary broadcasting tised tests.The prima donna's voice was licence,itis approved by the Postmaster -General, loud and clear ;the applause was plainly These Reaction Sets are supplied and all B.B.C. and other royalties are paid. heard." complete with all equipment (exceptvalves)at the following Why not inquire as to the wonderful ranges which are prices : 2 -valve 25 guineas obtained even with a 2 -valve ?The number of 3 -valve ..30 guineas gratified users all over the country is multiplied daily. 4 -valve ..35 guineas ROGERS, FOSTER & HOWELL, LIMITED RADIO ENGINEERS, Telephone: No.265. Edward Road, BIRMINGHAM. Telegrams: " Autowire."

To Wireless Traders We Specialise and others in manufacturing the BurTon Radio Parts I SALE BY AUCTION at in 25, York Terrace,CLAPHAM. BRASS AND ALUMINIUM Send us your enquiries (fminute from Clapham Road Tulle and Railway -station).

WIRELESS COORS ttllNlliflti comprising 1,50o Pairs HEADPHONES (4,000 ohms), goo VALVES, too LOUD SPEAKERS, 5o AMPLIFIERS, 50 1-, 2- and 3 -VALVE WIRELESS SETS,- Crystal Sets, Valve Detectors, H.T. Batteries, Condensers, Terminals, etc., etc. EX -GOVERNMENT GOODS including HEADPHONES, MARCONI SETS & APPARA- TUS, Tuners, Galvanometers,Coils, Transformers, Plugs and Jacks, Simplexand Duplex TelegraphSets, 300 Double Current Keys, Soo Accumulators, Soo Telephone Sets, Ammeters, BridgeMeggers,Relays,Handphones, Telegraph Instruments, 8 -Way Remy Switches, etc., etc.

To be sold by Auction in lots to suit large and small buyers, on the premises as above, on TUESDAY, JUNE 12th, AT 12 O'CLOCK SHARP. On View Junet ith and morning of Sale. Catalogueson application of the Auctioneers, THE Special parts made Send us sample and to your requirements. we will quote you. SOUTH LONDON MERCHANDISE MART YORK TERRACE, CLAPHAM. Messrs. C. F. & H. BURTON Telephones: Brixton 3409. Telegraphic Address Chancery, 7720. " Londsigs, Clapcom, London." Progress Works, Wireless Stocks received for Sale by Auction or purchased. Write for terms. BERNARD STREET, WALSALL. ,0....~ PHONE: 560 WALSALL 628 Popular !Tireless Weekly, June 9th, 193,',.

THE STORY OF THE MERCHANT OF VENICE" Which will be broadcast by the London Station (2 L 0) on June 12th.

SHYLOCK, the Jew moneylender. credit of his merchandise -laden ships which tonio's defence herself, and disguised as a ANTONIO, a rich merchant. were due to arrive at any moment. Shy - lawyer, with Nerissa as her clerk, they BASSANIO, Antonio's .friend. lock granted the loan on condition that if arrived at Venice on the very day of the GRATTAN% Portia's servant. it were not repaid by a certain date, the trial. . PORTIA, an heiress. penalty should be that Antonio would Portia's masterly conduct of the trial and NERISSA, Portia's serving maid. forfeit a pound of flesh from any part of her ultimate and crushing defeat of Shylock his body that Shylock wished.Antonio aretoowell-knowntoneeddetailed THE chief character study of this play agreed to this, and Bassanio was able to win descriptionhere.Afteritwasover, is Shylock, the Jew moneylender, who Portia for his wife.Gratiano and Nerissa, Bassanio, who throughout the proceedings lived at Venice, and who was re- who served Portia, were married at the had not recognised his wife, went with nowned for his severe treatment of all who same time, and each lady presented her Antonio 4o thank her, and she persuaded borrowedmoneyfromhim.He washusband with a ring from which they her husband to give her the ring she had universally hated, especially by the Christian vowed they would never part. Originally given to him.Nerissa played a Antonio, who . would grant loans without The festivities of the marriage were some- similar jest with Gratiano, who also failed interest.Antoniohad animpecunious what marred by the arrival of a letter from to recognise his wife.This led to pretty friend called Bassanio, who was in love Antonio announcing that his ships were complications afterwards, . and the tragic with Portia, a wealthy lady, heiress to a lost, and that Shylock insisted on claiming beginnings of the story end with Gratiano's large estate.To pursue his courtship he his pound of flesh.Bassanio and Gratiano merry oath that : asked Antonio for the loan of 3,000 ducats. set out post haste for Venice, and Portia, Antonio had no money just. then and so after a careful consultation with a lawyer " While I live I'll fear no other thing borrowed the sum from Shylock on the named Ballario, decided to conduct An- So sore, as keeping safe Nerissa's

BROADCASTING TRANSMISSIONS. GREAT BRITAIN. Hours of Wave -length Station Call Sign. Transmission. Items Transmitted. in Metres. Remarks. London ..2L0 Usually -5.30-I1 p.m. .. Musical Items, News, etc. 369 Every Weekday.

Newcastle .. 5 N 0 5.30-10.30 p.m... If 10 1. 400 Manchester .. 2 Z Y 5.30-10.30 p.m. .. 385 Birmingham.... 5 I T ft 5.30-10.30 .. . 425 Glasgow .. 5 S C 5.30-10 30 p.m... . 415

Cardiff.. 5 W A 5.30-10.30 p.m... 353 BELGIUM Brussels (1) . . Brussels 12 noon (G.M.T.) ..Weather report .. 1100 Working clays. 4.50 p.m...... Aeroplane traffic 1100 When necessary. 6 p.m. .. ..Concert 1300 Sunday,. Tuesday andThursday. HOLLAND

The Hague.. P C G G 3-5 p.m. (G.M.T.) ..Concert . 1050 Sunday.

8.40-9.40 p.m. ..Concert 1050 Monday & Thursday

The Hague.. P C U U 7.45-10 p.m. ....Concert . 1050 Tuesday.

Laboratorium Heussen) 9.40-10.40 a.m. 1050 Sunday.

The Hague (Velthuyzen) P C K K 8.40-11.40 p.m. ..Various . 1050 Fidday. )(midden (Middelraad) P C M M 8.40-11.40 p.m...Concert .. . 1050 Saturday.

Amsterdam P A 5 8.10-11.10 p.m. ..Concert and News . 1050 Wednesday. FRANCE

Lavaffois-Perret Radiola1 S F R 2-3 p.m. (F.S.T )..Music .. 1780 . Sunday. Stock Exchange News 1780 ..Every day. 5.15-6.15 p.m. ... Instrumental music 1780 .. Pt

8.45 p.m. .. General News.. 1780 ft 9-10.30 p.m. ..Vocal and instrumental concert 1780..-

Paris (2) (Eiffel Tower) ..F L ..0.40 a.m...... Weather Forecast 2600 PI

11.15 a.m. ....Weather Forecast .. 2600 3.30 p.m. .. Stock Exchange News .. 2600 6.20 p.m...... Weather Forecast, Concert .. 2600 tf 10.10 p.m. ....Weather Forecast 2600.. Ecole Superieure des P.T.T. 7.45-10 p.m. ....Radio Concerts .. 450 Tuesday, Thursday, Radio -Riviera (Nice) 2.30-7.30 p.m. .. Radio Conferences.. 450 J Saturday; 11 a.m. News, Concert, tzigane 460..Every day, News, instrumental Concert.. 460..

9-10 p.m. . Latest News, Concert .. 460.. GERMANY, CZECHO-SLOVAKIA, AND SWITZERLAND Berlin...... L P ..0-7 (G.111.T.)..-Financial News, etc. .... 2800 Every day. (Konigswusterliattsen) 11-12.30 4-5.30 p.m.....Financial News, etc...... 2800..

Prague ....- . P R G ..7-11 a.m. and 3 p.m.Weather News, General News.. 1800.. 9-2 p.m. and 9 p.m. Concert ...... 4500 . Geneva ...... H B 1200.. The British Broadcasting Stations transmit on Sundays between 8.30 and 10.30 p.m., and at varying times during weekday mornings and afternoons.The programmes appearing in the daily Press should be consulted for full details. (1) If, at the indicated times, a station has to receive or transmit service communications, the weather transmission will take place after these communications.Tuesday :Operatic selection on the gramophone.Thursday :Various on gramophone.Sundays :Various by artistes. (2) Special concerts given during the evening are announced in the course of the preceding transmissions. Popular Wireless Weekly, June 9th, 1923. 629 Woodhall-Wireless Componentsareevolved by experimenters, for experimenters Examine these prices :they are right to suit your pocket. And the articles are designs upon which we were working long. before " Broadcasting " days.They are of reliable construction-made to give service, easy to assemble, P ion efficient and simple to work with.

EVENTUALLY you'llcometothe Variable Condensers Assembled completeas shown withaluminium Unit System because itis the only end -plates and ebbnite bushes, for panel, mounting. method which enables you to add Adjustablebearing, pccurate spacing;alu- Valves and change - yoUr Circuits minium vanes 2i gauge ;attachedtopanel by

drilling one -hole only. " when you will. . P 1143 Plates . 5 6 Price List of Units Therefore why not start for home construction now with the Peto-Scott P 1.16 13 , 6 6 P 117 25 No. I. Tuner Unit . .27,'6 No.2. Condenser Unit 4?'- System-you'll save P 118 31 No.3. H.F. Amp. Unit 13/,1 money and gain useful P 119 43 10 6 P 120 57 12 - No.4. Detector Unit. 17/6 experience. The first step '3 extra. Knob and Dial i,9 extra. No 5. L.F. Amp. Unit 33/6 is to send 6d. for a copy Postage, Cabinets for I, 3, 4 & 53/6 of"Radio "-anillus- for No. 2 .. 7'- Woodhall vari °meters Post,i(je Pd. pc. Unit (xi ra, hot trated Booklet describing P 112 I.I pow over £2. for full efficiency the whole System Put one of these in your set, and increase range and signal 'st rength. Extremely close coup- ling(approx.1 -16thbetween Peto-Scott Co. Ltd. windings). Internalwinding firmly fixed by special process.' 64 High Holborn, W.C.1 Eliminates dead-end effect and capacitylosses. W.L.with 100 ft. aerial, 250 / 750 metres. For A.T.I. as supplied; orwithsmallbasket -coilin series,thisformsamost efficientanode tuninginduct- ance. Withmassiveebonite knob, as shown (or knob and halt, and terminals. Postage 1'3 extra.Bracket's moveableforpanelortable mounting. Woodhall No. 2 SPECIFICATION. Set comprises solidbestToe 46 BROWNIE ebonite drilled detector panel, Variometer wound induction coil, tuning slider.screw clamp crystalWIRELESS" 325/475 metres wave -length cup,bestqualitycrystal, universally jointed detector, ConstructedofPaxolin tubing giving accurate and easy ad- (not cardboard), it is equal to ebon- justment, terminals, screws,CRYSTAL RECEIVER. itein insulation, and more rigid. and all parts for. assembling POST The walls allow _close coupling, - by our patent method. 7/6 COMPLETE.BY$l6 and the bearings are accurate and every part necessary for simple erection.A Scientific Achievement. robust.Wound with S.C. wire; Guaranteed equal to sets costing many times the price. attached to panel by drilling ono Full and complete instructions enclosed with each outfit. holeonly ;completewithter- London make. Money returned if not as advertised. minals, and fitted with n READ WHAT THE TRADE PRESS SAYS: knob and dial. " Electricity," Feb. 23rd. Postage 911. extra. V 7 " The voice might have been that of a speaker in the same room. .. The set is a marvel of value. .. We anticipate that it will make quite a stir in the wireless world." Send postcard fur folder 'The Brownie Wireless and all about it." The J.W. B. WIRELESS COMPANY, Perikon Detector 19, GARRICK STREET, LONDON, W.0.2. Adjustabletension,instantly fixedon (When writing nientiwt (FirstFloor) "sensitive spot." Vibration cannot dis- Popular Wireless.") Near Leicester Square Tube Station. turb.Complete with crystals. P i07(Nickel plated).. 36 P io7a (Brass) 3.3 Postage bd. extra, Dustproof Detector Neat, with ball -joint,and 9-cf.gold

"MAGNIPHONE" Cat's -whisker: P 1o8 (Nickel plated) ..3/9 LOUD SPEAKER P ro8a (Brass).. 3/6 Postage,6(.1.extra.Special Guaran- ischarming everyone, and making new teed super -sensitive crystal, I/. extra. friendsdaily withitssuperior, mellow, Ask your Dealer for Woodhall-Wireless Components.If he does not stock, order direct by post from us, giving your dealer's name and address. Quote and natural tone. number a, well as description of article required.Money back in 7 days if You certainly must have one to complete dissatisfied.Postage free on orders of 30,'- and upwards: your set. .£3 10 0 each. heWoodhall-WirelessManfg. Co., 15, FURNIVAL STREET, LONDON, E.C.4. SOLE MAKER : Call at the Wireless Den in Tasks Court I T 0 LONDON J. W. GREENWOOD, (nextfor door to Patent Office), Furnival Street, EXPERIMENTERS. allyour Radio requirements. .*. .'. Electrical Instrument Maker,SKIRCOAT GREEN, HALIFAX. Telephone: Holborn 5919. Radio- Call Letters 2 H P Popular Wireless Weekly, June 9th, 1923.

::.results really marvellous "...... RESULTS WERE REALLY MARVELLOUS. We read 2 L 0 with two pairs of 'phones on This letter is typical of many we receive from users of table, at 3 ft. distance. our valve sets all over the country. Beard songs clearly at 9 or 10 ft.distance. Some clients get the U.S. concerts consistently.You 1 thinkitiswell see, the secret of this big -distance reception is that we worth trying my Loud Speaker after results build our sets with the very utmost reaction allowed by on two pairs of the P.M.G.Valve users know what that means. 'phones as above." ExtractfromaScottish letter on reception in North These valve sets are so simply made that a novice can Britain. operate one in half an hour.Complete from aerial to phones £20, carriage paid. Write to -night for lists giving particulars of our crystal sets and famous 'phones. The British L. M. Ericsson Mfg. Co., Ltd., International Buildings, 67 73, Kingsway, W.C.2.

WARNING When you ask for Ericsson 'Phones look for the name ERICSSON BEES TON stamped thereon Don't accept Continental" 2 - YALYE stub' as Ericsson's RECEIVER

VALVES Areyou a" Pirate " ? We stock all makes for sale to the THE P.M.G. has now begun to grant a large trade on usual terms. number of Experimenters' Licences. If your earlier application for one has been CRYSTAL Radio turned down, we advise youtotry again. Press Many keen amateurs-although possessingthe We specially draw attention to our requisite amount of wireless knowledge-have been wonderful " Pinnaclite."Everyone Series refused because they did not conform to the Post invited to try this.Price1,'6to No. 11. Office requirements. 2,16 per piece. The object of this book is to show you exactly what you should know before you can be granted THE WHOLESALE ELECTRICAL CO. (1922), LTD. this Licence. 78, CHARLOTTE STREET, LONDON, W.1. Remember the Experimenter's Licence will Sets, parts, and sundries in stock. give you much greater freedom than the 411Constructor's Licence (even if the latter is issued) and your position is legalised once and for all. lilabioPretie,tto, ELEcTRoNITE Devereux Court,STRAND,W.C.2. The WORLD'S MOST FAMOUS CRYSTAL Free, all bsot. &Ilene or post RHYME No. 2. free direr(, Her pretty ears were covered with the 'phones ; Her pretty face with music was alight ; Hor spirit soared to meet the dulcet tones Made crystal clear by our Electronite. TRADE SUPPLIED RADIO SUPPLIES Wireless Licences 254, HIGH HOLBORN. LONDON. 'Phone: HOLBORN 2188. Sole Agents for Lancashire and Cheshire : &how to obtain them Messrs. HENRY HOLLINGDRAKE & SON, LTD., PRINCES STREET, STOCKPORT. By E Redpath Poputa-r Wireless Weekly, June 9th, 1923. FURTHER PRACTICAL IDEAS.

allowed to fix, the pins on which they werewith the needles.Solder leads to each JOINING AND SOLDERING wound were withdrawn.It was then mount- needle, and take them to a small tapping WIRES. ed on a fixed condenser of .001 capacity. switch.In this way, a sensitive point may Through one of the holes usually foundquickly be found, while the detectoris drilled in the ends of the condenser for a dustproof. AFACT to bear in mind when construct- wood screw, a terminal is passed on which * * ing apparatus is that all joints must It is a good idea to give your inductance not only be strong mechanically but a coat of shellac occasionally-varnishing also electrically.Fig. 1 shows the manner it from top to bottom, and not left to in which two wires should be joined to- right-thus ensuring that the shellac gets gether, prior to soldering, if they are to be well between the turns, and insulates them subjected to any mechanical strain. from one another where the enamel has Where a wire is to be held beneath a lock - been broken off.When dry, scrape the nut or a flat -headed screw, the wire should part where the slider makes contact, free be passed completely round the screw, as from the shellac. in Fig. 2A, but should not be allowed to cross itself, as in Fig. 2B.An insufficient quantity of wire beneath the nut or screw head, as shown in Fig. 2c, is also a bad plan The internal view of the compact crystal set. A SIMPLE LOUD to adopt, as such a connection possesses was screwed a crystal cup, and on a terminal SPEAKER. practically no mechanical strength, and passed through a hole at the other end was will easily become disjointed. fixed a copper wire wound as in photo. The whisker should fit loosely so that by AVERY simple form of loud speaker Cause of Corrosion. loosening the terminal holding it, a long isshownintheaccompanying In cases where more wires than one arelongitudinal movement is obtained and the diagram. The instrument illustrated to be attachedtothe same screw, the natural tension on the spring allows a cross isefficient, and possesses an advantage differentwires should be separated by movement. The whole iswired up in over the majority of loud speakers in that washers, or,failing this, they should bethe usual way, the case being left to the it is cheap and can be constructed in about twisted together to form one comparatively ingenuity of individual readers. three-quarters of an hour, provided that thick wire, and this should be clamped theessentialcomponents aretohand. down beneath the screw -head as shown in These consist of an old gramophone or Fig. 2a. phonograph horn and a fairly large tin of Do not cover any joint with insulating the type used by certain manufacturers tape unless the joint has been soldered. for packingtoffee,a rubber gasket,a The rubber compound cpntained in the soldering iron, and a stick of soft solder. tape possesses in many cases a certain The gasket may be fashioned out of, an proportion of sulphur which will form a thin film of copper sulphide, which will, in time, work in between the wires and impart to the circuit an unnecessary and unde- sirable high resistance.

The complete set as described in the above short article.

A FEW HINTS. old piece of thick rubber, such as a piece of rubber mat or old motor -car tyre.Cut a hole in the lid of the tin just sufficiently Here is a good tip for those with limited large to Jake the narrow end of the horn. aerial space.If your house is fitted with Care should be taken to see that the horn electric light, and metallic casing is used fits accurately, so as to simplify the soldering to protect the wires, try connecting the process. aerial terminal by means of a length of A COMPACT CRYSTAL wire to a convenient part of the metallic Doubly Useful. casing. Excellent results have been obtained The telephone receiver should be fitted SET. by this means, even with a crystal. And it against the rubber gasket, as shown, the is found to be more effective than a frame gasketitselfbeing placed between the THE photographsofthischeap, yet aerial. telephone and the cover of the tin. remarkablyefficientcrystalset, * * The gasket serves a double purpose, as, will be found to be practically self- With the followingdevice,thechief in addition to keeping the telephonein explanatory. The two small basket type draw -back of using galena-the difficulty place, it will serve to obviate to a certain inductance coils were wound continuously of keeping 'the sensitive point-may be extent the undesirable "resonance" usually on a short length of rubber hose pipe to the Overcome. Choosealongishpieceof associated with loud speakers. wave -length of the required broadcasting galena, and, having mounted it with as As a further precautionagainstthis station, and by alternatively winding and much as possible protruding, get a bonetrouble, a few stripsofinsulating tape testing with crystal and 'phones, the in- thimble-which will just fit over the crystal wound on the inner surface of the horn ductance value was obtained correctly to a cup-and drill a number of holes in it, to will -be found to help: -A' further small- hole turn. hold tightly a few gramophone needles. must, of course, be cut in the side of the The tube and coils were then dipped in Place the thimble over the cup, and make tin to permit of the entry of the telephone molten wax, and having been drained and contact with the galena at several points leads. 632 Popular TT ireless Weekly, June 9th, 1923.

North London Wireless Association.* Mr. F. S. Angel gave his 8th paper on ele- mentary principle, his subject being, " Recti- WIRELESS CLUB REPORTS. fying and Detecting," at the 129th meeting, on The Editor will be pleased to publish concise reports of meetings of Wireless clubs and May 14th. associations, reserving the right to curtail the report if necessary.Hon. secretaries are Hon. sec., Mr. J. C. Lane, Physics Theatre, reminded that reports should be sent in as soon after a meeting as possible.Reports sent NorthernPolytechnicInstitute,Holloway in cannot appear in this paper in less than ten days after receipt of same.An asterisk Road, N. denotes affiliation with the Radio Society of Britain.

The Hornsey and District Wireless Society.* Tarrant, a member of the physics staff of the At a meeting held on April 30th a demonstra- college, on the subject of electrons. tion was given on the society's new receiving set. Hon. sec., N. Miekle, Esq., 544, King's Road, The set, which was constructed by a member of Chelsea S.W. WIRELESS the committee, Mr. W. Trotinan, is on the unit system, and contains 5 panels connected by IN SUMMERTIME brass strips.The first panel contains 3 con- Radio Association, Brockley and District Branch. densers :thisis followed by high frequency, Professor P. M. Baker, B.Sc., A.M.I.M.E., COMPETITION. detector, and 2 low frequency panels.The set A.M.I.E.E., gave an interesting lecture on Fri- is mounted on a baseboard 3 ft. long by 15 in. day, May 25th, at Gladstone Hall, New Cross wide, and each paneliseasily detached to Road,on" CrystalandValveCircuits," (A further selection ,from the hundreds of enable members to inspect the wiring. When not showing how to construct various types of sets in panel form. postcardssentinbycompetitorsinthe in use the whole set is enclosed by a polished The time allotted to, the pro- Sunimertime" competition appears below. mahogany cover. fessor was limited to one hour, and he, therefore, Hon. sec,, Mr. H. Hyams, 188, Nelson Road, could not say all that he had intended. He will, The result and the name of the prise -winner Hornsey, N. 8: however, be continuing his lecture at a later will appear as soon as possible.) date. Leyton Radio Association. During June, July, and August the meetings The 9th meeting of the above association was will take place on the last Friday in each month. Ma. ERNEST S. CLEGG, 34, Montague Therefore, the next meeting will be on JuneRoad, S. Tottenham, N.15 : held at the Russell Mission on May 1st. A letter 29th, when Mr.Geo.Sutton, FiR.A.,will was read from the Radio Society of Great lecture. " I think that in order to keep up the Britain to the effect that this society's applica- interest in wireless throughout the summer tion for affiliation had been duly approved. Hon.see.,R.0. Wafters, Grove House, After a short lecture on Morse by Mr. F. F. Brockley Grove, S.E.4 (letters only). Months, the B.B.C. could arrange lectures Betts, the members proceeded to listen in to and talks on popular sports by well-known 2 L O's May -day concert until 9.30 p.m., when The Sydenham and Forest Hill Radio Society. athletes.The district councils could alsc the wiring of the society's new detector panel A lecture was given recently before the above instal sets equipped with loud speakers in was carried out. society on " Elementary Electricity," by W. V. parks, etc., so that a large proportion of the New members will be welcomed. Pegden, Esq. (the chairman), , starting from public could hear these programmes." Hon. sec., Capt. H. Thorley, C.A., Russell magnetism.It was proposed that the chairman Mission, Leyton, E. 10. should give a lecture on the above subject, once a month throughout the year. MR. ALBERT H. WEEDON, of 23, Tabley Wimbledon Radio Society.* Hon. sec., M. E. Hampshire, 139, Sydenham Road, Holloway, N.7 : A most interesting and informative meeting Road, S.E.26. was hold at the above society's headquarters, " The boom in wireless will, of course, 59, Church Road, on Thursday, May 10th.In slacken, but if the third (constructor's) licence a short lecture, Mr. C. E. Palmer Jones gave a Raymald Wireless Club. is issued, it will be given a decided boost most instructive half-hour on " The Construc- A meeting of the above club was held on up again.If this occurs shortly, it will have tion of Valves," and was greatly appreciated. Thursday, the17th - ult. It was originallythe effect of keeping up interest in wireless All interested in radio telegraphy and kindred arranged that Mr. F. Boulden should deliver a sciences in Wimbledon and district are cordially lectureonthe" ConstructionofPortable during the sumnier.A friend of mine is invited to join, and the hon. sec., Mr. C. Stokes, Receivers " (proposed to be used during club's already arranging his aerial .with the lead- 6, Worple Avenue, Wimbledon, S.W.19, will' outdoor demonstrations), but he was unfortu- in, in his summer -house.Wireless in the welcome applications for new membership. nately prevented from so doing. garden, the portable set on the boat up the Mr. J. Ayres kindly filled the gap, and gave a very lucid explanation on " Inductance, and river, at country picnics, and on the beach The Fulham and Putney Radio Society.* will all be in great vogue. At a crowded meeting held at the headquarters, Its Relationship to Wave -length." In this way I Fulham House, Putney Bridge, on Friday, Particulars may ho had from the secretary. consider the interest of the listener -in will May 4th, Mr. H. B. Gardiner gave a lecture on Hon. sec.,Mr. F. E. Baker,28a,Estella be held through the coming summer." High Frequency Alternators and the Production AVenue, New Malden. of Wireless Waves. MR. P. GIBSON, of 14, Alexandra Road, _ Mr. Gardiner firstdescribed the principles Tottenham Wireless Society. employed, and illmi9ted his points with models On Wednesday, May 23rd, Mr. F. Haynes gave Stockton Heath, Warrington : and diagrams. He then went on to describe the a lecture to the above society on Electro- " A few ideas which might make summer various commercial types of machines in use, Static Loud Speakees." broadcasting more attractive: and the various devices employed to overcome He pointed out that in electro-magnetic loud " 1. The main items to be given after 8 the mechanical difficulties. speakers the distortion increases with the power .or 8.30. Altogether the lecture was very instructive in use,, whereas, eleetro-static loud speakers are " 2. The women's hour to contain attrac- and much appreciated by the crowded meeting. remarkably free; from this defect.Mr. Haynes After the usual votes of thanks, Mr. Gardiner first explained the theoryof themachine. tive and useful recipes for summer promised to give a further lecture at a future pointing out that if a semi -conductor be placed drinks and dishes. meeting. across it, the attractive force is very large. " 3. Music by good composers, or else In his instrument, the semi -conductor is a Hon. sec., J. Wright Dewhtirst, 52, North End cylinder of agate, and the conductor is a brass popular songs and recitations of Road, 'West Kensington, London, W. 14. shoe made to fit tightly round it.The shoe is lighter kind. connected to the diaphragm of the loud speaker " 4. Talks on- Nottingham High School Wireless Society. and the agate cylinder revolved by worm gear. (a) Sport of week. (Day's sport quite The Nottingham High School wireless society Between the spindle of the cylinder and the fully in news bulletin.) has just held an exhibition in conjunction with brass shoe a choke coil and a battery of 200 the photographic society of the same school. volts is connected together, with the output (b) Gardening. There are about twenty members of the wireless of a receiving circuit. (c) Natural History (not treated too society, as it is restricted for membership to The vibrations. received alternately help and technically). those in the science sixth form (in which form hinder the steady voltage, and so vary the (d) Holidays-characteristics of suit- itis studied as a branch of physics).The attraction between the shoe and the cylinder; able pleasure resorts. photographic society is open to all boys in the thisistransmitted by a metal arm to the school. diaphragm. (e) The- house, decoration, etc. The exhibition was held in the prayer hall, The hon. sec.will be pleased to forward (f)Politics (short summary) once a as itis the largest room in the building, on particulars to anyone desirous of joining the week. Thursday, May '24th, from 6 p.m. to 9.30 p.m. society. (g) Motoring,motor -cycling, and The exhibits were .mostly of an experimental Hon. sec., S. J. Glyde, 137,- Winchelsea Road, walking,inducingpractical nature, arranged almost entirely by the boys. Tottenham, N.17. hints on care of machines and suggestions for tours for each Fulham and Chelsea Amateur Radio and Social North Belfast Radio Association Society, Chelsea Polytechnic, S.W.3. .The above club was recently formed at a class. A meeting of the above society was held on meeting held on May 24th.Particulars can be (h) Station itself (difficulties, Tuesday, May 15th, When a most interesting obtained from the lion. sec., H. C. McFerran, alterations, improvements, lecture and demonstration was given by Mr. Esq., 32, CI i ft onv i Ile Avenue, Belfas% methods)." Popular Wireless Weekly, June 9th, 1923. 633 MARCONI'S LATEST New Popular Marconiphone Brings ALL Broadcasting Stations within Range A new and improved Two -ValveMarconiphonehasbeen perfected and is now on sale. With it, no matter what part of the country youlive in, you can listen -in with perfect results to all the BritishBroadcasting Stations from Glasgow to Cardiff. Price Reduced Owing to the enormous demand created for this instrument, it has been found possibleto economise largely in overhead charges. The public is given the benefit of these economies, and the New Marconiphone Vz is on sale everywhere at E 16:3:6 without accessories-or£24complete

`Che Vriumph of the aCaster cl(Cind THE NEW MARCONIPIIONE Ask your local dealer at once about the New Marconiphone V2. .All orders areT;ir7; dealt with in strictrotation. MARCONI'S WIRELESS TELEGRAPH COMPANY LIMITED Marconiphone Department, Marconi House, Strand, London, W.C. 2

-ACME RADIO SUPPLIES CO. imminumininninuminunniniminutiniumuumumm BOPHONESBRITAIN'S BEST GUARANTEED CRYSTAL SETS, enclosed MARVELLOUS EFFICIENCY -crystal, lidded cabinet, variometer tuning, B.B.C. - - - - - 32- each MARVELLOUS PRICE TRANSFORMERS I.V. - -14;- Per FILAMENT RHEOSTATS - - - 24 16/6pair SWITCH ARMS, superior quality, lacquered 1/4 Plus 1/- extra for postage. FIXED CONDENSERS - - - - 1,6 VARIOMETERS, wound for Manufactured entirely in our works, Broadcast Goswell Road and City Road, under wave -lengths ------mass production, hence the quality and price. DITTO, on ebonite - - - - 7j- We specialize in the manufacture of PRICE LIST FREE ON APPLICATION. Precision Tools, stamped and turned parts, inlarge quantities.Send us your enquiries. 1, LONSDALE ROAD, KILBURN, N.W. 6. We are experts in- the production of Carriage paid on all orders over 20s. Magnets of all shapes and from Tung- Please remit sufficient postage.Balance will be refunded. ston or Chrome Steels. SPECIFICATION. Case. Best hard Aluminium, solid Ear Caps.Solid ebonite of ample drawn and accurately -finished. size, best, finish mod correctly pro- SensationalReductions Magnets. Latest type horseshoe portioned. pattern of finest Tungston Steel, re- Insulation.This is a particular BEST CONTINENTAL SUPER -SENSITIVE FEATHERWEIGHT 4,000 OHMS sultingin strong and permanent feature and receives careful attention, DOUBLE HEADPHONES, easily detachable Headbands, LaminatedPole magnets. finest materials only being used. Shoes. Aluminium Ear -pieces, Ebonite Caps, and self-adjusting Headband; Head Bands.Made from best 17/- per pair, postage lid. Core Pieces.Finest quality of quality Spring Steel, copper plated, Ditto, Adjustable, 21/6per pair, post 6d. special soft iron, with fibre insula- oxydized, and relieved, giving beau- Basket Inductances,150-4,000 metres, per set of 6,2/6;per set of7, 3/6; post ting cheeks. tiful finish. 3d.Complete with S diagrams and calibrations. Wire. Each earpiece is wound with Testing.Every earpiece is tested Pair of Coils,for broadcast wave -length,14per pair. bestEnglishhighconductivity thoroughly during, and afteras- 3 -waySwitches,mounted on Ebonite, 2 in. x 21 in., Laminated Arms, first-class copper Wire to 2,000 ohms by special machines. sembly. finish.Suitable for change -over and multi -valve, 2/S each, 3d. postage. Finish & Workmanship.Of Basket Coil -holders, adapted to fit Standard Tuning Stands; the very latest; Diaphragms.Made from selected the best possible throughout. - 1/6 each, post 3d. Iron, perfectly flat, to ensure perfect Assembly. Byskilled labour imder H.F. Transformers: " A," 150-235, 1/9; "13," 320-490, 1/3; " C," 550-810,1/6; tone. expert supervision, "D,"790-1,801), 2/.;" E," 1,650 -2,900 -metres, 2/6 each; postage 3d. 47 S.W.G. D.S.C. Wire, sufficient to wind one II.R. Ear -piece, 1/- per bobbin; r'i1e'L.aigerr totousreitnudrnamcaagse(htiln ifithinindoatvss.atisfied, and

GUARANTEE, 1 ditto, enamelled,10d. perbobbin. Doublequantity,1/6 per bobbin, post lld. B. D. & Co. (Edward A. Boynton), Admiralty & War Office Contractors. Works: -107-173, Goswell Road, London, B.C.1.1-9, Goswell Place, Scientific Supply Stores, London, E.C.1.361-363, City Road, London, E.C.1. 7'ilephone: Olqikeno.eil erss. Offices: 173, Goswell Road, London, E.C.1. HOP 414177, 7 7. 6, Newington Causeway, London, S.E.1. Popular Wireless Weekly, June 9th,1923.

tedious.The series parallelswitch mayof coursebe omitted, but is a useful addition to any set. * * RADIOTORIAL. " FILAMENT "(Basingstoke).-I have broken the filament of my valve.Can I repair it at AllEditorial Communications to be addressed The Editor, POPULAR home as I believe it costs a great deal to have them repaired ?

WIRELESS, The Fleetway House, Farringdon Street, London, E.C.4. If the filament is broken only in one place and only a very small gap results, probably the two ends can he brought together by tapping the valve.In this ease you may be able to mend the filament as According to the calendar Summer has arrived, but from cne reader will be the limit for one letter. follows.Connect the two filament legs across the atthe time of writing it is a fact that is difficult to Allquestionsshould be addressed to POPULAR accumulator, 6 volts should be used, and tap until credit.It is to be hoped, however, that the weather WIRELESS Queries Department, Room 133, Fleet - the two ends of the filament meet, they willfuse will improve so that new recruits to the ranks of the way House, Farringdon Street, London, E.C.4. together after one or two attempts.A repaired army of listeners.in will be able to enjoy to the full Readersarerequested to send the necessary valve does not, of course, last as long as a new one, summer wireless and all that it means.Extravagant postage for reply. and ifrepairedbysome firmusually takes a slightly pictures of punts on the river and picnic parties in larger current than it did previously.The charge is verdantglades,completewithportablewireless The Editor desires to direct the attention of about fis.fid. to have them repaired at the works, apparatus, have been drawn by enthusiastic artists, but his readers to the fact that, as much of the in- ,so. ti is not really so very expensive ccosidering the - somehow the idea seems to fall flat with the town formation given in the columns ofthis 2niptr initial cost of a new valve.Repaired valves act dwellersandotherunfortunateswhoseoutdoor Vel'Ywell, and though they are not quite as efficient facilities for amusement do not include boats on the is of atechnical nature and concerns themost as the new valve they form exceedingly good emer- river and other such delights.To theseI would recent developmentsinthe Radiovorld, gency vale es. recommend wireless teas on the lawn or, if no lawn is some ofthe arrangements and specialities * * * available,inthegardenor" backyard."Itis subjectofLetters wonderful what a difference a few cheap deck chairs described may bethe. B. D. K. (St. Albans.). -.-I intend putting can make to the most confined and " concrety " Patent, and the amateur and trader tro.uld in an aerial -earth switch and a series -parallel " garden " when the sun is shining and " Hark, hark be ?cal adrised to obtain permission of the the lark!" is filtering through a pair of comfortably patenteesto use the patentsbefored int/ so. switch.What are the connections of same fitting 'phones.A nice warm summer twilight after a strenuous day in the city-or on the farm-spent in a deck chair with the " phones," will tend to soften the attitude of the most carping critic against the V broadcasting programmes.Some people say wireless is essentially a winter diversion, but to those whose good fortune it is to be able to command the river, the pristine glade and the shaded lawn, or the imagina- tion to transform sixteen square feet of concrete to such, wireless will be but in bud during the winter months and in full bloom during the summer. " STANDT1"(Taunton). -1 should be much Our companion paper, WIRELESS REVIEW and SCIENCE WEEKLY, has been received in such a obliged if you would give me a diagram of a genuinelyenthusiastic manner thatithasfully tune and stand-by switch, and give directions qualified its relationship with POPULAR WIRELESS. for manipulation of same. The policies and contents of the two papers, however, do not in anyway overlap, and because you have purchased the one it does not follow that the contents of the other would in any way be duplicated.This has, of course, been fully explained before and everyone interested in wireless science should make a point of purchasing both journals, for in so doing everything that matters in wireless will beadequately covered week by week from A to Z.Finally, I must emphasise the point that POPULAR WIRELESS will in no way be affected in respect of its contents nor will WIRELESS REVIEW draw upon POPULAR WIRELESS for its subject matter.An adequate staffof experts and contributorshave beenengagedtosupplyboth periodicalswith thehighestpossiblestandard of wireless and science material, and I honestly believe the combination of two such papers to be the strongest that the world has yet seen. The EDITOR. Owing tothe enormousnumberofqueries receiveddailyfrom readers of POPULAR The above diagram shows a switchingarrangement suitable for your requirements.The earth salt, I WIRELESS,Ihave temporarily decided to limit Above is a suitable diagram. TO tune in pu the number of questions sent in by one reader to switch to " stand-byposition, and tune on pri should be in the left-hand position to earth the three.Readers are asked to keep their questions mary coil aloneuntil best results are obtained aerial. The studsforplacingthe condenseri as short and as concise as possible in order that Change to" tune," andthen readjust. but t.hi, series or parallel are marked S. and P., so you shoal the minimum of delay can be exercised in answer- time -with the aid of the secondary.Without thi lisle no difficulty be followingthem.When the ing queries.Until further notice three questions switch the tuning of a loose-toupled circuit is ver.. (Continuedon page636.) THE " BEAUTY " CHORUS OF THE RADIO OPERA COMPANY. Popular,Wirelesg Weekly, June 9th, 1923. 635

Be guided by the opinions expressed by experts: RADIO INSTRUMENTS LTD. H. W. SULLIVAN, LTD, " We have no hesita- " In our opinion, the tion in recommending this Claritonegives better Loud Speaker. It is freer reproductionofboth voice from distortion than any and musicthanmany other Loud Speaker we othersimilarlypriced have tried,and a thorough- instruments that we have ly efficient reproducerof tried." radio telephony. H. HOLLINGDRAKE cE SON, ASHLEY WIRELESS TELE-

LTD. PHONE CO., LTD. "Reportsfrom all " We have tested these quarters are unanimous against a numberofother in praiseofthehigh - Loud Speakers, andweare qualityofthe broadcasting ofthe opinion that your reproduction." Claritone isbetter than THE RADIO TELEOLA. severalso - called best. "It wasofsuch quality Loud Speakers now being advertised." and efficiencythatwe could make it our standard PETTIGREW &MERRIMAN, OLD, PROD DIE 1/ORt, for all purposes." LTD. TOP RADIO-TELEOLA. L. MeMICHAEL, LTD. " Everyone is delighted

106 DREAT PORTLAND STREET " The adjustment waswith the freedom from LONDON, such that exceptionaldistortionand'tinny' clarity of speech Trw_,,grip, and sound so common to other music was produced." typesofLoud Speakers." 1501 'Ml.

Sie " CLARITONE" Pp...Mon the waft., aR0 umv ant LOUD SPEAKERS 611en op,11 tape et., Pao., 11,er oleo, Not It.N:P.of LINID :=P:IOTIV:ru7si=aed A RESULT OF INTENSIVE RESEARCH WORK -A PRODUCT R.anxy fartt .t OF Pree Nobipot pets. THE FINEST INTELLECTS IN BRITAIN'S RADIO' INDUSTRY

oaCNO TEE -E01_ FOR CONCERT HALL OR FIRESIDE

LTD. ',ELEONONE CO Vol:tux/3s L I ST ASHLEY MANUFACTURERS riSith LIVERPOOL. 15,) PRICE 110 Merv, AUTOMATIC TELEPHONE MFG. CO., LTD., W 295-2000 ohms £3/5/0 W 296. 120 ohms MILTON ROAD, EDGE LANE, £3/2/6 \V 290-2000 ohms LIVERPOOL 1:612/6 W 291- 120 ohms

SCI:sine SOLE DISTRIBUTING AGENTS :

ASHLEY WIRELESS TELEPHONE CO.,LTD., '`AAA.0. 69, RENSHAW STREET LIVERPOOL "dealer Wireless- We'e:':/y;: June -9th', 1923. 63 6 RADIOTORI AL QUESTIONS AND ANSWERS. (Continued front page 634.)

condenser is in series you decrease your wave -length while inparallel you increaseit.The switching circuit is connected to the earth and aerial terminals of the set in the ordinary manner.

H. W. S. (Sheffield).-How can I tell if my set is oscillating and causing interference to others ?How can I stop the valves howling ? Damp your finger and then if on touching the aerial terminal and on removing the finger a distinct '111111111111111111' click is heard in the 'phOnes you may be sure, that 1111111111111111111L your set is oscillating.Try the following, any of which may be the cause of howling.Earth the iron cores of L. F. transformers and keep all transformers as far as pffssible away from each other when building a set.Try a different. value of grid leak, a variable one is a great help if you are constantly changing your valves as each valve will require slightly different . treatment.And lastly, and this is -very important, try and keep all wiring as much at right angles as possible, parallel wires often cause a great deal of troubleinthismanner.Thegridconnections should also be as short asis convenient-, while if KR valves are employed itis advisable touse potentiometer grid control. * * * " Kovr," (Chatham). -11 a conductor or coil is Moved in a magnetic field a voltage is. produced in the coil.Is there any method of determining the foltage that is ,generated ? Yes, this east easily he calculated providing that you know the strength of the magnetic field through which the coil passes.Suppose that the strength cl Li(,,,, the fieldis so many -lines -per cm. and -that con duetor passes through at the rate of one cm. per second.That is, it cut*' hat nuriber of lines of force per secondNov the E.M.F. (volts) will be change of flux volts 10' x time in seconds. if the number of lines cut, or rather cubraced, by Throat -like Tone time conductor at one moment is xl and at another moment is x,, then if the intervening periodist seconds, the average E.M.F. induced is THE purity of the tone reproduced x1-x, E M volts.

by the Peto-pan Super --the 10' t - Now, suppose a coilis used insteadofasingle clear Speaker-is a revelation conductor, and that the coil has N turns of wire. Time to those who have only heard the E.M.F. will then be (x, -x,)N distortedeffects from other Loud volts, t :. 10' Speakers. because we must take into account the fact that each of the turns is cutting the same number of lines of Made in two Models Its wonderful powers of reproduction are force in cacti period of time.For example, we will obtained, firstly, by a double sizeddia- take :a coil of 400 turns passing through a magnetic With curved Hdrn : phragm (adjustable by an external lever), field at.d cutting the lines of force at 100,000 per 4,000 second. and secondly by means of a moulded horn NOz ohms ofnon -resonatingmaterialshapedto a E.M.F. 63/- throat -like opening exactly conforming to t1 ir irith straight Horn: the laws of acoustics. - 400 (100,000 - 0) 4,000 volts because there °hms The Peto-pan Super isthe ideal Loud 1 x 10' 50/- Speaker for indoor and fireside use where is no change in flux density. lthitot purity of tone is the first essential.Its soft This gives E.31.F,-1 ----'4 volt. 99 High Holborn, W.C.1. mellow voice rendersit an indispensable * * * adjunct to every Valve Receiver.Compare CRISTO (Woolwich).-On two occasions my 3 Wellington Street, iton actualtestin ourDemonstration crystals have gone dead.Is there any way of :: Strand, W.C.2. Lounge. preventing this ? Crystals have a habit of going dead, but you seem very unfortunate to lose two in this manner.it is advisable to handle the crystals aslittle as possible. Brush them over with a camel -hair brush frequently, PETO-SCOTT Co. Ltd., 64, HIGH HOLBORN,W.C.1 to get rid of any dust.A bath in methylated spirits often rejuvenates a crystal to asurprising degree. The cats -whiskers are liable to become corroded, and often need cleaning with emery or sand -paper.Gold and silver cats' -whiskers have a distinct advantage over other metals, as' they do not corrode.Do not fix your crystals in their cup with ordinary solder, as the heat is liable to impair their sensitivity. (Continued on page 638.) YOU CAN ASSEMBLE YOUR SET with the certainty of se a Badiax outfit. You may adopt the utib e,ilding up an Ex- 1111111111llllr tensibleI.cy r,iceri,a1System,or rig IIIIIIIIII Petopa n Super selecta Will [AiledSetto snit your localityandtaste.Everythingis planned, and our diagrams and book- lets-tosaynothingofourun- equalled personal service to clients- arc invaluable. A splendid 1 -valve set -tiu &tax Spriakot MEMcoats 39/6. Ask for our catalogue Gited Ad. and advice, stating your ideas. LTD., 10, Radio Rouse, a PercyWE SATISFY St., Tottenham I°. Court Rd., London; W.1-: Popular Wireless Weci:ly, June 9th, 1923. 631

CONDENSERS QUALITY PRODUCTS AT POPULAR PRICES. Because we concentrate on manufactur- ing condensers you get good deliveries. DUBILIER MICA CONDENSERS Types boo and 600A for Wireless Receivers. DUBILIER CONDENSER, TYPE600, DUBILIER CONDENSER, TYPO600, Type 600 in capacities from o'cloor mfd. to 00005 with soldering tags only with grid leak clips - mfd., supplied with grid leak clips and soldering tags. Type 600 in capacities from 0'0005 mfd. to 0'005 mfd. and Type 600A in capacities from o.000l mfd. to 'oos mfd. supplied with soldering tags only. Trade terms and descriptive Each leaflets of these and large power PRICES: 0.0001 mfd. to 0-0009 mfd. (inclus.) 2, 6 DUBILIER CONDENSERS will 0-001 mfd. to 0.005 mfd. (inclus.) 3' - be sent on request. GRID LEAKS :1 Mr. to 5 Mr...... 2 6 THE DUBILIER CONDENSER CO. (1921),1.'1'13. DEPT. E, Ducon Works, Goldhawk Road, London, W.12. 1111111111111, DUBILIER CONDENSER, TYPE 600A Telegrams : Telephone DUBILIER GRID LEAK "Hivol!con,'Phone,London." Hammersmith 1034. LE.P.S, 12.]

WIRELESS !WIRELESS !WIRELESS !and EVERYTHING for it. We insistonbeing the DON'T PAY MORE ! Cheapest in Great Britain. NOTE. We areexclusively WIRELESSNOT DABBLERS! Reliable goods at less than so-called Wholesale Prices (to the Public) " DON'T BE BLUFFED." - ERICSSON " HEADPHONES (Con. NUTS, 2 B.A per doz.210. PLUNGER SPRINGS,complete ...... eatiliId. tinental).Ourprice,stamped B.B.C., NUTS,4. 5,6 & 8 B.A per doz.2d. SLIDER ROD,brass,13is.long, 1 in. per pair 15/3 WASHERS. 4 B.A per doz Id. square.drilled each 31d. "SUPER" FRENCH HEADPHONES. WASHERS, 2 B.A per doz.11d. SLIDER KNOB each 2d. Brand new. 4,000 ohms, and guaranteed FILAMENT RESISTANCES, smooth SWITCHES ON EBONITE.S.P S.T. each pair tested per pair1519 action, marvellous value 1/101d. & 2/. (qualitythebest)-. each1/6 SIDPE HEADPHONES,4,000ohms, CONTACT STUDS. with nuts and SWITCHES ON EBONITE,S.P D.T. our price 17/3 washers per do.50. (quality the best) each1 / 11 THOMSON HOUSTON HEADPHONES. STOPS,with nuts and washers per doz.70. SWITCHES ON EBONITE.D.P D.T. (French) 4,000 ohms, our price 18 / 11 TERMINALS,with nub & washers, (quality the best) each2 / 9 BROWN'S FEATHERWEIGHT HEAD- each 1d.. 150. & 2d. CONDENSER SPINDLES, all- sizesin PHONES,4,000 ohms, our price 27/11 EBONITE KNOBS, 2B.A.,each2d., 3d., & 40. et ock, front eachlid. MARCONI R. VALVES 13/6 SPACING WASHERS,large per doz21d. SCREWED ROD, 2 B.A., 12in.long, MULL ARD ' ORA " VALVES 12/9 SPACING WASHERS,small per doz.lid. each 3d. DUTCH VALVES 8/9 CRYSTAL CUPS,2 screw eachId. SCREWED ROD. 4.A.,12in.long, (All tinaranteed New). CRYSTAL CUPS.4 screw each 2d. each 210. L.P. TRANSFORMERS,Ratio5 to1. FIXED CONDENSERS,allcapacities,each 1110. RUBBER -INSULATED LEADING -IN Allguaranteed.(Postage1 / -) eachII / 3 EBONITE, cut to anysize by machinery WIRE per yard11d. CRYSTAL DETECTORS,Adjustable 1/35 while you wait per lb.3,6 INSULATORS,whitereel,2in.,each CRYSTAL DETECTORS,enclosedin TELEPHONE TERMINALS,nuts& ltd. per doz.1 / 4. Celluloidunbreakable case 2/3 washer, each150 per doz.1 / 4 INSULATORS,whiteEgg, each 2d., SWITCH ARMS,best makes 1/3 & 910. W. 0. TERMINALS.nuts& washer, per doz. 1 / 9 AERIAL WIRE.7 / 22, guaranteed bard- each2d per doz.1/9 SPECIAL HERTZITE CRYSTAL, drawn copper, 100 ft..(postage 1/..) 2 / - PANEL BUSHES,drilled,each15d., largepiece each101d. CONDENSER VANES,fixed or moving, per doz. 1/4 WOUND INDUCTION COILS(Pest. per doz 3/d. TOP CONDENSER,bushes,each10.; age 9d.). Real Gold Cat's Whiskers each 2d. per doz. 110. 12 x 4 9 x 4 8 x 21 6x3 6 x2 Per doz.1;13 BOTTOM CONDENSER, bushes,each 2(8 2/5 2/21/11 1/8 Real Silver' at's Whiskers eachId. Id per doz.9d. TAPPED INDUCTANCE COILS,20 per doz.Bd. VALVE LEGS,nut & washer, each10.; tappings wound to 1,600 metres each 2/11 CONDENSER SCALES, 0 to 180...earli 31d. per doz 100. VARIOMETERS (TubeType)complete IVORINE LABEL SET.12different VALVE PINS, nut &washer, 10.; with knob 3111 readings thest71d per doz. 9d. DOUBLE 'PHONE CORDS,full length 1/41 "ELKAY" WIRELESS CO.,225, Bishopsgate, London, E.C.2. Half -day closing, Saturdays. Trade Supplied -Accumulators charged on premises. Open Sunday 11-2.30. Please remit ample postage. Telephone: Bishopsgate 2292. Populpr Wireless Weekly, June 9th, 1923.

to RADIOTORIAL TED QUESTIONS AND ANSWERS. BUY STANDARDISED PETO- (Continued from page 636.) WIRELESS SETS " WAvEmErEn " (Manchester). -Referring SHOPSOILED AND CLEARANCE to your article on the " Amateur Wavemeter sonic time back, how can one measure C.W. BARGAINS NOW AVAILABLE. SCOTT,Li.. wave -lengths when harmonics can be heard on several adjustments ? SAMPLE BARGAINS : This can be done quite simply by using a little Crystal Receivers, excellent results, wonder- algebra. Harmonics are invariably exact multiples ful value - £1 7 6 reduced to S,..I4 3 Introducing a New Branch : ofthefundamentalwave -lengths. Thus,the firstharmonicoj,say,1000metreswould be One Valve Panel Receiver - £7 10 0 500 metre., and the second 333; metres, and so on. reduced to L4 19 6 If on a certain coil you tune in a signal, and you know it to be, say, 500 metres, and then flnd the Three Valve Receiver Cabinet - £16 5 0 3, Wellington St., silent point " of the same station at 000 metres, reduced to .(147 6 then you can tell that the fundamental wave -length A complete list gladly sent on demand. will be some number multiplied by 600, and the same number times 500 plus 500.Now let x represent the Deferred Payments Arranged. Strand, W.C.2. unknown number, and y the fundamental wave- OUR NEW CATALOGUE IS NOW In order to serve customers living near the length; then both600 x x and 500 (1 + x) = y. READY. West End we have opened a new Branch at Therefore, eliminating y,600 x - 500 x + 500. SEND FOR FREE COPY. 3, Wellington Street.A full stock of Peto- By subtracting500 xfromboth sides we Scott components will be carried and offered vet100 x = 500 ;therefore x = 5,and revert- THE SERVICE Coy. Ltd., at the usual Puto-Scott low prices. ing back, 600 x 5 and 500 x 6 is the fundamental wave -length, viz. 3,000 m. This wave -meter Will cover 289-293. HIGH HOLBORN. a very useful range, and both high and low value LONDON, W.C.I. Special opening offer: coils can be calibrated by means of harmonics. i * Accumulators R. S. R. (Parkgate).-I am continually being liir I XI ELM SS. worried by a loud buzzing sound in my 'phones, Agents wanted bywell-known London manufacturer to sell wireless sets to private caused by a power -station quite near. How persons.Good commission.Give references, at less than cost can I prevent this, as it is almost continuous age, and experience.Anyone having spare The accumulators are all filled with acid and during the evening transmissions ? I am time may apply.Agents must be prepared fully charged.They cannot be sent by post. using a three -valve set, H.F. and L.F. topurchasedemonstratingsetatvery speciallow' price.Write for particulars to Try a capacity earth.This is formed by stretching 6 volt 20 amps. 12/6 wires beneath and parallel to the aerial about six feet Box 366, W. S. CRAWFORD. Ltd., above the ground, and well insulated from it.Failing 233, HIGH HOLBORN, W.C.1. 4 volt 20 amps. 10/6 this, the only other alternative is to " shield " the set. Use tinfoil for the purpose.Shellac the panel well, as....autairk 144L-..- MiIrmffolar HEADPHONES. and when well dry give it a second coating, and at GenuineBritishF.ricsseR. Stamped B.B.C., the same time give one side of the tinfoil a good 4.000 ohms 25/6 coating.When nearly dry but still sticky, apply the ELECTRADIX RADIOS' The LADIES' Headphones,verylight, 4,000 foil to the side of the Cabinet and panel, giving a third °hula,- with TOBTISHELLITE Headbands 21/- " ULTRA " adjustable magnets, 4,000 °Inns, coat when dry;Cut away the foil where the holes:go Immediate Delivery rr- leather -covered Headband 30/ through the panel, and place well -shellacked brown "_.ULTRA " non-adjustable leather -covered paper over the foil.The brown -paper isall added from our Huge Stocks. Headbands, 4,000 ohms 201 - precaution against short circuiting, and is well worth VARIABLE CONDENSERS. the time spent in preparing it. Complete with- knob scale, pointer, and instructions. Everything from a Wave Meter to and TOP and BOTTOM EBONITE PLATES, ready * * * bushed and connections made. Neatly boxed. an Earth Clip. Parts Assembled for No Name (Skipton).-Is ittrue that the complete. Panel Mounting. " dull -emitter "type ofvalvelasts much The best equipped City depot. .001 7/6 12/6 COME AND SEE US. .00075 6;6 II/ - longer than the ordinary type ? .0005 5/6 ' 9/6 9, Colonial Avenue is first opening on .0003 43 8/- Although this type of valve Is rather expensiN e. .0002 3//6 7/- we think that you will find that it will eventually leftinthe Minories,nearAldgate 0001 ,3/2 6/- pay, especially if you have trouble in getting your Station, Metropolitan Railway. Vernier (Readyassembled) 3/ accumulators charged.The L.T.current can be AERIAL INSULATOR. obtained from a primary battery, as the filament of Reel Type ...... eachlid. Baby Shell...... each 3d. LESLIE DIXON &Co. AvenTui.i1G6 Egg Type each 3d. LargeShell.....each10d. this type of valve only needs to be red hot to give good LEAD-IN INSULATORS. results.An ordinary dry cell of large capacity is 9, Colonial Avenue, London, E.1. SimplexLead -InPatent. Inamore damaged quite SatiShietory. The filament will be found to last windowIramesl 1/6 much longer than the ordinary valve.It takes about Ebonite Tubetype,Weil mall, from 1/- *3 amps, anti a voltage of only 1.8 volts, giving wonder- BUY " AMAX " CRYSTALS. Aluminium Pulleys 114 & 1/9 fully silent working and clear reception. HERTZITE, PERMANITE, TALITE,1/6 perbox. Galvanised Pulleys 8d. ELECTRONITE, ZINCITE,1/-perbox. GALENA, Ebonite Knobs, tapped 2 B.A., with brass * * * BO:FINITE, SILICON, COPPER -PYRITES, 6d. per box. nut., let quality, 31d.; 2ndquality. 21d. IntervalveTransformer, MAX -AMP." A. T. (Coventry). -What is an auto -trans- WONDERFUL VALUE. guaranteed. 21 / See that our " Amax " label is on the box, High -Frequency Transformers, Broadcast former ? containing from 2 to 6 large Crystals - wave -length 4 /9 This is a special type of transformer used for a Aluminium Condenser Vanes,fixedand small step-up or step-down of voltage.It consists SOLD BY ALL DEALERS. moving dozen 8d. Spacing Washers, Small, 2d.doz.; large,doz.3d. of a coil of wire wound on an iron core and having THE AMAX CRYSTAL CO., Valve Legs, with nuts and washers, 9d. doz.; four tappings, two together at one end, another part Red Lion House, Red Lion Ct., Fleet St., E.C.4, way along the winding and the last at the further ValveeagleId. Holder, turned Ebonite and 8nuts, end of the coil.For a step-up effect the primary 1st quality 1/3 Reactance on the Anode will Crystal Detector, fully adjustable each 2 / 6 circuit is connected to the bottom end or beginning bringintiledistant stations Crystal Detector,glassenclosedforpanel of the coil and to the tapping part way along it.The and double your amplification. mounting eaelt 4/ - secondary is then connected to the common terminal Our principle is approved P.M.G. Crystal Detector. glass enclosed, mounted on . whereto the primary was connected, and to the other and doesn't radiate. base each 413 RADIAX Regd.VariableRe- Coil Plug Mounts. with strap and connector 1/- end of the coil.The position of the tapping depends actance Coilforairwave- Terminals, large telephone, 2*(1.; Mk. III Aid. upon the ratio of step-up that is required.Suppose lengths,10/-. TunedAnode Filament Resistance 3/-8,2/3 there are N turns between the beginning of the coil Coilforsame,topluginto Fixed Condensers, ineboniteeases,tested and the tapping, and M turns in the whole coil -that any H.F. Transformer Sockets, and guaranteed correct capacity..0002, 3 or 350-500 metres, 5/6. 5. 113; .001, 2 or 3 1/6. is between the two secondary leads, then the voltage If you haven't Grid Leak, 2, 3 or 5 Megohnis (Pet o -Scott type)1 / 6 step-up will be proportional to the ratio S, because H.F. add our Unit. -Brass Clips for same per pair 3d. H.F.Unit, inOak Switch Arms, completewithknob,collar the voltage of N will of course be balanced by the Case, 26/6. washer, bush nuts, etc., best totality laminated 1/3 counter E.M.F. of the turns N, though the flux from IIVariable Condenser.0003 -211,1 quality 10id. Thus a voltage will forsame, Contact Studs, i in. x 1 in doz.4d. N will interlace the whole coil. rase, 14/6. in RADIAX Contact Stops doz.7d. also be induced into the part of the coil that is not RADIAX LTD., 10, Radio House allillft " FETOCITE," the Crystal with the " Multi included by N.This being added to the voltage in N FereyStreet, Tottenham Court490WE SATISFY YOU spots "allsensitive,completewithsilver Road, London, eats -whisker 2 - will give the secondary D.P. -as :4. This type of When ordering by Past,kindly send ample postage. transfortner is connected conversely for a step-down Balance refunded. Orders ore,. £2 post free. effect, but is only useful in cases where a small voltage increase or decrease is required, and not where any A GENUINE OFFER Demonstration Lounge: 99, High Holborn, W.C.1. large variation of pressure from primary to secondary Head Office : Braila(: 3, Wellington Street, W.C.Y. is likely to exist. of best quality 4,000 ohms FRENCH HEADPHONES. TO WIRELESSINVENTIONS.EXPERIMENTERS. PATENT YOUR Write quickly, enclosing P.O.for 64, High Holborn, They may prove very valuable. Parttculars and consulta- 17 6 and secure this bargain. tionsfree.BROWNE. &CO.,PatentAgents, E. CRANE, 13, SALLSNTD.OriAntiGTON 9.Warwick Court, Holborn, London, W.C.1. Estab- lished 1840. Telephone :Chancery- 7547. Popular Wireless Weekly, June 9th,1023. 639

Fp3HULLO -,EVERYBODYsrnaaz

ALL GOODS ORDERED BY POST VARIABLE CONDENSERSmust be accompanied by the Correct ASSEMBLED AS ILLUSTRATED Post Prices marked on each article. Drilled Ebonite Ends to fix yourself 1 /- per pairextra The quality and value given do not permit of them being sent otherwise. Approx. Cap. No. of in Mfd. Plates Price No rubbishy catch lines here. All real value for money. '001 57.6/6 PLEASE NOTE. Rubber Lead-in Wire (good), 12 yds., 1/9.By post, 2/6. Befl Wire, 12 yds., 8d.By post, 1/.. ' 0005 294/6 Twin Flex, 12 y&., 1/9.By post, 2/.. Switch Arms,10d.,1/-,1/3,1/6.Post, 6d. each extra. Rotax Accumulators, 4v.40 amp., Carriage, 2/ - each. '0003 19 3/3 Fixed Condensers. Good value. 11d.,1/3. Post,6d. each extra. H.T. Batteries, (30 volt, 9/..Carriage, 2/- earls. H.T. Batteries, 15 volt, 276.Carriage, 1/- each. ' 0002 13 2/6 Ebonite Valve Holders,10d.,1/-,1/3. Post, 6d. each extra. Basket Coils, " Oojah," set of 7, 5/,By post, 6/- set. . Basket Coils, 2/8 and 3,6set.Post, 6d. extra. '0001.. 7 2/3 InsulatedSleeving,5d. and 6d. length. Crystals (Mounted), itertzite, 1/..By post, 1/6. Crystal Detectors, on ebonite, 1/5.By post, 2/, Perikon Detectors,enclosed with 2crystals, 2/4.By Vernier3 1/9 post, 3.3. Perikon Detectors, suit expensive set, 3/9.By post, 4/6. Enclosed Detectors, 1/8,2/9,3/6,3/9. Post,1/- each NOT THROWN TOGETHER. extra. Valve Pins, slotted, 7d. doz.By post, 1/.. COMPLETELY ASSEMBLED AS SHOWN Aluminium Vanes, 22 gauge, 5d. doz. By post, 9d. doz. TappedCoilson Ebonite,10 tappings, broadcasting ,ize, price 2/6.Post, 1/- each extra. --4911. -001 8,1- S.P.D.T. Switches on Ebonite, 1/9, 2/6 each.Post, 9d. D.P.D.T. 2/6,3/6 each.Post, 9d. -0005 5/11 Accumulators,0 v.60a.,absolutelythebest,- 35/-. Carriage, 2/- extra. -0003 4/11 Slider Knob and Plunger, 3d.By post, 7d. Terminals, W.O., Telephone, P.O.and allpatterns, including nuts and washers, not junk, 2for 31d. .0002 3/11 1/6 doz.By post, 1/- doz. extra. Aerial Wire, 100 ft., 7'22, 2/11.By post, 313. -0001 3,6 IntervalveTransformers, very best,25/.. Also12/6 each, 16/, 20/- each.Post, 1/- each extra. Vernier 3/3 Knobs, bushed 2 B.A. (best), 3d. each.By post, 7d. 3 Way CoilHolders, Ebonite and brassfittings,716. Post, 11- extra. ALL ORDERS BY POST MUST BE Dubilier Condensers, at usual prices. Telephone Transformers (R.I.),20/.Post,1/6. ACCOMPANIED by 1/3 per set EXTRA. H.T. Batteries, 30 volt, 4/6; 30 volt, 5/..Post, 1/- each - OTHERWISE NOT EXECUTED extra. Telephone Leads, long,1/..Post, 6d. extra. Filament Resistances,1/6,1/8,2/-,2/6,3/-Post,9d. extra. Transformers,L.F.(RadioInstruments,Ltd.),25/-. " BRUNET" FRENCH PHONES 1/. 4,000 ohms (different headbands) . . . . 22,6 and 25/ - French Phones, leather headband, 4,000 ohms . 15;'6 and 17/6 B.B.C. Phones, best quality 17/- and 19/6TO CALLERS ! T.M.C., 4,000 ohms, stamped B.B.C. . . . 24/6 pair. (Phones supplied by T.M.C. themselves, taken from expensive sets to clear.) ,,P,Vtit.3, I sell everything you want for your home madeSets. No junk.No " MUZZLEPHONE" CRYSTAL SETScheap job linesAll low in price, in handsome polished case.B.B.C. Royaltypaid,r4 Post 2 6 but first-class quality. or with pair of 4,000 ohm phones, aerial wire, etc., 50:--'1"0/ TRADE SUPPLIED TRADE SUPPLIED

H111111111111111111111111111111. 71111111111111111111111111111111111E =Phone : GERRARD 4637 "..- ---2 Right Opposite =-7-- Ivia RAymoND -;OPEN 9 to 8 ==-4-- DALY'S= = = - Saturdays - 9 to 6 p.m. kn - GalleryDoor -... AA = 27,LISLE STREET,W.C.2 a: '41 9IIIIIIIIIIIIIIIIIIIIIIIIIIIIIII1 RA TIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIW nn RAFWAWAVAPAPASTAFTWAs,pWAFTWAVIIPMVAPWAVNFAFAVAVARAVARTIPTIFTWARAWWWWWWW,WARIPAVARAPAPAPAPARAFRFARAVNITAFIWARAVVFAFAVARAFTITA C Pcpufar Wireless TVe2!:ly,-June 9th, 1923. positive metal, the metal being deposited upon the cathode by a- high voltage dis- RECENT WIRELESS charge in vrteno. INVENTIONS. 195,461.-C. W.C. BECKMAN & The following abstracts are specially con- P. ALEXANDER.-INDUCTANCES.- tributed by Mr.Harold J. C. Forrester, Tuning inductances having stationary and Fellow of the Chartered Institute of. Patent pivoted coils movable like the pages of a Agents, 88-90, Chancery Lane, W.C.2. book, have special crown wheels on the pivot pins of the coils.Pinions rotated by ONE IS WAITING FOR YOU. operating handles engage the crown wheels, It is just what you want.Covers Units Grant of the following Patents can be and thus a fine adjustment of the positions. and Sets in parts for home assembly. How opposed and printedcopies of the full to extend the range of your Set. Reac- of the coils may be obtained. tance apparatus at small cost.And the specifications purchased. The crown wheels are made of insulating - whole range of components and sundries. RADIAX. LTD., 10, Radio House, Percy materialwitha separatecircularrack Street, Tottenham Court Road, London, which may be of metal let into the lower W.I. Maceula 490. 194,765. - E. POLLOCK.- surface of the material, so that the coils are VALVE RELAYS.-Two or more diode perfectly insulated. - valves are interposed in the output circuit TELEPHONES- of an alternator and when they are cold no r=NOTE MY PRICES current passes.The circuit is such that an 195,546.-N. F. S. HECHT.-VALVE ontinental) output transformer is energised only when GENERATORS.-To preventover -heat- E.V. (B.B.C.) 19/6 the filaments are heated by currents induced inginapowervalveduetonon- C.E.S. Silk wound to 4,000 ohms in corresponding transformers by a micro- functioning, a condenser' shunted by an guaranteed.Perfect reception, phone or key -controlled circuit. A low - auxiliary valve oscillated by the power superior finish - - -21/- frequency alternator may have the micro- valve is inserted in the high-tension supply. 15/6 The condenser isthus periodically discharged, FRENCH, 4,000 - phone or key circuit shunted across it, but but should oscillation cease, the auxiliary Delivery at once. No waiting. Cash with Order. for a high -frequency alternator the current is valvebecomesnon-conductive and the POSTAGE supplied through an interrupter from a condenser blocks the high-tension supply. 1 pair, 9d.2 pairs, 1/-4 pairs, 1/3 separate direct current generator. ROBT. DEANE, 195,589. --WESTERN ELECTRIC CO., N.1.01 195,102.-A. M.LOW. - TRANS- 137, Englefield Rd., London, FORMERS. - One winding e.g.the LTD.-RECEIVING SETS.A cabinet secondary, of a high -frequency transformer contains a loud speaker, -a phonograph, a -wIrtEic..ruc- has some of its turns of smaller diameter wireless receiving set, and a motor -generator The Electrically Tested VARNISH than the others so forming two sets of turns mounted upon springs to reduce vibrations. POWDER. which are arranged, eccentrically.Thus a The loud speaker may be connected at will Quickly made sip.Iteeps indefinitely. small high-tension current and a larger to a microphone operated by the phono- High Insulation. low-tensioncurrentofdifferentphase, graph or to the wireless receiving set, the Sold in packets 1,'2 and 2/3, post flee, useful in the wireless control of torpedoes, motor -generator being driven by house -main from KEMPS, Electrical Works, aeroplanes, etc., are produced. current and supplying current to the wire- Brook Lane, Ashley Road, Bristol. less receiving set and the microphone circuit of the phonograph. ------, WIRELESS INVENTORS-----'''-'-H' 195,310. - P. HEMARDINQUER.- Patents and Trade Marks, Advice Hand -took AERIALS. -A frameaerialis com- and Cons. free, --13.T. KING, Regd. Patent Agent (G.B. & U.S.A.), 146a, Queen Victoria bined with a table, being wound upon a St., E.C.4:'Phone: Central 682.36 yrs. refs. vertical wooden frame which also serves instead of legs to support one end of the FOLLOW THE CROWD --Beginners Guide to Wireless ---y table:part of the table top forming a shelf BOUND EACH DAY FOR Explains, in plain everyday language, everything you wish to know about Wireless Telegraphy. withintheaerial.For portability,the HOW TO ERECT, CONNECT, AND MAKE shelf portion anfl the ]egs may be hinged. the apparatus required, and full instructions SPENCER'S STORES for making coils, tuners, and complete valve Glass or ebonite rods may support the 4-5, MASON'S AVENUE, and crystalsets.Instructions and diagrams corners of the aerial. BASINGHALL STREET, for a two -valve receiver are alone worth four times cost of the book.112 pages, price IS., LONDON, E.G. 2 : : postfree. --SAXON RADIO CO.(Dept.14), 195,337.-FORGES ET ATELIERS SPECIAL OFFER. South Shore, Blackpool DE CONSTRUCTIONS ELECTRIQUES FRENCH PHONES-C uaranteed-16S. DE JEUMONT.-INDUCTANCES.-An PRICE LIST POST FREE. agglomerateofironfilingsor magnetic powder and insulating material is moulded ACCUMULATORS, ETC. NEW AND GUARANTEED. to form two ring -shaped pieces adapted to 4 -Volt, 25 -Amp Celluloid 11/3. Postage 1 f -. encasearing -shapedloading -coilwhen 4 - Volt, 40 Amp., 17/6 6 - Volt, 40 - Amp., 25 /6 clamped together by a central rod, an air 4 80 ,', 27 / - 6 80 ..., 36/- 4 100 33/ 6 100 45/- space being left at the centre. Packing I I 6 extra. Packing 2/. extra. B.T.H. It " Valves 15 /- 36 -Volt. H.T. Battery Renown 8/6.Postage I 1-. 60., 14 /-. .. 1 /. 195,410.-A.M. LOW.-DISTANT Cash with order. Goods despatched per return. CONTROL.-In the wirelesscontrolof LOWKE & SONS, LTD., NORTHAMPTON. aeroplanes, torpedoes,etc.,a rotary in- terrupter breaks up the emitted waves into A..,"....TO THE TRADE-PROMPT DELWERY.A.." WOUND INDUCTANCE COILS. timed impulses which when of a certain Wound on Waxed ItnpregnatedFormers,with .26 S.W.G. Enarn., and finished with a dressing frequency operate a selective switch in the of the well-known "HARDICOL" Shellac Varnish receiving apparatus. Cement,ensuringaperfectandreliableroil. 6x3 6x4 12x2 12x2'12 x 312x3112x4 1/-1/11/8 1/91/101/11 2/ - eacheach earls each each each each 195,440.-GENERAL ELECTRIC_ CO., By the Dice,,.Carriage Forward. Cartons Free. Ter., .1" el rash with Ord,. AshleyWireless LTD. - VALVES.- Electric discharge PEPPER 33 Ft.13 'X 1H1 E la n, devices have a " soft " vacuum to increase "%en/ 181, Philip Lane, Tottenham, N.15."114 the potential gradient tit the cathodes, they TelephoneCoLtd. are coated with a highly electro-positive 69RenshawSt Liverpool substance such as thorium or sodium. Such THE NEWTONIA WIRELESS FACTORY Sole AVents a cathode may be obtained by coating an FOR ALL WIRELESS PARTS AT FACTORY PRICES anode of relatively electro-negative material 13/15, WHITCOMB ST., W.C.2. such as nickel with a salt of an electro- Regent 6469. LONDON. POPULAR WIRELESS WEEKLY.

NOTICE To All Engigedin '-ENGINEERING FREE WRITE FOR PART 1 TO -DAY THE BENNETTCOLLEGE ENCYCLOPAEDIC ILLUSTRATED ;DICTIONARY OF ENGINEERING CIVIL MECHANICAL. ELECTRICAL,MOTOR, ETC, ETC..

PART .

SHEFFIELD. To extend the name of The THE BENNETT COLLEGE clitite.ktcet Bennett College to everyono i0YANtor engagedin thedifferent iwancheq of EneineerUia, we are publishing an Illustrated Dictionary of Engineering ik %Mud' in about 24 Monthly Parts.Ion "an have each monthly part as it comes out FREE -3d. Postage only to pay. Handphone which has been specially THE CONDITIONS ARE THAT TOTJ send your name and address' your age and occupation, with three jenny stamps (to cover postage), designed for ladies. writing your .name and address very clearly.\\-e shall then place you It has no headband name on our Free List, and send you Part 1 at once. The to catch ortear the hair. Beautifully others will he forwarded as issued.Address your appli- finished,very comfortabletouse and cation to --- (Do not fail to give the par- ticulars required, and use wound to 4,000 ohms. this full address.) HANDPHONE - - - 15/3 each. Inclusive of all taxes. Postage He will use Fellows Headphones with GOSSAMER two earpieces in light die cast non -ringing "SENSIFONES" are the Latest and Best thing in Head- metaland woundto4,000ohms. phones, and to convince you ofthis we offer them to you on a HEADPHONE - - 21/6 perpair. SEVEN DAYS' FREE TRIAL Inclusive of all taxes. Postage 1/ - after which period, if you are not satisfied, Fellows Radio Instruments are British Made your money will be immediately returned. DO NOT BUY CHEAP FOREICN 'PHONES. throughout and guaranteed. EXTRA LONG CORDS. Itisbettertobe safe than sorry. Fitted with Magnets made inim aspecially prepared t: Folt FREE LIST. and expensivesteel,and FELLOWS MAGNETO Co., Ltd. y arranged and LONDON, N.W. 10. adjustedtogivea loud,TOWNSHENDS ITO., ERNEST ST., Telephone : Telegrams: clear note wi thou td istortion, 5I- BIRMINCHAM. WILLESDEN 1550-1. " QUIXMAG," 'PHONE, LONDON WIRELESS1134:31SUErriiE SETS FOR. Sheet, rod and tubing in nil sizes kept in stock and cut to any required size while you vait,or sent by post on receipt of cash We can turn anything in Ebonite. THE EBONITETURNERY WORKS (BARGE, WARREN & RIDCLEY, Cm), 91/92, Great Saffron Hill, London, E.C.1. 'Phone 8572 CENTRAL. STERLIN

BRITISH MADE COMBINED VALVE AND CRYSTAL RECEIVING SET

No. R.1570.

Photo 7,y Bunter Miss Doris Lemon as Nedda in " Pagliacei." TheidealreceiverforBroadcastReception, Reproduced by exclusive - permission o and the best possible setfor Opera Reception. the British National Opera Company, Ltd. APPROX. WAVE -LENGTH RANGE 280 - 2,800METRES, RECEPTION RANGE 150 MILES.

USES A DULL EMITTER VALVE REQUIRING ONLY 1"8 VOLTS FOR THE FILAMENT.

This instrument will enable you to derive the greatest possible pleasure from " listening -in " to GRAND OPERA AT COVENT GARDEN and will introduce you to one of the highest forms of musical art. You will then he more than ever anxious to hear the actual performances. PRICE : Complete with High and Low Tension Batteries, I pair of Head Telephones (2,000 ohms), and all necessary plugs and cords, but exclusive of Dull Emitter Valve, £20-15-O 1 Dull Emitter Valve for above- £2 extra.

To be obtained of all dealers, or direct from: STERLING TELEPHONE AND ELECTRIC CO., LTD., TELEPHONE HOUSE, 210-212, TOTTENHAM COURT ROAD, LONDON, W.I. Telephone: Museum 4154 (7 lines). Telegrams: "Cucurnis, Wesdo, London." BIRMINGHAM: CARDIFF: MANCHESTER: NEWCASTLE ON -TYNE : WORKS: 15o, Edmund Street. to, Park Place. 14, St. Peter's Square. 9, Clavering Place. Dagenham, Essex. The above instraMent bears the B.R.C. Seal.

Printed and published every Friday by the proprietors, The Amalgamated Pres:,(1922), Ltd., The Fleetway House, Earringdou Street, London, E.C.4. Advertisement Offices: Messrs. J.11.Lite, Ltd., 4, Ludgate Circus, Loudon, LX.4.Registered as a newspaper and for transmission by Canadian Magazine Post.Subscription rates: Inland and Abroad, 17/4' per annum, far-six month.Sole agents for South Africa: The Central News Agency, Ltd.Sole agents for Australia and New Zealand: Messrs. Cordon R (dutch, Ltd.; and fur Canada: The Imperial News Cu. (Canada), Ltd.41tisday, June 914.1923. REGISTERED AT THE G.P.O. AS A NEWSPAPER POPULAR WIRELESS WEEKLY, Jt NE Ibth, 19:0, HINTS ON PANEL DRILLING. Popularireess No. 55.Vol. III. SCIENTIFIC ADVISER: SIR OLIVER LODGE, F.R.S., D.Sc. June 16th, 1923.

The Aunt and Uncles - of 2 L 0 Receive a Present.

FEAT URES IN THIS ISSUE. Birmingham's Melody Man. Photographing Electricity. Simplified Power Amplification. Constructional Hints. Wireless in Northern Ireland. Well-known Artistes of 2 Z V. And an article by Dr. N. W. McLachlan, M.I.E.E., on the " Reproduction of the Pianoforte." POPULAR WIRELESS WEEKLY. Jtrne 1Cth. Ma. li " BROWN " LOUD SPEAKERS with new improved Curved Horns requisites of a Loud Speaker THEare pure tone, clear articulation, and good volume of sound. The BROWN Loud Speaker possesses all these qualities in a marked degree. Type H. 2 has been designed to meet home requirements, both as to volume of sound and price. PRICES H. 2 (Small), Low Resistance. 120 ohms, height 12 in.£3 0 0 H. 1 (Large). Low Resistance. 120 ohms, height 21 in. £6 5 0 nigh Resistances for either size, 2,8 to 5: -extra THE BROWN MICROPHONE AMPLIFIER TLis amplifiergivesamagnification much greater than that obtained from a two -valve amplifier. Catalogue, post free, givesyou details PRICES. of our Wireless Headphones, LoudLow Resistance (120 ohms input) £6 0 0 Speakers ,Transfornicrs&A rnplifiers High Resistance (2,000 ohms input) £626 Sole Manufacturers : S. G. BROWN, Ltd., London Offices and Showrooms. (REF AIL ON L IL to which the Public are requested to address all orders if unable to obtain through local dealers : fbALORK 19, MORTIMER STREET, LONDON, W.1. 2 -VALVE RECEIVING CABINET Head Office and Works /Trade Only), Victoria Road, North Acton, W.3. A high-grade instrument at a very low price. Thissethasbeenespeciallydesignedfor receiving broadcasting, and complies with all the Postmaster -General's regulations.It can be used either for listening -in with headphones or HULLO !!! C.Q. WILL DAY CALLING with a loud speaker.

THE LATEST MARVEL, a pair Additional interest and use is secured because of Midget Headphones, weigh it will receive all amateur transmitting stations under 4 ounces, 4,000 ohms. within a range of 20 miles. TheFellophone Call and test these at our is mounted in a handsome oak cabinet, and is showrooms ...... Price 21/- per pair sent out complete with H.T. battery, 6 volt A THOROUGHLY RELIABLE accumulator, 100 ft. aerial, 2 shell insulators, and PAIR OF HEADPHONES, one pair of Fellows 4000 ohms double head- stamped B.B.C...... 20/- per pair phones, but without valves. I00 feet 7 25 Stranded Copper Aerial Wire ...... I /10 per coil British Made Throughout. Mode under Moreoni1 leen, nod approved by the B.B.C. and HAVING PURCHASED THE WHOLE OF A MANU- Post Dinaet,:eoerul. FACTURER'S STOCK OF GUARANTEED 7,22 HARD PRICE COMPLETE £ 1 2 inclusive of all taxes DRAWN AERIAL WIRE IN 100 FT. HANKS, WE ARE ABLE TO OFFER THIS AT THE LOW PRICE OF without valves. Carriage - - 2 '- 2i2 PER HANK OR 2/- FOR 50 HANKS AND UP. EXTRA FOR 2 VALVES . . - 30 - EXTRA FOR ADDITIONAL FELLOWS Sheet Ebonite, Grade A, cut to any size DOUBLE HEADPHONES, 21/6 Postage, 1,-) Every requisite in Stock for Wireless TRADE SUPPLIED. These are only a few of our bargains.Do not fail to send for our Price List gluing the lowest prices for the best FELLOWS MAGNETOCo.,Ltd. quality goods.Postage on all goods extra. LONDON, N.W.10. Writefor our new Catalogue,now ready. : Telepros:re Do not fail to try the NEW "DAYZ1TE," Regd. 11 I=1560-1. " QVIN:11.4C," 'I'DONE. LONDON. The super marvel Crystal with Silver Detector Point at 2,6 each, or mounted in Brass cup, 2 10, Postage 3d. extra. E.13' WILL DAY, LTD., 1 %Lisle St.,Leicester Sq., London,W.C.2 g 'Phone: Regent 4377. Telegrams : Titles, Westrand, London. .10-eeyfood3iffeWf towil Popular Wireless Weekly, June- Hith,_ 1923. 641 POPULAR WIRELESS

June lCth, 1923. SCIENTIFIC ADVISER, SIR OLIVER LODGE, F.R.S.,D.Sc. [Every Friday. TOPICAL NOTES AND NEWS. Taxing Aerials. " Ragtime " for 2 L 0. The Amplion Loud Speaker. TA X " of £1 has been imposed by T AM told by Miss Toni Farrell, the well- ONE of the most popular loud speakers on A"the L.C.C. on wireless aerials installed known1 composer of Ragtime," that the market and one of the most on their Housing Estate, near Catford. she is going to write a song entirely perfect, must be the Amplion. I was On making inquiries, I am told that " offi- for broadcasting. in a famous stores the other day when a cially it is not a tax, but a deposit, return- series of comparative loud speaker tests able to the tenant when the aerial is dis- were carried out, and the Amplion scored pensed with," providing that no damage has heavily-over what, I suppose, I must not been done to the property. " WIRELESS REVIEW AND SCIENCE mention. WEEKLY "-No. 4 out next Tuesday. "Problems of Long -Distance Telephony,"by Dr.J.A. Fleming, F.R.S., and aspecial Well Received. practical wireless article by Sir Oliver Lodge. Valves Repaired. FROM lettersI and the B.B.C. have ORDER YOUR COPY NOW! THE Radio and Electrical Supply Co., 29, received,thebroadcastingof .the Paternoster Row, London, E.G.4, " TwelfthNight "was verywell inform me that they can undertake received.The B.B.C.'s letters' numbered the repair of broken valves and re -exhaus- about 400.I have not had time to count Search for the "Perfect." tion to any degree of vacuum for 6s. 6d.I. mine, but it is a large number. 0 isstillendeavouring to obtain think I will send a few of my " derelicts " 2" perfect " tra iission, though it is along to them. * difficult to see exactly where improve- Congratulations. Long Distance Recep- T FEEL sure that tion. 1 our readers will OWNERS of multi - join me in con- valve sets living gratulating Miss near a broad- Kathleen Nesbit for casting station will be the hard work and pleased to hear that - the success she made arrangements have of the production. been made to close * * * downthevarious Miss Ellen Terry. stations for half an hour every evening. TALKING to Miss This will enable long- Ellen Terry the distance reception to .other day, be carried out with- before she had broad- cast, I asked her if out interference. she feltnervous. * * * " Yes. Andit is " Closing Down." strange that I should THE stations will do so, considering my close down for profession.It is like half an hour as waiting for the follows : 2 L 0, 7.30 dentist." to 8 p.m. : 2 Z Y and * * S C,7.45 to 8:15p.m.; 5 W A and 5 N 0, 8 Tears in the Studio. to 8.30 p.m. ;5 I T, MANY listeners -in 8.15 to 8.45 p.m, may have * * . heard t h e break in Miss Ellen The Bar Lightship. Terry's voice when MANY people shecametothe Mr. L.C. Poole (left),of 16, Market Place, Carnington, Nottingham, operating his efficient reoeivins have been dis- moving scene of station.Right :another view of Mr. Poole's set. appointedat Hubert and Arthur. not being able to get It was a great effort for Miss Terry, for she ment is to be made, unless itis in the the Bar Lightship, Liverpool.The reason acted and delivered her part. as -if she were resonant effects of the studio and perhaps for this is probably that the power used is on the stage. It was a most touching scene, the occasional lisp from the microphone. only 100 watts,with an effective range and the few in the studio were greatly of about 40 miles.It i3 obvious that a moved. higher power installation is not necessary as the distance from the,lightship to the Peculiar Ringing Echo. harbour is only about 11 miles. * * nining with Mrs. Jack London. the peculiar ringing echo that * AT dinner the other evening Mrs. Jack -PERHAPSoccurred frequently on Sunday even- Automatic " Call-up," London,thewifeofthe famous ing was due to some of these tests, COMMUNICATION iscarriedon by novelist, told me that she thought though it was not regular enough to suggest the Marconi bell system whereby a broadcasting was " Just fine ! "" I would that the blanketing had been ireinOved. We bell rings at the harbour offices when like to have a set," she added, " but I guess could still do with a little less of that " far- the lightship is calling, thus working like I can't travel and listen -in, too." away -in -a -field effect. (Continued on page ,642.) Popular Wireless Weekly, June 16th, 1923

NOTES AND NEWS. Birmingham on June 4th, where it met with Send for Particulars. an enthusiastic reception. MESSRS. The British Z.M. Ericsson Mfg. (Continued from page 641.) . * * * Co.,Ltd., InternationalBuildings, Further Items. an ordinary land line telephone.There are 67-73. Kingsway, will be very pleased no definite times of communication, the ON June 18th part of the "Merchant of to -forward all paiticulars to all interested in arises. Venice" is to -be broadcast from 2 L 0, telephone efficiency. lightshipcalling when necessity and on July 11th, from 8 to 9, we shall The wave -length is 400 metres. * be able to listen to the last dress rehearsal Mr. -Edgar Wallace. Wireless and St. Dunstan's. of the great Handel Festival, which is taking TALKING to Mr. Edgar Wallace, the place at the_Crystal Palace.Quite an orgy famous journalist and author, he told IT glad to see what a great deal wireless of good things to look forward to ! is doing for the blind of St. Dunstan's. me, in regard to broadcasting and Looking through the " St. Dunstan's copyright, that in his opinion the opposition Wireless in Summertime Competition was ridiculous, and that broadcasting is the Review " the other day I was surprised The £5 prize in connection with this com- to see that a special part was devoted to petition has been awarded to Mr. P. Gibson, finest publicity one could have. wireless, and several letters were printed of14, AlexandraRoad, StocktonHeath, Warrington, to whomachequeforthat Carmen Dale. *which had been received from blind ex - amount has been forwarded.The details of soldiers reporting results. his entry appeared on page 632 inthe last THE other night I was listening to Miss * * issue of " Popular Wireless." -L Carmen Dale singing in the London Long Range on Crystal. Broadcasting Station Studio, and was ONE especially was interesting, that of The Heart of a Receiver. surprised at the nervousness she displayed.' anex -soldier, withacrystalset THE telephones are theheart of any On inquiring the reason, she said, " I can't situated at Cirencester, who reported receiver, crystal or valve, andfor see my audience. and I am always nervous good reception both from the London and really first-class results they must be if I am afraid that I am not singing just right." the Birmingham broadcasting stations. first-class themselves-not just anything * of 120, 2,000 or 4,000 ohms. Special Children 's 2 L O's " Jam Jar." Stories. 2L 0 have changed MR. DRAYCOT theirmicro- M. DELL, the phone again. In famous child the place of our old ten'sstorywriter, friendthe" sugar tells methathe box," therenow may writespecial stands a much smaller stories for broadcast- erection, consisting of ing, and possibly will one cylinder only,and tell them himself. known as thejam * * * jar."It was estab- Wireless Medical lished a few days ago, Advice Free. and has been a great ARRANGE- success. MENTS have * * been made by the Norwegian and B.B.C. Critics. Swedish Govern- T DO not think the' ments for the trans- 1attackonthe missionofmedical "Shakespeare advice from the night " in a certain Bergen and the weeklypaperwas Gothenburg Radio quite deserved. Stations gratis incases Though it may have of sickhess of accident been open to criticism .on board ship. as regards " acting," itcannot be fairly The Devil's Wireless. compared with the SOME time ago the stage representa- Admiralty est-' tions. Wireless is still ablished a wire- young, and will do a lessstation on the lot yet, and I for one island of St. Kilda, am glad I do not live so that the islanders Off for a wireless picnic.Some Glasgow -youngsters transporting their wireless gear ; ina more "peacefurj could communicate to the countaride. age. with the mainland...in case of stormy weathers but the set has never Must be Comfortable. A Special H.F. Valve. been used.With good old-time fear of the - 'HEY mw.=t-13e-seeeitive, they mustgive T 48 -always best to choose your valve to devil and all his machinations they refuse to Isuit the_purpose for which you want it, seek help by wireless. strong signals in their full strength, - they niust-reproduee broadcast pie -- andthenew Cossorvalve,made grammes -in all their volume and purity, they specially for H.F. amplification, should be Wireless. at Bleak House. must withal be robust and comfortable. in great demand in this respect. DURING a visit to Broadstairs I noticed * * that a wireless set had been installed at Bleak House, made famous by Not Officially Approved. Dickens years ago. In Peace and Was. ACOUNTRY correspondent tells me WI TH all these essentialsof a good that he can hear .2 L 0 quite well on telephone, the famous " Ericsson " . a crystal set by clipping his aerial A New Opera. make comply. In pre-war days the terminal to the earpiece rest of the telephone.

T AM interested to learn that an opera Navy used them, during the war the RAY., The ordinary earth -is --used, -but-the aerial, 1 from the pen of one of our leading and in these more peaceful days of broadcast of course, consists ofthe'phone lines. English composers, Dr. Ethel Smyth, is and transatlantic telephony they stil 1parry It is not a " stunt." however, that is likely to be broadcast on June 22nd.It is called their Message of efficiency to the ever - to meet with,the P.M.G.'s approval. . " Fête Galante," and was produced in widening circle of listeners -in. ARIEL Popular Wireless "Weekly, June 16th, 1923 643 REPRODUCTION OF THE PIANOFORTE, By Dr. N. W. McLACHLAN, M.I.E.E., of the Marconi Research Works, Chelmsford. In this article Dr. McLachlan deals with a very interesting source of distortion.It will be remembered that in order to obtain efficient transmission of pianoforte music the B.B.C. introduced their now famous " machinegun " microphone. This instrument consists of several independent microphones arranged in such a manner that reproduction of both high and low notes with the greatest of efficiency is possible.Readers who listened -in to 2 L 0 during the time when only the one suspended microphone was employed, will be able to appreciate the vast improvement obtained since the introduction of the new form of transmitter, more especially in respect of the pianoforte.

TO everyone who has attempted piano- wind type ;(d) the value of the increment WIRELESS (seeNo. 53). Moreover,all forte reproduction, whether on the and decrement at the beginning and end of the deleterious effects mentioned in that gramophone or for broadcasting, the a sound-in a word, the damping of the article occur when the diaphragm of the inherent difficulties have been patent.It instrument. microphone-unless, of course, it is of special is the purpose of this article to investigate The discriminatingtonalqualityof design-is subjected to the impulsive music the reason why the piano is so difficult to various classes of instrument is independent of a pianoforte. With the ordinary carbon reproduce accurately. We are not con- of the .relative phase relationships of the granule microphones the acoustic effects are cerned with the intrinsic quality of any differenttones in a musical sound, but peculiar. particular pianoforte, althoughitisof variations in quality of instruments of a interest to mention that this depends on particular class depend to a certain extent Selective Properties of Diaphragms. the design and material used for the sound - on phase.The question of overtones is of The diaphragm executesitsown board, its seasoning, the diameter, length, great interest scientifically, and it may notenharmonic series of natural vibrations-i.e. and material of the strings, the shape and be out of place to cite a case from the they are not in the ratio 1, 2, 3, 4, etc., with material of the hammer point, the mass of writer's experience. the forced acoustic vibration due to the same, the duration of contact and the One of the copper loaded strings in the particular tones from the pianoforte super- force of the blow-the two latter factors author's pianoforte was broken and replaced posed, and the effect on the whole appears controlling the amplitude of vibration of by another string. It was impossible to bring to be much more highly damped than the the string-the striking distance ofthe the two strings into tune, beats always being actual sound. The result is the production of hammer from the end of the wire, and the produced.On examining the string, the oscillations of different amplitude, frequency design of the framework generally. new copper loading wire' was found to be of and damping from the original musical different diameter from that of the unbroken sounds. A. Comparison. string.Moreover, although the unisons or Owing to the selective properties of a From the dynamics of the instrument it fundamental notes of the strings were in diaphragm (resonance effect), the important is easy to see that pianoforte music is of the tune, the overtones were not, and gave upper partials of a note in the upper register percussive type.When the wires are struck beats.This seems to show that the over- (treble) which determine the characteristics by the hammer, the sound reaches its maxi- tones in a loaded pianoforte string do not of the instrument are deleted, as are the mum intensity very rapidly, and therefore form a strictly harmonic series --that is, they fundamentals in the bass.When a series of the initial increment or rate at which the are not 2, 3, 4, etc., times the frequency of notes (chord). is struck simultaneously, the sound grows is very large.If the sound is the fundamental or unison. diaphragm is bewildered and the combina- prolonged by holding down the key, it dies tion tones created are aurally unpleasant, away gradually,unless,ofcourse,the Peculiar Acoustic Effects. and yield the well-known banjo effect.In sustaining pedalis employed ;but the The shortcomings of ordinary vibrational order to secure good pianoforte reproduction, decrement is small in comparison with the systems used for acoustic reproduction have it is essential to use special forms of micro- increment. already been set forth in detail in POPULAR phone. During the complete cycle of operations there is no period during which the sound isof uniform intensity-i.e.thereis no steady state, so that we are really dealing with a transient state, or one which is dhanging continuously.With a violin the greater portion of a note is of a steady nature, although the initial and final periods are highly damped.In pizzicato playing, :he percussive effect obtains, but it is not so violent as in the case of a pianoforte. - There is also a transient effect in violin playing when increasing or decreasing the intensity.When this is gradual, the tran- sient or impulsive effect is small, and when sudden, the effect in the reproducer is masked by the steady tone which follows. A comparison can be made between spark and continuous wave transmission on the one hand, and between the pianoforte and the violin on the other. The spar'k is electri- cally impulsive or percussive, whereas the greater part of continuous wave transmission is steady, there being the usual growth and decay periods. Characteristic Tonal Quality.

' The peculiar timbre or characteristic tonal quality of a musical instrument is due to (a) the relative intensity of the overtones to the fundamental-(b) the number of overtones present and their frequency relation to the fundamental-i.e.whether theseriesis harmonic or enharmonic ;(c) whether the instrument is of the percussive, bowed or The experimental station assembled by Mr. L. C. Solomon. of MmHg, St Anne's Rd.. Faversham. Kent. 644 Popular Wireless Wee1ay, June 16th, 1923: BIRMINGHAM'S MELODY MAN. In this interview a special POPULAR WIRELESS representative obtains some veryvaluable and interesting information from 5 I T'S musical director on the subject of " radio-itis " or wireless stage fright.

WHEN I visited the studio at Witton- baritone who had just sung his firstradio artiste occupying this most strange of stages. an outerdistrict of Birmingham item and was endeavouring to analyse his It was his first experience also, and it was where the Birmingham broadcasting impression. obvious that for the first moment or so he station has found a temporary home-I I think if I sang here a great deal," he was not at all sure of himself.He stam- was introduced first to Mr. _Percy Edg r, said, " I should become a tenor.I could mered, the slightest of stammers it was the director, and it seemed that I had not get the notes off my chest.There was true, and when he broke into the opening timed my visit well. no vibration in them at all." sentence his manner of utterance-short, In the artistes room, or waiting -room, " What class of artiste is most affected by clipped words-revealed that he was slightly I found the members of a male voice choir as the studio conditions ? " I asked the Melody nervous. well as several soloists, and not one of them Man. When I returned to Mr. Edgar's room to had previously had the experience of per- " Well, I think it is the humorist who resume our talk I asked him if many artistes forming for broadcasting, of singing their suffers mat.He, more than any other, exhibited signs of " microphone -funk " or a best and most popular numbers to an unseen expectssomethingfromhisaudience. new kind of stage nerves. and unknown audience.They were com- He wants some sign of interest, he wants to paring impressions, and it was interesting know that his jokes and his manner are Regarding the Future. to note that scarcely one of them was fully getting to them.He expects to hear them " Indeed they do ! The other day, for satisfied with the ordeal, though, of course, laugh.Here he sings his most popular example, I had a particularly striking ease. everyone enjoyed it from the point of view of number into the microphone, and when The performer was a very well-known novelty.One or two members of the male he comes to his patter he speaks across the concertsinger.He had been used to voice choir agreed that it seemed more mouth. When he comes tothepoint singing before large audiences. He sang formidable than that of singing in com- which never before has failed to incite a quite well, and when we asked him to petition at an Eisteddfod to an audience laugh he naturally waits for it.Nothing sign the book, as every artiste is asked to do, of many thousands. he had to wait a few minutes before But my impression was gained only doing so.He was shaking so much from those who actually described that it was impossible for him to their experiences, and since it was hold a pen, much less write his rather a difficult kind of interview name.I have seen many of them it is possible that there were some like that.There is no doubt that' of them for whom the realisation of there is wireless Stage -fright." the magic of wireless had coloured "What do you do ? " the imagination, and who, as they " Well, I assure them that there sang, had seen, if only in the mind's is nothing in it, nothing to worry eye,thedrawing -roomin some about. I tell them that as soon far-offvillagein which a family as they have startedI'llslip out listened -in. and listen -in, and "that if everything I mentioned this point to Mr. isall right I will pat them on the. Edgar, and he related his own first back.Of course, I invariably pat broadcast experienceto me.An them on the back." entertainerfor many years, well The Melody Man went on to speak known and popular throughout the ofBirmingham's futureconcerts. Midlands, when he gave his first " We are planningbigdevelop- et constructed by Mr. L. W. Gandell, of 43, GrosvenorPark wireless number probablyit was The a Boa, Walth am stow. ments," he said. ` The programmes easy for him to feel that his audi- that wearetransmittingn o w ence was there, even if he could not see it. happens. There is a deadly silence, and most are not to be regarded with what we are " I knew they were there.I enjoyed it. probably a cold shudder runs down his going to do in the future. We are putting Before I bad been transmitting a minute I back. in a permanent orchestra, starting with one could see my audience smiling.'Tis true offour members and comprising piano, I found myself waiting for the actual laugh Alleviating Conditions. violin, 'cello, and flute, and they will give at first, and I find myself waiting for it now. " There, you see, to be really successful selectionsofeverything,varying from Of course, it is there, and even ifit does as a radio artiste you have to imagine that dance music to a sound classical programme; not reach me that night, it has been known to audience.You hItve to see it listening to It will be capable of giving a whole night of reach here by a post during the next day you.Towards that end Mr. Thompson chamber music if necessary.In fact, it is my Or so. and I have tried to produce, as far as idea to set apart one night a week for a possible, the actual conditions of the stage. really classical programme, for it has been Humorists Affected Most. In fact, I have wondered whether it would our experience so far that it is little short of a. " The main point for a successful wireless not be helped by building a miniature stage, human impossibility to please everyone, item," he observed, " is for the artiste to so that the artistes could feel more at home." and, therefore,ifwe setasidecertain realisethataudience.Itissomewhat " Why not hang a representation of a nightsforcertain,programmes, then difficult at first.In a measure the con- crowded auditorium behindthemicro- those who listen -in will be able to please ditions of the studio are against him.He phone ? " I suggested boldly. themselves. stands on a little platform before a little cur - He laughed. likemicrophone.The heavydraperics, " Yes, that might be of use," he com- Mr. Edgar's Ambition. and the thick carpet, the emptiness of the mented." But we manage, I think, to studio cause embarrassment.The effect of suggest it in a measure by following this " In addition to instrumental and vocal ' damping 'is to get out all resonance and method.The artiste waits in the ante -room musical programmes, we also intend to make the artiste feel as if the voice is not until his turn -is due.Then he is admitted include talks on educational subjects such as carrying as it should do, and thus they and he hears his number being announced. literature and a number of other subjects endeavour to pierce their way through it. He steps forward, and as he advances we ofgeneralinteresttothe community. In fact," added Mr. Edgar, " I have noticed turn on additional lights, giving the idea of And when any public men are passing this beads of perspiration on their foreheads from the limelights which normally flood the way we hope to get them to break their their exertion towards that end." stage. He steps upon the little platform, and journey and to give a talk.It is my Mr. Edgar's remark was an interesting starts off." ambition," he concluded, " to provide and corollary of an observation which had been For a. few moments I `sat in the studio, and maintain something that will even surpass made to me a few minutes previously by a it happened that ahumorist was the 2 L 0." Popular li'ireless Weekly,' June 16th, 1623. 64i PHOTOGRAPHING ELECTRICITY. The taking of oscillograms is an extremely interesting operation, and one that all amateurs desirous of obtaininga clear conception of what happens in an electrical circuit under certain conditions, should attempt.

OHM'S law states that the current in any A very small mirror bridges over between the strip the vibration of the mirror about a circuitmultipliedbyaconstanteach leg of the strip. Tension is put on the vertical axis will cause the spot of light to number is equal to the potential difference loop by means of a graduated spring attached move along a horizontal line, through the applied. The constant number is commonly to P. Now consider a small current flowing zero point, the displacement from zero being called the " resistance " of the circuit, and is from Tl, through the loop, to T2.In the the amplitude. The eye, in general, cannot different for different circuits.In symbolsleft leg attached to Tl, the direction of the detectvariationsin amplitude as these the statement is E=RI, where E is the current is upwards, and at right angles to the occur, but photographs are easily obtained potential difference, the I resultant current, flux passing between the poles.By apply- using ordinary cinema film. and R the resistance. Now this is only trueing one of the " finger " rules it will be seen when E is steady, such as the pressure at thethat the effect is to cause this leg to advance The " Kinematograph" Camera. terminals of a battery. E may vary period- in a direction upwards at right angles to the To obtain a graph of the variations, that ically-that is, it may go through a emu ringplane of the paper. Since the current coming is the wave form, with respect to time, it is series of similar values in similar intervals down the other leg of the loop to T2 is in the necessary to move the film in a direction at of time, as does the current in a circuit underopposite direction, this leg tends to recede. right angles to the direction of the to-and-fro an alternating potential, or it may vary The total effect is to cause the small mirror movement of the spot of light.Fig. 2 shows continuously, as does the current in a tele-to rotate through a small vertical angle. the optical system of the oscillograph and phone circuit. The instrument is a modification of the camera.The source of light is an arc, the suspendedcoilgalvanometer,thestrip rays of light from which are focused into taking the place of the moving coil. an intense ray on the mirror M, by the con- In the oscillograph the magnetic field is denser C.M. being set at a small angle to the DIAGRAM OF riv..5/01V comparatively very much more intense than verticalplanereflectsthe rayslightly 0.50/./ OCRAPH P I in the galvanometer, and the re -resistance downwards, as shown, through the lens F to of the vibrator to torsion is much greater than that of the coil suspensions, whilst in comparison with the moving coil, its inertia LII4CAAAI Of OPTICAL SYSTEM is almost negligible.Further, as in the 31.10W/NC 17(.11 analogousoscillatory circuits,oscillations CAMMA are prevented by the introduction of a certain amount of pureresistance, and finally the whole movement is immersed inthat viscous liquid, castor. oil. The instrument is then quite dead -beat. Measuring the Current. When a varying current is passed through N the strip, the deflection of the mirror is a measure at any instant of the current.By focusing a beam of light on the little mirror, the beam can be used as an index, and made to give an image on a screen.If the ric2 position o the spot of light be marked at the zero position, on applying a current to the mirror N. The focal length of F is such as to give a sharp image on the film.The In either case it is of importance for the a mirror N simply serves to throw the ray correct design of the circuit to know exactly upwards, where it is usually convenient to how ' the currentisvarying under' the have the camera. The film rolled on a spool changing potential.The rate of change of in the camera is driven past the aperture current at any instant of time may often with uniform speed by means of a toothed becalculatedmathematically,butthe sprocketengaginginitsperforations. actual variations of current can be photo- Another spool is designed to take up the graphed with a modification of the kine- exposed film which has passed the aperture. matograph camera by means of the Oscillo- graph. A Simple Camera. For a great many purposes a record of from one to two feet is sufficient, and the The Oseillograph. camera shown in Fig. 2 is of a much simpler The instrument is shown diagrammatically construction.The one used by the writer in Fig. 1. NS, the field magnet, is a circular takes 15 inches of film. It consists of a light- ring of steel, square in cross-section, from proof box containing a wooden drum, wide which a narrow gap has been cut away to enough to hold the film, and mounted cen- form a pair of poles, between which a strong trally on a steel shaft. The bearings are gun- magnetic flux passes on magnetisation. The metal bushes fixed suitably in opposite ring may be wound with a magnetising sides of the box. A pulley is attached to the winding, but is often simply a permanent spindle for driving purposes, which may magnet. Suspended in the gap between the be effected by means of a spring belt from poles is the moving part or " vibrator," a small motor, geared down to a suitable consisting of a very fine flat strip of phosphor speed. The aperture is a slit in the bottom of bronze, doubled over the ivory pulley P, the box, parallel to the shaft and opposite and fixed at each end at the terminals T1, the lowest part of the drum. A shutter ar- T2.The strip also is guided by pasAing rangement, which need not be described in over the grooved pulleys GG. The Duddell Oseillograph, (Continued on page 646). 646 -Popular- WirelesA--Weekty, June -16th, 1923.

Fig. 4 shows the waved ex voltage and PHOTOGRAPHING current in an A.C. arc circuit, and Fig. 5 shoWs the effeet on the wave formai of the CONSTRUCTION OF ELECTRICITY. addition of a certain capacity.Resonance (Continued frond page 645.) is produced with a current wave whose fre- quency is 15 times that of the fundamental, THE TRANSMITTER. that is, with the 15th harmonic. detail, opened the aperture at the start of the record, and closed it on completion. Investigation of Distortion Effects-, The film was fastened along the periphery SINCE broadcasting commenced, of the drum, one side of the box being Where transformers have iron cores, such hundreds of amateurs have taken up removable for this purpose. as intervalve or telephone transformers, if wireless for experiment and research, not properly designed, great distortion of and possess transmitting and experimental The Use of the Instrument. the current wave form may be produced. licences. Fig. 6 shows an oscillogram of the distortion Naturally every amateur wants to under- The taking of oscillograms is a peculiarly produced by a small core -type transformer stand the fundamental principlesofhis fascinating study. Two vibrators (or evenworked at a high flux density. The form of hobby, and the detailed action of every more) may be used in the same instrument, the wave supplied to it was a smooth sine - instrument that he employs. when films of current and voltage may be shaped one.The distorted wave gives a The transmitter, commonly known as taken simultaneously, and so we can actually good idea of the resultant of a fundamental the solid back transmitter, has a button see what is happening in a circuit at any and third harmonic.The oscillograph has whose vibrating side is clamped to a light instant of time.Suppose a steady voltagebeen of great value in the construction of diaphragm. telephones which distort speech and sounds rco least, -and the distortion due to the telephone Construction of the Microphone. AIiKKJ receiver can readily be seen. The distortion is of course partly mechaniCal, but this gives The mouthpiece is of a very hard high a quality test for telephones.Fig. 7 is an quality ebonite to withstand rough usage, GOWNS and is clamped to the face plate by means oscillogram of the vowel sound '6, and Fig. 8 of a brass bush.The face plate is heavily one for ee. The vowels are true musical notes, constructed of solid brass and given a plating the waves repeating themselves regularly, of topper which is then oxidised.The back $01 33 0.3 0-4 IS YCOM HT cacmN, "Raw m MAKZMCL case is similarly finished. The bridge is a brass forging, heavily of 100 volts be applied to a circuit of re- made to support the transmitter button sistance 10 ohms, then by Ohm's law the rigidly, and is screwed to and insulated from current flowing will be 10 amperes.Now, f/C 4 M.COROOT werAGC B CURRENT/NA C ANC CIPC

SUPEWTONE LOUD SPEAKER CLIENTS have asked us times out of number for a loud speaker in keeping with the quality of our other products.But we delayed-with a purpose. And after months searchingexperiment, drastic selections and rejections, we have produced the Ericsson Super -Tone Loud Speaker. It has been well worth waiting for.Of an astonishing purity in tone it faithfully reproduces every voice -modulation, every intake of the breath, every musical note in splendid volume without the slightest suspicion of "tin " or distortion. Excellent for drawing -rooms where loudness with purity of articu- lation is sought for. Beautifully finished in dull metal and walnut 18 inches high. PRICE 80f. write us to -day for Lists. THE BRITISHL.M. ERICSSON MANFG. CO.,LTD., International Buildings, 67-73 Kingsway, W.C.2.

Selling Agents: Selling Agents: Manchester: 105 / 107, Nottingham:W.J. Corporation Street. Purse & Co., Traffic Birmingham : 14 / 15, Street. Snow Hill. N.E.England: Mil- Scotland 57. Robert- burn Ho. Newcastle - son Street. Glasgow. Super -Tone on -Tyne. Loud Speaker Popular Wireless Weekly, June 16th, 1923. 648

Faded signals maybe built up Hillsmay again by using the LISSEN absorb REACTANCE (Prot. Patent) signals method of H.F. amplification LISSEN REGENERATIVE - Length 43" HILLSmay absorbor deflect radio Diameter 23' signals, forests also.In cities, too. (P.Patent) Dial 2'," where there are large steel structures. REACTANCE communications, particularly on the shorter All the efficiency of the LISSEN REACTANCE method is embodied. and to it there is added full regenerative wave -lengths, may be considerably interfered effect. REACTION IS NOT OBTAINED WITH A SWINGING COIL.In combination with the LISSEN with, without your being aware of it.If you REACTANCE, this new LISSEN REGENERATIVE -REACTANCE forms for two stages H.F. an unequalled amplify at radio frequency by the LISSEN combination.Either unit may be used alone for one stage H.F., and will amplify even loud signals, ani, add REACTANCE (prov. patent) method, how- range, power, sensitivity beyond compare. ever, you will build up the weakened wave - The LISSEN REGENERATIVE -REACTANCE is so sensitive, that under many conditions both aerial and energy thatpenetratestheshieldedarea, earth connections may be dispensed with. Complete with switch-no awkward soldering-fitted in a few minutes- and pass it strongly on to the detector valve. no complications.Lissen one -hole fixing. and sonegativeanyshieldinginfluence. Range 150to4.000 metres-FULL REGENERATION over whole range. Price- £2 - 12 - 6 Blue print and instructions sent with each. Tune witha LISSEN-VERNIER CONDENSER (price12'6) for best results. This is designed for fine tuning of H.F. circuits. AMATEURSCounterfeits may be offered you. Take no substitute. LISSEN RE ACT ANCE (Prov. If your dealerisnot equipped toserve you, senddirectto Patent)-STILL TO BE USED. factory, post free. Apply on Range 150to600 metres 27/6 DEALERS: Please order through factor, or send direct. (6 tappings) complete .. trade heading for list.LIST 6d. Range 150 to 10,000 metres (IItappings) complete..32/6 Blue print shows two easy connections. LISSEN COMPANY1 Lissen one -hole fixing.Perfectly simple 8-16, WOODGER ROAD, GO LDHAWK ROAD, to use for one or two stages of H.F. Highly efficient. Adds great range and power. SHEPHERD'S BUSH, LONDON, W.12. Self-tuned-Lissen Vernier recommended, =_--_ 'Phone 1072 HAMMERSMITH. however, if aerial reaction is used.Rapid tuning-n3 lengthy searching.No switch N.B.-Close to Goldhawk Road Met. Rly. Station 'or Shepherd's to connect.Al! complete. Bush (Central London), or Hammersmith Tube. LISSEN APPARATUS - WELL THOUGHT OUT, THEN WELL MADE

ICI

/.tcyouHave NOT RECOGNITION Further recognition for the a VALVE SET famous R.I. Transformer. adopt the rzea--1 best and The R.I. Transformer is uni- use versallyacknowledged the most perfect intervalve trans- former ever produced, and is known and used throughout SCIENTffA C YSTAILS the universe. It has been adopted in all the 1'6 each or 3 for 4.- post free. famous circuits at present in useand isinvariablyre- commendedbythe radio SCIENTIFIC METALS C? LTP (1.1-1,1) expert, Tohn Scott -Taggart, P.Inst.P., Rare MewlsSpecja 1.7:fds Member of LII.E., describing IMPERIAL HOUSE. swAzd the famous S.T. too Circuit:- Telephone:REGENTKING "The two transformers used in this set were actually those manufactured byRadio Instru- ments, Ltd. Three or even more of these transformers -can be used in HERE'S WHAT YOU WANT AT THE RIGHT PRICE one instrument without dis- EX -GOVERNMENT BARGAINS tortion. Itisideal for Power Ampli- HIGH -TONE REED -TYPE BUZZER, 2/9, postage Out. TheFamous R.I. fication. MORSE -TAPPING KEY, with Silver Contacts, 13, postage 3d. Many new transformers now 800-0HM SILK -COVERED EUREKA RESISTANCE BOBBIN, approx. appearing are close imitations cGft.. V-, postage 2d. Intervalve Audio - in external appearance of the TRANSFORMER, Ratio 150 to 1 oluns. 1 -,postage 4d. R.I., but are unable to give Brunet Type Headphones, 4,000 ohms, 16(6, postage 6d. FrequencyTransformer. the results only obtained with Continental Featherweight 'Phones, 4,000 ohms, 17/-, postage 5d. the actual transformer. 4 -inch Tens and UnitsTappedCoils,idealforallBroadcastConcerts, Price- g 1 - 5 - 0 Look forR.I. on every in- 20 tappings in all, 2/6, postage 31d. strument. Insulated. Eyelets tor Indoor Aerials, 1/6 per doz.. postage SsI. Pocket -Lamp Batteries,4.5 volts each, for snaking up High Tension, 3/3 per doz., postage 9d. RADIO INSTRUMENTS, LTD. D.P. 2 -way Switch on Ebonite, for Series Parallel and Multi -valve Circuits, 2/9, Managing Director:J. JOSEPH, M.I.E.E. postage 3d. Chief Designer: W. A. APPLETON, M.B.E., M.I.R.E., late Admiralty Technical Research Officer. Weston Belays,theSuper -SensitiveRelay fortheRadioExperimenter; operates on 30 micro -amps.; 16 each, postage 9d. ONLY .ADDRESS-Works, Offices and Showrooms : 12, HYDE ST., NEW OXFORD ST., W.C.1. Scientific Supply Stores, 'Phone :Regent 6214-54 Telegrams :" Instradio, London." (E.P.S. 59) ll'aioZ7:1.126, Newington Causeway, London, S.E.1. Popular Wireless Weekly, June 16th, 1923. 519 SIMPLIFIED POWER AMPLIFICATION. By CAPTAIN IAN FRASER, C.B.E. Almost any audio -frequency circuit can be styled a " power " amplifier wbcn excessive H.T. voltage is Employed, but the efficient " power " amplifying circuit must be so arranged that it is capable of SAFELY standing the increased pressure. This article clearly shows how this can be arranged in a comparatively simple manner.

T GATHER from conversations with a was most marked.The removal of the them, or perhaps both, cause a variation, 1number of amateurs who have not iron had another advantage which was to which usually has an audible frequency, to reached a very advanced stage in their lower the impedence of the transformers, be passed through the secondary of the experiments with Wireless Telephone Re- and thus bring them into closer sympathy first transformer in the amplifying unit. ceivers,that the words " power amplification" with the T.15 valves, which have a lower Coming thus into the grid circuit of the last convey to them the idea of something rather impedence than the R. valve.Later this power valve the amplitude of this audio - difficult and requiring much apparatus, result was slightly improved by replacing frequency current is immensely magnified, additionaltothe note -magnifying units the second transformer from which the iron with the distressing result I have referred they, already possess.This is an erroneous had been removed, by a much larger coil to.Much can be done to minimise this idea, as I hope to show by a brief description such as those utilised in the construction of ripple by the use of high capacity con- of experiments I have carried out in this theMagnavoxpoweramplifier. This densers and choke coils placed respectively subject. transformer is of the one to one type-that across and in the main leads before they is to say, the primary and secondary are are connected up in the plate circuits, but Increasing the H.T. wound with the same wire and the same my experience showed that it was not a The phrase " power amplification " usually amount of wire. Incidentally the two wires convenient or practicable proposition.Six refers to amplification of audio -frequency are wound on to the " former " together, microfarads, and as much inductance as I currents. and is affected with apparatus which provides a much tighter coupling could provide from secondaries of old induct- which is similar in design to ordinary note - than is obtained when the primary is wound ance coils, etc., etc., do not cure the evil. magnifiers.The power amplifier is in fact onfirst,and the secondaryissuper- a note magnifier in which are employed imposed upon it. Transformer Connections. valves and transformers capable of standing I have utilised this combination for a I then adopted the expedient of run- a higher potential in the plate circuit than considerable time and can recommend it as ning my detector and first note -magnifier is normally used. with 100voltsin Ipossessathree - the plate circuit. valve unit, supplied by and utilising the T.15 one of the leading firms, valve as the last note constructed for R. type magnifier with the 240 valves, using one as a volt d.c. main in its detector and two as platecircuit.With note magnifiers. I this combination only started my experiments atwomicrofarads in power amplification condenser across the by merelyincreasing main was required to the potential on the givealmostperfect plates of the two R. freedom from ripple. valvesbeing used as The explanationof low frequency magni- this is that the varia- fiers. I found that a tion in thecurrent pressure of about 140 An experimental 4 -valee set constructed by Mr. C. W. Reardon, 31, Brookfield Avenue, Walthamstow, E.17. from the main is rela- voltsgave thebest tively small, and pro- results, and if this figure was exceeded no an easy and inexpensive method of con- duces but little effect when it is in the out- greater amplification was. obtained, but in verting a double note -magnifier intoa put circuit of the last valve, a very different fact the quality of the reproduction appeared power amplifier for use with a large loud proposition from that first explained, when to be prejudiced.Ishould notadvise speaker.I might mention that with this being introduced in the output circuit of the experimenters to employ so large a voltage unit I have on more than one occasion given first note -magnifying valve it was energising on ordinary R. valves, for to accommodate a demonstration to an audience of between the grid of the second valve and causing the valve to this potential it is necessary to 75 and 100 people, in a large hall. greatly increased variations in the plate increasethefilamentbrilliancybeyond circuit in which the telephones are included. that for which the lamp is constructed, and Using D.C. Main Supplies. This final arrangement I use constantly. though this does not appear to do the There' isavailable at my station 240 The results are not quite so good as those valves any harm it very materially affects volts direct current from the municipal obtained by the use of two T,15 valves and their length of life. mains.The inconvenience of using 300 the dry batteries, but I prefer it because of In this same experiment I went up to as volts provided by dry batteries and the the fact that it dispenses with large dry high a figure as 240 volts, and finding deteriorationof these batteries when a batteries which, for constant working, are a, thatthetransformer, whichofnormal relatively heavy current such as that taken source of trouble. though extremely good construction, would by two T.15. valves is required, led to my Some beginners are apt to be careless stand this abnormal strain without any investigating the possibility of utilising the about the way in which they connect up appreciable effect, I utilised it for my next main.The beginner may imagine that a transformers. When the secondary is super- experiment. direct current from a municipal main would imposed upon the primaryitismost be extremely suitable for the purpose, but important to see that the inner and outer Excellent Results Obtained. he will be disappointed, for immediately he leads of the primaries and secondaries are I obtained two T.15 valves, and applied connects up he will hear a roar not unlike properly connected.The outer lead from to their plates a pressure of 300 volts. This the distant sound of an aeroplane.At a primary winding should be connected to greatly increased amplification, but brought least this was my experience.It is caused the plate of the valve which precedes it, with it a certain amount of distortion.I by the fact that though the current is and the outerofa secondary winding then took out bothtransformers,and often called " continuous," itis, in fact, should be connected to the grid of the valve removed those parts of the soft iron wind- caused by a number of impulses following which follows it.When high- degrees of ings which were surrounding the copper each otherinrapid succession,as the amplification are used the effect of wrongly windings, leaving only the iron core through brushes on the big generator pick up the connected tran§formers, particularly in the the centre of the former. As would be ex- current from the swiftly revolving com- case of the secondary winding,is most pected amplification was slightly reduced, mutators.-These impulses themselves, or marked, a noticeable diminution in signal but 'the improvement in tone and quality small surges in the 'voltage resulting from strength being at once observed. 6,;0 Pamela? Wireless Weekly, June 16th.,1923.

fact that our minds can listen to several " planes " of harmony that are unrelated to each other, at the same time, without WIRELESS IN NORTHERN IRELAND. annoyance or difficulty.This is"aural By T. P. ALLEM, B.Sc. inhibition," or, as the composer callsit, "horizontal listening." Therefore, when the mind islistening attentively by one ear only, it automati- IN Ulster there is an ever-growing interest London is a mystery. Usually one cannot cally deafens the other by inhibition ;a

in wireless matters, and were it not for get any sort of results from 2 L 0 until after the restrictions placed upon amateurs 9 o'clock in the evening, but then they come state which, if it persist, as it may, becomes by the Government, I should say that the in very strongly.The Guards' band, on a case of nervous deafness, and a source of Ulster district would be successful in experi- Tuesday the 1st, was an excellent trans- trouble to the sufferer. mental work. As things are now, no trans- mission; and was perfectly clear to me with That this is a danger will be borne home missions are permitted, and, to my -knoVir- My 'phones hanging on the wall.Consider- to one if he should experience a fright ledge, only one experimental transmitting able fading is noticeable on 21 0 and seems such as I had recently.My friend com- licence has been issued (a temporary one for to affect this station most. plainedof" funny ears."Idiagnosed six months), while the aerial used has to be itas" wirelessear,"and aboutfive a frame aerial and not exceed one foot square. Spark " Jamming." minutes later he nearly jumped under a' Such severe restrictions only penalise the For a long time, the enjoyment of the motor -cycle, because, as he said, he " mis- genuine experimenter. broadcasting was marred by the trans- judged the direction of the horn." For half For experimental receiving or " broad- missions on spark, from the steamers leaving a minute I cursed all ex -Government single casting " sets, one mustfirsthave the Belfast at 9 o'clock ;but latterly no trouble earphones ! Yourstruly, permission of the Home authorities, and of this sort haS been experienced; though we J. BARI-WOOLLS. after that the actual licence must be ob- still suffer a little from the police trans- 39, Poole Road, E.9. tained ;a lengthy process. missions. Eiffel Tower, Radio-Electrique, Konigs- To the Editor, POPULAR WIRELESS. Room for Improvement. wusterhausen, and the School of Posts and Dear Sir,-It-may interest you to know A large number of local people have been Telegraphs are all quite clearly received on that I receive Cardiff and Birmingham on the three -valve set, While several amateurs the Super- Crystal Set, the construction of refused permission to have even- a " broad- which was recently described in POPULAR casting licence, although the inust unin- have received American transmissions. Representatives of most of the large WIRELESS. The reception is under quite telligent novice knows how harmless the normal conditions-the aerial used being of B.B.C. set is. Rut despite these -.petty wireless firms are already covering Ulster, troubles, those of us who have been for- and fine results are being obtained on Mar- the usual twin type, approximately 50 ft. tunate enough to obtain licenoes have been coniphone and Gecophone two -valve sets. long and about 15 ft. high.I should be getting results.Glasgow's is, of course,the It has been suggested that the B.B.C. pleased to hear if any other reader has strongest transmission in this area ;and should open a relay station in Belfast for ranged this distance. several people, -one a Belfast man, claim to the benefit of crystal users, and I hope that Yours faithfully, be able to hear this station on a crystal set, something in this line will be accomplished. 62, Woodville Road, S. R. DONALDSON. while it certainly can be heard on one -valve Golder's Green, N.W. 11. without reaction. Two valves, 1 H.F. with The Editor, POPULAR WIRELESS. reaction on anode, bring in the station quite CORRESPONDENCE. I comfortably on the headphones, and an Sir,-As it seems to be the rulerather extra valve as a note magnifier will work a than the exceptionto use 12 or 14 -inch loud speaker and give a fair volume of sound. The Editor, POPULAR WIRELESS. inductances as tuners for crystal sets,I The programmes- given by 5 S C are very Dear Sir, =I would like to warn your should like to suggest the following idea good, but twolittledefectsstrikethe readers, per P.W., of a new " wireless " for cutting out the " dead-end effect " listener -in.Firstly, the announcer speaks a danger.I have found that many people who generally experienced when using only a littletooquickly,andsecondly,the usesingleearphones, such as ex -army small amount of a long inductance. generator hum, or so I take it to be, is very 'phones, arc suffering from artificial deafness Instead of leaving the end of the winding prominent.This hum is so unmistakable in one car, brought about by the use of " dead," as seems to be faiionred by most that I can tune in the Scotch station by the single ear -pieces. handbooks on the subject, this end should hum when no speech is available. I will make an explanation of this curious be connected straight to earth, which is The children's stories in Glasgow might phenomenon.It is caused in this way : in most cases the slider rod, or, in the case be improved a great deal, if children are Most people are naturally more efficient of a tapped inductance, the switch arm. really to be interested.After all, children on one side of their bodies than on the other, This method has proved highly satis- are not at all interested in other people's and thisis equally the case with regard factory in all cases in" which it has been letters, and they are usually the first of us to the ears ;that is, we can usually hear tried by the writer. ' to notice any change in a person's voice, so, better with one ear than with the other. I remain-, yours faithfully, I think the operator should speak as he Consequently, the enthusiastic owner of a " ELEcrttoxrrs." would, and does, to " grown-ups," and not wireless set which has only one single ear- 239, Ripple Road, Barking, Essex. attempt to talk " to the children."I think piece naturallyuses the stories from the London station are his more efficient ear. examples of how the children's hour should Now the mind begins be conducted. todo damage. One cannot keep out sound The Mystery Station. from the other ear by Manchester still seems to have trouble means of cotton -wool, with its microphone, and most of its words and mostlisteners -in are unintelligible here, although the singing will admit that it takes is very good, and also the orchestral trans- some considerable time missions. The 2 Z Y morning transmissions for the mindtosift - seem to be clearer than the evening ones, and out thesignals from the voice distortion seems to be at its worst the extraneous noises. when the time signals are being explained. That mental process is Newcastle is very clear and distinct, but termed " aural inhibi- rather weaker than the others ; while Bir- tion," and it is a sur- mingham requires a little extra tuning to prisingly efficient pro- get in properly.Cardiff is very good, and cess: Ifany reader the quality of its -programmes is excellent. doubtsthis, lethicn May Icongratulate thisstation on its- reicall that much of our announcer, whose words are always crisp ni-odern, first-claSs

and clear here, on three valves. - - rlietsia N based- .on theA-1.vidve.set constructed by M. F. V. Rogers. hi 205. Chichester Rd.. PortsmOnth. Popular Wireless Weekly, June 16th, 1923. 651

EVERYTHING FOR WIRELESS OOIL HOLDERSIn Harrods Wireless Lounge (Second Floor) everything can be obtained by the amateur for building setsCONTACT STUDS Speciallydesignedtoand conducting experiments, and wireless experts are always in attendance to giVe advice and information.With nut and washer. reduce capacity effects Small 1,6 Largese/ - w3ay13/62a, 11 /- GRID LEAK AND TELEPHONE CONDENSERS TRANSFORMERS Splendidlymade and Price Each 13 :a neatin appear- A I. HORNS for LOUD ance. Eachit' SPEAKERS CONDENSERS 22 incheshigh. e e TELEPHONES. gli (Fixed).Made from Price..Each Most efficient, best quality Mica and Curved Pattern . sensitive and Copper Foil. All111 /. Price Each 2/6 reliable.2,000, resistances. Each LI Postage on each 4,000,or 8,000 VOLTMETERS .. ohms. DOUBLE POLE, DOUBLE THROW KNIFEPocket type. Most e /9 CONDENSER SWITCH,mounted on china.Heavy EachU/ VANES. Made from Per copper clips and blade. In-l&/ reliable. 22 S.W.G.Hard rolled pair sulated handle. Eacha is COIL PLUGS sheet,surface_ matted Fitted with brass inserts and edges polished. D.P. one way. Each andconnection1 /6 Fixed 1 Rotary 1 3/6screw. Each I / per doz. I/per doe.I// SEND FOR SLIDER KNOBS IVORINE SCALES Useful when making own Flat, semi -circular, for FREE BOOK inductances. Smooth FULLY polished finish. - Condensers, Vario- Orders value meters,Couplers,etc. ILLUS- Each 90. Engravedblock,C andover sent TRATED POINTERS. Best 05-180° Each1./0. post free brass or aluminium. 1 INSULATORS 1.; centre. Each1 D. Useful for many pur- REACTANCE poses. Bobbin type. 0 VARIABLE INTERVALVE REACTION UNIT FORMERS. Most Weight, 2 ozs. Each OIL This Unit will enormously add to the efficiency 111 useful to experimenters. Egg type. Weight-C of your instrument and may be safely used Inside diam. 3 ins. Out- 2 OZS. EachLID. during the hours of Broadcasting. Each 4"/ side diam. 4 ins.7 /6 Shell type. Weight 1 / EachI / 31 ozs. Each / TERMINALS EARTHING CLIPS SERIES Pitio,AEL Barrel type 2 B.A. 4d. These are SWITCHES well tinnedon Ebonite INTERVALVE REACTION UNITBarrel type 4 B.A. 3d. to ensure certain IQ baseboard. LEADING -IN TUBES. Finest quality 0/6 Telephone.Each 4a. contact. Each OD. 4/6 obtainable Various lengths. From AM. Made from finest materials,W.P. type. Each 4d. Unmounted, inelud- thisshort and long range ing stops and HARRODS Ltdstuds .. 2/6Wireless Department 2nd Floor ril-ictienits. 38/..LONDON SW1

THE A NEW DEPARTURE IN KNIFE SWITCHES Made specially for F.Z1 411 PRECISION VARIABLE 4.1 CONDENSERS Panel Mounting. n NICKEL FINISH. NEAT APPEARANCE. still retain their SUPREMACY over all others offered at the SPRING CONTACTS. prices. They are DESIGNED, Themost suitable switches for changing overH.F.orL.F., not made, and series -parallel, stand -bye or tune circuits, etc., etc. riThe ACME of No.19/20, Single Pole, Double Throw, 1" Centres - - 1/6 PERFECTION. No.19/21, Double role, Double Throw, x I" Centres - 2/3 Post 2d. Accuratelyandcompletely assembled, including OUR MOST POPULAR TYPE CONDENSER IS STILL KNOB and DIAL. WITHOUT EQUAL FOR CORRECT CAPACITY AND USEFULNESS. Nofiddlingabout Large METAL to METAL looseningscrewsandconnections, TESTIMONIAL. simply pull out from clips when you One of many unsolicited.bearings. ONE HOLE only re- wish to try another capacity. Oakleigh, quired for FIXING to PANEL. EVERY CONDENSER TESTED AND Lynmouth, Gentlemen, Devon. Avoid imitations and insist on ENGRAVED CORRECTLY. I am highly satisfied with con- a J B. NOTE THE RANGE :'01,'02, '001,'002,'004, den.ers received, and thank you for '005,'006, prompt attention, Please send me '00I 8/6 '008,'0001,'0002, '0003, '0004, '0005, lea snore, forI think they are the '0006 and '0008 M.F.D.S.Also intermediate sizes. GRAFTON ELECTRIC best value on the market. '0005 - CATALOGUE Yours faithfully, 7- PRICE, with Clips, 2,'- each, post 2d. F. A. HARRIS. '0003 - 59 Packing and postage extra. One only, 9d. Two, 1 -. VERNIER 4 - GRAFTON ELECTRIC COMPANY, DIRECT FROM 54, GRAFTON STREET, CONDENSER TOTTENHAM COURT RD., JACKSON BROS., SPECIALISTS LONDON, W.1. 8, Poland St., Oxford St., London,W.1, Telephone: MUSEUM 241. Works: SLOUGH. Trade enquiries invited. Or through your Dealer. 'Phone: Gerrard6187. ------Have you sent for our100 page Catalogue Post 311. Free Popular Wireless Weekly, June 16th, .1923. Buy your Loud Speaker where e WORLDS' THE this sign NAT MONEdREGIS you see ABROAD , W IRELESS LOUDSPEAKER p MANUFACTURED BY THE PIONEERS IN LOUD SPEAKING TELEPHONY. ALFRED GRAHAM & COMPANY. Demonstrations at our Showroom : St. Andrew's Works, Crofton Park, LONDON, S.E.4. THE ALGRAPHONE SALON, 'Phone: Sydenham 282o/1/2. 'Grams :Navalhada, Catgreen, London. 25/26, Savile Row, SCOTLAND: Mr. F. M. Milligan. Regent Street, 25, Renfrew Street, GLASGOW. IRELAND: London, W.1. Mr. A. R. Munday, 41, Chichester Street, BELFAST. 'Phone :REGENT 1075. CANADA: Messrs. Burndept, of Canada, Limited, 172, King Street West, TORONTO.

---)EPENDABLEw, >HESTAVOX II< RADIO SERVICE 2 -ValveReaction Receiver Aerial Wire, 7j22 bare copper stranded, 100 ft.26 Insulators. Reel, 1d. Egg, 3d. Shell, 6d. la Variometers, silk wound, fitted with Ebonite . Dial Knob...... 46 ,

Crystal Receiving Set, Variometer tuning...100 unassembled70 Crystal Detectors on Ebonite'base ... &2/ - ,.....--.;...' .. ,,,..-,..., . . Glass covered ... 36 ...... Oojah Basket Coils, set of 7, 150-4,000 metres50 ii ......

Slab 8, 150-26,000 76 IP ii.e ,. f 0 Basket Coils, our specialline,setof6, 170-3,500 m. 26 Coil Holders, 3 -way Extraordinary value 1-86 2-j ) 66 Intervalve Transformers, not rubbish 12/-,1216,16 i 6 Valves, soft, Dutch, ideal for detecting ... 106

hard, amplification... 116 Amplion Loud Speakers upwards from 2 126 £5.6:6 Variable Condensers. For Panel Mounting. In Celluloid Case '001 ... 12/6 ... 15/- 0005 ... 10/6 ... 13/- deposit secures immediate delivery of the above wonderful .0003 9/6 ... 11/ - instrument, whichwillreceive ALL BritishBroadcast Telephony, and is stamped B.B.C., and approved by P.M.G. HEADPHONES- The balanceispaidintwelve monthly instalments of " SIDPE " 4,000 ohms 1008,000 ohms 12 6 06/7 each on the usual hire purchase system, including

Insurance. "BRITISH" 4,000 1008,000 12 6 Wireless Receivers and Accessories to any value are supplied on the same terms. "BRUNET" 4,000 126Pival 12 6 Write at once for Catalogue and Full Particulars. WATERLOO ELECTRIC Co. THE "HESTIA" ENGINEERING COMPANY, 129, Waterloo Rd., London, S.E.1 32,Palmerston Road, Acton, London, W. 3. HOP 5649.Closed on Thurs. r p.m. Sat. 9 p.m.Other nights, 8 p.m. 1 minute South Acton Station. (N.L. or District Rlys.) CATALOGUES FREE. Showrooms open 9 a.m.-6 p.m. Telephone: Chiswick 586. "Ote°12010,Wikeeir1,1selbeibAbs00.16- Popular Wireless Weekly, June 16th, 1923. 65,; CONSTRUCTIONAL HINTS. By H, E. COWLEY. Some useful words of advice on the subject of the construction of wireless apparatus,more particularly with regard to " finish." This is the factor that renders the " home-made " set professional in appearance; it is quite easily obtainable with a little care, as this article clearly shows.

is 1 waste of money to decide on your of emery -cloth and paper (the emery -cloth result obtained is an endless whirl of an ITcircuit and straightway go to the neat- gradually getting finer as you obtain a attractive and pleasing appearance.This est wireless dealer, buy the parts, and better finish) work the face into a beautiful'idea may be modified by making distinct positively push them together.An evening flat surface, making sure that you keep the little circles, each one overlapping the other spent with a piece of paper and a pencil will " grain " in one direction only. This is best perfectly evenly and symmetrically over the save you much after regret and add greatly done by obtaining a piece of wood which whole surface. to your joy when showing the finished in- you can conveniently hold and folding the No. 3.Scraping.I think this method is strument to your friends. the most attractive of the three, and with After deciding on your circuit take the practice it may be done as quickly as any paper and pencil and arrange all your knobs, method ;another advantage isthe fact switches, terminals, etc., as conveniently as that the surface need not be perfectly flat. possible ;do not cramp them, but at the First clean the work and then obtain an same time keep them together with the old flat file and grind off the teeth from all different knobs and switches evenly placed. sides, and on the end grind a very slight An Improvised Lathe. radius (this should be on the broad side of If you intend at some future da to to add the file).Take off the very- sharp corners another unit, keep this in mind and allow and edges, but only very very slightly, the accordingly.Decide on the shape of the point being that they must cut, yet at the cabinet, whether you will have a sloping same time not be sharp like a knife.Hold front or one with a lid, or just a plain box. the work in the vice, the handle of the file or Personally I have found that a sloping front scraper in the right hand, and gently pressing with all tuning switches, and a fiat top with the handle of the scraper down on to the the valves or crystal installed upon it, is by work with the left hand, scrape the metal far the most convenient and attractive. with short forward pushing motions in all Make sure that the different parts clear directions.When finished a very beautiful one another ;by this I mean that you light and shade effect is obtained. should notice if the transformer is liable to touch the filament resistance, or whatever Lacquering and Polishing. it might have near it, and above all make A few hints on lacquering will probably sure that you can, with convenience, make all be useful. First obtain some " old gold " cold lac- the necessary connections. When your design is decided upon in quer and put this into a cup or some re- every respect the -next thing to do 'is to buy ceptacle sufficiently large to take the largest the necessary materials and commence the item to be lacquered. Warm the article to actual construction. be treated to about blood heat, and dip it If you are not the proud owner of a lathe bodily into the lacquer, take it out at -once then you are somewhat held back, but I and give it a good shake in order to remove have found that quite excellent plain turning all unnecessary fluid, and stand it on one may be done with the aid of an ordinary side to. dry.I should state that metals to handdrilling machine and a few fides. be treated in this way should be perfectly Hold the brass or whatever other metal or clean ;do not even touch them with the material you wish to turn, in the chuck, hands, but hold them with clean rag or and fix the machine in the vice or on the pliers, or an even better method is to bind bench ;then with the left hand, turn the them round(in some place where the lacquered surface does not show) with thin handle and with the right file the material The compact and efficient receiving station into the shape required. assembled by Mr. S.G.Freudmache, 59, Calmont wire, the wire then comes in handy for Road, Bromley, Kent. hanging them up to dry. Metal Finishing. In the making of the cabinet little ban be Ebonite may be finished up on its edges emery -clotharounditand workingit said here, but the following tips may prove by planing with an ordinary wood plane or backwards and forwards over the work, useful. by filing ;if you intend to plane it makefinishing off with what is known as blue - Before polishing always fill the grain with sure that the plane iron (or blade) is sharp black emery -paper grade " F." some wood-filler-whitewash or whitening and not set too coarse, or you will find your is quite good for this. ebonite in pieces. Curling and Scraping. Mahogany polished in its natural state The next thing to be considered is the No.2. Curly grain.This method is looks very ugly ;it should always first be methods of finishing metals.The best way very attractive, although it is only an im- stained to a deep red with" Dragon's to make the edges look smart is to draw - provement on No. 1 method.Prepare the Blood." file them.This is done by holding a very surface as in No. 1, making sure that up to If you have never tried French polishing fine cut file, commonly known as a Swiss this stage all looks well, and- then obtain before do not start on a well -made cabinet, file, in both hands, and drawing the file about an inch of round wo sd-a piece cut for quite excellent results are obtained by crosswise along the length of the work, a very from the end of a pencil will do quite well, painting the polish on with a camel -hair fine grain finish is the result.There are and on the end of this glue a piece of blue - brush.Two, or sometimes three coats may many ways of finishing metal surfaces, espe- back emery -paper the samesize as the be necessary, but as the polish dries very cially brass, three of which I will describe, section of the pencil or wood.Put this into quickly this is no drawback.Use a very but one method only should be used on the chuck of your drilling machine or lathe, wide brush, one inch and a half or two each instrument, as a mixture of different fix the machine in the vice or on the bench, inches will do, and paint the polish on very finishes gives a rather poor effect to theand revolve the chuck and emery pad with quickly, not going over the work more than completed instrument. the left hand while the right gently presses once.The second and third coats can 1. e No. 1.Straight grain.With a file clean the work against the pad, and at ,the same given after a lapse of an hour or an hour an I the surface, and then with different gradestime working circles upon the metal.The a half. 65 Popular Wireless' Weekly,' June 16th, 1923.

BRITAIN'S BEST BOPHONES MARVELLOUS EFFICIENCY Behold ! rim MARVELLOUS PRICE HAVING alreadysecured the Manchester business for Com- V BEST ponents at the right price we have COMPONENTS decided to give Amateurs in all 16/6 :L.: parts of the world an opportunity Plus 1/- extra for postage. to get them at " V BEST" prices. Manufactured entirely in our works, Goswell Road and City Road, under WE have organised a Mail Order ../..

GUARANTEE. returned to us undamaged, within 7 days. F1LA3fENT RESISTANCES. A realpiece of apparatus each 2 / 6 FILAMENT -RESISTANCE, ebonite dials, engraved each10(1. FILAMENT RESISTANCE, circular engraved scale each 9d. B. D. & Co. (Edward A. Boynton), FORMERS, PIRTOID, for Honeycomb Coils each 3d. INDUCTANCE TUBES, specially impregnated, 12 ins.long.2 in. Admiralty & War Office Contractors. to4 -in.dism., 4d. each; 45 -in.diam.,511.each;5In.to 1-0, Goswell Place, 6in. diam. each 7d. Works :-167-173, Goswell Road, London, E.C.1. INDUCTANCE SLIDERS, withspring and plunger each 45d. London, E.C.1.361-363, City Road, London, E.C.I. INDUCTANCE SLIDER ROD, 13 in.,drilled each 4d. Telephone: Clerkvnuell Ws. Offices: 173, Goswell Road, London,E.C.1, INSULATORS LEAD-IN,sturdyebonite,terminalseachend. 6 in., 10d. each; 12 in each 1/1 IVORINE TABLETS.Black onwhite,or white on black En- graved. A nice job. AERIAL, EARTH, 'PHON,ES, ,etc.i;,each ad. INSULATING SLEEVING per yard 5d. INSTRUMENT WIRES. A huge stockof specially purchSeed wire inall coverings.Perfect.At bargain prices.Send 11d. stamp for price list. INSULATING SILK SHEET per sq .ft.1 / - KNOBS, EBONITE. Blindbushed,2B.A. One qualityonly - THE BEST each 4d. MICA. Pure ruby.Pieces 25,,in. x 25 in each1(1. NUTS. Brass, Hexagon, 2,..,& 4 13.A,-,per doz., 3d.; 5 & Buy VOLUOMETER 6 B A. per dozen 25d. RESISTANCE WIRE for filament resistances per yard Id. ROUND LOCKING NUTS, 2 B.A., brass each2(1. SCREWED BRASS ROD,12 -in.- lengths,2B.A.;each3fid.; guaranteed apparatus 4 B.A. each 3d. SHELLAC, Flake per packet 6d. SWITCH ARMS' 4 -LEAF.Splendid knob; hefty bush. Beautifully polished: with nuts and spring washer each 116 everytime. TERMINALS -nott nitwits. STANDARD Pattern, ,accordingto size,per doz., 1 / 6, 2/-, 2 / 6. TELEPHONE, per doz., 2 /6; -', WASHERS, BRASS, 2 toscrewper 6 B.A dozenper dozen 2/615(1. "VOLUOMETER" is not only WASHERS, COPPER SPRING, each 1d.; per dozen 8d. VALVE SOCKETS, with nut and washer. each1(1. a guarantee of the best work- VALVE PINS, with nut and washer each Id. manship andmaterial,bat VALVE HOLDERS, with 8 nuts and 4 washers each10(1. ON the strength of the above prices you have doubtless guarantees your satisfaction as already decided to send us your order. But perhaps you well. Insistonseeingthis want some scientific components also. Then take our advice- trade mark on allapparatus. Buy the Best, don't be "Pennywise, pound foolish." VARIOMETER 26'6 WE SUPPLY SCIENTIFIC COMPONENTS. CRYSTALS(J.L.Cartwright & Carborundum, Copper Pyrites,Galena,Bornite,IronPyrites,Silicon,Manganese, per box, 6d. Beat Ilertzite or Zincite, per box, 1/-. WOOD'S METAL 6d. FIXED CONDENSERS (J. L. Cartwright & Co.'s) each 21 - GRID LEAKS (J.L. Cartwright & Co.'s), 1, 2,3, 4, or 5 meg.2/ - HEADPHONES, Western Electric, 4,000 ohms per set 32/ -Western Electric (while they last), '8,000 ohms per set 32/- -Special French, very sensitive per set 15/ - LOUD SPEAKERS, Western Electric, 4,000 ohms each 50/- TRANSFORMERS, High -frequency plug-in type(J. L. Cartwright & Co.'s) double groove. No.1,350, 6j6; No. 2,550, 7-; No. 3,930, 7/8; No. 4, 1,400, 8/-; Nu. 5, 2,000, 816; Variometers and Varicouplers No. 6, 3,500, 9/-; No. 7, 10,000, 106. TRANSFORMERS. Low -frequency (J. L. Cartwright & Co.'s)...ea.211- from12/6to26/6. No -Telephone (.7. L. Cartwright & Co.'s), while they last each 12/ - VALVES. Ediawan A.R. Type,each 15/-; Marconi Osrain,It. cardboard used. H F Tuned 'Me each 17/6 VALVES DUTCH 9/6 AnodeReactance200 - 2,800 CASH WITH ORDER. Moneybackifnot entirely Metres 25/6. H F Trans- Please remit ample Postage,anybalance returned. formers from 4/-. satisfied. If your dealer does not stock VICTOR BEST Co., thempostcashdirect t o TYPEC12:6 The Component King, HUGE Dept. P, 24, LONDON ROAD,ADVICE S. T. HOSKEN, STOCKS MANCHESTER. FREE (Opposite London Road Station). 19, Eagle Street, Holborn, London,W.C.1. Telephone No.: City 9242. Popular Wireless Weekly, June 16th, 1923. (3,5,7

THE ANTENNA STAR OF EILVESE. BOOK REVIEWS. By Dr. A. NEUBURGER, our Berlin Correspondent.

The WirelessPress,Ltd.,havejust THE curious star we show in our figure the available high -frequency energy. Then published a new handbook, entitled, " How can easily give the impression that an antenna current of 450 amperes at a wave- to Build Amateur Valve Stations,"by it is the microphotograph of a" radio- length of 14,600 metres can be obtained. Philip R. Coursey, B.Sc. (Eng.), A.M.I.E.E. laria," a class of animalcules living in the As can be seen, the aerial system is easy to Thisbook,whilecontainingonlysix water, which, as is well known, shows many survey, and is remarkable by its elasticitychapters, gives full constructional details variations, a good deal of which have the and stability. for making a one, two, or three valve set structure of a star.But the star has nothing on the unit system.One chapter is de- to do with the 15,000 Volts. voted to an explanation of the use of the water and is no valve and gives many usefulcircuits. living being.It The power of the station is derived from But perhaps the most useful section of this is a model of the two generators, though no steam-engines work is that which contains a complete great aerialof or turbines are used.The current is taken listof components, together with a de- Eilvese, one of from the water -power station at Doverden, scription and explanation of each.This thetwo great which supplies a three-phase currekt of 15,000 chapter contains over forty photographs German radio volts.This is transformed to 5,000 volts, and other illustrations.A chapter is also stationswhich and then the current goes into a 650 PSgiven to aerial construction. entertain t h e service with America. Com- " TheRadioExperimenters' Hand- monly you hear book," Part II., by Philip T. Coursey, onlyfrom. M.A., B.Sc. (Eng.), F.Inst.P. (The Wireless Nauen, and Press.) therearenot This second edition of Mr. Coursey's manypeople book, as is explained in the preface, has been who know that brought out with the intention of keeping there is a second pace with peent developments, modifica- great radio sta- tions, and dhanges in the science of wireless. tion in Germany It is devoted to useful data and actual that works with quantitativedesign dealingwithradio the United receiving apparatus.Useful chapters arc States. given on tuning coils and the measurements Thereforeit of inductances and on condensers.Cal- will be ofin- culation of capacity is fully explained, and teresttoour the two chapters mentioned should be of readers especial use to our readers.Useful tables hear something are included,' and numerous examples of the working out of the various formulae about this sta- How the aerial wire arrangement would look The Eilvese Station, showing thetion, whichis from a point centrally above the main mast. are given. huge 800ft.mastwiththe buildings clustered at its foot.less known than Nauen, as it is three-phasemotor,whichworkstwo " WIRELESS REVIEW situated in a kind of desert, where it is continuouscurrentgeneratorsof 440 difficult to visit it.Eilvese lies on an isle volts1,000 amperes and 220 volts 240 AND of sand in the great fens of the L:ineburg amperes. SCIENCEWEEKLY, " Moor, very much out of the way.But its The 220 -volt generator serves as exciter situation is a very .good one for the pur- for the high -frequency machines, while the Published every Tuesday and on pose of the radio service, as its distance 440 -volt generator drives the two 184 and from Berlin, from Hamburg and Bremen, 165kilowattcontinuous -current motors, sale at all bookstalls and newsagents, and from the great industrial cities of the which are directly coupled with one or price 3d., is the authoritative journal Rhine, is nearly the same.Therefore from other of the two high -frequency machines. ofwirelessandpopularscience. all sides telegrams can easily be sent to The rotors of these machines give 3,000 re- Eilvese by cable. volutions per minute, so that good cooling Two Aerials in One. is absolutely necess- The aerial has, as shown by our star, the ary.For this pur- form of a double -cone umbrella antenna. pose a special pump- The main mast has a height of 250 metres, ing and compressed and is surrounded by six smaller masts, airinstallation was each of which is 120 metres high and stand built,andtheoil 460 metres away from the main mast. The forthe bearings is aerial itself is composed of an umbrella of cooled inaspecial 16,000 centimetres capacity, and a second way and is made to cone or ring arranged round that umbrella circulate freely. with a capacity of 34,700 centimetres. Both Thetransmitters aerials are isolated each from the other, and are tunedfortwo eacji one has its own connection with the frequencies of 30,800 station. and 20,800 periods, . The aim of this arrangement is to gain the correspondingtoa possibilityof a " duplex service "with wave -length of 9,700 different waves. The umbrella aeiial works and14,600metres. alone for itself with a wave of 9,700 metres, For the moment the ring aerial alone with a wave of 14,600 Eilveseisa trans- metres. .In thefirstcase,the antenna ,mitting station, while current has a power of 180, in the second the receiving is car- case of 250 amperes.Itispossible to ried out at Geltow, switch both antennas together by using all near Potsdam. The Goldschmidt high -frequency generator employed at the Eilvese station. 656 Popular Wireless Weekly, June 16th, 1923. HINTS ON PANEL DRILLING. Poor panel drilling will spoil the look of any wireless set, and, providing ordinary care is taken, there is no reason why the drilling should not be as good as on any professionally made apparatus, yet this standard of perfection is rarely attained by the amateur. The following hints, describing methods used by the writer, may be of help to amateurs.

ebonite isa fruitful from each other ;these holes need only I-in. and the required length in.-and PENCILLINGsource of future on trouble and is bestbe quite fine, and can be best made with with a pairof compasses mark off on avoided.Take a sheet of fairly stiff paper an Archimedean drill such as is used for the arc B C equidistantly spaced points the same size as the panel, and mark with a fretwork. separated by thisdistance. Drill these cross the centres of the holes to be drilled, Now take three drawing -pins,sticking with a 5 B.A. clearance drill, if the studs making a note by each to show what size theirpoints into thethreeholesthus are 5 B.A., and drillthe centrepoint it must be. made, the patterncannotmovenow A out to 2 B.A. clearance, which is the -The holes should be arranged in such awithout the worker being aware of the usual' size for switch -arm screws. manner that the knobs, etc., which are tofact, and it is an easy matter, should this When using this pattern it is only neces- be put on will be as symmetrically placed ashappen, to replace the pattern in its correct position. sary to mark on the paper the centres of Now drill through the paper at all the the stud switches.When these are drilled points marked sufficiently to make a mark on the ebonite, when this has been done the paper can be removed. The ebonite should now be placed on a flat piece of wood. and PATTERN -4 --BOLT 1 the holes drilled out the size noted on the BEIM OIECI=E NN N. pattern,drilling,of course,allholesof EBON /TEA\ a similar sizefirst, then going on to the next. Multi -Stud Switehes. A breast -drill as used for metal drilling makes the cleanest hole, the bits " used for wood drillingare apt to crack the ebonite and break the edges of the hole. If any of the holes have to be tapped, drill out to 2 B.A. size, bolt the pattern to the a half -inch hole in the piece of wood used panel by means of a nut and bolt or an old for backing the panel, and place the panel terminal. Place the ebonite fiat on a piece so that the hole to be tapped is concentrically of wood which has a hole in it to accom- above the hole in the wood.Clamping a modate the bolt head (see Fig., 2), and drill panel in a vice, even between wood, for through the holes in the pattern straight the purpose of drilling a tapping should through the ebonite. A final dusting will never be attempted.Any countersinking complete the operation, and the assembly whichisdesired can now bedone, the of the set can be commenced. panel should then be This photograph shows the neat appearance of a paneldusted, and finished by whichisobtainedbydueattentionbeingpaid to symmetry. rubbinginvaseline, takingoff afterwards possible.If the paper used is graph paper all the surplus with a it will help the worker in placing the holes clean rag. correctly. Multi -stud switches The paper is now placed on the panel, seemto cause some which should have been trued up to shape, workers no small and, by means of paperweights or otheramount of trouble.A handy objects placed on top of it, the pat- very useful pattern was tern can be kept in its proper positionmade by the writer out whilst three small holes are drilled through of some sheet alumi- thosecrosseswhich arefarthest away nium four inches square ;a glance at Marking Out Positions. Fig. 1 willgivethe reader a better idea of this accessory than any written description. IP Rubthealuminium on one side with fine

o emery -paper. You will now be ableto a draw quiteeasilyin pencil, with " A ;'as thecentre, by A means ofa pairof compasses, the arc of a circle B C, using a con- 9 venient radius. Decide

o on the spacinr, of the studs, add this to the 0 8 C diameter of the studs- e.g., with j in.studs thespacing willbe Mr. Stanley Hilton, of 71, Orlands Street, Bolton, and the '4-valve set that he nct bas assembled, Popular Wireless Weekly, June Pith, 1923. WELL-KNOWN ARTISTES OF 2 Z Y. (By OUR MANCHESTER CORRESPONDENT.) Readers who listen -in to the Manchester Station will appreciate these brief notes of some of the artistes that have broadcast from 2 Z Y.It will bring listeners into closer touch with the performers and thus interest will be still further increased when the artistes again perform.

LOOKING back through the2 Z Y most wonderful experience of its kind thatnow in Manchester, is carving for himself programmes. for thelast four he had ever had.Such reports, of whicha name high on therollof musicians' months, oneisstruck by the fre- this is one example, speaks well for the high honour. One of Dr. Brodsky's most success- quencywithwhichwell-known namesstate which the technical side of broadcast-ful pupils,Mr. Hirsch has had a wide meet the eye.Probably the first we find ing has reached, even at this present stage,experience in orchestral and chamber as is that of that very brilliant soprano, Miss and it is the satisfaction of receiving such well as solo work, BeatriceSirette, reports that repays the staff of any broad-and one doubts with whom we casting station for its hours of arduous andif a more efficient sympathise in her unremitting toil, and gives encouragement leader tothe recent nervous to aim even higher. Radio Orchestra breakdown, which Some of the Pianists. could be found. forced herto Another old student of the Moscow Con-The 'cellist of the abandon her pro- servatoire, who for many years has givenRadio Trio was fessional dutiesjoy to Manchester, and recently broadcastSydneyWright, for the time from 2 Z Y, is Professor Carl Fuchs, the anditspianist, being. Soon after 'cellist, who in English concerts has longMiss Jessie Cor- hervisitcame been a familiar figure. niack, whofor Reaney Booth, of. A series of greatly appreciated half-hoursome months has Australian and.piano recitals are at present broadcast every,delighted t h e New Zealand Tuesday night ;and the pianist who so artistes as well as fame,whosegenerously showers his gifts on so wide, and listeners - in of dramatic inter - 2 Z Y with her One of Manchester's most MissAgnes Clarke, a most -to itscredit be it said-appreciative popular sopranos, popular 2 Z Y soprano. pretations one audience,is Mr. ()harming accom- Miss Elsie Juddah. Sundayevening Edward Isaacs. paniments.The ' delighted many listeners -in. Otherpianists other members of the orchestra ale Mr. The most famous violinist who has broad- who have charm- Alfred Stott, principal double bass to the cast from 2 Z Y is Miss Isolde Menges, who, "Halle " Orchestra ;Mr. Harold Widdup, ed the listeners - long a popular viola in the Halle ;Mr. with her husband, Mr. Tod Boyd, the com- inof 2 Z Y in- poser, has twice been heard from this clude Mr. Charles Patrick Ryan, probahly the most promising station. of- Manchester's young clarinet . players ; Kelly, Miss Annie Miss Keern McEndoo, the popular violinist " Most Wonderful Experience." Lord, Mr. Arthur of the Royal College in Manchester ; and Mr. Spencer,Miss Arnold Perry, the organist whose: reCenZ Probably the next artiste we meet who Annie Young calls up memories of brilliant public recitals (whose delightful Beethoven pianoforte recitals in the cit./ is Mr. Seth Lancaster, the only British interpretations of have created more than usual interest. 'cellist who has ever received a Royal com- modernFrench The " Talk " Items. mand to appear before the Queen. His workswerean accompanist, Miss Marjorie Clare, whose Among the speakers of 2 Z Y, the name; almost unusual Harold Derbyshire," the delightful songs at the piano have charmed eventinbroad- Maneuester baritone." that first call our notice are Professor Elliott many an audience, added to the enjoyment casting), Miss Smith; Professor Pear, head of the new of the broadcast programme by singing two Yvonne Tiano, Miss Jessie Cormack, and Psychologydepartmentat Mancheste r little plantation songs, which brought im- others. University ;Major C. H. Douglas, of Social mediate calls by telephone from Blackpool Mr. Hamilton Harris, a basso whose fame Credit fame ;Mr. J. E. Phythian, M.A., of and Southport for an encore. - has gone far beyond Manchester, gave a theManchester Recently,thewidely appreciated programme from Man- Arts Committee, mostfamouichester a few weeks ago.Another Man- who is giving a artiste at 2 Z Y chestervocalist,Mr.DaleSmith,has series of talks on wasMissSybil kindly consented to give, commencing on " Pictures and Thorntlike,who May 31st, a series of British song recitals, their Apprecia- at .the - time as-assisted by Miss Dora Gilson,hisable tion " ; Professor tounded crowded accompanist. A soprano, who has won theMiles Walker, housesatthe unstintedpraise of unseenlisteners,is whowill soon Prince's Theatre, Miss Florence Holding, whose voice has commence a series, Manchester, withbeen described more than once as the most of talks on "Voca- her wonderful in- perfect that the Manchester Broadcasting tional Selection" terpretation of Station has been honoured to transmit. Rev.P.H. the "Medea," Johnson ; Miss and in "Scandal," The Orchestra. Andrews, of the broadcast with It is difficult to single out any one of the "Manchester New Mr. Louis Casson, many other artists who have given their Thought School"; Mr.HamiltonHarris, the the other leadingservices to the new science at 2 Z Y. the Rt. Hon. the MissIsoldeMenges,-the famous basso, who has The present orchestra of 2 Z Y is pro-Lord Mayorof famous violinist, whohas appeared on 2 Z Y'spro- spirit in Miss upon two occasions charmed gramme several times. Thorndike'sbably smaller than that of most otherManchester, the 2 Z Y listeners -in. company, a scene stations, for the simple reason that the whose recent ap- from " As You Like It." studio in Manchester is not of very ample pealfortwomillionshillingsforthe In a few days' time, Madame Sophie proportions.The nucleus of this orchestra hospitalshas met withsuchgenerous Thomson de. Konshen will again visit 2 Z Y. one knew inthe form oftheoriginal support ; and many other famous men. One. listener -in who heard her sing ." I " Radio Trio,"thepersonnel'ofwhich Finally, FodenWilliamsandVictor Would tell of My Love," by Rachmaninoff, deserves special attention.It was led bySmythe, undoubteclly the most popular wrote delightedly to thestation imme-Mr. Leonard Hirsch, a violinist of greatentertainers ofthe station, are certainly diately afterwards, saying that it was thetalent, previously known in Dublin, and deserving of mention. G.3 Popular Wireless Weekly, June 16th, 1923.

water ;and from these rollers it passes up and down, scores of times, round pulleys, being finally wound, perfectly dry, on to WIRELESS AND THE CINEMA. drums or spools. Mr. Hepworth, the well-known filmproducer, givesinan interview In due course . these spools of film are with a special representative of POPULAR WIRELESS, his views regarding again unwound, examined, and pieced to- the possibility of wireless tele-vision in connection with cinematography gether, and thus, subject to everything and the synchronization of speech with the pictures (" talking pictures "). being found in order, the film is at last wound on to a spool in one continuous length, ready for the cinema projector. MR. HEPWORTH is too well known as " Do you think there is any possibilityWhen Wireless " Settles Down." the leading British pioneer in the film - of wireless playing a part in the synchroniza- production worldforany furthertion of the human voice with moving " You spoke of educational possibilities just reference to that fact to be necessary. But pictures 1" I asked. now," said Mr. Hepworth." What has been those who picture him, as the writer did, " Indirectly, perhaps.But so long as happening for years, and is happening now, simply as the chairman of a company who projectionisaccomplishedby mechani-is that the cinema isAmericanising the world. takes no active part in the work, may dis- calmeans,synchronizationmustbe Go where you will, you find American films, miss any such idea. dependent upon similar mechanical con- from tiny villages in the Welsh hills to New The interview took place at the world - trivances.If the theory of wave trans- Zealand.You may think it ah exaggera- famed studios at Walton -on -Thames, in Mr. mission we have been discussingwere tion, if you choose, but it is so. And when Hepworth's private workshop, whither hedeveloped, and true wave impression ofthe real educational stunt begins, it will retirestowork, pictures became a fait accompli, then wirelessbegin in America, and then America will coatless and with speech could, of course, be synchronized-utilise it to exploit the world for the benefit upturned shirtin fact, synchronization would be almostof American trade. And when it is too late, sleeves, when as- automatic, since the speed of transmission we shall follow in her footsteps." sailed by too manywould be the same.But in the present " Then, what is the remedy ? " I asked. worries. stage of development, the only sense in He shrugged his shoulders. " Will you talkwhich wireless can be applied isin the " That can only be effected by combined to me aboutmatter of music and speech during in- action --by educating the public-possibly wireless and the tervals." only with State assistance.The present cinema ?" I asked. tariff on imported films is insufficient ;but "How can I do No Direct Connection. even if it were effectual, in so far as this that ? " he replied. " Have you taken up wireless as a hobby, country is concerned, there are still our " Idon'tknow Mr. Hepworth ? " colonies and foreign countries that have anything about " No.I dare not, just now.In fact, Ihitherto constituted markets for our goods. wireless." could not take it up as a hobby.If I were " With all such inventions the commercial " What do youto take up wireless, it would be to undertake beginning is always the result of a craze for think of the theory research work, and I simply haven't the novelty.It was so with the cinema. The put forward by atime for it.That does not mean I shouldnovelty soon evaporated, and leftpro- Mr. Hepworth. writerinPOPU-. not like to, for I should, but one cannot do ducers with the task of providing for the LAR WIRELESS two things at once." demand for something really good. WEEKLY, to the effect that possibly, some " What about the transmission of pictures " It will be much the same with ,wireless. day, a means will be found for transmitting by such methods as are already in vogue ? " At present it is a craze. When that has worn pictures by means of wireless waves, so There, again, I see no direct connec- itself out, there will be no purchasers for that they may be reproduced on a screen by tion.You still require mechanical appli- the inferior sets that now flood the market true wave impression ? " I asked. ances-photography and a projector-toand find a ready sale, and the public will utilise such pictures for the cinema.It is demand something really good.Listening Not at all Hopeful. true that an individual picture thus wire- to ether -borne speech and music will no " No one would say anything is impossible lessed might be shown as a novelty, but itlonger be a wonder and novelty, and the nowadays," he replied. But I cannot seewould only serve as one of a number ofpublic will demand something better for any opening in that direction.I do not see topical subjects, to be shown for a few their money than they are prepared and are where one is to make a start on investiga- moments.Consider the length of film andeven glad to pay now.They will settle tion.It is conceivable that light itself and the number of separate pictures in it in-down to the serious enjoyment of wireless even colour might be transmitted and re- volved in presenting a play or any otheras a commonplace recreation." produced in that way, but the difficultyproduction of appreciable length. But come that appears to me insuperable is to re-with me.I will show you over the works." produce form. Visiblelightitselfisa We visited, first, one of the studios where complicated problem, in the sense that it isa number of players were being " filmed " SHORT ARTICLES propagated by waves of varying length andin connection with a play now in course of periodicity. Considerthereflectionof production ;then groped our way through light from that piece of brass-the infinitevarious dark rooms, with double,light - Especiallyofa constructional number of rays proceeding from an infinite tight doors, where films were being de- nature, are always welcome and veloped. ` number of points.The eye receives a little well paid forifacceptedfor bundle of those rays that travel in straight From these dark rooms the negative films lines.Even supposing that they could beare `taken and examined for faults, and are publication. Youmayhave in some way impressed on a Series of electro- then transferred to the printing depart- ideas regarding something really magnetic waves, 'I cannot see any possi- ment. bility of those waves being converted or interesting and worth passing on manipulated so as to reproduce form by Printing Films. through the medium of " Popular wave impression in the sense you mean. From the printing machine the negative Wireless " toother amateurs, " Oh, yes, I quite appreciate the attri-film is wound on to a spool, the positive butes common to light and electro-magnetic film passing on over a roller through the but feel incapable of expressing waves.If you come to that, you may run bath of fixing solution, and thence through yourself on paper.This should right through the spectrum, and say thatsuccessive water -tanks, where itiswell not deter you ;as long as the X-rays are invisible light, in somewhat the washed and rid of every vestige of chemicals same sense that ultra -violet rays are lightwhich would impair its life.Then it dis- details in the text and drawings rays.But, so far as we know, visible lightappears upwards through a slot in the are clear, the Technical Staff of is the only means of directly indicating ceiling into the drying -room above, which is " Popular Wireless " will do the form-the form of an object-and I cannot carefully heated and ventilated. see that this property can be, transferred to Here the film first passes over a succession rest. another class of wave." of cloth -covered rollers to rid it of surface Popular Wireless Weekly, June 16th, 1923. 659'

MA,PC9TcsRuIrAiNalY5

In your choice of a Wireless Valve itisofparamount importance that you select one which will serveyou faithfully.

You cannot do better than place your faith in the valve that rendered indispensable serviceto our fighting forces during the war and is now rendering faithfulserviceinthe world'slargest Wireless Transmitting Stations.

The same faithfulvalveis now available for you. MADE TO LAST. RENOWNED FOR UNIFORMITY OF QUALITY.

///7 2-1-'

Sold byElectricalContractors,WirelessDealers,and Stores (WHOLESALE ONLY). The General Electric Co., Ltd., Magnet House, Kingsway,W.C. (Branches throughout the United Kingdom and in all the principal markets of the world.) GGO Popular Wireless Weekly, June 16th, 1923.

minute positive nucleus or core.The for- mation of the atoms of the filament depends upon the material from which itis con- THE ELUSIVE ELECTRON. structed.It is stated that each tungsten A few facts concerning that wonderful ultimate particle of matter which atom, for instance, is composed of 74 elec- will give some idea of its size and activities. trons clustering round a nucleus which does not greatly differ from that of the copper atom. WHEN the filament current of the re-, each hour that the filament circuit is complete. Upsetting the Atoms. ceiving valve is switched on, the high- Itis not to be supposed that the same The manner in which the electrons are tension battery connected to the set electrons which leave the negative plate of arranged about the positive core appears and the instrument adjusted, the electrons the battery traverse the complete circuit, to be doubtful, but it is known that the size in the valve begin to bestir themselves.It returning to the cell by means of the positive of the electron in comparison to the distance is well known that the current which heats plate. While some of them may complete which separates it from adjacent electrons the filament has only a value, of just under the whole journey, it is assumed that, at is very small. one ampere, and it is hardly conceivable any rate, the same number of electrons When the electrical circuit is completed, that the heating effect of this current on reach the positive plate each second as start some of the electrons clustered around the the filament is sufficient to disturb about from the negativeplate.Some of the nucleus of the atom are influenced to such 7,000,000,000,000,000,000electronseach electrons on their journey will leave the hot an extent that they join the electron stream. second, in a wire having a cross section of filament and become free electrons in the This, of course, means that some atoms are about 24 millionths of a square inch. These vacuum which exists inside the valve, but left without their correct number of elec- are the figures given by Mr. John Mills of their place isfilled by others from the trons, and these atoms readjust their cor- the Western Electric Company, in a recent various connecting wires, and from the fila- rect balance from other electrons passing in issue of the " Wireless Age," and it- is be- ment. stream. yond the imagination to conceive such a The rate at which the individual electrons mass of tiny particles all in motion within "Free " Electrons. progress is very rapid, and it is this dis- the confines of the small electric light bulb Assuming that the wire employed is of turbance and its effect upon the atoms that known as the thermionic valve. - It is also copper, the path of the electron stream will heats the filament.The effect on the plate stated that in each cell of the storage battery lie through the copper atoms.These atoms or anode of the valve, which is, of course, molecules of lead sulphate form at the rate are each composed of a small number of charged positively, is to attract the electrons of approximately 25 thousand billion billion electrons (29 to be exact) surrounding a which have left the heated filament. BROADCASTING TRANSMISSIONS. GREAT BRITAIN. Hours of Wave -length Station. Call Sign. Transmission. Items Transmitted. in Metres. Remarks.

London 2 L 0 Usually -5.30-11 p.m. .. Musical Items, News, etc. 369 Every Weekday.

Newcastle 5 N 0 .5.30-10.30 p.m... SP 91 P. 400

Manchester 2 Z Y 5.30-10.30 p.m... 385 t t

Birmingham .. 5 I T 5.30-10.30 p.m... If f 425 t

Glasgow 5 S C 5.30-10 30 p.m... It 415 99

Cardiff 5 W A 5.30-10.30 p.m... 353 BELGIUM Brussels (1) . Brussels 12 noon (G.M.T.) ..Weather report .. 1100 Working days. 4.50 p.m...... Aeroplane traffic 1100 When necessary. 6 p.m. ..Concert .. 1300 Sunday, Tuesday and Thursday. HOLLAND The Hague.. P C G G 3-5 p.m. (G.M.T.) ..Concert 1050 Sunday. 8.40-9.40 p.m. ..Concert 1050 Monday & Thursday

The Hague.. PCUU 7.45-10 p.m. ....Concert 1050 Tuesday.

(Laboratoriurn Heussen) 9.40-10.40 a.m. 1050 Sunday.

The Hague (Velthuyzen) P C K K 8.40-11.40 p.m. ..Various 1050 Friday.

Ymuiden (Middelraad) P C M M 8.40-11.40 p.m. ..Concert .. 1050 Saturday. Amsterdam P A 5 8.10-11.10 p.m. ..Concert and News 1050 Wednesday. FRANCE Lavallois-Perret (Radiola) S F R 2-3 p.m. (F.S:T.) ..Music .. 1780 Sunday. Stock Exchange News 1780 Every day.

5.15-6.15 p.m. Instrumental music 1780 8.45 p.m. General News.. 1780 SP 9-10.30 p.m. .. Vocal and instrumental concert 1780 Paris (2) (Eiffel Tower) ..F L 6.40 a.m..... Weather Forecast.. 2600 ft 11.15 a.m. ., Weather Forecast 2600

3.30 p.m. .. Stock Exchange News .. 2600

6.20 p.m... .. Weather Forecast, Concert 2600

10.10 p.m. .. Weather Forecast.. 2600

Ecole Superieure dos P.T.T. 7.45-10 p.m. .. Radio Concerts .. 450 Tuesday, Thursday, Radio -Riviera (Nice) 2.30-7.30 p.m. Radio Conferences.. 450 Saturday. 11 a.m... News, Concert, tzigane 460 Every day.

5-6 .. News, instrumental Concert.. 460 Pt 9-10 p.m. .. Latest News, Concert .. 460 9t GERMANY, CZECHO-SLOVAKIA, AND SWITZERLAND Berlin.. L P ..6-7 (G.M.T.) ..Financial News, etc. 2800 Every day. (Konigswusterhausen) 11-12.30 4-5.30 p.m.....Financial News, etc. .. .. 2800 Prague .. P R G 7-11 a.m. and 3 p.m.Weather News, General News .. .. 1800 9-2 p.m. and 9 p.m. Concert .. ..4500 Geneva H B ..6-7 p.m...... Concert '.. .. 1200.. The British Broadcasting Stations transmit on Sundays between 8.30 and 10.30 p.m.,and at varying times during weekday mornings and afternoons.The programmes appearing in the daily Press should be consulted for fulletails. (1) If, at the indicated times, a station has to receive or transmit service communications, the weather transmission will take place after these communications.Tuesday :Operatic selection on the gramophone.Thursday :Various on gramophone.Sundays :Various by artistes. (2) Special concerts given during the evening are announced in the course of the preceding transmissions. Popular Wireless Weekly, -June 16411, 1923. 061

The Best Finish for Radio Cabinets With Johnson's Wood Dye you can finishthe cabinet of your Radio Outfit as well as an expert cabinet maker, and in anycolour youwish, to harmonise with your other furniture.It comes in fourteen different beautiful shades,all of which can be lightened ordarkened-fulldirectionsoneverylabel.Johnson's Wood Dye iseasy to apply. Itpenetrates deeply and brings out the beauty ofthe grain without raising it-it dries in four hours. JOHNSON'S WOOD DYE isused and recommended by most cabinet makers.They know thatthereisnothing that can equalitfor arich,everlasting finish. JOHNSON'S FREEBOOK ON POLISHING WAX WOODFINISHING An occasional application of Johnson's Polishing WaxTo allwho write for over the finish of Radio Cabinets, whether bought sets it, we will gladly send -GMe or horne made sets, will always keep it looking new, andour illustrated book gives a beautiful polish that will not collect dust or show PROPER finger prints.It will improve greatly the appearance of on theProperTreat- TREATivio all rabinets. mentof Woods. It ooRott;vidttils Renovates Ebonite explains how to obtain the best possible finish FURNITURE ja,linson's Prepared Wax isan idealpreparationfor on allkinds of wood, oestoring ebonite panels and other instrument boardsand itwill be a great AS used on wireless receiving sets.Furthermore, panels help toall treated with Johnson's Prepared Wax resist acid fumes those who are making their own C.1 OtitignIS°14 given off from the low-tension battery, and prevents that S. mgtiludoihoesnectes thick film of acid which you have no doubt noticed cover- outfits. 7hWecillso,oeyioiruosh,itn ing the whole of the ebonite panel, and causes a terrific leakage and bad results. Give Johnson's Prepared Wax a trial.You will be sur- prised at the wonderful clean appearance it gives, and the S. C. JOHNSON & SONS, LTD. " The Wood Finishing Authorities." better results you will get. (Dept. P.W. 6), West Drayton, Middlesex. Dear Sirs, Will you please send me your illustrated book, which S. C. JOHNSON & SON, LTD., explains the best way for finishing Radio Cabinets. "The Wood Finishing Authorities," My Name WEST DRAYTON, MIDDLESEX. My Address 662 Popular Wireless Weekly, June 16th, 1923.

WIRELESS !WIRELESS !WIRELESS !and EVERYTHINGfor it. DON'T PAY MORE 'CVheeaipnes::in oaerZt2,e.

=il!SISIMNOTE. We areexclusively WIRELESS -NOT DABBLERS! Reliable goods at less than so-called Wholesale Prices (to the Public) " DON'T BE BLUFFED." " ERICSSON " HEADPHONES (Con. NUTS, 2 B.A per doz.21d. PLUNGER SPRINGS, complete each id. tinental). Ourprice,stamped B.B.C , NUTS, 4, 5, 6 & 8 B.A per doz.2d. SLIDER ROD, brass,13 in. long,iin. per pair 15/3 WASHERS, 4 B.A per doz.1d. square, drilled each 314. " SUPER " FRENCH HEADPHONES SLIDES. KNOB each 24. Brand new. 4,000 ohms, and guaranteed WASHERS, 2 B.A per doz.11d. SWITCHES ON EBONITE, S.P S.T. each pair tested per pair 15/9 FILAMENT RESISTANCES,smooth (quality the best) each 1/8 SIDPE HEADPHONES, 4,000 ohms, action, marvellous value 1/ 101d. &2/ SWITCHES ON EBONITE, S.P D.T. our price 17/3 CONTACT STUDS, with nuts and (quality the best) each 1/11 THOMSON HOUSTON HEADPHONES, washers per doz.5d. SWITCHES ON EBONITE, D.P D.T. (French) 4,000 ohms, our price 18111 STOPS, with nuts and washers per doz.7d. each 2 / 9 TERMINALS,withnot & washers. (quality the best) BROWN'S FEATHERWEIGHT HEAD- 2d. CONDENSER SPINDLES, allsizesIn PHONES, 4,000 ohms, our price 27/11 each 14., 114. & stock, from each14d. MARCONI R. VALVES 1316 EBONITE KNOBS, 2B.A ,each 2d., 3d..& 4d. SCREWEDCREWED ROD, ROD, 2 B.A., 12 in.long, MULLARD " ORA " VALVES 1219 SPACING WASHERS, large per doz. DUTCH VALVES 8/9 SPACING WASHERS, small per doz.14d. SCREWED ROD. 4 B.A.,12in.long, (All CRYSTAL CUPS, 2 screw each14. each 2(4. L.F. TRANSFORMERSGuaranteed, RatioNew). 5 to1. CRYSTAL CUPS. 4 screw each2d. RUBBER -INSULATED LEADING -IN All guaranteed.(Postage 1/-) each 11/3 FIXED CONDENSERS, all capacities,each111d. WIRE per yard lid. CRYSTAL DETECTORS, Adjustable 1/31 EBONITE, cut to any size by machinery INSULATORS, white reel,2fn.,each CRYSTAL DETECTORS,enclosed in while you wait per lb.3/8 1 I d. per doz.1 / 4 Celluloidunbreakable case 2/3 TELEPHONE TERMINALS.nuts & INSULATORS, whiteEgg,each24., SWITCH ARMS, best !sakes 1/3 & 9Id. washer, each 114 per doz.1/4 per doz. 1 / 9 AERIAL WIRE, 7/22, guaranteed hard - W. 0. TERMINALS, nuts &washer, SPECIAL HERTZITE CRYSTAL, drawn copper, 100 It.(postage 1/-1 ...... 2/. each 2d Per don,1/9 large piece 1014. CONDENSER VANES, fixed or moving, PANEL BUSHES, drilled,eachlid., WOUND INDUCTION COILS (posit- tier doz 314. per doz. 1/4 age 9d.). Real Gold Cat's Whiskers each 2d. TOP CONDENSER, bushes,each Id.: 12 x 4 9 x 48 x 25 6 x 3 6 x 2 eclatierii. 1119 per doz. lid. 2/8 2/5 2/21/11 1/8 Real Silver 'ant's WhiskersPer BOTTOM CONDENSER, bushes,each TAPPED INDUCTANCE COILS, 20 per doz.8d. ld per doz.9d. tappings wound to 1,600 metres- each 2/11 CONDENSER SCALES, 0 to 180...each 3Id. VALVE LEGS, nut & washer, each Id.; VARIOMETERS (TubeType)complete IVORINE LABEL SET, 12different per doz 10d. withknob 3/11 reading' the set 714 VALVE PINS, nut & washer, each Id.; DOUBLE 'PHONE CORDS, full length 1/41 BATTERIES, volt, 3d. each doz. 2/9 per doz. 9d, BELL WIRE, tinned copper, 12 yds 6d. "ELKAY" WIRELESS CO.,225, BishopsgateLondon, E.C.2. Half -day closing, Saturdays. Trade Supplied -Accumulators chargedon premises. Open Sunday: 11-2.30. Please remit ample postage. Note new Telephone No.: Central 8544.

BARGAINS IN WIRELESS SETS THE ELWELL 4 -VALVE B.B.C.Set complete with both H.T. DIAMOND WIRELESS and L.T. Batteries, 'Phones, Valves and Aerial Equipment, EQUIPMENT List Price £42 10 0 - Our Price £28 10 0 CO., GECoPHONE 2 -Valve B.B.C. Set complete with all 184a, OXFORD STREET, W.1. accessories. List Price £25. Our Price £19 0 0 (CLOSE TO OXFORD CIRCUS). BURNDEPT ETHOPHONE Ill B.B.C. Set with all accessories.List Price £:3514 0.Our Price £27 10 0 We supply all types of Receiving Sets BURNDEPT ULTRA III.Complete with lN1 ARK II. TUNER, and have a large stock ofallparts Coils, and all accessories. List Price £47 17 0. Our Price£32 10 0 McMICHAEL 3 -VALVE PANEL. Complete with all and accessories at competitive prices. accessories Our Price £16 0 0 Frame Aerial, 'Phones, Loud Speakers and EXPERT ADVICE GIVEN. all accessories in stock at equally cut prices. INSTALLATIONS CARRIED OUT. CHARD & CO., 24, Gt. Portland St., London, W.1 ROCK BOTTOM PRICES.

FEATHERWEIGHT CCUMULATORS (leather covered) SPECIAL OFFER AT REDUCED PRICES p CONTINENTAL Popular Type. Clear Celluloid Cases.

r HEADPHONES So.Volt-IgnitionAet.A.H. Carr age.Cap. Amps. Cap. Price Extra. High Resistance 4 204 100 4 71 8 9/11 ALL 1310 4 20 10 12111 1/6 Adjustable Diaphragm 1315 4 30 15 1441 WIRELESS \\\\ Quality Unsurpassed 1320 4 40 20 16/11 133 4 60 30 22/6 } 2/3 ACCES- 13 4 80 40 297- Cash with Order EPR 142 6 40 20 2" 2'6 SORIES ACCUMULATORS 14306 60 30 33/9 ' 1440 6 so at have 40 39613,/6 1 7/6postage paid. 20 YEARS' 14506 100 50 466 KEPT Special Terms to the Trade. REPUTATION IN Accumulators RICHFORD & Go., Ltd.9, Phoenix Place, Mount charged on the 153, STOCK. AHLMANN (London', , Pleasant, London,W.C.1. premises day and FLEET ST., LONDON, E.C.4. night. Telephone :Holborn 5126. Estab. 1876. Popular Wireless Weekly, June 16th, 1323 66,3 AMERICA DISCOVERS GEARY. By HIGEAM BURLAC. When a real " ten -cent radio hustler " came over from the States expecting to find the " Briddisher " still delicately manipulatiAg coherers, Geary rose to the occasion and arranged that he should not be disappointed.

ADULL August day was drawing very " gather,"faltered Geary. 'whose paragraphs from " Perks' Primer On Pith perceptibly into an autumn evening. knowledge of the vernacular had faded, Balls and Scaling Wax," adding, to Mr. Clapham was obscured .in a kindly " I gather that you would like to be intro- " Winnabahm," " That, you know, is the mist- of rain, and Clapham's aerials were duced to some of my influential business English amateur's Great Charter." And steadilyleaking. The period wassix friends ? Sure-I will see what I can do." then, turning to the members :" Brothers, months after Geary was exported from " Gosh ! You're on. Yours cordially what are we without Pith Balls and Electri. those United States, and a casual observer, would ruther lamp a stainless steel, corn - fied Sealing Wax ? "Geary and several poking his nose into Acacia Villa, might on -the -stalk,patent -applied -for,nix -plus - others said,Hear, hear." Several members haveobservedAloysiusGeary,Esq., ultraBriddishbusinessfellerthan' a gravely said, " Ah, true, true ! " and three F.R.E.A.K., drawing a well -sucked lead -- goldanged, pink -whiskered wuggerzoo with were overcome with emotion, and hid their pencil across a small piece of ebonite. Yes, radium eyes, and when I'vesaidthat, faces. Mr. "Winnabahm " loosened his it was a grid leak in process of formation. believe me, I've said a mouthful." collar slightly, and gazed at Mr. Perkins, who For further information please see other " Ah, quite so.If you are in town began to speak again'. pages of this journal. to -morrow nightIshallbe pleased to Too- Much for America. introduce you to the Wireless Club. Several " Friends,I need hardly remind you The "Ambassador " Arrives. of the members are highly -connected in Mr. Geary had just licked 'his BBB in that when Aristotle discovered the business, and at least four have received Here a member rose and complained that readiness for another traverse of the line Newark on frame aerials." another,to wit, . WilliamDigson,. was .when the bamboo hallstand shook to the The man from Chicago leaned forward, sound of a knock at the front door.Dust- wearing a knitted waistcoat.Mr. Perkins his eyes alight with the unearthly fire which groaned aloud, and requested Mr. Digson to man ?Never at that hour-or without the appears in the optics of an entomologist who cry peculiar to his species. Hawker ?Did quit the premises. The incident then closed. is promised a visit to the haunt of a new " Holy beans ! " said Mr. " Winnabahm not' the plate on the front garden gate forbid,kind of bug. theinvasionsofitinerantmerchants ? to Geary. " Are you all loony ? " " Say ' he hissed." Can I really blow " Hide your smoke ! " replied Geary, " or Policeman ?Dash it !the dog -licence was in on a genwin Briddish Raddio Riot ? Me only seven months in arrears, the wireless they'll tie the can on us, too. I've no stand." heart's weak. Can I stand for it ? Do they ing here worth mentioning since' I aban- licence was unexpired, Mrs. Geary did not require references and a vote of confidence? suffer from kleptomania, and young Bill doned ' plain aerial.' " Is there a Strangers' Gallery ? Do they turn " You don't say ?Who is the left -eyed Geary hadn't done anything of note for down the light before they bring on the pre - several weeks, owing to the fact that he was flounder that got all het up about the other Armstrong hook-ups ? Let's getthere, guy's vest ? " in hospital.When Bill wasn't in hospital brother I recovering from motor -bicycle bites, he was Oh, him !That's Lord Lincrusta's out on bail.Better open the door and Pith Balls and Sealing Wax. cousin." chance it. Geary sometimes had lucid moments, and " Lemme have another lamp at him ! Can this was one of them. He sensed an air of you speak to him ? ' Geary cautiously pulled the latch and leg -pulling. Mr. " Winnabahm " on the " Not directly, of course, but through the swung the door inwards without enthusiasm irregular paving -stonesofa New York secretary." - (" Probably got to buy a ticket for the Railway- suburb, with his neckwear flying free, seemed "Say, does he live in the Tower of London? men's Fete ! "), and a voice said, " Mister to fit into the picture ;here, his friend's Ne' mind !Tell me what is this expurrment ' Winnabahm ! NormalSchoolenunciationandboob - the old nanny with the lopsided lugs is No one of that name " began Geary, hunting proclivities sorted ill with Clapham's working up to." but the voice thereupon proceeded with culture. A sharp lesson seemed to be " They're going to have a jolly evening more joyous and decisive intonation : indicated.For once in his life Geary (I with the club coherer, and their same nice " Waal, how's muh friend Geary ?Guess never represented Geary as a streak of light- dissolving views of eminent ex -engineers

you recollect Winnabahm of Chi. 'Member ning) was quick on the uptake. He fell for of the Clapham_ Waterworks." _ me picking you up four blocks easto' Mr. " Winnabahm " good and plenty. This overawed " Cordially Yours." Wannamaker's in the flivver and parking " Well," he said,it's true we're a mite " B' Gosh ! " said he." I wouldn't have youparallelwithConey. Cometo, slow over here, but you must make allow- missed this for a piece. What would happen Briddisher, and open up the wigwam ! " . ances for us.Call here at seven o'clock if I mentioned raddio here ? " Ultra -violetlightilluminatedGeary's to -morrow evening and I'll take you round Geary looked solemn. memory cells upon this Pelmanic oration. to see the boys playing at wirel-er-raddio." " I'm not sure. Under the constitution of Ah !It's Mr. Winterbottom. Dee -lighted. " Put it there," replied the visitor, and the club a committee would be formed first C'm in ! " he cried. when he had gone, Geary wrote a postcard. of all, but the regulations provide that this Mr. " Winnabahm " shifted his plug of may not sit until its terms of reference have Wrigley's to starboard, gripped, his sombrero " Pleasedto meet you, Mr.Winter- been ballotedoverfor three successive like a strong man in agony, and entered the biattorn,"-`saidMr.EzraPerkins,the annual general meetings,,;Eventually a Respectable Briddish Home. Clapham Wireless Wonder, on the following ruling would be drafted " Geary conducted him directly tothe evening." We are about to try a little Something between a sob and a howl studio --where the grid leaks were sketched -experiment, and welcome in our midst a butst from the dry lips of Mr." Winnabahm." --and sat him on the sofa which was con- visitor from the land of De Forest, Tesla, He rose and looked anxiously at the door._ structed when Victoria was a mother of and Booker Washington-not to mention " By the shining goats !Show me the schoolboys and horsehair was cheap. Edison, Confucius, Jane Addams and the sidewalk and lemme hit the grit.Those - gifted author of ' Who's Who in the nolasses quicksilver hombres will make me a honor- A " Genwin Raddio Riot." Trade.' " ary member if I don't shift my location. " Well. this is a pleasure" lied Aloysius " Cordially Yours " emitted a smothered Coherers ! .Aristotle Relay League to in the most approved manner. " Whatever gasp, and said he guessed Mr.Poikina Everlasting Petrifaction !Help ! " are you doing over here ? " could show him a few man-size, quick - Mr. Perkins, who was just then -solemnly " Snooping araound for kahntracts. Heard selling, mass -production, all -rubber, money - connecting a Wimshurst machineto a there was a few dallers left here, and guessed back stunts in four shakes of a broncho's Leyden jar, saw Geary slip out of the room - I'd hike across and collect same. Represent '*fly -whisk. in the wake of Mr." Winnabahm," and not the Oklahama Milling, Mining, and Lumber Mr.Perkins,slightlydazed,agreed. until the door had closed did he remove his SalesNegotiations (1922)Corporation. When the 'members had assembled, Mr. grey beard and with his colleagues give way Cordially yours, I should smile. Know any Perkins rose'and led them in singing "Rule to the holy glee which is the reward of faith- boobs ?Interdobde Kstrl Witinabahrn.' Britannia." after which he read six fruity ful workers who have done their lob well. 664 Popular Wireless Weekly, June 16th, 1923 of wireless " television "-in other words, the ability to see by wireless from, say, a WIRELESS CLUB REPORTS. London room, what is going on in a room The Editor will be pleased to publish concise reports of meetings of Wireless clubs and at. Liverpool.The list of contributors to associations, reserving the right to curtail the report if necessary.Hon. secretaries are the new weekly includes prominent wire- reminded that reports should be sent in as soon after a meeting as possible.Reports sent less experts, and Sir Oliver Lodge is to act in cannot appear in this paper in less than ten days after receipt of same. An asterisk as scientific adviser.-" The Times." denotes affiliation with the Radio Society of Great Britain. " Wireless Review " isthe latest and' most important addition to the ranks of North MiddlesexWirelessClub,100,Pellatt Bath Radio Club. wireless papers.Sir Oliver Lodge is its Grove, Wood Green, N.22. The members of the Bath Radio Club held a scientificadviser,andotherleading This club held a very successful meeting at radio auction and social evening at their head- experts compose its editorial board. Shaftesbury Hall, Bowes Park, N., on the 2nd quarters, the Red House, on May 11th. " The Daily Mail.". ult." As a change from the last meeting, when a The radio auction, held for the purpose of demonstration was given of commercially-inade enabling members to dispose of their surplus " Wireless Review and Science Weekly " wireless apparatus, the evening was devoted to a wireless gear, was conducted by Mr. Bertram is the latest and, without doubt, the most" lecture on " Workshop Wrinkles," by Mr. T. Fortt, of Bath, and proved very interesting. authoritativeofthe weekly magazines Weaire. Hon. sec., Geo. J. Barron Curtis, F.S.A.A., dealing with wireless.Teachers who are Hon. sec., Mr. H. A. Green, 100. Pellatt Grove, F.C.I.S., 6, Pierrepont Street, Bath. interested in this subject, and are anxious N. 22. Birmingham Experimental Wireless Club. tq keep: abreast of the latest developments, TheRadioAssociation,South Norwood and A very successful lecture and demonstration could not do better than subscribe to this District Branch. was given before the above club by Mr. Towers very beautifully produced magazine. At the Stanley Halls, South Norwood, on on the subject of " Receivers and Amplifiers for The Schoolmistress." Thursday, May 17th, a lecture was given by Broadcasting Reception." Mr. A. E. Saunders (a member of the branch), Some interestingresultswere shown by " Wireless Review " will be supported entitled :" A Few Considerations of Ether, impressing up to 15 volts on the grids of the bythestrongest editorialboardever Electrons,and Material Phenomena." The valves used, and Mr. Towers managed to intro- formed. . . atthe price of3d.,the chair was taken by Mr. S. W. Butters (5 V If). duce into his lecture a great deal of information value it gives is marvellous. Hon. sec., C. H. P. Nutter234A, Selhurst very useful to the experimenter. For those who wish to follow all the Road, South Norwood, S.E. Very good results wore obtained on the club's latestdevelopmentsofwireless,both aerial, and an instructive evening was spent. The Wireless Club, Ltd. Hon. sec., A. Leslie Lancaster, Lancaster Bros. theoretical and practical, itwillbein- The weekly lecture before the club at the & Co., Shadwell Street, Birmingham. dispensable.-" The North Star." Manchester Hotel, AldersgateStreet,E.C. 1, on Monday last, was of so interesting a character Concerning the. prize offer, the that it has been decided to print in pamphlet " Western Mail " says : form the lecture on " What is Ether ? " which " This offer is certain to attract wide- was delivered by Mr. T.F. Gaynor. Miss " WIRELESS REVIEW" spread attention among scientists and the Euphemia Smith, a trustee of the club, was in more brilliant amateurs, and it is designed the chair. PRESS REPORTS. to promote progress along a most fascinat-, . Registered office, 56, Long Lane, West Smith- ing line of scielltifie discovery." field, City of London, E.C. 1. SINCE the advent of broadcasting, in- In style, authoritativeness, and general The Radio Society of Highgate.* terest in the science of wireless tele- appearance, the new periodical, " Wireless A lecture and demonstration was given on phony has increased. A large section Review and Science Weekly," gives evi- May 18th by Mr. J. F. Stanley, B.Sc., A.C.G.I., F.R.A., his subject being, Selective .Tuning of the British public are not merely con-dence of being a valuable addition to the Circuits." The lecturer described a series of tent to " listen -in "; they want to " know list of technical magazines. experiments which lie had carried out in order why." The " Wireless Review and Science " The Glasgow News." to find the most selective receiver possible, Weekly," which makes its first appearance without entailing the expense of a large amount (price 3d.), is designed to appeal to their Listeners -in who want to understand the of apparatus. tastes. principlesanddetailsof wirelessare Hon. see.,J.F.Stanley, B.Sc.,A.C.G.I., It contains an offer of £500 for the most referredto the" Wireless Review and F.R.A., 49, Cholmeley Park, Highgate, N. 6. successful demonstration of the possibility Science Weekly."-" Daily Chronicle." An interesting pamphlet, entitled " The Radio Instruments, Ltd., are putting on CATALOGUES, BOOKS, History of a Lamp," has been forwarded to the market a new variableinter -valve us by Crowther & Osborn, Ltd., which reactance in order to give the radio experi- ETC. gives a general idea of their factory capa- menter and others desirous of constructing bilities. They also state that they are under -- their own sets an opportunity of using inter - ANEW type crystal detector has been taking the repair of wireless valves by a valve reaction during brbadcasting hours, placed on the market by Callen & special method which prevents there - avoiding re -radiation and yet get maximum Son, Ltd.,for which is claimedunique sagging of the filament. They even under- efficiency.The wave -length range is 200- features.It is known as the " Davis Patent take the repair of cracked stems.The 4,000 metres, and the component is fully Detector."The ball and socket joint has repaired valves are returnedexhausted approved by the P.M.G. been placed at the base of the selector sup- either" hard "or " soft " according to * * * port, and the selector arm is stiffly pivoted at customers' requirements.The cost is6/6 We are very pleased to see that the the top of this support. By this arrangement per valve. " Readers' Guideof- the public library of the motion is made continuous and gradual. Norwich contains quite a number of books We like the movement very much, but sug- on wireless telegraphy and telephony. gest that the cat's -whisker should he made The Metalastene Co. have sent us a sample of their patent jointing compound, * * * replaceable instead of being pinched in the selector arm as it is in the present design. concerning which they have had many " Progress "isthe titleof a booklet: letters from customers stating they have published by Bertram Day & Co., Ltd., used it for wireless work, particularly as a giving, fulldetailsoftheiradvertising We have received from Ward and Gold- means of making a satisfactory and lasting stone, Ltd. a copy of their April catalogue, scheme. joint on the end caps of " grid leaks."It is * * which includes complete sets and all com- very easy to use and is a metallic and * ponents. An interesting feature is their. Very neat crystal and valve sets are junior transmitting set which sells at a conductive paste. illustratedinthe new catalogue of the reasonable price, and should be a boon to * * * " Abbey Industries, Ltd."Of special note those who want a cheap yet efficient trans- Many people who have not decided on is their " Miniature " Crystal Set, which is mitting set and are not prepared to make any special make of set would take it as a smaller than the palm of the hand and has a their own apparatus.They also enclose a boon if they could see many makes of telephony range of 15 miles. sample of their chain braided 7/22 copper instruments at one address. A. J. Dew & Co. * * * aerial wire, which they state is taking the have issued a catalogue in which are many Henry Wiggin & Co., Ltd., manufacturers place of the single wire or the strand owing types of sets, and one can make a good choice of " Snake brand resistance wires and to the large reception surface.A sample from their showroom as they are agents for tapes have forwarded ustheirbooklet will be sent to anyone writing for same. many firms. giving full details of all their wires. Popular Wireless Weekly, June 16th. 1923. G35 CUT IT OUT ! You can eliminate all - the interference and confusion that now spoils your reception- Static, Morse, Atmospherics, and interrup- tions from transmitting stations other than the one to which you are tuned-by fitting to your present receiver, without alteration, an 3-EVC"Autoveyors" The only complete Absorber of Disturbances. British Patint 17703'22 Over-all Dimensions Price Length BreadthDeoth .0005 mfd.30s. Od.7" x44" x3 " *001 mfd.40s. Od.7" x 4r X 0J * Capacity essential for interferenceelimination. Wherever you may be, whatever the station you desireto receive,the" Autoveyors 3 - Electrode Variable Condenser gives you just what you want, exactly when you want it. Get one now andlearnthedelightof listening -in without disturbance. Obtainable from all reputable dealers or direct for remittance with order front :-- AUTOVEYORS, LTD., Radio Engineers and Contractors, 84 VICTORIA STREET, LONDON, S.W.1. Write for General Catalogue-the most comprehen- sivelistinthe WirelessTrade -3d., Post Free.

-O produce a loud speaker Twhich is worthy of the artisteswho nightly broadcast has been our am- SOLDER OR SORROW bition. A loud speaker which reproduces the fulness WHICH ;s it to be? of the violin, the delicacy The Wireless aspirant whoissatisfiedinleaving of the flute, the blare of the the connections of his aerials trombone and the charac- andsetterminalstolook teristic quality of the voice, afterthemselvesbyjust that has been our ambition twistingthemtogetheris and that is the guaranteed asking fortrouble. Apart performance of from the untidy appearance, 1MM & A 4ft careless connections are going k=1 to lower the efficiency of the \\N\ finestreceivingsetinthe world. SOLDERING will make doubly sure of them, and, incidentally, FLUXITE will make sure of the soldering.Solderingischild's play Loud -Speakers when you've a tin of FLUX ITE at hand to help you, or, better still, a Obtain one from Tour usual complete Soldering Set that we have had specially prepared for the con- stores,electricianorwireless venience of customers.Ask your Ironmonger or Hardware Dealer to dealer, and judge for yourself. show you the neat little We are confident your verdict will be 7E17.411LIMCirir SOLDERING SET Reduced Itisperfectly simple to use, and Price will last for years in constant use. It contains a special " small -space " 716 Solderingiron,withnon -heating The Telephone metal handle, a Pocket Blowlamp, Manufacturing Co., FLUXITE, Solder,etc., and full Limited instructions.Pike 7/6 sample Set, London Showrooms: post paid, United Kingdom. 68, Newman St., Oxford "True Music" St., London, W. 1 FLUXITE PRICE £6 10s. SIMPLIFIES SOLDERING All Hardware and Ironmongery Stores sell 1017ADINULCIDCCI FLUXITE in tins, price 8d., 1i4, & 2,8. TelLuc tool -kitof your car of Buy a Tin To -day. motor -cycle,orany soldering jobs about the home. FLUXITE LTD., 324 Bevington St., Bermondsey, England, EGG Popular Wireless Weekly, June 16th, 1923.

for broadcasting being 50 and 75 turn coils of the honeycomb type, the A.T.C. being in parallel with the A.T.I. The bank of condensers of 005-006 mfd. also should have some attention. Vary the capacities until RADIOTORIAL. best results are obtained.It inconvenient to have a variable leak in that position also-that is, across the bottom condenser. If you have 2,000-3,000 ohm 'phones you will probably find that these are snore All Editorial Communications to be addressed The Editor, POPULAR suited to the loud signals than are those of 4,000 or 8,000 ohnis, because when the circuit is functioning WIRELESS, The Fleetway House, Farringdon Street, London, E.C.4. correctly the signals from London should be un- bearably loud situated as you are. You will find on experimenting that the correct sizes of coils must be employed, otherwise the set Thousands of my readers have at one time or another will either howl continuously or will not oscillate at all asked me how they can take up a career in the wireless easily. and ,engineering line.It is obvious that broadcasting Naturally the happy medium must be found bas inspired many young men with the desire to enter where the set will howl if you let it, but where the some sphere of life where their knowledge of wireless UESTIONS howling can be controlled by means of the variable and engineering may be of benefit.The careers open leaks. to young men with a sound scientific training are many * and attractive, and in our new companion paper, " Wireless Review and Science Weekly," there will " SEMAPTIORE " (Burnham). - Can Lee- shortly commence a series of articles outlining the lanche cells be used for a carborundum crystal various ways in which profitable employment may be ANSWERS detector ?What cat's -whisker proves most obtained by those who have studied certain branches satisfactory with this detector ? Please give a of applied science. In No. 4 of " Wireless Review and Science Weekly " circuit using variometer and the above crystal, two special articles of great importance will appear. and details for variometer for broadcasting One is by Dr. d. A. Fleming, F.R.S., the famous in- D. N. (Nottingham).-Is there any direct purposes. ventor ofthe valve.Dr. Fleming deals with the problems of Long Distance Telephony, and no amateur ratio between the primary and secondary should miss this fascinating article. windings of a loose coupler ? The other is by Sir Oliver Lodge, F.R.S., Scientific No, there is no direct ratio. The secondary in con- Adviser to this paper and ". Wireless Review and Science junction with a suitable variable condenser must be Weekly."Each week our companion paper publishes constructed so that it will give a wave -length variation articles by the world's leading wireless and scientific coinciding as nearly as possible with that of the open authorities, and I urge every reader of P.W. to place a circuit, which consists of not only the primary winding standing order fora copy at once.These two papers of the coupler, but 'also the aerial and earth system. constitute the VERY BEST in wireless and popular Therefore, the secondary will, generally speaking, scientific literature, and should prove all -sufficient for require to have a greater value than the primary. As amateurs. THE EDITOR. a general rule the secondary has about 1 more turns than the primary, using a wire of about two or four owingtotheenormousnumber ofqueries gauges smaller than the latter.

receiveddaily from readers of POPULAR * WIRELESS, I have temporarily decided to limit the number of questions sent in by one reader to X. P. (Dulwich).-I am going to Vaahir three.Readers are asked to keep their questions (Rumania) and shouldlike to know what as short and as concise as possible in order that the minimum of delay can be exercised in answer- laws are in force over there as regards amateur ing queries.Until further notice three questions licences for reception. from one reader will be the limit for one letter. In Rumania the Director of Radio Communication All questions should be addressed to POPULAR controls all matters relative to wireless telegraphy. WIRELESS Queries Department, Room 138, Fleet. Authority to possess installations is given to scientific way House, Farringdon Street, London, E.C.4. institutions and also to those engaging in special Readers are requestedto sendthenecessary wireless research work. New laws and regulations are postage for reply. in course of preparation. We are of opinion that no broadcasting is carried on in that country yet. VARIOMETER TUNED CRse5TAI, CIRCUIT The Editor desires to direct the attention of * * CARBORUNDLIM 8,POT ENT I OtlEM his readers to the fact that, as much of the in- " SUPER " (Elstree).-I have built up the Three Leclanche cells can be used with this crystal. formation given in the columns of this paper Flewellingcircuitthatwas' published in We prefer, however, the ordinary type of dry battery, is of a technical nature and concerns the most POPULAR Wing,LEss recently, but cannot stop as it is more handy. A steel strip contact will give recent developmentsintheRadio world, it howling. Why is this ? best results with carborundum. Using cardboard some ofthe arrangements and specialities tubing for the variometer, a serviceable one for Probably your grid leak and condenser are not broadcasting wave -lengths will be 25 turns of 26 D.0 C. described may bethesubjectofLetters suitable. Try a variable grid leak of 0-5 megohms and Patent, and the amateur and trader would different sizes of condenser also.You will find that on both rotor and stator, the rotor being 31 III. din - be well advised to obtain permission of the a condenser of about '00025 will be most suitable. meter and the stator 4 in. diameter. The telephone patentees to use the patents Wore doing so. Try different sizes of inductances also, the usual sizes (Continued on page 668.)

DRAMA BEHIND THE MICROPHONE.

ANT] P.,\NAN.UPOrt MAIDEN Ito TRus-cy 5Theti. I RIDE_ TO t slotizeR PiAlDEri Ire DISTRESS DISTRESS t

C_LATTE RI IOF HOOFS f. Popuiur Wireless Weekly, June 16th, 1923. 667

No. 5 of a Series of talks on Peto-Scott Units. No Batteries orValves to buy Pat. ay/lied -start thefamous tor Peto-ScottUnit Systemwiththis novel Crystal Unit PRICE LIST OF UNITS FOR HOME CONSTRUCTION. Once again the Peto-Scott slogan 2. H.F. Amplification, Crystal recti- No. 1. TunerUnit 27/8 No. 2. Condenser Unit 42/ - of" EconomicalWireless "has fication and Low -Frequency Am- No. 6. Crystal Detector Unit 1518 plification. The man starting Wireless cannot been demonstrated by the intro- do better than commence with the abovethreeUnits(illustrated of below).They form a wonderfully duction a new Crystal UnitWhen the switch is to the right, it gives : efficient Two -Circuit Receiver, verysensitiveandparticislarly (No. 6). selective. Atany timeValves 3. Crystal rectification only with no for increasing its range or power_ can be added withobt making any As will he seen from the illustration,it H.F. amplification. alterations in the wiring ordis- bristles with original features.The Cry- carding a single piece of apparatus. 4. Crystalrectificationfollowed by No. 3. H.F. Amplifier Unit 13/6 stal Detector permits instant change of No. 5. L.F. AmplifierUnit 33/6 Low -Frequency amplification. No. 7. ReactodeUnit 28/6 crystalwithoutalteringascrew ora Cabinets for Nos. 1, 3,5,6 and 7 3/6 connection.Italsoallowscat -whisker For No. 2 7/ - Many experimentersprefertousea Postage 9d. per Unit extra, but paid adjustment over the whole of the surface over £2. of the Crystal. CrystalDetectoralwaysinsteadofa 32 -page Catalogue fully illustrated, 3d. Valve.To these we say, the Peto-Scott The Unit has been fitted with a two-way Unit System covers every possible require- switch which-when the Unit is workingment, and is invariably in accordance with with the remainder of the series-gives the latest practice. PETO-SCOTT Co., Ltd., four different combinations of circuits. Head Oflice It was the original Unit System and the When connected after a No. 3 Unit (H.F.only one to be licenSed under Marconi64, High Holborn, W.C. 1 Amplifier) and before a No. 5 Unit (L.F. Patents. Demonstration Lounge: to the left,it Amplifier), if the switch is 99, gives : Read all about the ingenious Peto-Scott High Holborn, W.C. 1 1. High -Frequency amplification fol-Unit Systemina24 -pageillustrated Branch : lowed by Crystal rectification. Booklet " Radio " (post free 6d.). 3, Wellington Street, Strand,

W.C. 2

No Batteriesor Valvesto buy for this efficient 3 -Unit Receiver

Gilbert Ad. Popular Wireleii'llieAli'JUne 16th, 1923.

RADIOTORIAL QUESTIONS AND ANSWERS.. (Continued from page 666.) 'condenser should be of about 001 mfd., while the potentiometer should have a resistance of200-300 ohms. The batteries should have a voltage of about 1'5 each, connected in series with the telephone tap- ping taken from the neutral point.

* * * T., G.(Barnet).-Ihaveatpresenta crystal set and am getting quite good results from 2 L 0, but wish to increase my range.I intend adding a valve, and should like it to work both as H.F. and L.P. at the same time.

Th above is a diagram giving a dual amplification circuit which can easily be used in conjunction with any existing crystal set.The circuit may require a little patience at first, but will give very good results. The aerial coil may be of the basket type with a variable condenser of '0005 mfd. across it, or else a 1-] slider or variometer. Condensers of '001 mfd. are put across the secondary of L.F. transformer and also across the telephone while a larger one Of '01 mfd. is placed across the H.T. Should the set at first refuse to function, a 0003 mfd. variablecondenseracross the turning coil of the original crystal set may im- prove matters.The diagram will make everything clear. and get better results * *- E. S.P. (Cardiff).-What is a step-down THE hood -shaped Grid and anode of transformer ?What can I do when the acid the COSSOR make use of practi- creeps or spills on anything to save a hole cally the whole of the emission of being burnt through ? A step-down transformerisone on which the electrons from its curved filament.The windings are so arranged that the pressure of voltage induced in the secondary will be less than the pressure result is clear, distortionless speech with a applied to the primary.Thus there are fewer turns remarkable freedom from microphonic in the primary than in the secondary.To stop the acid burning through where itspills, apply strong noises-perfect rectification under all con- ammonia solution, hut .keep the ammonia away from

the cells.A good plan to prevent the acid in the - . ditions with a high amplification factor cells from spraying or creeping is to put half an hich of oil on the surface Of the acid.Such oils AS This unique designisalso responsible " Blanco' " are best, as the oil should be properly prepared. - for the long lifeof every COSSOR- * * * its Grid construction isexceedingly D. A. N. (Bordeaux).-How many foils and Sold by all Dealers robust, and the curved filament cannot what thickness of mica shall I need for the 006 inWireless Com- fixed condensers in the Flewelling circuit ?Is - ponents and manu- possibly sagorfallout' ofposition. this circuit allowed for the reception of broad- factured by: casting in England, as I intend making it there? Cossor Valve Co. Ltd. Let, your next Valve be a COSSOR- For the condensers you mill need mica as dielectric nighbury Grove, N.5. then you will realise how well your Set '002 inches thick, and 11foils 2 by 3 centimetres overlap.Owing to the strong reaction properties of can really' perform. the set, it should not be used on broadcasting wave- For Detecting or Amplifying. lengths. C. E. V. (Ipswich).-What is the cause of, and the remedy for, sulphating ? Sulphating is generally due to insufficient charging, over -discharging, or allowing the battery to stand in a discharged condition.The best cure for sulphating is overcharging at a very low rate, not exceeding half the normal charging current.Sulphating can, how- ever, only be cured if it has not gone too far ;if the plates are too badly sulphated they will be ruined, and the only remedy will be to renew them.This applies especially to the positive plates : the negative plates will stand much more ill-treatment without destruction, and can often be saved when the positive plates are quite spoiled. * * * " TRANSFORMER " (Bideford).-How many turns and of what gauge wire shall I require to make a telephone transformer having a ratio of 8-1.Please also give details of a suitable former. The former is made from a thin ebonite tube, 31 inches long and of lin. internal diameter, with (Continued on page 670.) Popular Wireless Weekly; June 16th, 1n3. 669 MARCONI'S LATEST NewPopular Marconiphone Brings ALL Broadcasting Stations. within Range A new and improved Two -ValveMarconiphone. hasbeen perfected and is now on sale. With it, no matter what part of the country you live in, you can listen -in with perfect results to all the British Broadcasting stations from Glasgow to Cardiff. Price Reduced Owing to the enormous demand created for this instrument, it has been found possibleto economise largely in overhead charges. The public is given the benefit of these economies, and the New Marconiphone Vz is on sale everywhere at El6:3 :6 without accessories-or £24 complet*

Vhe Vriumph of the aCaster tXind THE NEW MARCONIPHONE V2. Ask your local dealer at once about the New Marconiphone V2. All orders are being dealt with in strict rotation. MARCONI'S WIRELESS TELEGRAPH COMPANY LIMITED Marconiphone Department, Marconi House, Strand, London, W.C. 2

GOSSAMER GRIFFIN WIRELESS SUPPLIES Co.,- "SENSIFONES 80, Newington Causeway, are the Latest and Best thing in Head- Hop 1806. LONDON, S.E.1. phones, and to convince you ofthis we offer them to you on a THIS WEEK'S BARGAINS. SEVEN DAYS' FREE TRIAL Complete parts for HIGH- POTENTIOMETERS CLASS CRYSTAL SET in- 300 ohms 4/- after which period, if you are not satisfied, MICROPHONES for your money will be immediately returned. cludingCabinetDetector, Amplifiers .. 2/6 DO NOT BUY CHEAP FOREICN 'PHONES. Var. Condenser and Tapped 3 -way Coil Holders EXTRA LONG CORDS. is be safe than sorry. Coil,Assembled mounted on Oak It betterto but unwired Cabinet 13/ - Fitted with Magnets made ..21, - .. from aspecially prepared SEND FOR FREE LIST. and expensivesteel,and WATCH OUR WEEKLY SNIPS. scientifically arranged and adjustedtogivea loud, I TD"., EIRNEISTC ST., No Junk-All Quality Goods-No Rubbish. clearnote withoutdistor lion.TOWNSHENDS,1. B RM N HAM. Expert Advice Free. ListFree. The ideal E LECTRONIT E INSULATING VARNISH The WORLD'S MOST FAMOUS CRYSTAL RHYME No. 4. No faintest murmur broke the silent night, HARDICOL No faintest tintinnabulation of the 'phones. Then someone whispered try Electronite, SHELLAC INSULATING And deadly silence changed to merry tones. :: VARNISH CEMENT :: TRADE SUPPLIED Guaranteed made from pure Shellac, A saturated RADIO SUPPLIES solution in the cold.Perfect for all insulation work, 234, HIGH HOLBORN, LONDON. Enquiries invited from the trade. 'Phone: HOLBORN 2188. 6d. and 1/-Bottles.Also in BULK, Sole Agents for Lancashire and Cheshire : Messrs. HENRY HOLLINGDRAKE & SON, LTD., HARDICOLISOBTAINABLE FROM THE PRINCES STREET, STOCKPORT. USUAL DEALERS AND THEMAKERS: A. F. HARDING & CO., LTD., EXMOUTH ST., STEPNEY, E. 670 Popular Wireless Weekly, June 16th, 1923.

STEEL TUBULAR MASTS RADIOTORIAL QUESTIONS AND ANSWERS. Light, Strong, and Easily 301 t. 40/- Erected,madein10 -ft. (Continued from page 668.) sections. of best Weldless 40ft. 66/- Steel Tube. Agood Aerial 50f t. 77/6 two blocks ofin. ebonite drilled to fit snugly over the ends.For the secondary wind on 1,200 turns of No. 38 S.W.G. (about f oz.), wrap some cartridge 60ft. 90, - paper over this secondary winding when complete, Mt. 1201 - will add the power to act as inter -winding insulation. For the primary ofanother Valve you will need 31 07.g. of No. 42 S.W.G. The core is to your Receiving formed of 10 in. lengths of 22 -gauge iron wire. IF you have had your application for Set. * an Experimental Licence refused, Each Mastiscorn. it is probably because you do not know pietawith Halyard V.T. N.(Bexhill).-I wishto make a and Pulley, Steel Guy variometer to tune between about 300 and the Post Office requirements. The Lines,Shell - typo object of this new Book is to explain Insulators and 1,000 metres. How many turns of what wire exactly what you have to know and Strainersforeach Guy Line, Base Plate, shallI require, usingshellacked cardboard the requirements you have to fulfil Peg and Finial, before the 1,icence can be granted. 4 Ground An. formers 1What size formers shall I need ? chors of li ins. Read this book and apply for the angle iron, fitted On the rotor you will need about- 55 turns of Licence again and legalise your posi- withRingfor No. 24 S.W.G. D.C.C. on a diameter of 3 inches. The tion at once and for always. Guy Linea. stator should have the same numbet of turns of Pointed ready for erection. No. 22 S.W.G. D.C.C., diameter 4 inches. Published by: List free. 5- Trade Supplied. S. E. D. (Thorpe Bay). --1 have been told RADIO PRESS LTD., that a short aerial should be used for:the DEVEREUX COURT,STRAND. reception of the British broadcasting stations. W.C.2 Is this correct ? I had intended to -usea 60 ft. double aerial,- but have been told that 1 should use a 60 ft. -single aerial for preference, and also that it would he better to use a 60 ft. single than one, say, 90 ft. long. ABBEY ENGINEERING WORKS, Your information is quite correct, and a single WATTON, NORFOLK. aerial is 'fter than a double one if, it,is to be over 50 ft.long.- This is taking into consideration the TO LET.-WELL-hQUIPPED WORKSHOP AND fact that you are using it for broadcasting, of course. Wireless Licences PREMISES AT CHISWICK, ideally suitable for With regard to the choice of a shorter single aerial, the manufacture and assembling Wireless Sets.-For sale, reasons why a long aerial is to be avoided are these. In including benefit of profit Rentals of part let £200 the first place, an aerial has a fundament alwavedength, Show to obtain them £1,000 for immediate sale.GREVILLE'S, 48, Upper and to tune to stations sending on various wave- Berkeley Street, London, W. lengths it is. necessary mostly to add inductance on to it in order to increase its wave -length and bring DUTCH VALVES.7/6EACH Guaranteed.Cashwithorder.Tradetermson it to that value,Avhere it will correspond or be in tune ape Heat ion .-HARRIS -RUSSELL, LTD., "CRYSTAL!!!" -xith that of the desired station.If the natural wave- 15, GREAT CHAPEL ST., LONDON, W.I. We Guarantee our" SPECIAL " length of the aerial system Is above that of the trans- 'Phone: Regent 1791. CRYSTALtoINCREASE THE mitting station, then the capacity factor must be yoursetatleast attacked and reduced by placing a condenser in VOLUME of Set Ms. The next point to consider is that of potential. Reacta.nce on the Anode wt DOUBLE its PRESENT STRENGTH bring,inthedistantstations A detector is a potential operated device, and there- and double your amplification. You require the BEST CRYSTAL. fore it is as well to tap the detector circuit off across Our principle is approved P.M.G. We have it! Sensitive all o_er. points of as great a difference of potential as possible. and doesn't radiate: -- Therefore, the inclusion in the aerial circuit of a RADIAX Regd.VariableRe- Testimonial. End June, 1923, actanceCoil-forallwave- "HAVE HEARD OF YOUR SPECIAL reasonably sized inductance is advantageous.Fur- lengths, '10/, TunedAnode ther, the introduction of capacity is, as is well known, Coilfor same,topluginto CRYSTAL AT GOODMAYES, disadvantageous, owing to the damping that results. any H.F. Transformer Sockets, 15 MILES AWAY." Therefore, a moderate aerial with a fair amount of 350-500If you metres, haven't 5/6. Price with special silver cat's -whisker. inductance in thesetisnecessary for obtaining H F. add our Unit. 113Post Free. efficient results on the shorter and broadcast wave- H.F.'net , inOak '

lengths.It most be added that height is the impor- Case, 26 /S. , - TO BE OBTAINED ONLY FROM- Variable Condenser tant factor in aerial efficiency. .0003forsame,in RADmx. "Howard" Electric less Co.. * * * . 11, GEENLANES RADIAR LTD., 10, Radio House AMMISIK NEWINGTON GREEN. LONDON. N. P. S. (Berwick).-What are the necessary PercyStreet, Tottenham Court WE SATISFY YOU alterations for adding an L.F. amplifier to a Road, London, W.I. 3111,ett,ri 490 fisteoessweositeokme BUY THE INTERVALVE TRANSFORMER crystal set of the single slider type, with as with a push behind it, guaranteed, £1 4s. Od. BUY "AMAX" CRYSTALS. few alterations as necessary to the existing Drawing -roomVartoinet ers 17 HERTZITE, PERMANITE, TALITE,1 / 6perbox. Headphones rewound to 1,000 ohms each P&G' 5 crystal set ? ELECTRONITE, ZINCITE, 1 / -per. box.GALENA, 2,000 7(6 BOR.NITE, SILICON, COPPER -PYRITES, 6d. per box. No alterations whatever are necessary to the 4,000 . 10 / WONDERFULVALUE. existing crystalset.The couplingof the valve (Postage extra). See that ourAmax" label is on the boa, amplifier circuit is obtained by means of an inter - X. E. Hampshire, 139, Sydenham Rd., S.E.26. containing from 2 to 6 large Crystals. valve low -frequency transformer.This is connected so that the primary leads take the place of the SOLD BY ALL DEALERS. 'phones on the crystal set-thatjs, the primary of THE AMAX CRYSTAL CO., the transformer goes to the telephone terminals of Red Lion House, Red Lion Ct., Fleet St., E.C.4, the set.The 'phone blocking condenser may be left as it is across these terminals.The secondary of the transformer is connected to the grid of the valve and WIRELESS INVENTORS to the negative side of the low-tension accumulator. Patents and Trade Marks, Advice Hand -book The rest of the valve circuit is, as usual, plate to the and Cons. free.-B. T. ICING, Regd. Patent 'phones and thence to the 'high tensionpositive Agent (0.B. ik U.S.A.), 146a,QueenVictoria terminal, the negative of this battery being con- St., E.G.4. 'Phone: Central"682.36yrs. refs. nected to the negative of the low .tension accumu- lator.The positive of this latter then goes to the filament resistance arm, and then from the resistance TO THE TRADE. wire of this to the filament of the valve.It is always TELEPHONES. VARIABLE CONDENSERS. INSULATORS advisable to insert a blocking condenser across the FILAMENT RHEOSTATS. DIALS. TRANSFORMERS, etc' 'phones-about '001 mfd. will be O.K.-and a fairly DELIVERY EX STOCK. SEND FOR LIST AND SAMPLES. large capacity -condenser acrossthehigh tension EBONITE SHEET. PANELS. TUBES. battery of about '02 mfd. to smooth out any irregu- COPPER WIRE, Enamelled, 'Cotton or Silk Covered larities in its discharge. Cables & ElectricalSupplies,Mica House, Of fordSt.,CaledonianRd.,London,N.1. Telephone : Noel/43109. E. L. (Bradford).-I do not quite under- stand how theluned anode circuit is connected. ----Beginners Guide to Wireless----, Is it a satisfactory method of coupling ? , Explains, in plain everyday language, everything The tuned anode method of coupling will be found AshleyWireless yon wish to know about Wireless Telegraphy. to be a very efficient method.The plate of the HOW TO ERECT, CONNECT, AND MAKE first- valve is connected direct to the grid of the the apparatus required, and full instructions second, a small condenser being placed in series while TelephoneCo.Ltd. for making coils, tuners, and complete valve a grid leak is placed between the grid and the earth 69RenshawSt.Liverpool and crystalsets.Instructions and diagrams of the second valve.The tuned anode coil is con- for a two -valve receiver are alone worth four nected between the plate of the first valve and the Sole 0) A.jenis times cost of the book.112 pages, price is., positive side of the II.T. battery.A small variable post tree.-SAXON RADIO CO. {Dept.14), condenser of ISM 2: -or -0003 mfd. is shunted across the South Shore, Blackpool coil for tuning purposes. Popular Wireless Meekly, June 16th,1923. 071

RA RARA

hi hi RA iiE5gPA 2 hi hi WA HULLO EVERYBODY hi RA OrlIN hi hi FA FM hi hi FA VA hi UM ALL GOODS ORDERED BY POST PA RA hi hi FA A VARIABLE CONDENSERSmust be accompanied by the Correct hi hi VA FM hi hi Post Prices marked on each article. P A WA ASSEMBLED AS ILLUSTIttl.TED hi hi FA FA The quality and value given do not h i kA RA FA Drilled Ebonite Ends to fix yourself 1/- per pair extra KY hi permit of them being sent otherwise. FA FA hi hi Approx. Cap. No. of VA FA No rubbishy catch lines here. All hi in Mfd. Plates Price RA FA hi hi real value for money. PLEASE NOTE. hi hi RA PR hi .001 57.6/6 RAMA RA hi h i CA Rubber Lead-in Wire (good), 12 yds., 1/9.By post, 2/6. hi hi Bell Wire,12 yds., lid.By post, 1/- dozen. AA FAFA Twin Flex, 12 yds.. 1/9. hi hi '0005 294/6 By post, 2/-- dozen. PA FA Switch Arms,10d.,1/-, 1/3, 1/6.Post, 6d. each extra. hi FA FA Rotax Accumulators, 4v. 40 amp., 17/-. Carriage, 2/ - hi hi each. hi F 19 Fixed Condensers. Good value. 11d.,1/3. Post,6d. hiA '0003 3/3 A FA each extra. Frh'i PA H.T. Batteries, CO volt, 9/-.Carriage, 2/- each. hi hi H.T. Batteries, 15 volt, 2/6. MA FA Carriage, 11- each. hi hi '0002 13 2/6 Ebonite Valve Holders,led.,1/.,1/3. Post, 6d. each FA hi hi extra. FA BasketCoils, " Oojah," set of 7, 6/..By post, 6/- set. hi hi RA Basket Coils, 2/8 and 3/6set.Post, 6d. extra. hi '0001 7 2/3 Insulated Sleeving, 5d. and 6d. length. RAPA PA hi hi Crystals (Mounted), If ertzite, 1/..By post, 1/6. A PA Crystal Detectors, on ebonite, 1/5.By post, 2/.. hi hi RA Perikon Detectors, enclosed with 2 crystals,2/4. By hi PA Vernier... 3 1 /9 post, 3/3. PA RAPM h i hi Perikon Detectors, suit expensiveset,3/9.By post, 4/6. PA VA Enclosed Detectors, 1/8,2/9,3/6,3/9. Post,1/- each hi hi PA MA NOT THROWN TOGETHER. extra. hi hi Valve Pins, slotted, 7d. doz.By post, 1/-. VhiA Aluminium Vanes, 22 gauge, 5d. doz.By post, 9d. doz. RA WA COMPLETELY ASSEMBLED ASSHOWN TappedCoilson Ebonite, hi hi 10 tappings, broadcasting FA FA size, price 2/6.Post, 1/- each extra. hi hi log -001 8/- S.P.D.T. Switches on Ebonite, 1/9, 2/6 each.Post, 9d. PA FA hi hi D.P.D.T. 2/6,3/6 each.Post, 9d. FA hi '0005 5/11 Accumulators, 6 v.60a.,absolutelythe best,35/-. FA FA Carriage, 2/- extra. RA hi Slider Knob and Plunger, 3d.By post, 7d. each. hi PM '0003 4/11 PA hi Terminals, W.0., Telephone,P.O.and allpatterns, h i WA hi including nuts and washers, not junk, 2 for31,(1. XA WA '0002 3/11 116 doz.By post, 1/- doz. extra. KA hi LAI VA Aerial Wire, 100 ft., 7/22, 2/11.By post, 3/3 hank. WA hi '0001 Intervalve Transformers, very best,25/, Also12/6 hi FR 3/6 WA hi each, 16/, 20/. each.Post, 1/- each extra. A Knobs, hushed 2 B.A. (best), 3d. each.By post, 7d. hi Vernier 3/3 RA PA 3 Way CoilHolders, Ebonite and brassfittings,7/6. RA hi Post, 1/- earn extra. hi FA Dubilier Condensers, at usual prices. RAPA ALL ORDERS BY POST MUST BE Telephone Transformers (R.I.),20/. Post,116. RA UM hi PA ACCOMPANIED by 1/3 persetEXTRA. H.T. Batteries, 50 volt, 4/6; 30 volt, 5/-.Post, 1/. each hi '44 - OTHERWISE NOT EXECUTED - RA hi Telephone Leads, long,1/..Post, fid.extra. hi WA 1/6,1/8,2/-,2/6,3/-Post,9d. hi Filament Resistances, hi P A each extra. AA hi RA Transformers,L.F.(RadioInstruments,Ltd.),25/.. RA Post,1/-. LA RAPA W A " BRUNET " FRENCH PHONES hi RAFA D.C.C. WIRE STOCKED AN ha VA 4,000 ohms (different headbands) (post 1/6 pr.) 22/6 and 25/- 22, 24, 26, 28gauge. WA hi A MA RA k2 B.B.C. Phones, best quality . . (post 1/6 pr.) 17/- and 19/6 WA RAWA hi hi VA T.M.C., 4,000 ohms, stamped B.B.C. (post 1 / 6 pr.) 24/6 pair. TO CALLERS ! WA hi hi RA taken from expensive sets to clear.) (Phones supplied byT.M.C. themselves, I sell everything you want for your hi RAY VA hi k2 WA ERICSSON E.V. (not the imitation phones with WA hi home - madeSets. No junk. No hi wooden earpieces) Double Headphones per pair1 7/6 RA hi cheap job linesAll low in price, hi Post 1/6 pair extra. FA RAFA hi but first-class quality. hi FA PA hi RA ON FRIDAY, SATURDAY AND SUNDAY FA hi hi FA WA KA TRADE SUPPLIED FA SPECIAL CHEAP PRICES TO CALLERS MA hi hi FR FA hi hi RA WA hi LUIIHIMINIIIIHIM111111111111112.1 FA " '1111111111111111111111111111111111E hi = RA AA = - Phone : GERRARD 4637E hi FL-- RightOpposite RA hi hi h i hi M. RAYMOND OPEN 9 to 8 P A hi :DALY'S = Saturdays - 9 to 6 p.m. E VA GalleryDoor-_ Sundays - 11 to 2 p.m. = hi 27, LISLE STREET, W.C.2 EE

-TI111111111111111111111111111111 PL.h11 PA! i FAWAFAVAWAWARAWAWAVAWAVARAVAWAWAWAWAWAVAWAWAWAWAWAVAFAWAFAWAVAFAFAMAWARAWAVAFAVARAWAVARAWAWAWAWAVAKAWAFAVAPAVARAFAWAFAFW,WWVA Popular Wireless Weekly, June 16th., 1923

sponding to directional receiving stations. VALVESREPAIRED The pointers p.re controlled by the search RECENT WIRELESS coil of their respective station and intersect We can renew the fila- to indicate the position of the sender.The ment of any make of INVENTIONS. map may be- squared and numbered, and a

Valve and re -exhaust to shiporaeroplane underdirection and The following abstracts are specially con- any degree of vacuum. tributed by Mr. Harold J. C. Forrester, having a similar map may be advised of

Fellow of the Chartered Institute of Patent its position number. Electric lamps may be PRICE 6/6 each, plus 6d. Agents, 88-90, Chancery Lane, W.C.2. provided beneath the squares to illuminate postageforsingleValves. automatically the square indicated by the

pointers.

THE RADIO A ELECTRICAL Grant of the following Patents can be SUPPLY CO., opposed and printed copies ofthe full 195,987.-BRITISH THOMSON- specifications purchased. HOUSTON CO., LTD.-VALVES.-In 29, Paternoster Row, E.C.4. valve generators which simultaneously pro- 'Plme : CENTRAL7669.

duce oscillations of radio and audible fre- e) ***** 195,856.-C. C. CULVER.-DIRECT- quency the amplitudes of the L.F. and H.F. CONTINENTAL ERICSSON PATTERN ING AIRCRAFT.-To enable an aircraft oscillationsarelimitedrelatively by a 'PHONES (4,000 ohms). 143/9 post free. to locate accurately alocalising station Send P.O. for 16/9, and receive one of the best Head- particular circuit arrangement. phones produced per return. My 'Phones can bein- on the landing field, the effective plane of spected at any time at my showroom. ORDER NOW , AS STOCKS ARE RAPIDLY DIMINISHING. - the loop aerial may be inclined to the axes 195,990.-BRITISH THOMSON- 11.E. ANSON, STATION APPROACH (1-.13.& S.C. of the aircraft. The pilot can thus descend xis Stn.), SVDENHAM, S.E. 26. HOUSTON CO., LTD.-AERIALS.-An in a spiral whilst keeping the station signals earthing system for transmitting aerials at a maximum. comprises a number of wires buried beneath 195,891.-E.Y. ROBINSON.- and extending transversely of the aerial for VALVES.-To produce" hard " charac- a distance of two' or three sixte,entlis of a BROADCASTING teristics in a valve with a soft vacuum, a wave -length,andcollectsaboutthree- Users of Valve Sets and cathode of the type providing a concen- quarters of the capacity current which nor- Amplifiers should trated source of electrons may have anmally falls outside the area beneath the communicate auxiliary heater, and is placed very close aerial. (about 0e5 mm.) to the anode, shields being Twolongitudinalwiresconnectthe with:- provided to confine the current within thetransverse wires, alternate ones of which n w 992, Finsbury Avenue, space between the electrodes. are connected to bus wires, the aerial being Y2 :: LONDON, E.C.2. is of a multiple -tuning type. and they will hear of something to 195,718.-C. LORENZ AKT. GES.- their advantage.Enclose stamp. TRANSMISSION.-Choking coils are arranged in a transmitting circuit, and their effect varied by the operation of the trans- RADIOSETS mittingkey,sothatcontinuous wave EXCELLENT OPPORTUNITY transmission is choked when the key is On Easy Terms of securing atless than manufacturers' cost CRYSTAL All makes of Wireless Receiving Sets and and VALVE SETS, AMPLIFIERS, ACCUMITLATORS, open. etc.Best-known snakes.Whole show -room stock to be accessories supplied on extended pay- cleared.List on application.Write, G. E. W., 10. ments. Choose your Set-We do the rest. Long Acre, London, W.C.2. 195,814. - G.CASTAGNOLI. - IN- Send for Catalogue and full particulars. YOU CAN ASSEMBLE YOUR SET DUCTANCES.-A basket or honey -comb with the certainly of slleeo., if you get a Radial outfit. coil is diametrically pivoted within a helical THE NEW TIMES RADIO CO. You may adopt the unit prin. pie of building up an Ex- tensible.ExperimentalSystem,or coil, preferably by clamping° it between a 66 Hatton Garden, London, E.C1. &fort a combined Set tosuit your localityandtaste.Everythingis pair of strips, one of which carries pivots planned, and our diagrams and book. which are jmirnalled in the former of the lets-tosaynothingofourun- equalled personal 'service to client's- helicalcoil, and also form leads to the RADIAXare invaluable. A splendid 1 -valve set costs 39/6. Ask for our catalogue basket coil. " KNIVETOWN " WE SATISFY you ytaksiDaydA"X".LTD.,10.1tadio stating your ideas. House, KNIVETOWN Wound with Percy St., Tottenham Court Rd., London, W.1.. 195,838. - WESTERN ELECTRIC Silk Covered CO., LTD.--SIGNALLING.-Interference Wire.. 20 7 TO WIRELESSINVENTIONS. EXPERIMENTERS. PATENT YOUR between a ntir of signalling stations They may prove very valuable. Particulars and consulta- tionsfree.BROWNE &CO.,Patent Agents, having a cent.raT'&ntrol station is mini- Wound with Enam- 9,Warwick Court, Holborn, London, W.C.1.Estab- mised both for transmission -and hornodyne elled Wire, lished 1840. Telephone :Chancery 7547. eachlayer reception by compounding a number of Insulated .. 1 /6 frequenciesradiatedfromthecentral A GENUINE OFFER station. This may be accomplished by ?Afrind(iiinnit r.y. 15 , of best quality 4,000 ohms suitable arrangements of harinonic genera- TRANSFORMER FRENCH HEADPHONES. tors, modulators, de -modulators, amplifiers, GUARANTEED. Write quickly, enclosingP.O.for rectifiers, filters, etc. FromallWireless Shops,ordirect ft -,7,,-; 17/6 and secure this bargain. 140, Stray's Inn Roati, E. CRANE, 13, SALISNTD,OVADIN GTON S. CORRt, 195,903.-IGRANIC ELECTRIC CO., L./cra/7w-M L'SULL 2342." LTD.-RESISTANCES.-A rheostatfor panel mounting has a spiral spring resist. THE NEWTONIA WIRELESS FACTORY ance stretched round a drum beneath the FOR ALL WIRELESS PARTS AT FACTORY PRICES X 3/1 5, WHITCOMB ST., W.C.2. panel, a spring finger in contact therewith, ELECTRADIX RADIOS Regent 5469. LONDON. and an operating spindle rotatably mounted in the panel and carrying either the drum or ImmediateDelivery the spring finger. A vernier resistance from our Huge Stocks. FOLLOW THE CROWD consisting of a smaller drum and resistance carried by a second spindle within the first - Everything from a Wave Meter to BOUND EACH DAY FOR mentioned spindle may be provided, each an Earth Clip. resistance having its own spring finger and The best equipped City depot. SPENCER'S STORES, a separate operating knob. COME AND SEE US. , 4-5, MASON'S AVENUE, 9,Colonial Avenue is first opening on BASINGHALL STREET, 195,982.-INTERNATIONALT RADIO- leftinthe Minories,nearAldgate : : LONDON, E.O. 2 : : TELEGRAF & TELEPHON COMPAQ/ft Station, Metropolitan Railway. SPECIAL OFFER. VED WAHNOE & PETERS.-DIREC- FRENCH PHONES-Guaranteed-M, LESLIE -DIXON &Co. Averueeki166 TION FINDERS.-Two or more pointers 9,Colonial Avenue, London, PRICE LIST POST FREE. are pivoted upon a map at positions corre- It; it Jun: 16th, 1923. POPULARWIRELESS WEEKLY. iii

NOT/CETo All Engaged in ENGINEERING EDISWAN

ri4:14r Diction-

PlftwIT (Cutor MI ; ll115111111E0 ary CI /ONARY Of ENGINEERING CIVIL MECHANICAL VALVES E,EETRICALIMOICIR. ETC ETC. FREE. PART I. Noiseless

To extend the name of the Bennett College to ev..cgon, engaged inthe different branches of Engineering, we . arepublishing anIllustratedDictionaryof Engineering, inabout 24 monthly parts.You can Sensitive have each monthly part as it comes out. - FREE -3d. Postage only to pay. The be notary isf r,,10 those engaged in any of the following trades :Engineering, Civil, Mechanical, Eire- I /Robust tries),Structural,Motor, Sanitary,Boiler,Internal s Combustion,Draughtsmanship,Marine,Shipbuilding. : Naval Architecture,Building,Architecture,Quantity I Surveying, Aviation, Chemistry, Foundry Work, Metal- I There is no better Valve lurgy, Matriculation. Mining, Surveying and Levelling, Telegraphy, Telephony, Wireless, and the conditions are for wireless work than the that you send your name and address, your age anti I Ediswan Type A.R. It is occupation, with three penny stamps Ito cover postage), I writing your name and address very clearly.We shall : silent working, sensitive, I then place your name on our Free List and send you 1 and essentially strong. It Fatt 1 atonce.Theotherswillbeforwardedas .I issued.Address your application fully to: I gives high amplification, isverycompact, and (Do not failto give Department D 106, I extremely economical theparticularsre- I L quired and use this The Bennett College,._.I in current consumption. -NH address.) Sheffield. This Valve-made by the makers ofthe world- famous Ediswan Electric Lamps- has been specially designed for operation on low plate voltages and isparticularly recommended for amateur work. 1111AT USERS SAY :-..-1typical example ofthe splendid results constantly being brought to our notice:- " Dear Sirs, Dudley, 1-6-1923. Last Deeember I purchased one of your A.R. type receiving ('elves, and I could not wish for a better Valve. My set is a home Post Free Orders made, single Valve, variometer tuned. My aerial is 18 ft. high and t to ft. long, With this I can receive Glasgow, 250 miles distance,New- castle, Manchester, London, Cardiff, Birmingham 12 miles away. HEADPHONES

Double Receivers, FEDERAL, 4,000 ohms .. .-. 23/6 We have had very considerable experience in the de-

velopment and manufacture of the Thermionic Valve.. The Os ii ERICSSON (continental) B.B.C., 4,000ohms17,6 first experiments in connection with investigation of ,tile BRUNET (French) 22/6 "Edison Effect," on which the working of a valve depends, were carried out at our Ponders End Works by Prof. J. A. PI FELLOWS B.B.C. 21/- si Fleming, who teas the Company';.:cientirricAdviser. ti IS SIDPE (French) IP 19/6

al PP STERLING B.B.C. 32 '- Single Receivers, BRUNET (French), 2,000 ohms10 6 BRUNET (French), 4,000 ohms 12 6 T.S.F. (French), 4,000 ohms .. 10,- PRICE 15s. FELLOWS B.B.C., 2,000 ohms15/6 DESCRIPTIVE LEAFLETS FREE ON REQUEST. Also manufacturers of complete Receiving Sets, Accessories, and H.T. and L.T. Batteries. Ask your usual Thaler, and if unable to supply send us ACCESSORIES a post card with his name and address. Finest Quality L.F. Transformers (5.1 Guar- THE anteed) .. 12,6 Switch Arms (Best quality) .. Filament Resistances (1st Quality) .. 2/6 EDISON SWAN ELECTRIC Rota x Accumulators, 4v. 40 amps. not sent f 16'- 6v. 4o amps.) by post t 25/ - CO., LTD., Ebonite Dial;, o-iSo, bored in centre ... Contractors to II .11. Admiralty, War Office, Royal Air Force Valve Holders, 1st Quality 123 5, Queen Victoria St., E.C.4, and 71, Victoria Street, S.W.1. WORKS: PONDERS END, MIDDLESEX. FOWLER & BRIGDEN Branches in all Principal towns 130,EUSTON ROAD, LONDON, N.W.1. Tel.: - - - Museum 4827 14 sTER...n BRITISH MADE RADIO HEAD TELEPHONES High Grade Instruments, unsurpassed for quality of workmanship, and the ideal Telephone Receivers for broadcast Opera, being specially designed to giveclearreproductionof Radio speech and music.

Mr.Frederick Blarney, as Samson in Will enable you to derive thegreatestpossible "Samson and Delilah." pleasure from "listening-in"to

Reproduced by . exclusive permissionof.theBritish GRAND OPERA NationalOperaCo., Ltd. AT COVENT GARDEN and willintroduce you to one of the highest forms of musicalart.You will then be more than ever anxious to hear the actual performances. No. B 1260. Each receiver is fitted with a double pole permanent magnet, adjusted to give concentrated action on a stalloy diaphragm. The cases are of aluminium with swivel and trunnion movement, which, together with the smooth and well finished ear -caps. 'ensures a perfectly comfortable fit to the ears.Adjustable coslettised steel headbands are supplied, which will not corrode or lose their shape.Each instrument is complete with 6 ft. of flexible cord and pin terminals. Weight 10 ozs.

RESISTANCE PRICE 120 ohms the pair (in series)£19 6

2000 1 PP PP £1 110

4000 PP £1 12 0

8000 11 £20 0

To be obtained of all dealers. STERLING TELEPHONE AND ELECTRIC CO., LTD., Manufacture's vl Telephones and Radio Apparatus, etc. (WHOLESALE ONLY). TELEPHONE HOUSE, 210-212, TOTTENHAM COURT ROAD, LONDON, W,1. Telephone :Museum 4144 (7 lines). Telegrams:" Cucumis, Wesdo, London." BIRMINGHAM: CARDIFF: MANCHESTER: NEWCASTLE -ON -TYNE: WORKS: 15o, Edmund Street. ro, Park Place.14, St. Peter's Square. 9, Clavering Place. Dagenham, Essex.

Printed and published every Friday by the proprietors The Amalgamated Press (1922), Ltd., The Fleetway Rouse, Earringdon Street, Loudon, E.C.4. Advertisement Offices: Messrs. J. H. Lile, Ltd., 4, Ludgate Circus, Loudon, E.C.4.Registered as a newspaper and for transmission by Canadian Magazine Post.Subscription rates: Inland 4k I)(1 Abroad; 17,4 per annuls], 8;8 for six months.Sole agents for South Africa: The Central News Agency, Ltd.Sole agents for Australia and New Zealand: Messrs. Gordon & Clutch, Ltd.; and fur Canada: The Imperial News Cu. (Canada), Ltd. Saturday, June 11th, 19!23. POPULAR WIRELESS WEEKLY, JUNE 23rd.1923. R LI; IST I CR ED AT 'rm.= .P .0. AS A NEWSPAPER. CONSTRUCTION OF A SPHERICAL VARIOMETER. ire ess PRICE 3d.

No. 56.Vol. III. SCIENTIFIC ADVISER : SIR OLIVER LODCE, F.R.S., D.SC. June 23rd, 1923.

FEATURESIN THIS ISSUE. Double Crystal Circuits. An Accumulator H.T. Battery. A Series Parallel Switch. Reaction-Its Uses and Abuses. Page of Practical Ideas. Two Methods of Magnifying Signals. And special articles bythe Bishop of Birmingham and DameMay Whitty. June 23rd, 1923. 11 POPULAR WIRELESS WEEKLY.

>11IESTAVOX II IS WA 121 2 -Valve Reaction Receiver [EDTVALVES

COMPACT ECONOMICAL RELIABLE

I

deposit secures immediate delivery of the above wonderful instrument, whichwillreceive ALL BritishBroadcast Telephony, and is stamped B.B.C., and approved by R.M.G. The balanceispaid intwelve monthly instalments of SENSITIVE 16/7 each on the usual hire purchase system, including SILENT Insurance, Wireless Receivers and Accessories to any value ROBUST are supplied on the same terms. Write at ones for Catalogue and Full Particulars. EDISWAN THE " HESTIA" ENCINEERINC COMPANY9 MEANS THE 32,Palmerston Road, Acton, London, W. 3. I minute South Acton Station.(N.L. or District Rlys.) BEST VALVE-- Showrooms open g Telephone: Chiswick 586. Actual performance has proved beyondall question the superiority of the Ediswan Valve for wireless work. Every day adds to its reputation. TYPE A.R. TYPE R. I 15/- 17/6 HULLO !! C.Q. WILL DAY CALLING 1 Vv'e have had unique experience in the development THE LATEST MARVEL, a pair and manufacture of the Therm ionic Valve. The first of Midget Headphones, weigh experiments in connection with the investigation under 4 ounces, 4,000 ohms. of the " Edison Effect " on which the working of a valve depends were. carried out at our Ponders Call and test these at our showrooms ...... Price 21/- per pair End Works by Prof. J. A. Fleming, who was the A THOROUGHLY RELIABLE Company's Scierktifie :Adviser.. PAIR OF HEADPHONES, USERS SAY: EI typical example. of The splendid results constantly being brought to our stamped B.B.C...... 20/- per pair notice:- I00 feet 7/25 Stranded Copper "Dear Sirs, Dudley, 16.'1923. " Last December I purchased one of your A. R. type Receiv- Aerial Wire...... 110 per coil ing Valves, and I could not wish for a better Valve.My set is an home-made single Valve, Variometer tuned.My'aerial is HAVING PURCHASED THE WHOLE OF A MANU- 38 ft. high and rso ft long, with this I can receive -Glasgow, 25o miles dudance, Newcastle, Manchester, London, Cardiff, Dir. FACTURER'S STOCK OF GUARANTEED 7,22 HARD mingham is miles away." .. DRAWN AERIAL WIRE IN 100 Fr. HANKS, WE ARE Also manufacturers of complet: Reed-I.:1gSets, ABLE TO OFFER THIS AT THE LOW PRICE OF Accessories and H.T. and L.T..991:'-rics.Dealers 2;2 PER HANK OR 2/- FOR 50 HANKS AND UP. should write at once for particulars and terms. Descriptive leaflets free on request. Sheet Ebonite, Grade A, cut to any size. Every requisite in Stock for Wireless. TRADE SUPPLIED. THE These are only a few of our bargains.Do not fail to send for ourPrice List giving the lowest prices for the best EDISON SWAN ELECTRIC quality goods.Postage on all goods extra. CO , Write for our new Catalogue, now ready. Contractorsto H.M.Admiralty, War Office, Royal Air For, 123/5, Queen VictoriaStreet, EC. 4. Do not fail to try the NEW "DAYZITE," Regd. and 71, Victoria Street, S.W.1. The super marvel Crystal with Silver Detector Point at NIORKS1 PONDERS END, MIDDLESEX. 2,6 each, or mounted in Brass cup, 2.10, Postage 3d. extra. Branches in all Principal towns WILL DAY, LTD., 19/ Lisle St.,Leicester Sq., London,W.C.2 .EVERYTRINCji ELIECTRICAUI 'Phone: Regent 4577. Telegrams : Titles, Westrand, London. Popular Wireless Weekly, June 23rd, 1923. 613 POPULAR WIRELESS

lune 23rd, 1923. SCIENTIFIC ADVISER, SIR OLIVER LODGE, F.R.S., D.Sc. [Every Friday. TOPICAL NOTES AND NEWS.

Miss Ellen Terry's Appeal.' should keep quietwhile tests are being made. A Useful Application. MISS ELLEN TERRY is very pleased Wireless societies should organise " reaction hunts," and scotch some of these nuisances. REPORTS of a race meeting were 'phoned with the Special appeal that "P. W." is by wireless over a distance of 100 miles, making in connection with the blind, Birmingham's Popularity. and the results of the various races and has promised to send an autographed were thus made public a very few minutes photo of herself to every contributor who I T' S programmes are becoming very after the race. gives ten shillings or more.I feel sure that 5popular with the average listener -in, our readers will support this appeal to their and the nature stories are in great utmost. News Items. " WIRELESS REVIEW AND SCIENCE WEEKLY "is THE authoritativejournal QUITE a number oflisteners -in object Send to " Ariel." of wireless and popular science. No. 5will to the news items, and some have BY the way, all contributions should be contain many most interesting articles written to me to say that they prefer written by leading authorities, and willbe sent to " Ariel," c/o. "The Servers of onsaleatallbookstalls andnewsagents to hear music rather than news that has been the Blind League," 3, Upper Woburn on Tuesday, 26th inst.,price 3d. published in the papers three hours earlier. Place, W.C. ORDER YOUR COPY NOW! Others, however, take quite an interest in * * the news, and I know some who would rather TheFieweIfing hearthoseitems "Super." than anything else. IHAVE recently You cannot please been trying the everybody. Flewelling " Super " and really wonderful results are The "Brownie' obtainable, Birming- Receiver. hambeingloudly THE J. W. B. audible on an indoor WirelessCOM- aerial two feet long pany have sent at 15 miles north of me along one .of

- London. The circuit titeir " Brownie " iscertainlyworth receiversfor test. trying, but up to the This little set,which present,.t hough retails at 7s. 6d., is amplificationleaves worth every penny nothing to be desired, of that sum.I it has been impossible connecteditto to cut out the high- quitean ordinary pitched whistle with- aerial 12 miles away out decreasing signal from 2 L 0, and the strength.However, reception was I shall Persevere, for excellent-quite as the set is much easier gbod as that obtain- to control than the able with another Armstrong `! Super," and muchmore and seems to be quite expensive receiver. as effective. * * * * * * Less Reaction. Hardly ! THE reaction fiends T WAS invited by are still hard at 1 Mr. Harry Tate work and trying tosee his their utmost to ,ruin Controllingthe traffic at Epsomracecourse bywireless.An aeroplaneequipped withtransmitting apparatus sketch, " Broad- everybody's hovers over the course and gives directions. casting," atthe reception. Not Coliseum.It keeps content with heterodyning the waves from demand among the country folk. thewholehousesimplyrockingwith the broadcasting stations, they are devoting Personally, though living nearer London laughter. Itcertainlydoes,notre- themselvestojammingtheamateurs; than Birmingham, I always have to tune -in quireanexperttounderstand his especially on Sundays. After all, such con- to the latter station when the Poultry Talks sketch, and the information that he gives duct is of the " dog in the mangertype, are on. his audience did not come out ofPOPULAR for misused reaction is of no use to anyone, * * * WIRELESS Or "Wireless Review." least of all to the perpetrator of the squeals. * * * * Broadcasting in India. T. 8. Amateurs Jammed. ACORRESPONDENT tells me that if 1. HEARD 2 V J vigorously protesting to a broadcasting were to start in India DRIVING home in his car after the per- 1confrere that it was no usetesting it would have a tremendous boom. formance,Iwasamused by the owingtothe" howlingcondenser Demonstrations of wireless telephony have numberof the vehicle, which innocently twiddlers."After all,it is from amateur been carried out by the Posts 'and Tele- advertisesf he name ofthis well-known research that a great many usefuldiscoveries graphs Dept., and very successful results comedian-T. 8 (Tate). are made, and neighbouring" reaetionists " have been obtained. (Continued on page 674.) 674 Pobular 'W'reless 114ekly, June3rd, 1J23.

The moment an engine arrived at a Are and " Haven't You Heard ? " NOTES AND NEWS. wanted help, all the men would have to do THE technical staff of P.W. are busily (Continued from page 673.) would be to run out the aerial and ask for engaged with coils and aerials, volt- assistance. meters, and ammeters, and gadgets of * * * all descriptions, while the technical editor Solving the Licence Problem. -" Fete Galante." wears a tired and harassed look.Everyone THOSE who Wish' to. know how to solve seemsengrossedand 'preoccupied,and the P.M.G.'s difficultiesshould see THE synopsis of the new opera,'`Fete Galante," to be broadcast to -night when I inquired the reason, they all said, Harry Tate'sversionof" Broad- " What, haven't you heard ? " casting." He -tells you how to do away with June 22nd-will be found on page 398. By the way, the " July1 I th, in the the Post Office altogether.I am still work- Carrying Out Tests. ing out his idea, and will let you know the paragraph under the heading" Further I SAID that I hadn't, and so the editor results later. .Items," of last week's issue of PM., should deigned to explain." It's the P.W. have read June 11th. Combination Set," he said, " a wonder- H. T.'s Land Yacht. * * ful gadget, specially constructed for p.W., H. T. has fitted awireless set to his land Miss Ellen Terry. and the staff are busy testing it under all yacht,andwilltour the whole will be pleased to hear that Miss sorts of conditions." country, leaving London about three YouEllen Terry, who has now joined the - * * * weeks'timewithhis" Broadcasting"" band of listeners -in, may give us the Looks So Simple ! company. pleasure of hearing her broadcast again "THE constructional details are going to * * * from the London station. I be published shortly in P.W., and we The First Wireless Singer. canguarantee that everyone who MR. EDGAR COOPER, who was tha Wireless Telephony in Denmark. makes it will be more than satisfied.Up to first man to sing " on the wireless " AREADER of P.W. in Denmark tells now it has exceeded all expectations.as to in the days when the Marconi Corn- me that great advance's in wireless its capabilities." So now it's out, and what's pany were experimenting at Chelmsford, telephony have been made -in that more, I intend to tackle the construction of hasrecently diedathisresidencein country.On MayI 1th a regulartele- such a set myself-it looks so simple. Springfield Road, Chelmsford Amateur Trans- missions. A Lonely Station. T ISTENING to the ASMALL island amateurst h e north of Ice- otherevening, after2 L 0bad - land, known as Jan Mayen, is to be closed down, I was let far hunting pur- surprised at the num- poses.Itis unin, ber of loud signals habited except for a obtained from smallwirelessex- stations whose situa- perimentalstation. tions could not be The operator, must traced on any list of have a cheerful time, call signs.It would asthisislandis be ofgreatassist- noted for blue fox ance to the smaller and Polar bears. amateurs-those who experimentonre- * * * ceptionalone-if Wireless for Pollee. their more advanced THE New York brothers would an- police propose nounce their district to have wire. - when they give their less installations call -sign. fittedto motor- * * * cycles, so that mes- Helping the Experi- sagescanbere- menters. ceived by the police- IWAS trying out men when the 1a peculiarly diffi- machines are travel- cultcircuitat ling at a high speed. the time, and was * * * A free broadcast entertainment provided by the Marconi Co. aScarborough. rather anxious to see India and Wireless: what were its capa- - T HAVE received information that broad- phony connection was opened up between bilities.But, though I hunted high and -1casting in India will probably be limited threewirelessstations(0 X E, 0 X A. low among many lists of amateur stations, toa.. single company, composedof 0 X L), so that any person in Denmark I could not find half of these I had heard British and Indian firms. Non -British firms can call up any other person in Bornholm working. will not be allowed to participate. and vice -versa. No listis issued by the Post Office, and so thelistshave tobe compiled * . An Iron Aerial Pole. New Districts. Coverei. from information sent in by the amateurs themselves.In this ease an announcement, AN iron pole used as an aerial mast CERTAIN difficulties were encountered such as "5'C P, Ealing calling," would be assists,in doingawaywiththe at the start, but these will be soon greatly appreciated by experimenters. danger from lightning.Those who overcome.This advancement means * * use other types of masts should connect that telephonic communication will soon be * an earth wire from the top to the bottoni established over districts where the laying Coal Miners Listen In. to act as a conductor. of a cable was impossible. WILL coal -miners in the near future of * * worktotheaccompaniment * * * wirelessmusic ?Anexperiment Wireless for Fire Engines. Wireless Lighthouses. was carried out at the Dykehead Colliery, MAJOR W. B. ZA PPERT,ofthe TN the very near future, I am told, we are Lanarkshire,theotherday,withan Alexandria Fire :Brigade,said- he 1 to expect -that most of the lighthouses Ethophone fdur-valve set.with excellent proposes inhisbrigade -toinstal andlightshipswill-have wireless results. itvirelesa telephony apparatus on each engine. installations. ARIEL, Popular Wireless Weekly,. June 23rd,.1923. 67:5,

THE CONSTRUCTION OF A SPHERICAL VARIOMETER. By GEO. SUTTON, A.M.I.E.E., F.R.A. Without doubt variometer tuning is one of the most efficient methods, and is suitable for both valve and crystal work. A reliable instrument of this nature will prove an extremely useful accessory, and in the following article Mr. Sutton details the construction of the spherical type.

()NE type of variometer is made up of If at first you don't succeed, try again. the walls, as it will have to be stiff enough to V two cylinders, one sliding inside the The ball should spin on the skewer as a support the No. 26 D.C.C. wire which we other.But in this simple case, the pivot-without lumping over to one side- are going to wind on it.With thin knitting - variations of inductance will not be on a if the skewer is straight and goes through pins, quarter out this ball, as we did the very liberal scale.With the rotating form the middle of the ball.In a gas flame, heat other, and insert the eight nails in each of variometer, a difficulty may be experi- theprojecting point of the skewer and cheek-being careful not to make too small encedin making a" wirelessly good " slowly withdraw it into the ball.This a circle with the nails (about two inches connection between the rotating part and operation will make a detestable smell, but will do) else it will not be easy to wind the fixed.But, generally, a flexible wire it will also make a sticky permanent hole the wire on theball.Wind as before. connection can easily be arranged. in the ball, through which the penholder- Twenty-six turns on each side of this ball which is to be the spindle will be about right.Give the two wire - of the variometer-will, wound balls several coats of shellac varnish, later on, be pushed. and they will appear as in Fig. 5. Pull the skewer out and reverse its direction, The Pivots. so as to burn the hole in The writer tried to obtain hollow card- the other side of the ball boardballs, but was unsuccessful. He aswell. But do not thought that they would be firmer and overdo this operation, as possibly cheaper than rubber ones, but the the penholder needs to latter have served his purpose. be a tight fit when finally Shape out two pieces of soft wood about pushed home. one inch thick, square on three sides, and Now, putting a thin carved out on the fourth side, so as to fit

splinter of wood as a the large hollow ball. , That is, so that when guide where the pen- holder will ultimately be, drive another thin metal 111111111111111111 I skewer orknitting - needle through the ball, soastocrossthe Though there may not be much in it, the direction of the first at right angles.And writer favours the rotor being connected test the accuracy of your work by spinning between the two halves of the stator ; the ball on the skewer as a pivot, as before. where the windings of the latter are, per- It will save trouble if this skewer also is on force, divided to allow of the spindle to go the seam of the ball. through to support therotor.With a spherical rotor and a spherical stator, the Details of Windings. IMU111=111101111I maximum capacity of the windings occurs Now take some one -inch wire nails, and when the direction of the windings imposes push eight of them half -way into each.side the maximum inductance, and so extends of the ball-at an equal distance from the the ball is cut in two, each half may_ be the range of wave -length tuning. second skewer-so that they form a ring not secured to the wood by a small screw and Having got so far, some of my readers less than one and five -eights inches in dia- washer through theplain" cheek "or may ask why go to all this trouble, when meter round the skewer as a centre (Fig. 1). blank space in the centre of each stator we can get quite good results with a sliding Do this on each side, as the photograph winding. tuner and a little variable condenser ?The shows. Thread a stout ,needle with the end A strip of brass is screwed down across answer is that, properly constructed, the of,s length of No. 26 S.W.G. double -cotton'the top of the blocks, connecting them to- variometer gives better results than the covered wire, and push it across the cheek gether, with a hole in the centre of the sliding tuner ;and is so smoothly variable, of the ball.That is, so that it goes in at brass strip through which the penholder that no condenser is needed within the range the cheek and comes out inside the ring made can be pushed and form the top pivot hole of the instrument.A condenser may be by the eight nails. for the rotor.The bottom pivot drops into added in parallel if it is desired to extend Leave about sixinchesofthiswire a hole in the wooden base of the instrument. the wave -length range. threaded through the ball, for the end of (Continued on page 676.) the winding.And then Tight Fit Required. start winding the rotor Now the question ofcostarises. A wire round the nails, till moulded variometerrotorball,atthe you have got about thirty present time, costs 3s.6d., and the two turns on. Then pass the halves of the stator rather more. The rotor finishing end of the wire part of a cheap and efficient variometer can temporarily through the be fairly easily constructed. Most of us pivot hole for safety, while who have played with children know the the wire is being shellacked kind .ofball whichismanufactured of firmly down into its place spongy rubber and is therefore unburstable. (Fig.2). This winding It is possible to get one of about two and must be begun at each three-quarter inches in diameter for six- side near the nails, so as pence. Take a metal meat skewer and, to wind " uphill," the only starting at a point on the mark which goes possible way. round the ball showing where the two halves Now procure a hollow of -the mould met when the ball was made, rubber ball about two and carefully push the skewer right through the three-quarterinchesin middle of the ball. diameter, not too thin in 676 Popular Wireless Weekly, June 23rd, 1923. having hooks, where they fasten on to the eyes cn the boat, (see Fig. 2), and go can be WIRELESSIN SUMMER TIME. unhooked and the poles taken out of socket, e and laid down flat when not in use.The A few suggestions regarding the possibilities of fitting wireless up on small boats and cars. aerial itself would ,also be detachable from " the poles.The type of aerial used would, of course, be judged by the capabilities of the 'set. TO the keen listener -inthe summeractual musicbeing played many miles shOuld offer even greater pleasure away. How many people stop to think than did the winter monthS."For-"and realise when lisitening:in that there is what could be more delightful than to sit in noactualmaterialconnection between one's own garden' on a summer evening, transmitter and receiver. listening to an extract, say, from Grand Opera. A lead in this case would be taken from the 'phone terminals of -the set to a On the River. headphone distributor block in the garden, Picture a glorious summer evening on the so that several pairs of 'phones could- be upper reaches of the Thames, with the sun used; and in the case of a loud speaker, just reaching the end of his journey across electric lighting flex forms an excellent lead the sky, and gradually sinking down, down direct. below the horizon, tinting sky and river with all the gorgeous,. ever-changing colours of Nature, and, as one by one the birds cease their singing and all is peaceful and still, Fig. 2. out of the silence comes the sound of " The Moonlight Sonata " on a grand piano, not To the motorist, music by wireless can from one loud speaker, but from many on always be within his reach wherever he is, different parts of the river, to the accom- and one must admit that a wireless picnic is panying light of a steadily rising harvestsomething of a novelty-to be miles out in moon, and the lap, lap of the stream as the the country wiffi not a soul or habitation craft glides slowly along. for miles around, and to hear the well- known voiceof,say, 2 L 0 announcing, For the Motorist " The next item on our programme-" An aerial is easily fitted in either punt or An aerial is easily connected, say, be- skiff : a six to ten foot pole fastened at stern tween the side of the windscreen of the car Fig. 1. and bow, with a five-foot spreader either and the branch of a local tree, the wire end, but in the place of the two usual wires, being carried coiled on a reel in the car, the To the river enthusiast wireless is a boon, four would be used, as per Fig. 1. earth connection being formed by pushing for when once installed in either punt or The earth is formed by a wire fastened a copper plate of suitable size into the skiff it has the advantage of the gramophone down the side of the boat to a plate below ground, a lead soldered to the exposed end in- this respect-that there is no moving the water -line.The poles would be held and taken to the instrument. According to about to change the record, and that it is in position as shown, in.. the sketch, and the range and power 'of the set, so 'phones far more entertaining, as one is hearing the would be detachable, the straining wires or loud speaker would be used.

is nearest to you, round the . stator in a given, the .variometerwilltuneinits direction similar to that of the hands of a longest wave -lengths.And upon the ball THE CONSTRUCTION clock.Turn the rotor so that the windings being turned on its pivots through half a OF A SPHERICAL on it take the same direction.And, finally, circle,thevariometerwilltune inits VARIOMETER. the winding on the other, half. of the stator shortest wave -length. No condenseris should run round, still in the same direction, necessary within the range of the instrument, (Continued from. page 675). finishing off at the centrewith a wire but that range may be spread over a lower which goes to the other _terminal on the series by means of a variable Or fixed con-

base (Fig. 3). - denser in series, or lengthened out by a The two outside ends of the wire wound on condenser in parallel. the rotor ballare threaded insideand No Condenser Necessary Fixed condensersare,ofcourse,the brought up through the spindle hole along- 'If you -are left-handed, there is no objection cheaper-the --variations for tuning being side the penholder and with a piece of thin, to the wire going in the other direction,but left to the variometer.When this vnri- flexible wire connected to the outside ends all the windings must follow the same way ometer was completed (Fig. 4),it was put of the wire of the stator.The wires then round, otherwise the instrument -will not into the receiving circuit, and the rotor. just brought from the inside of the stator coils - be efficient.Variations of construction may happened to be in a position-with regard will be made offonto the to the stator-to tune inthe terminals of the instrument. LondonBroadcastingStation, The connections will then be which came in with very good asinthediagramFig.3. volume and clarity. That is, the left-hand terminal will be connected to the extreme ATHIN layer of bicarbonate inside wire of the left half of of soda placed on the bot- the stator winding ; and the last tom of the Wooden accu- turnof -thissideconnected mulator carrying box will neu- by a flexible wire to the wire tralise any acid that spills, thus coming out of the top of the saving the bottom of the case rotor alongside the 'penholder. from rot caused in this way. The wires of the largest and * * most equatorial turns on the For those who charge their rotor are joined together, and the accumulators at home the Sim- ends tucked into the material of plex Electric Company's the bail, out of the way.To check the occur to the ingenious, but if the foregoing " Andy "Fuse Wire Wallets, containing wiring :Place the assembled instrument so instructionsarefaithfully carriedout -a supply of. 5 and 10 amp. tinned- copper : that one end is towards -you. And, assuming success is assured. fuse wire, should be. useful. A.card of .infor- tliat the wire goes from the terminal which With the windings following the order mation and fuse wire tables is also enclosed.. 911 .WAVk Popular Wireless Weekly, June 23rd, 1923. 677 MISS ELLEN TERRY AT 2 L O. NOTE.-A special appeal is being made by "Popular Wireless " in order to obtain assistance for the " Servers of the Blind League."Miss Ellen Terry has promised to send a photograph of herself, autographed in her own handwriting, to every kindly contributor sending remittances of 10s. or over to that deserving charity.Letters should be addressed to " Ariel," "Servers of the Blind League," 3, Upper Woburn Place, W.C.1.

AFEW weeks ago, on behalf of POPULAR an undertone rehearsed the passage she was her own eyes were blurred with the tears WIRELESS,I had thehonour of soon to recite.She seemed quite uncon- that genuine feeling can alone provoke. demonstrating to that great doyen scious of her surroundings or of the presence Quickly she took the handkerchief that her of the English stage, Miss Ellen Terry, the of other people, for she was living a, part, daughter gave her, and hastily brushed wonders of wireless telephony.For this throwing out her left arm while she held the the tears aside.Fearful lest her mother occasion I used a six -valve Marconi portable volume in her right hand, slightly raising might waver, Miss Craig whispered the set and had no aerials to worry about.All I her voice, then restraining it to a whisper. cue. had to do was to open my magic box, attach telephones, and tune in.Miss Terry was Miss Terry in Tears. An Exhausting Ordeal. enraptured at the result, and considerably Intense though the suspense must have At length, and all too soon, Miss Terry's mystified at being able to hear singing and been, happily it was not long before Mr. memorable recital came to an end.It music from Marconi House emanating from Burrows appeared, and, with his customary had been a remarkable performance, and thisinnocent -lookingbox,without, any courtesy, escorted Miss Terry and Miss Craig those of us who were present knew that this visible connection from the outside world. into the blue -curtained room of 2 L 0. truly great artiste was sparing no pains to Miss Terry's first impressions were duly Miss Terry's friend and I followed.Mr. give of her very best to make it a real published in this journal, and also that she J. C. W. Reith, the general manager, was success. The nervous strain imposed had expressed the hope that she would be able present also to greet Miss Terry. taxed even her wonderfulvitality,for, to broadcast. When all was in readiness the studio was directly it was over, Miss Terry rose with a quickly emptied by special request, only murmur of relief, and sank exhausted into A Marvellous "First Night." Miss Terry, Miss Craig, Mr. Burrows, and a chair. In a few minutes, however, she That wish, as many of you now know, myself remaining. had recovered, and listened attentively to was fulfilled, when, last week, our beloved Miss Terry then sat on the arm of an herdaughter,whoreadthetouching Ellen recited to many thousands of listeners - armchair drawn up to the little polished appeal for the Ellen Terry Home for the in one of the most moving passages of table, on which a reading -lamp had been Blind, in the name of her famous mother, Shakespeare-the scene between Hubert placed. who is its patron. andPrinceArthur. When MissCraig Never have I been so hadfinished, Miss thrilled with the noble Terry spokeafew lines of our illustrious more affectionate poet as when I listened words of farewell to, to Miss Terry's impas- her many admirers. sionedreading that I cannot conclude night. thisarticlewithout From the moment I . saying a few words met Miss Terry as she ofappreciationfor stepped from her car Miss Terry's splendid on that eventful even- exampleincoming ing, she was full of forward outofher excitement and high well - earned retire- spirits. Shecould mentforno other talk of nothing else purpose than to serve but her debut before herfellow -creatures. an audience that Broadcasting is a would have filled boontothousands manyhundredsof offolk,andthere theatres. It was a How wireless can lighten the lives of the blind.Patients and nurses of the Royal London Ophthalmic canbeno greater " firstnight "that Hospital listening -in. proof of Miss Terry's was too stupendous thoughtforothers to visualise.Could one imagine an edifice The other lightsinthe studio were than by the unselfish entertainmentshe a hundred times the size of the Albert lowered, leaving the reading lamp on the gave to listeners -in the other .,night. If Hall, crowded to its utmost capacity, each table to bathe the central figure in that united applause had been possible, London, person present being able to hear every silent room in a flood of yellow light. How I am sure, would have echoed with the syllable and every modulation of her voice, impressive she appearedin her stately sound of cheering for miles around. one can then grasp some idea of the feelings bonnet and long cape !She looked around of an artiste sensitive to the presence of so her with a smile, all ready to begin, while Practical Demonstration of Gratitude. mighty an audience for the, first time, as her daughter stood just behind her mother, This, unfortunately, was not possible, but I am quite sure Miss Terry must have waiting to help hershould anything go amiss. her great audience can show their gratitude been. In a few moments the voice that had in another and more effective way, and that A performance was taking place when wrought a spell onplaygoers a while is by responding generously to Miss Terry's Miss Terry, accompanied by her daughter, ago, a voice that had been heard in com- appeal for donations to her blind institution. Miss Edith Craig, a friend, and myself, pany with such famous players as the late Contributions should be addressed to entered the lounge adjoining the studio of Sir Henry Irving, broke the silence.It rose " Ariel," c/o " Servers of the Blind League,". 2 L Q.Quite a host of distinguished and fell,it quivered and pleaded for the 3, Upper Woburn Place, W.C. 1. persons had foregathered to meet the great eyes that had done no harm. And presently, I hope that money will come rolling in actress, but the silence politely enjoined in when she came to the most poignant lines : for this charitable institution.Miss Terry the precincts of the studio forbade any will then know that her performance was demonstrations other than whispered salu- " Have you no heart ?... Will you put well appreciated, and will be encouraged tations. out mine eyes ? accordingly to broadcast again. During the ordeal of waiting, Miss Terry These eyes that never did nor never shall produced a volume of King John, and in so much as frown on you ? " "ARIEL." ; pul a i i re e.s. s -W eekly, June 230, 1923.

and the _needle. then olsed al?pve it. _The. needle is next lowered until it just touches

the crystal. " CRYSTAL PRESSURE. The needle is now raised a definite small Describing the method of carrying out, and the results obtained distance -3 mm. or in. is convenient- ' from a series of interesting experiments. registered by a mark on theupright. Weights arg now placed on disc P, and the needle thus depressed. THE results and outline of the following The detector is connected to there- experiments conducted by the writer ceiving set in the usual manner, and the A Few Readings. 'may possibly be of use to readers needle lowered on to the crystal, which is The vveiglits'are adjusted until the most interested in crystal reception. movable in the cup, until signals are heard. position is obtained.The weight is noted, and When the weight required to The pressure of the contact req.-fired by A sensitive spot on the crystal is selected, depress the spring the 3 mm. or other fixed crystals used in wireless reception varies dillance (found by experiment)issub- enormously, and is, of course, very intimately trakted from this, ,the result is the force - connected with their stability in use. with which the contact must press on the The whole of the apparatus can be crystal for befit rectification. easily constructed at home, with the one At present only the following crystals exception of the micrometer movement. havebeenthoroughlytestedbythis This, however, is not absolutely necessary, method : and readers may find means of modifying Zincite-13ornite, 18-25 grm.This weight the apparatus in this-respebt. is fairly- critical for best results. A is an old microscope rack and pinion Galena, 1.2-2-5 grm:Critical. movement.Into the movable arm a brass Silicon, 2.6-6 grm.Not so critical as tube, B, is screwed, right through which above. paises a large knitting needle; C; Hertzite, 3-4.5 grm.Critical. Rectarite, 3-8 grm. Not so critical as

Hertzite. The Balance. Carborundum gave very peculiar results. The tube contains a fine spring, D, made A very sensitive position was often found by. winding No. 32 S.W.G. German -silver with a pressure of about 20-25 grm.As wire round a pencil.The knitting needle the- pressure was increased the sensitivity is soldered to the top end of the spring at usually fell off at -first and then quickly S., To the top end of the needle a disc of increased, never, however, quite reaching its cardboard, P,isattached in any con- former value.It was still quite sensitive venient manner. with a pressure of nearly 1,000 grm. To the lower end a gramophone needle, Having consideredthe aboveresults, N, is fixed by a terminal connector, T. ,.-80/11/7E the conclusion the writer came to was that This can be replaced by a cat's -whisker or for the reception of fairly strong signals the crystal cup ifdesired for perikon com- perikon conbinations could not be beaten, binations,Themethodofusingthe hut that reetarite was slightly more suit- apparatus is as follows .: 12 able for weak signals.

Creed automatic transmitting key is the last the necessary switching operations on the link in the chain of automatic apparatus. heavy currents in the transmitting aerial or THE 300 -KILOWATT. As previously described, the message toin circuits associated with it. CREED. AUTOMATIC be dispatched is prepared by a Morse key- There is practically no limit to the power board perforator, the perforated tape being for which this design of key can be con- TRANSMITTING KEY. passed on through an automatic Wheat-structed, since it is only a question of a stone transmitter. The transmitter controlsrelay of sufficient power, and of a suffi- IN a previous article the latestCreed a small direct current that serves to operatecient number of pneumatic motors and telegraphic apparatus wasdiscussed, the transmitting key itself which performs contacts. so it now remains to describe the Auto- matic Transmitting Key for high power transmission. In order that the Creed receiver may function properly, thesignals mustbe transmitted automatically, the reason being that the receiver is only adapted for the reception of signalsthe speed of which' does not vary more than a small- per- centage in either direction. Moreover, the length of the signals should' nOt vary more than 25 per cent, or one -quarter of a dash length, in either direction.. With no greater error than this the receiver actually corrects inaccuracies. The Last Link.

Again, one of the features of the receiver isits high speed of reception,gip that, to The 300 -kw. obtain full advantage of it, it is necessary Creed Key. for transmission also to be carried on at a mirth greater speed than could be attained by manual methods. That, of course, is all to the good, and of great ,benefit in com- mercial telegraphic correspondence, and the Popular Wireless Weekly, June23rd, 1923. 679

Mr. Leslie Henson and Miss Dorothy Dickson, Principals in " The Cabaret Girl," at the Winter Garden Theatre, find time between acts to indulge in the pleasures of " Listening -in" on a Two - Valve GECoPHONE Set. The Pleasures of Broadcasting remotely situated you may be, with a GECoPHONE you are HOWEVERin touch with the British Broadcasting Stations, and can enjoy to the fulleveningsof keen pleasure andprofitableinterest. An Aberdeen user writes : " The efficiency of the GECoPHONE Set is remarkable, and the fine finish and workman- ship of the whole apparatus is specially noticeable.The G.E.C. are to be congratulated cm their production, both on account of workmanship and moderate price." The triumph of the GECoPHONE is solely attributable to the painstaking research and vast manufacturing experience of its makers-The General Electric Co., Ltd.-pioneers in the fields of Wire'ess and Telephony. GECoPHONE CRYSTAL GECoPHONE CRYSTAL GECoPHONE 2 -VALVE SET No. 1 SET No. 2 SET Complete withone setdouble head- Complete with oneset double head- A mahogany cabinet set, complete with phones and aerial equipment. Approx. phones and aerial equipment. Approx. valves, all batteries and one set double range 25 miles. range 30 miles. headphones. Approx. range 100 miles. Price complete- £510 0 Price complete - E9 150 Price complete-£25 00 GEC0PHONE,i " LISTENING -IN" SETS Sold by principal Electricians, Stores, Wireless and Musical Dealers, Sole Selling Agents for the Music Traders in Great Britain and Ireland : Columbia Graphophone Co., Ltd., 102-108, Clerkenwell Road, E.C. (Manufacturers and Wholesale only) THE GENERAL ELECTRIC Co., Ltd., Head Office: Magnet House, Kingsway, London. S 'opular Wireless Weekly, June 2.3ri, 1923.

Look for IV' these marks when buying Bring the Stars Ericsson of Opera to your Home Telephones. hear them thro' Ericsson 'Phones- BUTevery voice -modulation, every intake of breath, every liq'uid note of the tenor Selling Agents: or soprano, unspoilt by distortion-too Scotland : 57,RobertsonSt., common a 'phone -fault. Glasgow. Newcastle -on -Tyne : Milburn Ilse. Prices 31 /- 2,000 ohms, 32/- 4,000 ohms. Manchester;so5/so7,Corpora- tion Street. Write to -night. for Free List. Nottingham : W. J. Furse & Co., The BRITISH L.M. ERICSSON MFG. Co., Traffic Street. International Buildings, Birmingham :14115, Snow Hill. 67/73, Kingsway, London.W.C.2.

THE REMARKABLE CRYSTAL RECEPTION TELEPHONY from 380 miles was the record achieved on one of our standard Crystal Sets, and proves the efficiency -J B of their construction. For Flat dwellers living within 8 PRECISION VARIABLE- to so miles of a Broadcasting Station they are ideal, as they will operate from an indoor aerial.We are the actual manu- CONDENSERS facturers; and undertake the repair and reconstruction of get the BEST RESULTS from amateurs' sets at moderate charges. your set. To purchasers of our sets we are always willing to give help The ACME of and advise at any future time. PERFECTION VELOPHONE CRYSTAL SET, illustrated on left, stamped E3 SCIENTIFICALLY DESIGNED, - 7 - 6 and no PANEL can be UP TO VELOPHONE L.F. AMPLIFIERS, illustrated in centre, E3- 0 - 0 DATE without them. VELOPHONE CRYSTAL SET, stamped B.B.C. E2 -19 - 6 Completely assembled with 'PHONES AND SPECIAL AERIAL EQUIPMENT KNOB and DIAL. All in Polished Mahogany Boxes. El - 7 - 6 ONE HOLE only for FIXING Precision Variable Condensers, 0005 .. '7- 0 tk, PANEL.Large METAL to 6 - 6 METAL BEARINGS. 95,GREAT PORTLAND STREET. By their use BIG IMPROVE- H. G. DALY,LONDON. W.1.(Entrance Langham St.) MENTS canhemadeat Telephone: MAYFAIR 3340. Carriage paid on all orders SMALL COST. Can be inspected and purchased INE == Va...... MEI VS in LIVERPOOL at !.001 8/6 ; Messrs. LEWIS'S LTD. 00075.. 8/- g IIiretess Department. '0005 .. 7/-; RANELAGH STREET. '0003 .. 5/9 5/ - \,0"E.R2 Packing and Postage eox.tria: FERNIER00 : One only, 9d. . 4 /- ; Obtainable through your dealer ordirectfrom :- JACKSON BROS. Condenser Specialists, (First Floor), 8, POLAND STREET, OXFORD STREET, LONDON, W. 1. TRADE ENQUIRIES INVITED. 'Phone: Gerrard 6187, P6puun- Wzrele.s. ec'zly, June 181

DOUBLE CRYSTALCIRCUITS. By SEXTON O'CONNOR. Requiring no local current and en account of its low initial cost, cost of upkeep andease of manipulation, the crystal detector receiver is to be preferred to a valve set in cases where its sensitivity is capable of covering therange of reception required. Could this sensitivity be considerably increased, the crystal set wouldno doubt very extensively replace existing valve sets, and in the following article valuable suggestions for research in this direction are given.

THE chief disadvantage of the crystal wound in" spiral "layers upon a 4 -in. so to speak, spills over from the top of the as compared with a valve lies- in the disc, and then joined in series to a second variometer,finally escaping through the fact that it will not amplify received similar disc, likewise wound with sixteen relief path afforded by the parallel circuit signals, and so cannot be used to operate turns of the same wire.This will be found containing the crystal and 'phones. a loud speaker.On the other hand, the tobringin2 L 0 perfectly.The two For this reason the crystal is said to be a difference in cost is so much in favour of discs should be placed one on top of the " voltage operated " device.It is not a the crystal that the beginner isusually other,and separated by a distanceof, " current operated " detector like the older quite content to put up with the limitation roughly, I in.The crystal and 'phones electrolytic devices formerly used in wire- of a single pair of headphones, and to pass arc wired across the discs from aerial to less telegraphy.It will now, perhaps, be them in turn around those of the family earth as shown. clear why it is only a half-truth to say that circle who are anxious to share the thrill of The currents picked up by the receiving the currents picked -up by the aerial pass ." listening -in." aerialflowstraightthrough theaerial through the crystal. wire to earth.Many people think that It must 'also be remembered that the they flow through thecrystal.In one aerialcurrentsareoscillatory-thatis, sense this may be accepted, but, strictly they swing to and fro in opposite directions speaking, it is not true. both up and down the aerial.Precisely the same effects will therefore occur at the Operation of Detector. bottom end as at the top of the variometer. As will be seen from the figure, the crystal and telephones do not lie in the straight path of the aeriaLThey form a SWITCH branch circuit across the variometer.The resistance of the crystal may be anything from 10,000 to 20,000 ohms, and that of the telephones from 4,000 to 8,000 ohms, so that together they make a total high - 1111111111 resistance path varying from - 14,000 to TYP/CAL 5/N GL E. 28,000 ohms. On theother hand, the C/RCUTZ resistance of the wire forming the vario- meter amounts to less than an ohm.It F/G / follows that the aerial currents taking the PARALLEL CRYSTALS CPI / /49/R Of obvious " line of least resistance " should PhywES . THE 2,00 CRYSTAL /5 With a good aerial and earth circuit it is shootstraightthroughthevariometer KEPT /N READINESS SHOULD hr AA. quite possible to use two pairs of 'phones direct to earth, leaving the branch circuit inseries with asinglecrystalwithout containing the crystal_ and 'phones severely seriously lessening the audibilityofthe In other words, the " return half " of each alone.- - wave received by the aerial finds its upward signals,particularlyifoneisworking It happens,_ however, that theaerial within ten to fifteen miles of the broad- passage clogged or impeded at the lower currents areofvery high frequency- or earth end of the coils wound upon the casting station.Any attempt to add a roughly; 800,000 a. second. in the case of third pair is, however, generally accompanied cardboard discs.Accordingly, just as there broadcast signala.' Also, the wire of the is a " back voltage " tending to" spill by such a distinct " fading awaythat the variometer has been designedly coiled into pleasure oflistening degenerates into a over" through the crystal circuit at the top many turns so that it is endowed with the end of the variometer, so there is a second strain. peculiar electrical quality called inductance, By making use of a second crystal in voltage " bulge " at the bottom which also, which eaunes it to, offer a high impedance triestofindrelief through the branch the manner about to be describeditis to high -frequency currents. possible, however, to double the number of channel via the crystal and telephones. 'phones that the set will normally carry without appreciably affecting the strength "Paralleled " Crystals. 1 reception. It is here that the peculiar property of The only extra cost is a matter of three the crystal comes into play.It can pass shillings or so for a second crystal and holder, current in one direction only, and not, in plus the price of the additional 'phones the other.Strictly speaking, it would be that the set will then carry. better to say that it passes far more current in one direction than it does in the other. Construction of a Variometer. The result,however,ispracticallythe As a preliminary it may, perhaps, be same whichever way it is put.An excess helpful to set out the simple principles of current will pass through in the more which underlie the action of the crystal favoured direction, and it wins through in receiver, and to indicate one or two methods the form of tiny pulses all aimed in the same in which the theory may be tested in prac- way.Thesecombinetogetherandso tice by the aid of a second crystal. PARALLEL CRYSTALS succeed in vibrating the telephone diaphragm Figure 1 represents the simplest receiving 2 PA/R5 OF PA/ONES at a rate which depends upon the, signal set it is possible to make.Apart from the pitch imparted to the transmitter at the crystaland'phones,itconsistssolely F/G 2. broadcasting station. The backward thrusts of the aerial and a " variometer " made by due to the return halves " of the aerial. winding flat coils of wire in and out of The result is that although the currents current are, in effect, wiped out. radial slots cut in a cardboard disc.Such _" get through " the variometer to earth Having explained the simple theory of a variometer can be made from start to they have a struggle to do so.The in- crystal reception, we will return to. a con- finish in a quarter of an hour.For those ductance " impedes " - them, and tries to sideration of the possibilities of " double who have a standard 100 -ft. aerial, twenty- thrust- them back.This back thrust or crystal" circuits. eight turns of No. 26 D.C.C. wire should be " back voltage " effect accumulates, and, (Continued on page 882.) 1;82 PcpOrry, alrd, 1923.

suddenly goes crazy and refuses to yield a To utilise the arrangement shown in Fig. sensitive spot promptly on demand. This 6 itisnecessary to bare the telephone DOUBLE CRYSTAL has been known to happen.But it can be flex at the junction point M, where the avoided by, the simple expedient of keeping separate leads branch off to the two ear- CIRCUITS. a second crystal ready to " take charge." pieces, and to connect the " series " wire (Continual from page 681.) The most advantageous method of using (joining one earpiece to the other) across to two crystals is, however, to be seen in the the earth end E of the variometer.The circuits illustrated in Figs.4,5, and 6. In the first place, it is clearly possible Fig. 4 is the simplest diagram.It will be to place a second similar branch circuit, seen that here the crystals are placed in containing a crystal and a pair of 'phones, " reversed " directions in the two parallel across the variometer in parallel with the branch circuits.The crystal A, as before, first, as shown in Fig. 2. will give a relief path to the voltage accumu- Here the voltage " bulge " at the top of lated at the top end of the variometer, and thevariometerisgivenanadditional corresponding signals will be heard in the reliefpath.If each crystalis adjusted pair of 'phones marked 1.The crystal Si, to maximum sensitivity the " back volt- on the other hand, will not pass current age " will distribute itself equally without in the direction " crystal to cat'swhisker," favour over both relief channels, and will and therefore, so far as the voltage pressure consequently operate both 'phones.As at the top of the variometer is concerned, in Fig.1, the return halves " of each the right-hand branch circuit does not DOUBLE STRENGTH ON aerial oscillation are again " washed out," exist.Accordingly,thefull amount of / PAIR or PtiONES because owing to the peculiar rectifying available energy passes through the crystal FIG.6. action of the crystal combination they are A, and is not " split " between the two unable to pass from the crystal to the parallel circuits as was the case in Fig. 2. voltage at the top end of the variometer cat's -whisker, although they can readily will, then drive current -through the crystal Double Rectification. A, around the lower earpiece of the tele- do so in. the reverse direction-i.e., from iihOne, and so through the point M to the cat's -whisker to crystal. It will be remembered that a second earth end E, whilst the " return " voltage At the same time such a circuit would voltage " bulge " or pressure is also formed at the point E passes via the point M, the in most eases not result in any appreciable at the bottom end of the variometer coil, upper earpieceof the 'phones, and the increase in signal strength.If, however, which, in the arrangement of Fig.2,is reversed 'crystal B, across to the upper there is 'an ample supply of " juice " in simply " wiped out 'or lost.In Fig. 4 end of variometer. theaerial, thearrangementwillprove this " lost energy " is now utilised because ' The signal strength then heard in the superiortothe useof two telephones it can pass through the crystal B from 'phones' will ,be that' drie to the combined placed in series with a single crystal.By effect of both currents--i.e., the double opening out a second relief path, the total effectofrectifying both halvesof the resistance of the branch circuits is halved, aerial oscillations: ..

and each- crystalcan therefore operate with a somewhat greater efficiency.In Testing Effective Opposition. short, a greater percentage of the total In conclusionit must be added that available energy can be utilised , inthis satisfactory results with double rectification circuits can only be obtained by the exercise of a little care and patience.Unless both Switching Over. crystals are of equal sensitivity and care- An alternative method of arranging two fully .adjusted, some of the current that DOUBLE RECTIFICATION crystals in this fashion is shown in Fig. 3. ACTUAL "TRYOUT` FOR shouldpass entirely through the crystal Here both crystals feed the same pair -of 2 PAIRS OFPHONES A, Fig. 4, will succeed in getting through 'phones.'Apart altogether from any in- the crystal B,thereby,lessening the full crease in signal strength, itis sometimes cat's -whisker to crystal, and so actuate the signal strength obtainable in A.Similarly useful to have a second "adjusted " crystal 'phones marked 2.There is, however, no the crystal A may by-pass some of the handy in case the first goes " dud."If passage through the crystal A, because the " return " voltage that should pass entirely fitted for this purpose one of the crystals path in that circuit is not open in the through B.A littlecare will, however, should be provided with a small switch, direction " crystal to. cat's -whisker." succeed in reducing this " leakage " effect, which may be left open so long as the first The complete circuit, therefore, utilises which can inpractice be measured by crystalisactingefficiently.Shouldit the whole of the available aerial energy in tapping the telephoneleadsacross the suddenly go " off colour " after a more or the 'phones instead of loiing or wasting terminals, a, d, in Fig.5. When very less prolonged spell of duty, it is a simple half of it,as is the case in the ordinary little or no sound can be heard with the matter to switch in the second crystal rectifying action of a single crystal.In 'phones across the points. a, d, it is obviOns (which has previously been adjusted to other words, we are obtaining " double that the crystals A:and B are effectively in rectification." opposition, and therefore the best results Fig. 5 shows a more convenient lay -out will be obtained from both 'phones when for the set, both pairs of 'phones being arranged for double rectificationin the arranged on the same side of the panel manner previously described. board.Otherwise it is identical with the circuit of Fig. 4. "POPULAR WIRELESS" SPECIAL APPEAL. Fig. 6 shows an arrangement for utilising Can you realise how awful it must be to be double rectification with a single pair of deprived ofNature's greatestgift --sight? 'phones in cages where, for some reason Can you imagine the loneliness of perpetual -darkness, the inability to see the green fields, or other, it is normally only possible to get thefruit -trees inblossom, theglorious very poor signal strength. flowers, and the faces of those one loves?If you can, then you will not hesitate to send acontribution tothat deservingcharity, Double Strength Signals. " Servers ofthe Blind League," which is DIXIBLE RECT/I/CATION doing so much to alleviate the distress of SIMPz/fiEL) DIAGRAM Both earpieces of the ordinary headgear the blind. few pence,' a few shillings, a are wound in series.That is to say, the few pounds, how little it isin comparison to the good it can do when applied to such a current from one terminal, after flowing noble purpose! Miss Ellen Terry has pro. maximum sensitivity) so as to pick up the through one earpiece, passes down a return .mised to- send. her photograph autographed signals with a minimum loss of time.It is leadto the junction pointof the two inher ownhandwriting to everykindly contributor sending remittancesof10/.or most irritating to lose the best portion of flexible leads and then up again to the -ever to "-Arieli"--efo--" Servers Of -the Blind the.most interesting item on the evening's other earpiece. and so back to the second League," 3,. Lipper . Woburn Place, W.C.i. broadcast programme because one's crystal terminal Popular Wireless Weekly, June 23rd, 1023. Ga3

.1 ').

MULLARD SUPERIOR (P5 WIRELESS 40 VALVES.

pROBLE MS arise inevery phase of life, and the power ofconcentrationdoes not always _solve them, but whenthe problemisone of valves you can se.The Thinker straighteninghis heavy back -andsmilingbecause thereisonly one solution-

MullardObtainable from all high-class electricians, wireless dealers, etc.

/1,17-ot. of the Mallard Radix Valve Co., Ltd., 7Ialham, S.W.r> 084 Popular Wireless Weekly, June 23rd, 1923.

We,the DUBILIER CONDENSER CO. (1921), LTD., offeran 14:7 APOLOGY toallthosecustomerswho havebeenkeptwaitingfordeliveryofour " VANICON "VARIABLE CONDENSERS For the first time in the history of this company we have failed to give prompt delivery. This position has arisen entirely through our insistence on obtaining the best raw materials, without which we will not manufacture an article, as we know that by this policy we can guarantee you complete satisfaction. Having now overcome all difficulties regarding supplies of materials, which measure up 0 our standard, we are in a position to give prompt delivery of the Vanicon in the following standard capacities : 0003 mfd. 17/6

.0005 £1 0 0 = .0007 1 2 6 = 001. 1 5 0 = IF YOU WANT THEBEST RESULTS FROM = ----. t ...,..... ,,,,---..-. YOUR SET INSIST ON DUBILIER CONDENSERS. -,..--E .------; The = ..-----,-.-:------Dubilier Condenser Co. (1921) Ltd., Dept. E, = Ducon Works, Goldhawk Road, Shepherd's Bush, W.12. = Telephone : Hammersmith 1084. Telegrams .Hholtton, 'Phone, London. 5ffirnrnillninllinillillillilliminiwillinuinumfillilluffiuminuiffirnunllilifillilininillilwilllluiffiffiviffilluthillilluillwilliuriitirrn?iiififfilliffinfir,

SPECIFICATION. Set comprises solid best The 66 EMOWNIE ebonite drilled detector panel, DEPENDABLE wound induction coil, tuning slider,screw clamp crystal cup, bestqualitycrystal WIRELESS" universally jointed detector, giving accurate and easy ad- justment, terminals, screws, CRYSTAL RECEIVER. RADIO SERVICE and all parts for assembling by our patent method. 7/6 COMPLETE. "CC Aerial Wire, 7/22 bare copper stranded, 100 ft.26 Contains every part necessary for simple erection. A Scientific Achievement. Insulators. Reel, 1 A. Egg, 3d. Shell, 6d. Guaranteed equal to sets costing many times the price. Full and complete instructions enclosed with each outfit. Variometers, silk wound, fitted with Ebonite London make. Money returned if not as advertised. Dial Knob...... 46 100 READ WHAT THE TRADE PRESS SAYS: Crystal Receiving Set, Variometer tuning... " The voice might" Electricity," have been Feb. that 23rd. of a speaker in , unassembled70 the same room... The set is a marvel of value... Crystal Detectors on Ebonite'base ...3,'-&2/ - We anticipate that it will make quite a stir in the Glass covered...... 36 Wireless world." Oojah Basket Coils, set of 7, 150-4,000 metres50 Send postcard forfolder "The Brownie Wireless and all about it."

Slab 8, 150-26,000 76 The J.W.B. WIRELESS COMPANY, Basket Coils, our specialline,setof6, 19, GARRICK STREET, LONDON, W.0.2. (When tiriting mention (FirstFloor) 170-3,500 m. " Popular Wireless.") Near Leicester Square Tube Station. Coil Holders, 3 -way Extraordinaryvalue{ 86 2- } l 66 Intervalve Transformers, not rubbish 1 2/-, 1 2 / 6, 16/6 The ideal Valves, soft, Dutch, ideal for detecting ... 106

hard, amplification... 116 Amplion Loud Speakers upwards from 2 126 INSULATING VARNISH Variable Condensers. For Panel Mounting. In Celluloid Case 001 ... 12/6 ... 15/- 0005 ... 10/6 ... 13/- HARDICOL 0003 ... 9/6 ... 11/ - HEADPHONES- SHELLAC INSULATING " SIDPE " 4,000 ohms 1008,000 ohms 12 6 "BRITISH"4,000 1008,000 12 6 :: VARNISH CEMENT "BRUNET" 4,000 126Pival 12 6 Guaranteed made from pure Shellac. A saturated solution in the cold.Perfect for all insulation work. WATERLOO ELECTRIC Co. Enquiries invited from the trade. 129, Waterloo Rd., London, S.E.1 6dl. and 1/- Bottles.Also in BULK. IlOP 5649.Closed on Thurs. r p.m. Sat. 9 p.m. Other nights, 8 p.m. HARDICOLIS OBTAINABLE FROM THE CATALOGUES FREE. USUAL DEALERS AND THE MAKERS: 1/6/4460416,12.~46,11,11.16.4eri4 A. F. HARDING & COLTD., EXMOUTH ST., STEPNEY, E. Popular Wireless Weekly, June 23rd, 1923. WIRELESS AS A SOCIAL ASSET. By THE BISHOP OF BIRMINGHAM.*

THOUGH wireless may be said to be in ising a. person of distinction to the people. overcome by fusion of parishes. But few itsyouthandwill undoubtedly For example, despite the important placeparishes care either to lose their indivi- develop in many directions, I cannot the King occupies in modern life, there areduality or to give up their church.In but regard it as a most extraordinary feature people who never get the opportunity of some parishes there are only 100 to 150 of the times.Whereas, for example, the seeing him, much less hearing him.Yet people, in others, say, 250 to 300, and they cinema does not seem to have realised its could they, on some special occasion, say onmay get congregations of 40 and 50.It is possibilities of developuient, it, seems likely his birthday, hear Isis voice by means of difficult to find clergy for each of them.It that wireless will, and Ibelieve thatit wireless, they would get in vitally effective might be possible, I imagine, to have say, touch with him in that way.There is, oftwo clergymen to six parishes, to each of course, more than the mere voice in that which they would go in turn, the others aspect. There is the " one's self " in ithaving a sermon broadcast to them. which establishes the person broadcasting,as ,,Court a real vital personality. " Concerts. In civic affairs, too, I think it has great Considering wireless as a means of social opportunities, though, of course, we are onlyenjoyment, I think it is. providing another on. the threshold of them. When one con- example of the tremendous simplicity of siders its possible' application to the serviceenjoymentinour- Englishpeople. In of religion I can understand one's heart and Birmingham you can see it plainly.It is conscience being influenced by the broadcastpositively surprising at times to go up a address, but I am not quite so sure that itcourt somewhere in the city and see people can be used for the worship in which a man (lancing together.Court concerts in Bir- may join.I am afraid it would not become mingham have been a great :part in their the same reality.But the broadcasting of life, and perhaps wireless broadcasting will a service to, say, elderly people whom agehelp, too, in this way.This is ' realry the and infirmity prevent from attending atgreat requirement of the Age-to give joy church, should be useful.The family could to life, to give greater contentment and less be gathered in one room, they could have inclination for class to' get against class. some kind of service, and then listen -in to And you cannot do that better than by the address. giving them something wholesome, and that Broadcast Serra:m.5. can be given by wireless.Educationally, I think wireless will be useful in spreading To broadcast to a large building in which the best accurate information.It might agreat number of people are gatheredbe possible for the student, standing before together is another matter. Without seeinga machine, to be advised and instructed by the preacher, would one be able to keepa teacher before a similar machine miles oneself in tune with the service ?I am and miles away. But it is only commencing doubtful whether being led in prayer by to serve in our daily life, and its possibilities the priest speaking through the microphoneare immense. would haVe the same influence as were he .1n an interview. present.There might be so many other Turning on some music.The rat belongs to things which would distract the attention, Mr. R. T. Wanvow, of 179 Moorland Rost whereas the very presence of a clergyman Don't forget that your filament rheostat Weston -super -Mare. diminishes them.Religious service dependswill assist you in. tuning as much as your so much upon atmosphere, and though non- condenser.Heterodynina- canoftenbe has a really great future, particularly when attendance at church would not affect thecut out by reducing the voltage on the to the means of hearing there will be added, sermon, it would affect. the service. When filament.Theresistanceshouldnever as is promised, the means of sight by wire- I spoke on Good Friday I stood beside the be put fullout when a freshly -charged less. I think that broadcasting will be microphone, -andfelt that sermon as much accumulator is being connected. immensely valuable, for one thing, politi- as if I had my Con- cally.If we can bear a speech by any greatgregation in front- of politician, any leader of the State,itis me.In a way I was bound to be more effective than to read itlost to my surround- in - the newspapers, though, of course,I ings. Of course, that know there are men whom it would be better may have been tp read than to hear broadcast. R, is due partly to the fact easeiatial, I imagine,. for successful broad- thatI had been eastffig that a man should be an orator, and spending the whole he should always be prepared with what he of GoodFridayin wishes to say. 6 religious worship,I am led to think that 1Personalness." broadcastingmight 1 What has struck me from my own experi- bevaluableina ce of broadcasting is its " personalness."-diocese like mine if hen I broadcast a talk from the Birming- we had toface the ham station on Good Friday I was surprised problem, which at theresult.Ireceived many letters seems to be becoming thanking me, letters which came in some more and more places from people I had not seen for years serious,offinding Ind had almost forgotten. I received from sufficient _clergyfor yansfield, in Nottinghamshire, where I was theneedsof the born, letters from people who told me that Church. At the they had known my parents and were glad presenttime,with to have heard me.Wireless, to my mind, the- shortage of sup- The efficient aid vine apparatus constructed by Mr. H.T.Kirby,of tha has possibilities in the matter of familiar- ply, this can only be Laboratory, Custom House, London, F.C.3. 684 Popular Wireless Weekly, June23rd, 1923:

IS your receiver sufficiently sensitive to function as " Dead Spots" deflect signals, but well as it could be made to despite a shielded "dead spot " ? Some large building of metal construction they may be negatived by using the or a range of hills somewhere in the path of ether waves maybe deflectingyour signals. How doesyour re- ceivertreat the weakened waves that penetrate the LISSEN REACTANCE shielded area?Perhaps it is not fitted with LISSEN (P.Patent) REACTANCE, which would BUILD UP THE WEAK- ENED WAVE ENERGY and pass it strongly on to the method of H.F. Amplification. Detector Valve, and so negative any shielding influence. LISSEN REGENERATIVE REACTANCE LISSEN REACTANCE (P. PATENT.) PROOF OF ITS SELECTIVITY. --Itcutsout 2 L 0 from (P, ATENT.) directly underneath his station, and brings in the other Broad- casting and Continental Stations. -STILL TO BE USED. SENSITIVITY.-Aerial and earth connections can be dispensed Amplifies even loud Signals, and Atm 11111111111111111111101101 with under many conditions. addsgreatrangeandpower. Where aerial reaction is employed, , REACTION IS NOT OBTAINED WITH A SWINGING COIL-non-radiating. Range150 to 4,000 metres-REGEN- tunewithanew LISSEN ERATION OVER THE WHOLE RANGE. VERNIER-entirelysell -tuned 4 if aerial reaction not used. ....N. VD 8 Price £2 : 12 : 6 Complete. 150to 600metres.3 7/6 \` Blue print and instructions witheach.LISSEN ONE HOLE complete.. 1111111111101/1111111110 FIXING. ONE KNOB CONTROLS TUNING & REACTION. 150to 10,000 metres 32/6 TUNE with a NEW LISSEN VERNIER CON- complete.. DENSER (Price 12 6) barely I in. diameter, Blue print shows two simple con- and designed forline tuning in H F. circuits. nections-easy to use-no switch to connect-no awkwardsoldering- no complications-LISSEN ONE LISSEN TUNER HOLE FIXING. Not an ordinary plain wound, single ANY GOOD RADIO DEALER layerinductance. The L I SS EN TUNER combines thegreatestin- WILL SHOW YOU THESE- ductance per length ofwire with the IF HE CANNOT, TAKE NO lowestH.F.resistanceand least SUBSTITUTE-SEND DIRECT distributedcapacity. TO FACTORY-POST FREE. NO DEAD-END LOSSES-extreme efficiency-used with the LISSEN REGENERATIVE -REACTANCE it willcutout LIST 6d. 2 L 0-tunes in all Continental Telephony. Range 150 to 4,000 metres when tuned with a '0005 condenser -- preferably use Lissen Mica Variable Condenser, 17,6. LISSEN COMPANY Price 22/6 8-16, WOODGER ROAD, GOLDHAWK ROAD, Complete withit -pointswitchalready mounted-notapsto solder-panelortablemounting without alteration-engraved SHEPHERD'S BUSH, LONDON, W.12. dial-LISSEN ONE HOLE FIXING-simplymountand 'Phone':1072 HAMMERSMITH. inches. Diameter4inches. connectincircuit. Length 4 N.B.-ClosetoGoldhawkRoadStation(Met.) Shepherd'sBush LISSEN APPARATUS-WELL THOUGHT OUT, THEN WELL MADE. (Central London), or Hammersmith Tube. Buses No.IIand 32.

COMPLETE MET of PARTS For Assembling This Crystal Set (Asillustration). 3216 AmIgetting the best results Including Oak Cabinet( with binged lid).Size 8 in.x 6t in. s 5 in. height. Can easily he assembled complete from my receiver ? inabout an hour with screwdriver and pliers only. Illustrated Chart of Instructions included. What stationshouldIreceive from ? LIST of PARTS: 1Panel with 4 fixing screws; 1 Setof Parts for Variable Condenser;1Set of Parts Why do I not get them all? fur Inductance Switch; 1 Inductance Coil, complete; 1 PARIS (FL). SetofParts for Crystal and Detector; 1 What must I do to improve my Headphone Condenser, with Clips; 4 Bel ? TerminalsforAerial,Earth,and' Phone Is my tuning correct? Terminals, withnuts; 1Shorting Plug, III completewithSockets; 1 CoilofTinned THE TUNE-0-ORAPH 111 Copper Connection Wire. ANSWERS ALL THESE QUESTIONS & MORE. gfie z.l000t csaairiipaet4o -12-8 It enables the experimenter tofindthefaultsinhis TUNEO-CRAPIIS We thoroughlyrecommendour" BRIT - tunic,system,andsaves SITE "CRYSTALforCrystalSets, him tours' of trial. which issuper -sensitive onallpoints. E - It is a boon to the user PRICE 3/- PER OUNCE. of a Broadcast Set. PECIAL PRICES FOR QUANTITIES from H C. DALY, &rage Must rated Itisindispensableto MAKE'?, he British Central Electrical Co.,Ltd.,List 14 Wireless Sets thedealerwho wishes and Parts nt Money - to make comparative 95,G T 6/8, Rosebery Avenue, -London, E.C.1. saying Prices sent on tests of the different r 'Phane-Clerl,n well request. sets on the markets. /.. onocia,v Seven loaders'lire suppliedwitheach ais " Tuneograph," giv- ing the definite III I wavelength of III YOU HAVE BEEN LOOKING FOR London, Birming- 'so ham,S.F.R . Air- - A NEAT and USEFUL craft, ThePlague, Radiola, and Paris. Switch thatwill do for Additional loaders for anyspecial wave -length Series -Parallel and Multi - from 300 to 2,600 metres can be supplied. Valve Circuits, only 2/9 Price 3 / 6 each. G. Postage 3d. Aseachinstrumentis This Snitch can also be supplied without separately , calibrated, please retorts your base for mounting on own panel, 1110, Tuneograph when order.. postage 3d., or the separate parts,viz. ingadditionalloaders. PriceComplete Contact Studs, with nuts, 6d., per doz.; In thiscase11. extra 3916 post lid. Laminated Switch Arms, lid. is charged for return postage. postfree Allinstruments and loaders are scientificallycalibratedinour Laboratories each; post lid.Terminals, with nuts, before despatch, and are guaranteed accurate. W.D. or Telephone Pattern, 1/6 per doz., Full instructions sent with every Set. post 3d. per doz. Orders in strict rotation.Cheques and P.O.'a crossed.Don't delay. Scientific Supply Stores, Manufactured by. Phone: H. C. D A L Y,95,Great Portland Street, HOP 4177 126, Newington Causeway, London, S.E.1. LONDON, W.1. Tel. MAYFAIR 3349. Popular Wireless Weekly, June 23rd, on. 587

THE CONSTRUCTION OF AN ACCUMULATOR H.T. BATTERY. By F. CECIL CONNELLY. High-tension batteries of the dry -cell type have a very unfortunate habit of developing internal troubles at unexpected times, with the result that reception is impossible owing to a continual grating, crackling noise.The employment of an accumulator H.T. supply will obviate to a great extent such trouble, and will for experimental purposes supply a more steady current.

SEVERAL methodsofrevivingdry the other limb in the next tube.The opposite direction, and charge for half an cells for use in high-tension batter-sketch of the finished battery will make hour.Repeat this for a week, reversing the ieshave beendescribedinthese this clear. The other three long pieces should connections each day, then continue for columns, but the Leclanchecell-which be bent as in Fig. 3, and placed in the end another week without reversing the con- the dry cell really is-has many disad-tubes of the rows so that all the cells are nections, and giving it an hour each day. vantages.Its voltage is low, and it is very connected up in series.The small pieces of At the end of this time one set of plates messy.An accumulator battery is without lead are for the two end cells. The corks are will have a distinctly brown colour and the both these defects, and is by far the mostcut away at the sides so that they will fit others a grey colour-the brown ones are economical for those with electric lighting into the tubes when the plates are in position, the positive plates-and the battery is now and a hole is made through centre of each to ready for use. act as a vent.The corks are then soaked inparaffinwax.Someseparatorsare necessary between the plates ; 5:in. lengths Charging and Form- of glass tubing will do quite well, or strips ing from Alternating 0000 Current. of perforated celluloid may be used.The cells are then filled with pure dilute sul- .The previous phuric acid-density 1.220-and are ready instructions are, of 00005b course,fordirect for forming.It is possible to obviate the need for forming by using strips of old circuits;but by 110 0 00 accumulator plates instead of lead sheet. placing a" recti- fier " in the circuit A Small Charging Board. theAC. willbe turned intoD.C., 0 0 00 Thisappliance willbe necessary for and the same forming theplates, but, of course, any apparatus can be . nal accumulator charging apparatus will do. used for charging. A simple but effective one can be made as A rectifier can be mains in the house.. The battery described follows : Takea made asfollows : in this article has given satisfaction for several piece of hard wood Obtaintwolead years, and costs next to nothing in upkeep. 8 in. by 4 in.bylin., plates 3 in. by This battery is made up for 40 volts, butand on it screw an 7 in. by is in., and one aluminium plate the dimensions may be altered to give any ordinary tumbler 34 in. by 7 in. by -4,7 in.Two pieces of wood voltage, remembering that each cell gives switch, a " batten " in. byin. by 5 in.are clamped one 2 volts.The materials required are 20 lanipholder,a n d on each side of the aluminium plate and chemical test -tubes 6 in. long by1 in. intwo brassterminak 41 in. from one end.Then screw the lead diameter, 20 corks to fit, some 4 -in. glass With pieces of plates on to the strips of wood, one on each tubing, some A -in.lead sheet, and somerubber -covered side of the aluminium.get a 3-1b. earthen- wood.Take a piece of wood 4 in. by 51 in. copper wire connect ware jaM-pot and nearlyfillit with a by 7 in., and through it bore 20 holes 1 in. in one terminal to one saturated solution of bicarbonate of soda. diameter in the positions shown in Fig. 1.pole of the switch, The metal plates are placed in the solution Then get another piece of the same size, the other pole of the so that the wood rests on the top of the jar but 1 in. thick, and drill 1 -in. holes in it inswitch to the one and keeps the bottoms of the plates just exactly the same positions as in the first side of the lamp - off the bottom.Fig. 5 will make this clear. board, but only Tin. deep.. Then make holder, andthe Join the lead plates together and connect up the rest of the frame according to Fig. 6, othersideof the to one terminal of the charging board and with pieces of woodin. by 51 in. by 4 in., lampholdertoa the aluminium plate to the battery, the and place the test -tubes in position, so thatlength of twin flex, other terminal of which goes to the remain- the bottom of each rests in the shallowthe other wire of ing terminal on the board. holes in the bottom board. which is joined to the second termina .The other ends of 2"-a, the flex are connected to a lampholder 4,-; adapter connecting to the mains.

Forming. A suitable lamp must be placed in the 5r2 lampholder (200 to 220 volt circuits require a 32 C.P. carbon lamp, while on 100 to 150 volts a 16 C.P. lamp will do).Put the adapter from the charging board into a lampholder, and connect up the terminals o FIC2 to the H.T. battery, and switch on.If the connections are correct the lamp will light up.When it has been alight forhalf an From the sheet lead cut 19 pieces 12 in. hour, switch off and leave for a day.Next The battery is, of course, charged in the by 1 in., and two pieces 64 in. by 1 in. Bend day reverse the connections between the usual way when it requires it.It is an ad- . 16 of the long pieces as in Fig. 2, so thatbattery and the terminals, sothat the vantage to insulate it on porcelain. rubber, one limb of each niece goes in one tube, and current goes through the battery in the or ebonite legs. 688 P-optuar it vrelesc--Weekly, June 23rd, 1923. THE B.B.C. PLAYS. A CRITICISM BY DAME MAY WHITTY, D.B.E. DameMay Whitty is the principal of the Florence Ettinger Theatre School and is therefore an authority on the subject of Shakespearian drama production.

IWAS one of the many thousands who noisy to convey her mirth with sufficient other day of " As You Like It," looked very listened -in to Shakespeare's " Twelfth conviction.I suppose because there was puzzled for a minute, and then said, Oh,' Night " one Monday evening, and a no movement to help. On the other hand, you mean ' As You Were,' don't you ? "-; very interesting experienceIfoundit. some of the others were so determined to be That was the name of one of those fleeting Unfortunately, I did not hear the commence- clear that in one or two instances they over- revues with strange titles that' flit through ment, and so missed " the argument," the emphasised and were over -deliberate and our theatres.Such titles as " Why DWI explanation of plot, etc., and I don't know slow. And yet it seems to me to be hyper- You ? " or " What For ? " seem equally how far people who did not know the play criticism to fmd any fault, because the thing appropriate to me ;but, anyway, whatever could follow it, but it all seemed very clear was exceedingly well done, and one got a the title, it was more familiar to this youth to me ;it had been very skilfully arranged, sense of colour and atmosphere, and I than the loveliest comedy in the world. though it rather fell down towards the end. believe there ought to be a future for this And several times boys and girls have said.) Viola's and Sebastian'sfightswithSir work. " Oh, no ;I got so sick of Shakespeare at Andrew Aguecheek were difficult to grasp- There are so many people who have never school.I had to learn it as a punishment.", the explanation was inadequate, and it all read any of Shakespeare's plays, some who Think of the colossal stupidity of that ! seemed wound up in a great hurry ; and I have never seen any acted, and I believe cannot think that the stranger to this that to hear this -great poetry well spoken, Just the Voice. beautiful play-and I suppose such strangers with a real sense of rhythm and yet not to If broadcasting is to help to change such exist-could have possibly grasped " what lase the meaning, to have the words convey ideas, and I believe seriously it might help, happened at the end." the thought and make that thought clear- then a great responsibilitylies on the not-just to roll it out as sound-I think that speakers and those who are responsible for Atmosphere and Illusion. it would quicken interest, that the listeners - them. They haven't any accessories ;not The performance itself was well done, the in would want to know more ;would look only not any scenery, but everything on music delightful ; and it was very interesting uptheirShakespeares-there'snearly which the actor depends.Gone-his eyes, to me to listen to the which are the mirror spoken word without to his thoughts, his any personality or ap- facial expression, his pearance to heighten body, his gestures- or dispel any illusion. just his voice left in t, On the whole, the which to express all' wordwasspoken he is feeling, think- very well indeed, and ing, doing.And in carried withitat- losing all these one mosphere, character, is losing so much that and illusion. I should no lover ofacting likeparticularly to could accept what re- commend the Mal- mains as in any way

volio. One realised adequate ;it cannot the pomposity and possibly compensate fatuousnessofthe forthe art of the character, and one theatre. saw thatpainful The human voice smile and the yellow . can be a very beau- stockings cross gar- tiful instrument, and tered. The Olivia thereliesagreat was satisfying, too. The Marlborough Collegefieldwireless section at work. difficulty.The actor, One felt the melan- will-benecessarily choly, the feeling of ignorant of how it weariness and distaste, the gradual quick- always one on the- shelf, though probably sounds- to those listening -in, and I gather ening of interest inthe saucy boy who very dusty and neglected-and then, their that thereis enormous varietyinthe comes as Orsino's messenger, and the gra- desire and thirst for knowledge, for further instruments. used ;that while one person ciousness and simple dignity of the great acquaintance with thesemagical works using a head telephone gets- the voice very lady. stirred, they would begin to want to see how clearly, others listening to a horn-I am; The Viola was very pleasing, though- her they act, and the thought will come, " Well, ignorant of the correct names-the-sound - voice struck a more modern note, yet it was now let's go to the theatre and see for our- is metallic and like a bad gramophone reeord. attractive.I wanted more life, more sense selves." I suppose this can, and later on will be of fun in the " I left no ring with her " remedied, and if then the speaking of fine speech, but the love for Orsino was prettily Shakespeare as Punishment ! literature should waken in its hearers a expressed. , I've heard from a very indefatigable desire to know more and to see the plays, it Sir Toby Belch was a little blurred.It listener -in that she sees people sitting with is surely serving a useful purpose, and I must be more difficult to convey confused, their Shakespeares in their hands following should give considerable satisfaction. drunken speech and yet be clear whenithe words which are being broadcast, and there's only a voice and no movement to being immensely surprised to find how help ;and it must be infinitely hard on human, as welt as beautiful, is this writing actors not to have a notion of how it's really which hitherto they've regarded. as " too you have electric bells in your house, sounding. Sir Andrew was good. One visual- difficult for me."If broadcasting can help IFit is an easy matter to test if your crystal ised the foolish, timorous knight though one and dispel any ignorance of the greatest of circuit is as a buzzing -sound -should could not see him, and that was because the all poets ;ifit can bring . home to the be heard in the 'phones when the bells are speaker used the upward inflection almost. people the infinite treasure there lies for 'all rung if all is well. It is interesting to notice - continually. - who choose to avail themselves of this that you will hear the buzzing in the 'phones rMaria wasn't as clear as she might have knoWledge, then: it's doing alginfinitely good a fraction of a second before you hear the been ;again ratherblurred, rather too work. A young man to whom I spoke the bell- actually ringing. Popular Wireless Weekly, June 23rd, 1923. 069

TWO METHODS OF MAGNIFYING SIGNALS. The majority of readers will understand that H.F. stages of amplification are employed to increase therange of reception and L.F. to increase signal strength, but the " raison d'e,tre " may not be so clear.In the following article Mr. Blake provides a brief but lucid explanation.

THE experimenter having penetrated the tude), produce no effect on the detector. amplificationisto render louder or in- ether to the limit of his crystal re- Here high -frequency amplification comes to telligible signals which are weak when de- ceiver will, sooner or later, change our assistance and increases the amplitude livered from the detector circuit. over to valve working, or at least will add a of the oscillations until it is at least as great The difference between H.F. and L.F valve to his crystal in his quest either for as the minimum necessary for rectification. amplification may be usefully explained as more noise or longer distances.For the Hence the signals are " detected," and re- follows.Before being rectified the oscilla- is keen worker there always that one ceived in the telephones.The point to be tionsarereallyalternating currentsof station which is beyond his reach, and which particularly appreciated is that these weak extremely high -frequency which, producing he feels it imperative to hear, a fact which an alternating E.M.F. between the grid and sufficesto keep him tinkering,altering, filament of the- H.F. valve, cause equal and augmenting his apparatus without any variations of the grid potential on either apparent prospect of ever being satisfied. side of the working point, and thus give rise You may have noticed that motorists and to similar but larger oscillations in the plate amateur photographers are similarly afflicted circuit. with this divine unrest. After rectification we have to deal with The. Characteristic Curve. electrical pulses of low frequencies, and the Apart from the extra range which may reader may wonder how these unidirectional be attained by the use or addition of valves, currents can act through the transformer a new and extensive field for experiment is separating the detector from the L.F. valve. opened up, and many interesting and profit- It must be remembered, however, that although these pulses are always in the same able hours may be spent in trying out 'the direction, they do not maintain a steady numerous valve circuits.Probably most value.A pulsating current is one which graduates from plain crystal class to the although unvarying in direction varies in valve class begin their new studies by intro.: strength.It follows that if these pulsating ducing a valve to a crystal, and the questions currents are fed into the primary of a trans- at once arise as to how this new piece of appa- former, they will cause pulses of potential ratus may be used to the best advantage. to be induced in the secondary winding as a I therefore propose to explain the differences result of their the varying flux between H.F. and L.F. amplification, a these produce. As the secondary winding is matter we will approach by way of the connected across the grid and filament of detector unit, which is, of course; essential the L.F. valve, a pulsating potential effect to the use of either process. is produced on the grid, and large pulsations As is well known, the characteristic curve of ,current are produced in the plate circuit of a valve is similar in form to that of a of this valve. crystal.An almost ideal detector would produce a characteristic such as is repre- Disadvantages of L.F. Amplification. sented by the dotted line in Fig. 1.This oscillations were in the aerial circuit all the would ensure complete and perfect rectifi- time, but were not detectable until the From what has been said regarding H.F. cation, because if -the position of working H.F. amplifier was brought into play. amplification it should now be clear that were adjusted to the point X, the negative Low -frequency(or " note ") amplifica- L.F. amplification will not greatly increase half of the oscillation received from the tion is the magnification of electrical pulses the receiving range of a set, but will cer- aerial would be completely cut off.In of audible (called " audio'') frequencies. tainly increase the " punch " of any received practicetheseidealconditionsare not such as are obtained after rectification.It signal. obtainable, the curve being rounded off is most usefully employed for the operation Additional amplification after detection as shown by the full line in Fig. 1 of loud speakers. The main object of L.F. is often desirable, for- the reason that there is a limit to the num- H.F. More Efficient. ber of stages of H.F. It can be proved that the strength of a amplification which rectified signal is proportional to the square can be used; due to of the amplitude of the received oscillations, theirtendency to which means that if the amplitude of the self oscillation. : oscillations in the aerial are doubled, the The transformers signal intensity will be increased fourfold. for " note " amplifica- Therefore, it would seem that the more tion are fittedwith efficient method of amplification is that of iron cores, which are increasing the amplitude of the oscillations frequentlyasource before applying them to the detector, or, oftrouble owing to inother words, high -frequency amplifica- theirassistance in tion ;indeed, thisistrue, and for the picking up and mag- following reasons. nifying local and Inspection of the curve in Fig.1 shows parasitic noises, such that the oscillation to be rectified must as A .C. "hum" from attainatleast some definite minimum house -lighting circuits. value if rectification is to take place.In To the experimenter fact, a detector will often completely damp who has but one valve out very minute oscillations.Now our I unhesitatingly advo receiving aerials are continuously affected cate itsemployment which,on by very minuteoscillations A crystal set constructed, with an ordinary tea -cup forming the stator of the as ahigh -frequency account of their weakness (i.e., small ampli- variometer, by Mr. A. Brockhurst, of 4, Thorpe Road, Walsall. amplifier. 690 Popular Wireless Weekly, June 23rd, 1923. skilful hands be such a valuable asset, in inexperienced hands it can be the cause of REACTION: ITS USES interference for perhaps fiVe miles, depend- HINTS FOR AMATEURS. ing on the H.T. voltage and the degree of AND ABUSES. coupling. In order to keep within the P.M.G. requirements, reaction cannot be have anexperimentallicence used in conjunction with a single -valve set. IF youand have been given permission to erect Although with a three -coilholderthe an aerial longer than 100 ft., remember that INVARIABLY the first question a beginner reaction coil may be coupled to the C.C.I., 150 ft. is the maximum length if you wish in wireless asks, when he listens -in for thereby minimising interferenceit should to tune down to the 200 metre wave -length. the first time and hears the occasional he clearly understood that this is illegal eirdshrieks and groans produced by duringbroadcastinghours.Withtwo If you wish to make a really ideal con- reaction causing oscillation, are : valves (H.F. and detector) the reaction may tact between your crystal and cup, fill the " What is oscillation ? " be coupled to the anode coil. air space around the crystal with mercury " How is it caused ? " or tin foil.This often adds appreciably " For what reason is it done ? " to the strength of signals. The first two questions, being inseparable, had best he answered together.In the PENNY -IN -THE -SLOT When tuning a set with a, loud speaker, first place, an oscillatory electrical current it is a good tip to connect a large honeycomb in a wireless circuit is one that is surging to RADIO. coil to the 'phone terminals and place it and fro at an extremely high frequency.If over the output terminals of the telephone this is confined to the circuit (known as self - transformer.It is a matter of experiment oscillation), the fact is apparent either by an to find the right size coil, but the strength audible note in the 'phones or loud speaker, ALTHOUGH .rudimentary re dio- tele- obtained by this method should be equal or by any telephony that is being received phonic receiving sets can be erectedto another valve. being greatly distorted.A means often at a very low cost, " listening -in " * * * quoted of determining whether the set isto the wireless waves with a really efficient An ordinary pin sometimes makes quite a oscillating is to moisten the finger and place set bas hitherto been an expensive hobby. satisfactory cat's -whisker if you have lost same on the aerialterminal, which will It must often have caused-many a man's your proper one. produce a " popping " noise in the 'phones. heart to burn to read in his daily paper * * * that Miss To keep your aerial taut and to eliminate Experience Required. So- and- So, the risk of the ropes snapping, it is a good Reaction may be introduced into a circuit the famous tip to keep the aerial up, not by the usual by various methods, the most popular way, primamethod of hauling it up when it becomes known as magnetic reaction, being of intro- donna, wasslack, but by connecting the free end of the ducing a coil in the anode circuit of the going to aerial to a weight suspended over a pulley. detecting valve and coupling same to the enter tainThe weight should be equivalent to the A.T.I., C.C.I., anode coil or plug-in trans- 100,000force required to raise the aerial. former, the last two being in the case of people that * * H.F. amplification being employed.Either night, or Ordinary bicycle valves make good spind- of these methods will be found extremely that Mr. lesforconnectingrotortostatorin efficient, but it niust be borne in mind that variometers,ifheldin under the P.M.G. regulations reaction must position by suitable nuts not be used during broadcasting hours be- lor valvescrews.Small tween the wave -lengths of 300 and 500 nutsarepreferableas metres, in such away as to cause oscillation they do not take up so in the aerial circuit.The use of reaction much room requires acertain amount of experience.. * * * Any child can twiddle a knob and listen with A successful method of JohnBlank, the amplifying buzzer tones is delight to the . yells emitted, but to use great virtuoso, would reaction, gainingits advantages without as follows.Connect one move a great invisible wire of an 150 ohm ear- disadvantages, can only be accomplished by audience to tears and those who have had some practice. piece to the armature of to laughter that very the buzzer, the other wire evening, knowing the Why Use Reaction? being connected to the whilethat such negative terminal of the Perhaps it would be well to see what the delights were barred advantages of using reaction are ;briefly, a to him because he battery.This should great increase in signal strength, the writer givea magnification of didnotpossessa about three times. would consider the following figures give the receiving set. Such approximate comparative value of increase minor tragedies will, in signal strength with and without reaction, however, soon be a taking the unit of " 1 " as strength ofthing ofthepast, reception with crystal of London broad- thanks to an ingen- casting : ious little device Crystal .. .. which has just been launched on the Valve detector - 1.5 Valve detector and reaction, 3 French market. Valve detector, -reaction and It is nothing less than a coin -in -the - 1 L.F. ,. 10 slotradio telephone, which has very much the appearance of an ordinary It should be noticed that reaction very wall telephone.For less than the price largely increases the range of a receivingof a cup of coffee or of a glass of beer station. A single -valve set has a nominal anyone can listen to the news .broadcasts range of about 30 to 40 miles for high - or the excellent radio -concerts. power telephony,buttheadditionof Its success at the great sample fair, reaction usually doubles these figures. the Foire de Paris, held between May The question " For what reason isft 10th and 25th, was simply phenomenal, done ?" is then clearly understood when we no leSs than3,275 apparatusbeing consider these fads.Reaction is indeed a sold on the opening day.It has even wonderful discovery, but interference is thebeen bought for installation in hospital bugbear of reaction. Whilst reaction can in wards. Popular Wireless 117eekly, J&ne 23rd, 1923, (91

AMtritiro P

he lion

In188,.. Mr. Alfred Graham demonstrated the echroe first practical Loud Speaker. In 1893.. GRAHAM LoudSpeakers placed upon the market. In 1894.. FirstusedintheBritishNavy. Transmitters applied to Phonographs -the reason why the AMPLION for Loud Speakerreproduction. is undeniably the finest Radio Loud Demonstrations by Prof. McKendrick Speaker,and recognisedasthe at the Royal Society. World's Standard. In 1896.. NavalTelephonesdevelopedand It will be seen that the AMPLION adopted by the Admiralty. is not merely produced to meet a In 1898 ..Watertight Loud Speakers patented. sudden demand butisthe result Fitted on board many War Ships and of years of experienceinLoud Mercantile Vessels.Telephonic Sub- Speaker design and construction. marine Signalling System devised. In 1902..Complete Loud Speaker installations on centralbattery planerected on rash for Folder P.W. War Ships as sole means of com- munication. ALFRED GRAHAM & CO., In 1906 ..The most extensive naval installation to date including exchange system St.Andrew'sWorks, :: fitted to H.M.S. Dreadnought. CroftonPark,London,S.E. 4. Onwards ..Graham Loud Speakers applied to Sydenham 2820-1-2Navalhada. Catgrecn. London all sorts and conditions of service at SCOTIA ND : home and abroad, ashore and afloat. Mr. F. Milligan, 25, Renfrew Street, Glasgow. IIIELND To 1919 ..No less than 12,000 ship installations Mr. A. R. Munday, 41, Chichester Street, Belfast. carried out. CA NA Messrs.BURNDEPT OF CANADA, LTD., In 1920.. " AMPLION " Loud Speakers pro- 172, King Street West Tcronto. duced for Wireless and "AMPLION " Trade Mark registered. In 1922.." AMPLION " standardised by lead- ing manufacturers of radio apparatus.

'/1/IM1 /to ?7// F

Demonstrations at our Showroom THE ALGRAPHONE SALON, 25/6, Savile Row, Regent Street, London, W.1 'Phone: REGENT 1075 ///

191111111%1111 11111 1111111111111111111111111111 III 11111111111111111 1111111111111h, Popular Wireless Weekly. June 23rd, 1923.

To the Editor, POPULAR WIRELESS. Dear Sir,-One often reads articlesin which it is stated that satisfaction cannot be obtained by using a frame aerial with CORRESPONDENCE. one valve, but I myself have actually made three frame aerial sets (all identical) and have tested these ten miles from a broad- To the Editor, POPULAR WIRELESS. with not more than two cakes in11,-:e, your casting station with at least 18 single valve Sir,-I note that Mr. Guy Williamson has accumulators need never be sent out for discovered that it is a'n expensive matter to rechargingunlessyouarc particularly charge accumulators through specialre- enthusiastic, and use -the set for four or five sistance lamps.Owing to the wholesale hours at least every day. way in which this method of charging has Not only will your lighting bills show no been advocated by contributorstothe increase,but they may ihoW a small technical Press (this method also includesdecrease if the meter is of the " watt hour " the use of resistance mats, etc.), I have notype, as you are using only about 190 volts doubt -that many other wireless enthusiasts instead of 200.There is one small point to are wondering what is the matter with theirobserve when making the connections. bills for electricity. They fail to realise that on, say, a 200 -volt circuit, for every tfiree- No Risk of Leakage. pennyworth of current put into the accu- sets, tearing the B.B.C. stamp and using a normal outdoor atrial. mulator they are paying 8s.4c1. This is Break the lighting circuit at the minus because, they are only actually using aboutcontact of the main switch.All, lighting In each case the frame aerial has produced 6 volts of the 200 passing through the meter. switches are, or should be, inserted in the far better results.I have also tested a plus circuit, thereforeif you connect your frame aerial set with a two -valve set (1 Dec. accumulator in the minus circuitthere is 1 L.F.) with equally satisfactory results. no risk of -slight leakage taking place from I contend that the reaction permissible the accumulator when all switches are " off " with a frame aerial(which incidentally in, the lighting circuit.Many companies eliminates all interference) more than makes " earth " their negative mains; so that if up for the loss of an outdoor aerial. your accumulator is connected direct to These -articlesthereforestrike me as the positive main, it will discharge through being rather misleading to amateurs who any defective points in the insulation of the use single valve sets for broadcast reception, mains. especially to those who use sets bearing the

I am, yours faithfully, B.B.O. stamp. V.PASCOE WILLIAMS A diagram of the frame set with values is (B.A. Cantab.). shown above. 94, Desborough Avenue, High Wycombe. Yours faithfully, G. W. A. B. A SERIES -PARALLEL SWITCH.

Perhaps a description of the means which ACHEAP and efficient sub3titute for made by connecting four valve" legs," Adopted some time ago would be of in- theusualseries -parallel switch, or sockets, as shown in the accompanying terest. The main point is that two accumu=- which has the adVantage of taking diagrams. Two links which are needed for lators are used, so that while one is being up very little space on the panel; can be making the connections consist of valve used the other is being charged, and when pins screwed into a neither is in use both are being charged small piece of ebonite in series. F/G2 with a short strip of I want to labour this last point, as it is copper foil under the generally overlooked.Supposing there are nuts on the pins con- 2 amps. passing through the lighting cir- necting them to cuit, and the two"accumulators arein gether parallel, then each accumulator gets 1 amp. Fig. 1 shows the only.But if they are in series each gets aerial and earth the full 2 amps. connected together to A Convenient Arrangement. protect the set when not in use, while Figs. Of course, connecting them in series like 2 and 3 show the this will cause a bigger drop of voltage in aerial tuning con- the circuit, and if ordinary vacuum lamps CO/YDENSER/N5ERIE5 denser in series and are used they will be dimmed perceptibly, in parallel' with the but if gas -filled lamps are used even a 12 -volt inductancerespect- drop will -canse ,no perceptible dimming, ively.The arrange- Now that gas -filled lamps are very little F/G 3 ment has been in use .mere'expensive than the 'othertype, and on a crystal set for give nearly twice as much lightfor the OE some time, and has same Current consumption, there is no reason been found to be quite why they should not be fitted instead of assatisfactory,the the vacuum type. contacts being very My two accumulators are mounted per- reliablea n d t lie manently on a shelf near the main switch, connectionsreadily and the charging and discharging are con- changed, while t h e trolled by three double pole doule throw small space required switches, so arranged that either accumu- A o n the panel-the lator is charged independently or both in wholearrangement series, and that either, or both, or neither might be got into one can be connected to the set.There is no CONDENSER /N PaRALLEL FAG. 4. square i n c h-mako possibility of a " short " to the set. it convenient wheio The beauty of this atrallgement is that, spacC is limited. Popular Wireless Weekly, Jaye -23rd, 1023. 4/93 Guaranteed Wireless Components ONLY the finest Wireless Componentsare listed Our big manufacturingmanufacturinghere. The facilitiesenable us to quote lower prices and yet maintain the same high quality. " Variobloc " Variometer. An internally wound Variometer of high efficiency '- Most orders can be filled per return of post. conforming to latest American practice.Solidly Carriage extra but paid on all orders of £2 built with generous bearings which need no and over adjustment. Permanent contacts made with copper strip.Fitted with terminals Head office (for all Mail Orders) : and brass rod so that it can be in- 64, High Holborn, W.C.1. stantlyconvertedintoa Vario-17/6 coupler. Made in two patterns : Postage Demonstration Lounge : No. 1.250-720 metres, No. 2.256-840.6d, extra. 99, High Holborn, W.C.1. metres. Suitable for Redpath Units. Branch : 'WILL:MA.13LE CONDENSERS. 3, Wellington St., Strand, W.C.2. Complete with knob scale, pointer, and instructions, and TOP and BOTTOM - INSULATORS EBONITE PLATES, ready bushed and connections made.Neatly boxed. BARREL. Assembled for Panel CRYSTAL Very high break- complete.Parts 3/minting- ing strain, '001 76 ... 12 6 RECEIVER each 7d. -00071 68 SHELL. '0005 56 (De Luxe Pattern) Complete with best Green Vitreous EGG. '0003 43 China, Small size '0002 36 qualityphones, each 1/ - 3.2 6 - aerial wire and in- and light Vernier (Ready sulators.Nothing more to Miniature size, weight, Price£6-6-0 each 5d. each 4d. a..ssembled)... buy. HEADPHONES THE " FILTOFONE " DUAL CRYSTAL DETECTOR Specially c o n - Superiorquality, Very latest design adjust - To enable acat - with widecorn- able magnet, gives wonder- s tr u c te d to whisker and crystal or fortable xylonite fully clear tone.Magnets eliminate noises twocrystalsto be headbands.4,000 are circular-one pole within in the Loud used.Very convenient ohmsresistance. theother-thereforethe Speaker and to forany CrystalSet. Extremelysensi- centre pull on the diaphragm improvetonal Both Crystalstotally tive. Particularly gives absolutely distortion - quality. Merely enclosed in glass, and good value gi / lessreproduction. 4,000 connect between Per pair... &Ai" ohms only. Per pair,30/_ Set and Loud arranged sothat one Speaker. In pol- onlyisinuseata ished ma-ft /6 time. On a LOUD SPEAKERS hogany case,'I,/ Ebonitebase...u/ -thePeto-panSuper. Reproduced exactlyas used in the well-known THE "MAX -AMP " THE " MULTI -WAVE " PETO-PAN, but metal Finest quality intervalve AMPLIFIER horn now replaced with Transformer. F u 11 y ForII -F.Amplificationon moulded, unbreakable guaranteed. Tested to all wave -lengths, aboye 1,000 composition. Splendid 500 volts between wind- metres.No. 1 for coupling acoustic effects.Gives ings. Verysilentin between II.F. and. Detector, true tone values without action and free from all and No.2foruse where distortion.4,00063/- distortion more than onestageof ohms Each211 H.F. Amplificationisused. THE No. 1...8/6 No. 2...12/6 SWITCHES " TUNODE" ACCUMULATORS PLUG. SERIES -PARALLEL 4 volts, 10 amp. Permitsthe SWITCH hrs. continuous, 14/6 usual typeof Withbrassbush, 4 volts, 20, amp. honeycombcoil two nuts and spring hrs. continuous, 17/6 to be used as a washer ...2/6 4 volts, 40 amp. tuned anode coil Superior nickel -plated D.P.D.T., hrs. continuous, 27/6 withexception- without bases, ready with nuts 6 volts, 10 amp. ally good results. RADIAL SWITCH for mounting on your own Panel. hrs. continuous, 20/- Simply plug in 4leaf laminated. Extremely smart appear- 6 volts, 20 amp. H.F. Holder and Complete with bush, ance. Take up little room.2/6 hrs. continuous, 27/6All Accumulators add suitable nuts & washer, 1/3 6 volts, 40 amp. honeycomb/ft Cheaper quality, Ditto, but sin- 1/9 hrs. continuous, 421. add 1, -for packing gle pole only. coil.each NA/ IP

AERIAL MASTS Best qualitysteel THE " KOMPACT " CRYSTAL tubing,lightyet LEAD-IN RECEIVER. immenselystrong,The latestidea. inthreesections.Savesdrillingthe Complete initself for allBroadcast Wave- Makes a permanentwoodworkof the lengths. Consists of very selective Tuner, aerial: Paintedwindow frame, and with tapped inductance and variablecon- meetswithland- denserfor final tuning. Flrlejtrate-c1,8 50/7lord's approval. Crystal Detector fully enclosed within glass. Windowcan be Designed so that standard Peto-Scott Valve As above, but com-closed at any time. AmplifierUnits canbe addedforLoud plete with stayFitted in one /6 Speaker use atany time.Setsofparts wires, strainers,minute - A/ complete, withfullinstructionsfor homeI pulley,as/. assembly 10 etc. Mahogany Cabinet ... . 3,6 FinishedInstrument,testedand stamped37/6 Featherstone House, PET -SCOTT CO., LTD9 64,HighHolborn, W.C.1 001 Popular Wireless Weekly, June 23rd, 1923.

DONTONEPHONES 13RITAIN'S BEST U A High Frequency Reactance Set MARVELLOUS EFFICIENCY for Home Construction MARVELLOUS PRICE Ohms Per 4,000 16/6 £6-5-0 Per Plus 1'- extra for=1.47 EVERY DETAIL IS PLANNED AND THE PARTS GO Pair Manufactured entirelyin our works, TOGETHER LIKE A CHARM. GoaweLL Road and. City Road. under mass production : hence the quality and This Home Construction Set No. 24 P (as illustrated) is a mag- price. nificent " distance " Set which has been well tested and is designed We soecialiseinthe manufacture of for simple assembly with simple tools. Precision Tools stamped and turned - parts,inlargequantities.Send us. The handsome matted ebonite youi enquiries. Panel is fully drilled anti en- We are experts inthe production of . graved. The components such Magnets of all shapes, and from Tung- as. Condensers, etc., areall ston or Chrome Steela. made up, anti H.F. Trans- formers or Anode Coil (which- SPECIFICATION. ever preferred) and Variable . Case. Best hard Aluminimn,solid Ear caps.,Solid ebonite cf ample drawn and accurately finished. sire. best Itnislt and correctly pro- Coupling Reactance Coil are, Magnets. Latest type horseshoe -- portioned. included. pattern of finest Tungston Steel, re- Insulation. This is a particular sultingin strong and permanent feature and receives careful atten- The cabinet (Size 151 in. by12 in. magnets. tion,finest materials cnly being used.. by 12 ins)is made ofselected HeadBands.Made from- best -- mahogany in handsome Chippen- Core Pieces.Finest quality of quality Spring Steel, copper plated. dale finish, and when closed com- special soft iron, with fibre insula- ox yin zed, and relieved, giving berav pletely protects valves. ting cheeks. tiful finish.Tostin.Every Wire. Each earpiece is wound with The Set is in fact complete down earpiece is tested tothe minutest detail,with the st. Englishhighconductivity. thoroughly during, and a fteras- exception, of course, of Accessories, copper wire to 2,003 ohms by special embly. consisting of Aerial. Insulators, 40 - Finish & Workmanship. Of amp: Accumulator, 54 -volt. H.T. Diaphragms.Made [rpmselected to k -id-possible throughout. Battery. I pairsensitiveHead-Completeinstrudionsforassembling and iron, perfectly fiat, to ensure perfect. AS,F:31ItLY.By skilled labourunder phones and valves, which we canworking, together with diagrams, are furnished tone. expert supervisiort. supply for £3 15 0. We agree to returncastin full if not satisfied, and CUARANTEE. retu rued tous undamaged, within 7Int- RADIAX LTD., B. D. & Co. (Edward A. Boynton), 10, Radio House, Percy Street, Tottenham Admiralty & War Office Contractors. RADIAX Works :-107-173, Ooswell- Road, London. DoswellPlace, Court Road, London, W.1. London. E.C.I. 361-363, City Road, 1,0111,1011,E.C.1. agallaPhone Museum490(3 minutes Tottenham Court Road Tube Telephone: Meg-entre/I 6238, Others:17:1., tillaWell. lioaaL London. E.C.E WE SATISFY YCA.I Station).Hairs, 9-7.

AUCTION of WirelessApparatus FOUND!! An opportunity for Amateurs and Traders to secure small or large lots - The CHEAPEST and BEST for : Complete 2 and 3 -ValveReceivers-B. MarkI. e -Valve Crystal Cups, 1 screw at bottom, 3 at side..12,Z per Gross Detectors and Amplifiers. II. 2 -Valve Receiving Sets. Pillat Terminals, isix 2 B.A. with _NUT and WESTERN ELECTRIC CRYSTAL SETS.. WASHER.. -13,1 - VALVES. FRENCH HEADPHONES, LOUD SPEAKERS, BROWN'S HEADPHONES, Lowand HighResistance, Telephone Terminals,xx 4 B.A. with NUT "

MARKDI. SHORT WAVE TUNERS (new and perfect), and WASHER /1 50 -Watt Receiving and Transmitting, Sets (new and unused). Largequantitiesofmiscellaneousaccessories,Condenser, Ebonite Base Detector, adjustable .. 13,"- per Doz. Buzzers, Voltmeters. etc. inch Square Slider Rods, complete 6 a Inch 1 o AUCTION DAY,MONDAY, JUNE 25th, with Terminal at each end " f 3,18.4;'3 5,'-Doz. Time, 3.30 p.m.Catalogues on application. ALL PRICES ARE POSTAGE FREE. On view in a.m.-6p.m.Friday andSatiolayprevious. Terms :-CASH with ORDER. POWELL & POWELL H. VVARREN- ar CO 556, Oxford Street, W.I. 30, YORK ROAD, ERDINGTON, WARWICKSHIRE.

ACCUMULATORS SPECIAL OFFER AT JEARY "SENSIFONES" REDUCED PRICES(1,1ge Including B.B.C. Every settested TRADE MARK. and guaranteed.

Popular Type.ClearCelluloid Cases.- - olt-IgnitionAct. All. Carr. tato 27/6 age.Can.Amps. Cap.It rice Exm, ALL 1000 4 71 8 9.111 I 13itish Make. 1310 4 20 10 12-'11-13 1315 4 30 15 14/11 J WIRELESS Compare and test these with any other 1320 4 40 20 16,11 make, you will be convinced of their 1330 4 60 30 22,41 - 2 r3 ACCES- E P R 1340 4 80 40 29/- highquality.Lightweight,easily 1426 40 20 27/8, 1 SORIES adjusted, highly sensitive, detachable ACCUMULATORS 1430 6 60 30 33/9 j- 2 6 have 1440 80 40 39/6t3/, receivers. IMMEDIATE DELIVERY. 1450 100 50 45:6 KEPT 20 YEARS' Send your order NOW. REPUTATION IN Wholesale Agents for Isranie Stadia Devices. Accumulators RICHFORD & Co., charged on the STOCK. TheJEAIRT ELECTRICAL Co., Ltd. premises day and 153, FLEET ST., LONDON, E.C.4. 8, Lambeth Hill, &97, Queen Victoria St., E.C. fa night. Telephone: Holborn 5120. 1:-4.11).1 71; Also at GLASGOW,BIRMINGHAM, &c. 1 Popular Wireless Weeklyc June 23rd, 1923. 695 PRACTICAL IDEAS FOR THE AMATEUR. NOTE.- Readers are reminded that the Editor of POPULAR WIRELESS is alwaysprepared to give special consideration to short constructional articles of a similiar nature to those thatappear on this page.Such articles will be well paid for if accepted for publication.

-4-E130,v/it KNOB A NOVEL COIL TIP. 1111111 SOMETHING NEW 4111111111iir

;!,,, FPO/LATER 2 B.A. rim wigR INDETECTORS. 4 ---PANEL following is a very useful tip in the =D=E: WASHER THE RHEOSTAT FORMER making of solenoid coils, and is quite WASHER TO construct, purchaseat thenearest easy to construct.It is a device by LEAD PENCIL PHONE TERMINAL confectioner's" a "Smallglasstube which the pressure on the sliding contact 2 2 BA.NI./TO containing cachous, for a copper or can be varied Without any alteration to the 2 BA.ROD so. After emptying the tube of its contents, slider or rod, and also by which, coils may prepare two 6 -in. lengths of bell wire, and ' be easily interchanged. Neat Appearance. bare one end of each for a quarter of an inch. The pencil -line is drawn round the groove of the former, making contact with the brass CORK strip on one side only, the other end of line finishing in. from the strip, the shaded TO TO portion being filled in level with sealing - TERMINAL TERMINAL

wax, which forms a stop.The thickness of the lead pencil line depends on the degree of hardness of the pencil, and is best found by MERCURY CRYSTAL experiment. CONTACT CONTACT This instrument makes a neat companion to the Fil.Rheostat, there being nothing POWDERED ugly on the face of the panel. CRYSTAL MERCURY FIG. 1. In one length bend the bared part at right - angles to the insulated part of the wire. In the centres of the ends of the coil two Your contactsSICnow complete. Put the holes are drilled,for which two round - L-shaped wire in the tube and pour in a drop headed brass screws are procured, and in or tiro -of mercury so as to cover the bared the two pieces of wood which support the part of the wire, as in Fig. 1.The second coil two slits are cut, the same width at the contact is now put in on the opposite'side of diameter of the screws. the first and. bent over the side of the tube Next two washersare obtained into which EBONITE FORMER so that the bared part rests about one - the screws will fit, and which are slightly PENCIL LINE sixteenth of an inch above the surface of the bigger than their diameter.The washers STRIP BRASS BENT Be FI1TED A3 mercury. are put onto the screws, which are then SHOWN placed through theslitsin the wooden Obtaining Adjustment. supporters and screwed into the ends of A crystal is then powdered and emptied the coil. into the tube. The powder should float on the surface of the mercury and cover the Useful for Experimenters. bared part of the second wire, as shown in A FEW TIPS. Fig. 1. Two slits are made on each side of the The slits in the supporters may be made cork to allow for the outgoing ends of the by first drilling a number of holes next wires. to each other, and then sawing through If you do much experimenting with loose these with a piece of a hack -saw blade.The wires on a valve set, it is a good plan to construction will be better grasped from cover the valve sockets with short lengths the diagram. of rubber tubing.This will tend to prevent No measurements are included, for one shorting catastrophies. does not know what the amateur hasin his workshop,nor the thickness of the * * material used in making the coil. If you are using a double aerial of a fair This device will be found to be particu- length, it might be worth while arranging larly useful to the experimenter. a switch which will automatically cut out one wire altogether when required.The single wire would most likely he more efficient on the low wave -length. A VARIABLE GRID * A cheap way of labelling your apparatus is LEAK. bycuttingouttabsfrom advertisers' announcements and sticking them on.In An upright is glued to a small base and this way, labels with the words " 'Phones," the tube is clipped to this, as is shown in The following details of a variablegrid " Accumulator," " Aerial,"" H.T.", etc., Fig. 2.The ends are then bared and con- leak which has proved very successful can easily be obtained. nected to suitable terminals on the base. may be useful to amateurs.The parts * * Usually there is no need to search for a sen required are :1 rheostat former, 1 ebonite Should your 'phones be inclined to give sitive point, but if no signals are heard, tap knob, 2-ip. length of 2 B.A. rod, 3 2 B.A. weak signals, remove the cap and see how the tube lightly with a pencil, and this will nuts,3 plain washers, Ispring washer, many washerstherearebetweenthe give 'the desired result.This detector has 1 small 'phone terminal,.small strip fin. - diaphragm and ' the -magnets.If there are the advantage of being -du$tpmof and very wide brass; and 2 small screws. two, try them with only one. cheaply made. Popular Wireless Weekly, June 23rd, 1923. i941 BROADCASTING TRANSMISSIONS. In the following programmes full details of the Continentaltransmissions are included so that possessors of suitable receiving sets can take advantage of the manyinteresting items that these stations broadcast. From an educational point of view such material isinvaluable, more especially for such amateurs that may be studying one or other of the Continental languages.

- GREAT BRITAIN. Hours of Wave-length Station. Call Sign. Transmission. Items Transmitted. inMetres. Remarks. London .. ..2 L 0 Usually -5.30-11 p.m. . Musical Items, News, etc. 369 Every Weekday. Newcastle ..5 N 0 5.30-11 p.m. 400 PS 385 Manchester .. ..2 Z Y 5.30-11 p.m. lt 00 10 425 Birmingham...... 5 I T 5.30-11 p.m. .10 PP OP . 415 Glasgow .. .. 5 S C 5.30-11 p.m. P9 PP 353 PP Cardiff.. ..5 W A 5.30-11 p.m. 110 91, lf BELGIUM

Brussels (1) Brussels 11 a.m. (G.M.T.)..Weather report .. 1100..Working days. 3.50 p.m...... Aeroplane traffic 1100 ..Every day 8 p.m. .. ..Concert .. 1100 ..Tuesday & Thursday 6 p.m. ..Concert .. 1100..Sunday HOLLAND The Hague PCGG ..3-5 p.m. (G.M.T.) Concert 1050 Sunday. 8.40-9.40 p.m. ..Concert 1050 ..Monday & Thursday The Hague .. PCUU 7.45-10 p.m. ....Concert 1050 ..Tuesday. (Laboratorium Heussen) 9.40-10.40 a.m. 1050..Sunday. The Hague (Velthuyzen) P C K K 8.40-11.40 p.m. ..Various 1050.. FI iday. Ymuiden (Middelraad) P C M M 8.40-11.40 p.m. ..Concert 1050..Saturday. Amsterdam .. P A 5 ..8.10-11.10 p.m. ..Concert and News 1050..Wednesday. FRANCE

Lavallois-Perret (Radiola) S F R 2-3 p.m. (F.S.T ) 1780 Sunday. 12.45-1.45 p.m. ..News and Concert.. Stock Exchange News .. 1780 Every day. 5.15-6.15 p.m. ..Instrumental music 1780 8.45 p.m.' General News.. 1780 9-10.30 p.m. .. Vocal and instrumental concert 1780 2 2600 Paris (2) (Eiffel Tower) ..F L dr, 6.40 a.m... Weather Forecast.. 10 11.15 a.m. .. Weather Forecast.. 2600 99 3.30 p.m. Stock Exchange News.. 2600 6.20 p.m... Weather Forecast, Concert 2600 00 10.10 p.m. .. Weather Forecast 2600 Ecole Superieure des P.T.T. 7.45-10 p.m. .. Radio Concerts .. . 450 Tuesday, Thursday, 2.30-7.30 p.m. ..Radio Concerts 450 Saturday. Badio-Riviera (Nice) News, Concert 480 Every day. News, instrumental Concert... 460 9-10 p.m. .. Latest News. Concert .. 460 Lyons (La Doua) Y N ' 10.45-11.45 a.m...Concert 3200 Every day 3-3.35 p.m. Financial News and Aviation Reports3200 03 11 GERMANY, CZECHO-SLOVAKIA, AND SWITZERLAND Berlin.. L P :.7-8 a.m. (G.M.T.)..Financial News, etc. .... 2800 Every day (Konigswusterhausen) 11-12.30 a.m. 4-5.30 p.m.....Financial News, etc. .... 2800 Eborswalde.. ., 6.30-7.30 p.m. ..Concert ...... 2950 Thursday. 4-7 p.m...... Lectures and Concert .... . 2950 Sunday.

p R G Prague 7-11 a.m. and 3 p.m.Weather News, General News.. . 1800 9 a.m.-2 p.m. & 9 p.m. Concert ...... 4500 Geneva 1 1200 , Lausanne .. H It 2 ..5-6 p.m...... Concert ...... - Every day. The British Broadcasting Stations transmit on Sundays between 8.30 and 10.30 p.m.,and at varying times during weekday mornings and afternoons.The programmes appearing in the daily Press should be consulted for fulletails. (1) If, at the indicated times, a station has to receive or transmit service communications, the weather transmission will take place after these communications.Tuesday :Operatic selection on the gramophone.Thursday :Various on gramophone.Sundays :Various by artistes. (2) Special concerts given during the evening are announced in the course of the preceding transmissions.

Restful ease beside the babbling brook are.There is no need to explain any aerial SUMMER WIRELESS and listening -in seems a natural union.At,erection.Get your aerial up in the field, camp one spends the balmy summer even- with your set in or out the camp,and Elysium Wireless Enjoyment for Summer Campers. ings in calm and peaceful indolence.In is complete.It would be rather an inter- nine cases out of ten a camping party takes esting experiment to obtain one or more T is now quite a common sight during the a gramophone as part of the necessary im- of those hydrogen balloons so common with I- summer months to see the landscapepedimenta, and one might then go on to children during the summer.With as long dotted with the white temporary abodesdescribe the pleasant scene of the holiday a length as possible of the finest wire obtain- of that annually increasing migratory multi- makers reclining on the green slopes whilstable, send this floating aerial aloft straight. tude who seek rest in the lap of simple the- soft needle gives out the sweetest har- from the aerial lead of your set.This aerial nature" far from the madding crowd." monies on the still air. has the merit of being always directional, As a holiday this sequestration is ideal, always in the open away from any chance and when united to the joys of listening -in, In our homes we allof us prefer theof lost energy, and can be made of as great a the very site that is most suitable for the" set " to the gramophone.So why not heightas possible when thesupply of camp isperfect forwireless concert re- take your set with you on your holiday wire issufficient. ception.To get away from the busy haunts But how shall one bring 2 L 0, 5 N 0, or Much has been written, sung, and por- of men is to remove all those energy absorbing any other centre of delight into our midst ? trayed of the joys of the road, the pleasure buildings and jamming reacting aerials which Erect a pole in the field where the camp is of the country and open-air life, so let those are the appendages of that human to whom situated.Ifatree -isclose at hand, a who appreciate those daily delightful con- the appellation ofbroadcatcherhas been difficulty is solved.So take a couple of certs continue to enjoy the talent provided" given. insulators and a coil of wire, and there you amidst pleasant holiday- surroundings. Popular Wireless Weekly, June 23rd, 1923. 697 ehold ! 1111111.111i11111111111[11111111'1!I I INF!! 1'111111W 1.11 il",1111l1111i11111111111111111111:1 HAVING already securedthe SomethingNew! Manchester business for Com- V BEST ponents at the right price we have decided to give Amateurs in all THE COMPONENTS parts of the world an opportunity to get them at " V BEST" prices.

WE have organised a MailOrder V BEST MAGNOR A Department, and can offer all the following goods ea stock. PRICES LOUD SPEAKER AERIAL WIRE, 7/22s, Hard -drawn Bare Copper.... per 100 ft. 2/6 AERIAL WIRE, 7122s, Hard -drawn Enamelled per 100 ft. 3/9 AERIAL INSULATORS. Reel, each 26.,2 for 31d.; Strainer, ea.31d. AERIAL INSULATORS, Egg, each 24., 2 for 40.; Shell... - Bid. AERIAL PULLEYS, 21 in.Galvanised 6d. BATTERIES, Flash Lamp, 4 -Volt (Make your own H. T.), eaaaccili 56.per dozen 416 CONDENSER. VANES, Fixed or Moving per dozen 6d. CONDENSER SPACERS, Accurate. Small, per dozen, 3d.; Large, perdozen CONDENSER SCALES, IVORINE. Engraved, not Printed each 5d. CONDENSER DIALS, EBONITE. Engraved, beautiful finisheach 113 CONDENSER SPINDLES, Square Section, Screwed 2 B.A., Vernier to .0005, each 4d.; .00075 and .001 each 56. CONDENSER ADJUSTABLE PIVOTS each 3d. CONDENSER TOP BUSH, with flange each CONDENSER TOPS & BOTTOMS, drilled for standardfittings.e..eal.106.. CONDENSER, Fluted Knob & Dial combined, beautiful finishea.2/ - CRYSTAL CUPS, lifting Screws,beautifully finished each 2d.

CRYSTAL DETECTORS, Mounted on Ebonite.. Adjustable in every " 3, each 2/- CONTACT STUDS, 1 in.x1 in.,with NM and Washer..per doz.6d. CONTACT STOPS, i in.x/ in., with Nut and Washer...per doz.9d, CORE WIRE, Soft Iron perlealcbt;7613. COIL MOUNTING PLUGS, Universal Fitting

DUCONS.While theylast " each 716 EBONITE. Don't buy loaded Ebonite.Get maximum area for minimum weight (cut tosize).. per lb. 3/6 Manufacturer's scrap pieces,in -1.lb.parcels ...... per lb.216

EARTH CLIPS. Fit on water pipe.Adjustableto any size each 4d. FOIL COPPER., per sheet, 4d.. FOIL TIN, per sheet. 3d. FILAMENT RESISTANCES. A real piece of apparatus each 2/6 FILAMENT RESISTANCE, ebonite dials, engraved each 106. FILAMENT RESISTANCE, circular engraved scale each 9d. FORMERS, PIRTOID, for Honeycomb Coils each 3d. INDUCTANCE TUBES, specially impregnated, 12 ins. long.2 in. to4 -in.diam., 4d. (each;41 -in.diam., 5d. each; 5in.to 6in. diam. each 7d. 9CTUAL SIZE INDUCTANCE SLIDERS, withspring. and plunger each 4-d. INDUCTANCE SLIDLR ROD, 13 in.,drilled dch46. INSULATORS LEAD-IN,sturdyebonite,terminalseachend.a 6 in., 106. each; 12 in IVORINE TABLETS. Blackonwhite,orwhiteonblack. cEaenh-111 graved.A nice job. AERIAL, EARTH, 'PHONES, etc each 2d. INSULATING SLEEVING per yard 5d. INSTRUMENT WIRES. A huge stock of specially purchased wire inall coverings.Perfect.At bargain prices.Send 11d. stamp for pricelist. INSULATING SILK SHEET per sq.ft.1 J. KNOBS, EBONITE. Blindbushed, 2B.A. One qualityonly - THE BEST each 4d. MICA. Pure ruby.Pieces2t..in.x21 in each 16. NUTS'.Brass, Hexagon,2, -3,& 4 B.A., per doz., 3d.; 5 & 6 B.A. per dozen 246. RESISTANCE WIRE for filament resistances per yard 16. ROUND LOCKING NUTS, .2 B.A., brass each 2d. SCREWED BRASS ROD,12 -in.lengths,2B.A.,each 346.; 4 B.A. each 3d. SHELLAC, Flake per packet 66. SWITCH ARMS, 4 -LEAF.Splendid knob; hefty bush.Beautifully polished; with nuts and spring washer each1 / 6 TERMINALS -nottintacks. STANDARD Pattern,accordingto size,per doz., 1/6, 2/-, 2/6. TELEPHONE, per doz.; 2/6; No larger thanawineglass per dozen 2/ 6 WASHERS., 111A:SS, 2 to 6 B.A Per dozen 11d. WASHERS, COPPER SPRING, each 16.; per dozen 86. VALVE SOCKETS, with nut and washer each 16. VALVE PINS, with nut and washer each 16. but wonderful tohear VALVE HOLDERS, with 8 nuts and 4 washers each 10d. ON the strength of the above prices you have doubtless THIS wonderful little Loud Speaker surprises everyone. already decided to send us your order. But perhaps you want some scientific components also. Then take our advice - No grotesque trumpet. No cabinet required. in Buy the Best, don't be "Penny wise, pound foolish." itselfitisa thing of beauty, standing only four WE SUPPLY SCIENTIFIC COMPONENTS. inches high, and looking like a small tortoiseshell vase. CRYSTALS(J.L.Cartwright & Co.'s), Carborundum, Copper Pyrites,Galena,Bornite,IronPyrites,Silicon,Manganese, It floods the room with beautiful melody.No distortion. per box, 6d. Best Hertzite or Zincite, per box, 1/, WOOD'S METAL 6d. No vibratory noises. The sound is dispersed in all directions. FIXED CONDENSERS (J. L. Cartwright & Co.'s) each 2/ - GRID LEAKS (S. L. Cartwright & Co.'s), 1, 2,3, 4, or h-/ Spoken words can be heard with wonderful distinctness. HEADPHONES, Western Electric, 4,000 ohms per set -Western Electric (while they last), 8,000 ohms per set 32 /. -Special French, very sensitive Per set1?)//: Can be fittedto any receivingsetin a few seconds. LOUD SPEAKERS, Western Electric, 4,000 Mints cacti TRANSFORMERS, High -frequency plug-in type(J. L. Cartwright Simple and strongly made. Nothing to get out of order. & co.'s) double groove.No.1,350, 616; No.2,550, 7-; No.3,930, 7 / 6; No.4, 1,400, 8/-- No.5, 2,000, 8/6; No. 6, 3,500,El /-; No. 7, 10,000, 10/6. TRANSFORMERS. Low -frequency (J.L. Cartwright & Co.'s)...ea.21 /- POST 35/. FREE -Telephone(J. L. Cartwright & Co.'s), while they lasteach 121 - VALVES. Ediswan A.R. Type, each 15 /.; Marconi Osram, R. Type each 17/6 Complete with four feet of flex. and terminal leads. VALVES DUTCH 9/6 Demonstrations during broadcasting from 5.30 p.m. CASH WITH ORDER. Money backifnotentirely until 10 p.m. satisfied.Please remit ample Fostage, any balance returned. NOTE :The MAGNORA is only foruse with receiving sets which will operate an ordinary loud speaker. It cannot be used VICTOR BEST Co., with CrystalSets orSingleValveSets. .People who have The Component King, hearditusedwithonedetectorand two amplifyingvalves HUGE Dept. P, 24, LONDON ROAD,ADVICE havebeenamazedatthequalityand volumeofthetone. STOCKS MANCHESTER. FREE C. ErrtibiaTelephone Engineer (Opposite London Road Station). Telephone No.: City 6242: WASHINGTON HOUSE41CONDUIT -ST REGENT ST W 698 POptdar Wirelss Weekly, June 23rd, 19.23.

Harpenden Radio Society.* By the courtesy of the British Broadcasting Company, Ltd., members were recently enabled to visit the transmitting installation at Marconi House, and afterwards inspected the company'e studio at2,Savoy Hill, where Mr. Arthur Burrows kindly acted as guide. Other activities of the society have included an expedition to the London Terminal Air Station at Croydon, aswell asthe regular , meetings for lectures and practical work. Hon. " see. andtreas.,P.A.Anscombe, Wellington House, Harpenden. The club has been extremely fortunate in procuring as its technical adviser an expert of very many years' experience. Will all who desire The Editor will be pleased to publish concise reports of meetings of Wireless clubs and to learn more of this society please conununi- associations, reserving the right to curtail the repoit if necessary.Hon. secretaries are cute with the lion. sec., Mr. R. M. Atkins, 7, reminded that reports should be sent in as soon after a meeting as possible.Reports sent Eton Villas, Hampstead, N.IV.3. in cannot appear in this paper in less than ten days after receipt of same.An asterisk denotes affiliation with the Radio Soeiety of Great Britain.

Dewsbury and District Wireless Society.* Brown, takes place at the close of each lecture. CATALOGUES, BOOKS, Mr. Dransfield will continue his interesting Hon. sec., H. W. Winslow,3,Dock Street, talks on the elementary principles of radio, his Newport. ETC. subject being, " How to Get the Best out of Your Set."It is hoped that. the Central Liberal Club North London Wireless Association.* will be occupied by a record attendanee. Mr.V.J.Hinkley gavehis" Practical Hon. sec., Fred Gomersall, A.S.A.A. Demonstration of Valve Characteristic Curves." THERE are many crystal detectors on the Great interest was taken in the demonstration, market now that do not need constant South Dorset Radio Club. which was of considerable length, and each adjustment, but one worth mention is At a meeting at the Guildhall, Weymouth, on detail was carefully explained. April 27th, the above club was formed.The Hon. see., Mr. J. C. Lane. the " Perma-Fix," which, while it gives good business meeting was followed by a special results,is highly finished and extremely broadcastingprogramme, whichallpresent Ashton-under-Lyne and District Radio Society. neat.Being enclosed" in ebonite, it is per- enjoyed., The society's meetings during June will be fectly insulated and absolutely dust proof, The club has been fortunate in obtaining his devotedtogeneraldiscussions and various and will stand the maximum amount of Worship the Mayor of Weymouth (Councillor experiments, and it is hoped that any member vibration. This little instrument should W. J. Gregory) as president. who has anything to put forward or anydifficulty Weekly Morse Classes are being held, and lec- will bring it along, as it will be of interest tOthe certainly find its way toallcrystal set tures have been 'arrangedfor earlydates. remainder. users. Particulars of membership will be forwarded on Hon. see., James H. Marshall, 22, Warrington application to the hon. sec. Street, Ashton-under-Lyne. Hon. sec.E. B. Cartwright, 18, Newberry Messrs. Stanley Paul have just published' Terrace, Rodwell,. Weymouth. Barnet and District Radio Society. a very interesting new book on Wireless, The inaugural meeting of this society was held entitled " Radio Simplified,'l written by Hackney and District Radio Society. on Thursday, May 17th; with the president, Lewis F. Kendall and Robert P. Koehler. There were several interesting items at the Frederick W. Watson Baker, Esq., in the chair. There are nearly three hundred interesting weekly meeting of the above society on Thursday, There was a good attendance.After the May 31st, at the Y.M.C.A., Mare Street, Hack- president's address, the formation of rules and pages, with nearly 100 illustrations, mostly ney, E.8., presided over by the chairman, Mr. the enrolment of members was proceeded with. of circuits, eachhook-up " being printed H. A. Eptbn. When the business section had been disposed both diagramatically and pictorially. It isa Mr.Cunninghamreportedontheradio of, a demonstration was given by Mr. R. Cook, book that should appeal to the average demonstration which he had arranged the pre- the apparatus used being an Armstrong super - amateur, as it gives more details of the vious- Saturday in connection with the annual regenerative set with frame aerial.2 L 0 was dance of the National Cycling Union at Wood- well received. American circuits than have hitherto been ford.He stated that the demonstration was Hon. sec.,J. Nokes, Sunnysicle, Stapylton available over here. a completesuccess,and that through the Road, Barnet. * * ' * instrumentality of the Hackney Radio Society, The sole agents for the " Premierphone" he had arranged for a speech to be made from St. Pancras Radio Society. 2 L 0 on behalf of the Cycling Union. A club has been formed under the above title receiving sets are " The Lisenin Wireless Hon see., C. C. Phillips, 24-7, Evering Road, to assistall enthusiasts in St.Pancras and Co.," from whom we have received an London, E.5. neighbourhood in all spheres of wireless theory interesting catalogue giving full details of and practice. these sets, and also a full list of accessories, Tottenham Wireless Society. The subject of the meeting held on Wednesday, all of the highest efficiency. May 30th, was a debate on high -and -low fre- quency amplification.The chairman opened THE STORY OF "FETE GALANTE," Well known as the manufacturers of ale by describing the methods of H.F. Amplification, which will be broadcast via 2 L 0 on the further items being given by Mr. Ellis. Low - 22nd inst. types of electrical and wireless apparatus frequency amplification was next dealt with, The new one -act opera, " Fete Galante," bearing the trade mark " Grelco; 'the leading up as to what was the correct way of described by the composer, Dame Ethel Smyth, Grafton Electric Co.have issued a new winding the L.F. type of transformer, and the as a dance dream, isadapted from a story by the 100 page catalogue which deals with every comparison of various makes. Hon. Maurice Baring, and is not unlike the story Hon. sec.; S. J. Glyde, 137, Winchelsea Road, of " Pagliacci," though a little more fantastic type of electrical contrivance, well made and picturesque.The scene is laid in a moonlit and thoroughly reliable. Bruce Grove, Tottenham, N.17. garden, where " a play within a play " is acted before the King and Queen whilst the Fête * * * The Stoke-on-Trent Wireless and Experimental Galante is in progress.Pierrot, in love with Messrs. Burndept's new catalogue, besides Society. Columbine, is jealous of Harlequin, and in the At a meeting of the above society on May play is on the point of stabbing him. He alters detailing complete installations, also gives a 24th, Mr. T. R. Clark (vice-chairman) gave an his mind and quickly thrusts the knife into his full list of accessories, both for receiving interesting lecture," Adding a Valve to a Crystal own body.His self-sacrificeis prophetic of and transmitting. They recently put on the what is to be his real fate, for later on he sees Set." the Queen meet her lover in the moonlit garden Market averycompactportableset, Mr. Clark declared that for the Pottery dis- and he overhears their conversation. Suddenly stamped B.B.C., being suitable for the river trict, theresults of adding a low -frequency Columbineenters and imaginesthatitis magnifYing valve to a,crystal detector were not Pierrot, her own lover, who is with the Queen, for tennis parties. satisfactory, much better results being obtained and in her rage and jealousy she rushes off to * by adding a high -frequency amplifying valve. tell the King.The King refuses to believe Hon. see., F. J. Goodson, B.Sc., G.I.Mech.E., that Pierrot is the Queen's lover, and com- Joseph Hopley .& Sons have issued a mands him to tell him who it really is.Piermt catalogue of complete receiving sets and Tontine Square, Hanley. will not betray the Queen, and is taken to prison. amplifiers. Their unit system is specially Newport and District Radio Association. The feteproceeds with song and dance, worthy of note as an additional valve can At a general meeting, held at headquarters, when suddenly the stage becomes dark and always be added to an existing set without Memorial Institute, Queen's Hill, on Thursday, thereis silence, broken only by the frantic May 17th, Mr. J: T. Gray delivered an interesting scream of a woman. When the lights go Up, wiring alterations.Also of special interyst Pierrot's body is seen at the back of the stage is a two -valve " Regenerative Receivq, lecture on." Aerials," dangling from a beam, and the opera ends Buzzei- practiceforbeginners, under the with a " dance macabre." which is fully licensed by the P.M.G. for voluntary direction of Mrs. P. Hill and Miss broadcast reception. Popular Wil:eless Weekly, Jour' 23rcl, 1923. W39

Whyone Station only ?Bring all British Broadcasting Stations withinrange by getting a Marconiphone V2 No part of the Kingdom is beyond your reach. Soldata popularprice,the MARCONI- PHONE V2brilliantlyupholdsthehigh traditionsassociatedwiththe name "Marconi."Itgives results that are always perfectand sometimes amazing.

"C he 2' rtumph of the ,.`Naster nrind

Yourlocaldealercan supplyyou. Incase THE MARCONIPHONE V2 ofdifficultyapply to:- MARCONI'S WIRELESS TELEGRAPH COMPANY, LIMITED Marconiphone Department, Marconi House, Strand, London, W.C. 2

GRIFFIN WIRELESS SUPPLIES 80, Newington Causeway, Hop 1806. LONDON, S.E.1. THIS WEEK'S BARGAINS. " GRIFFIN " HEDGEHOG L.F. TRANSFORM-

ERS, 5-1 Ratio. Guaranteed unbeatable .. . 219- VARIOMETERS, 300-500 with Knob and Fixing Plato3/9 Single Ebonite Coil Stands ..2/4 H.T. Batteries, 60 -Volt, with Plugs . 9/6 4 -Stage H.F. Int-Valve TRANSFORMERS,. 150-.2,000 metres .. 1 at.. Taaaio3?rts%iEiaolas WATCH OUR WEEKLY SNIPS. No Junk-All Quality Goods-No Rubbish. OXQ Expert Advice Free. Lit Frei

1 WtreleseforAll -/6 1 John Scott -Taggart, F.Inst.P. you want to un- 2. Simplified Wireless 1 /- derstand Wireless, John Scott -Taggart, F.Inst.P. I'then yon need good, 3. flow to Make Your Broadcast Receiver 1 /6 dependable Books on John Scott -Taggart, F.Inst.P. thesubject.T hose Your Wireless WOODWORKING! 4. How toErect publishedby It adio Aerial Press Ltd.-and obtain- B. Mittell, A.M.I.E.E. 5. TheConstructionofWireless able at any Bookseller- Receiving Apparatus 1 /6 areproduced byan P. D. Tyers. organisation devoted 7. Row to Make a " Unit " TOOLS Wireless Receiver* 2,6 exclusively to Wireless E. Redpat h. Literature. You may 9.Wireless Val v es Simply be sure. therefore, that Explained 216 all Radio Press Books John Scott -Taggart, F.Inst.P. Our 1923 List (64 pages) of above, fully 10.Practical Wireless Valve Circuits 2;6 are thoroughly reliable John Scott -Taggart, F.Inst.P. and essential to every 11. Wireless Licences and How illustrated,issuretointerestyou. man who is taking more to Obtain Them l than a superficial 4:j1 Those printed in heavy type have been Enclose this advertisement with your interest in Wireless. published recently. Postage: lAd. per Book extra. application and a copy will be mailed ! toyouperreturnPOST FREE. tos ci GEORGE ADAMS (e!AT3'..) PUBLISHERS OF AUTHORITATIVE WIRE LESS LITERATURE J 4. D EVEREUX COU RT, STRAN D.W.C.2. 255/6, High Holborn, London, W.C. 1 Popular Wireless Weekly, June23rd, 1923.

and ispermitted by P.M.G. and yet uses reaction ?1)0 you advise the additional valve to be high or low frequency ? RADIOTORIAL. This circuit should fulfil your needs.It employs the second valve as a high frequency (H.F. ampli- fier) and will give greater range than will a low fre- AllEditorial Communications to be addressed The Editor, POPULAR quency magnifier.We- favour the tuned anode coil for the H.F. circuit, and the reaction from the de- WIRELESS, The Fleetway House, Farringdon Street, London, E,C.4. tector valve plate is coupled to this coil. The coils arc of the basket or honeycomb type, the latter always

being used when working on wave -lengths over 3,(l0 !". metres. The coil marked B may be dispensed with (the In this issue we publish a special interview with grid being taken direct to aerial and the potentiometer Miss Ellen Terry in which she pays a gracious com- to earth), but we advise its inclusion. Two double coil pliment to POPULAR WIRELESS.It was POPULAR holders are required.Should you dispense with the WIRELESS that was responsible for the suggestion coil B, you cannot couple C and D to A, as this will that Miss Terry broadcast her appeal, and we hope all UESTIONS cause reaction on the aerial.It is advisable to use 1. readers will assist our most loved actress in her noble potentiometer to control the grid of the H.F. valve, and- efforts on behalf of the blind. thus eliminate internal oscillation.It should have a' Arrangements have been made with Miss Terry resistance of approximately 300 ohms.'The condenser whereby she will present a signed photo of herself to C, is '0005 mfd. and C.. is 001 mfd.The coils, of all readers of POPULAR WIRELESS who subscribe course, vary for the different wave -lengths, butthe, 10 - or over to her fund.Details will be found on ANSWERS following will prove most satisfactory for the broad- other pages in this issue, and I sincerely trust the casting band of wave -lengths : A, about 50 turns B, response will be a great and successful indication of about 75 turnsC, about 75 or 100 turns :and 1), POPULAR WIRELESS readers' appreciation. about 50 or 75 turns, all wound with 26 S.W.G. D.C.C. Be sure to disconnect the potentiometer when the set R. F. S. A. (Radlett).-I have often noticed is not in use, otherwise the accumulator current will Our companionpaper" WirelessReviewand circuits in which a tuned plate is used, pro- Science Weekly " has scored yet another triumph, gradually leak away through its windings. Professor Albert Einstein, the famous originator of bably employing a variometcr, but some- the theory of relativity, has agreed to act as Special times just a coil and condenser, to give " iv - Physics Consultant to " Wireless Review and Science action'effects.Can regeneration take place, Weekly," and a special interview with him will appear shortly in that journal.Some of the greatest living as the coils are not coupled to the aerial in teientistscontribute populararticlestoour com- any way ? panion paper, and you will miss a weekly treat if you Yes, reaction can be accOmplished by this method fail to secure a copy regularly every Tuesday at the because regeneration will take place through the low cost of 3d. grid and plate of the valve, which form, as it were, a THE EDITOR. small condenser.If you care to work it out you can determine the required . plate inductance to cause such an effect.The formula is wattle complicated, Owingtotheenormousnumber ofqueries as you have to take into account the grid -plate receiveddaily from readers of POPULAR capacity of the valve.The formula is as follows: WIRELESS, I have temporarily decided to limit the number of questions sent in by one reader to 1 three.Readers are asked to keep their questions L as short and as concise as possible in order that W' (CmC +ern) the minimum of delay can he exercised in answer- ing queries.Until further notice three questions Where W = 2 rn, n being the frequency oftl e from one reader will be the limit for one letter. wave it is desired to receive. C'--- total capacity All questions should be addressed to POPULAR across the Inductance L, including the plate -filament WIRELESS Queries Department, Room 138, Fleet - capacity of the valve and the self capacity of the way House, Farringdon Street, London, E.C.4. inductance. Cm is the -grid-plate eupacity of the Readersare requestedtosend thenecessary valve, and u is the amplification factor of the valve. L and C are given in henries and farads.The postage for reply. method of finding the frequency of a given wave is to divide the wave -length in metres by the speed of " PLATO "(Hammersmith).- -Howmany Tire Editor desires to direct the attention of the wave, also in metres.As the waves of all wireless plates, moving and fixed, shall, I need for a stations travel with a speed equal to that of light, variable condenser of 1:101.mfd., the diameten his readers to the fact that, as.much of the in- that is, approximately 186.000 sulks per second, the formation given in the columns of this paper speed in metres will be about 300,000.000 per second. of the moving plates being 4 in. and 'usizei is of a technical nature and concerns the most So that the frequency of the wave willbe given by spacing washers of # in. thick ? Als'o number recentdevelopmentsintheRadioworld, A (wave -length in metres) copper foils for fixed condensers of '001 lab .some ofthe arrangements and specialities per second. and -0003 mfd. ? 300,000,001) described may bethesubjectofLetters With plates '036 in. thick you will need 16 movies Patent, and the amateur and trader would and 17 fixed plates for a. '001 mfd. variable condenser. be well advised to obtain permission of the " CA'SAR "(Milford).-Whieit isthebest patentees to use the patents before doing so. twovalve circuit that is not difficult to control (Continued on page 702.)

THE DIFFICULTY OF SATISFYING A DIVERSITY OF TASTES. 'WOriwolv 1-koRct`D MO1ORS

f

4/ 1''E ANTI - MoToRf sj

7,4;///

074

I. v.10 -vie s". t fymrirs RACIr44 114%.1-1(.0.7- 14014St, KEGPE STPSLS- Iri,(qess ireeko, June '.,rd, 701 gmHULLOad EVERYBODY=

ALL GOODS ORDERED BY POST VARIABLE CONDENSERSmust be accompanied by the Correct+ ASSEMBLED AS ILLUSTRATED Post Prices marked on each article. Drilled Ebonite Ends to fix yourself 1 /-per pair extra The quality and value given do not permit of them being sent otherwise. Approx. Cap. No. of in Mfd. Plates Price No rubbishy catch lines here. All real value for money. PLEASE NOTE. 001 57.6/6 Rubber Leaddn Wire (good), 12 yds., 1/9.By post, 2/6. Bell Wire,12 yds., 8d.By post, 1/- dozen. '0005 294/6 Twin Flex,12 yds.,1/9.By post, 2/ dozen. Switch Arms, 10d.,1/-,.113,1/6. Post, 6d. each extra. Rotax Accumulators, 4v.40 amp., 17:-.Carriage, 2/ cacti. '0003 19 3/13 Fixed Condensers. Good value. 11d.,1/3. Pcist,6d. each extra. H.T. Batteries, CO volt, 91-.Carriage, 2/- each. H.T. Batteries, 13 volt. 2:6.Carriage. 1/. each. '0002 13 2/6 Ebonite Valve Holders,10d.,1/-,1/3. Post, 6d. each Bask%xtr. Coils,ta " Oojah,"setof 7, 5/..By post, 6/- set. Basket Coils, 2/8 and 3,6set.Post, 6d. extra. '0001 7 2/3 Insulated Sleeving, 5d. and 6d. length. Crystals (Mounted), Llertzite, 1/..Bypost,1/6. Crystal Detectors, on ebonite, 1/5.By post, -2/-. Vernier... 31/9 Perikon Detectors,enclosed with 2 crystals,2/4. By Perikon Detectors, suit expensiveset,3/9.By post, 416. Enclosed Detectors,1/8,2/9,3/6,3/9. Post,1/- each NOT THROWN TOGETHER. Valve Pins, slotted. 7d. doz.By post, 1/.. COMPLETELY ASSEMBLED AS Aluminium Vanes, 22 gauge, 5d. doz.By post, 9d. doz. SHOWN TappedCoilson Ebonite,10 tappings, broadcasting size, price 2/6.Post, 1/- each extra. --ems .001 8,'- S.P.D.T. Switches on Ebonite, 1/9, 2/6...each. Post, 9d. D.P.D.T. Pt 2/6,3/6 each.Post, 9d. .0005 Accumulators,6 v.- 60a.,absolutely thebest,35/-. 5/11 Carriage, 2/- extra. Slider Knob and Plunger, 3d.By post. 7d. each. .0003 4/11 Terminals,W.O., Telephone,P.O. andallpatterns, including nuts and washers, not junk, 2 for 31d. .0002 3/11 1/6 doz.By post, 1/- doz. extra. Aerial Wire, 100 ft., 7'22, 2/11.By post, 3/3 hank. .0001 3,6 IntervalveTransformers, very hest,25/, Also 1216 each, 161-, 20/. each.Post, 11- each extra. Vernier Knobs, bushed 2 B.A. (best). 3d. each.By post, 7d. 3/3 3 Way CoilHolders, Ebonite and brassfittings,7/6. Past, 1/- eaen extra. Dubilier Condensers, at usual prices. ALL ORDERS BY POST MUST BE Telephone Transformers (R.I.),20/. Post,1/6. ACCOMPANIED by 113persetEXTRA. H.T. Batteries, 30 volt, 4/6; 36 volt, 51-.Post, 1/- each - OTHERWISE NOT EXECUTED - extra. Telephone Leads, lone.1/-.Post. 6d. extra. Filament Resistances,1/6,1/6,2/-, 216,3/-Post,9d. each extra. Transformers,L.F.(RadioInstruments,Ltd.),25/.. Post,11-. " BRUNET " FRENCH PHONES D.C.C. WIRE STOCKED 4,000 ohms (different headbands) (post 1/6 pr.) 22,6 and 25"- 22, 24, 26. 28 gauge.

B.B.C. Phones, best quality . . (post 1/6 pr.) 17/- and 19;6 T.M.C., 4,000 ohms, stamped B.B.C. (post 1,6 pr.) 24,6 pair. TO CALLERS ! (Phones supplied by T.M.C. themselves, taken from expensive sets to clear.) I sell everything you want for your ERICSSON E.V. (not the imitation phones with home - madeSets. No junk. No wooden earpieces) Double Headphones per pair 17/6 (Stamped B.B.C.) Post 1/6 pair extra. cheap job linesAll low in price, but first-class quality. ON FRIDAY, SATURDAY AND SUNDAY SPECIAL CHEAP PRICES TO CALLERS TRADE SUPPLIED

al11111111111111111111111111111r2 an = Phone : GERRARD 4037 E- RA = RA RAYMOND -OPEN 9 to as en RA = Saturdays - 9 to 6 p.m. EF-- h.)! = Sundays-- 11 to 2 p.m. = RA 27, LISLE STREET, W.C.2 !IA RA anF115.4 P(711SARAFFIRAIX7IRAFAXARAFARARAPAPArAFARIWARAIKAITAXAVARAWAR1PARAVAFAVARAglIG,FIFARIWARA RA RARARARA RARARA$A RA RARARARARA VARRSX,IRAPITPtligNR71 KIII,AUAtiadlIALIAttilt(J1 70.2 Popular Wireless Week% June 23rd, 1923.

them out you should be in possession of an experi- RADIOTORIAL mental licence, a they entail structural alteration of the B.B,C. set.'To tune in the set, you adjust the IT'S FREE crystal as usual, switch on the valve, and connect up QUESTIONS AND ANSWERS. the H.T. battery.Then tunethe valve netto the wave -length required, and at the same that tun" A NEW CATALOGUE (Continued from page 700.) the crystal set.You will probably find that the positions of the tuning arrangements on the crysta LARGE, WELL ILLUSTRA- set are different from what they were before you For the- fixed condensers, using mica '002 in. thick as added the valve. and they Will now read a much higher, TED-MOST INTERESTING- dielectric, use 6 plates 2 by 1 ems, for '001 nafd., and wave -length.If your crystal set is only provided:. YOURS FOR THE ASKING. 2 plates 3 by 1 ems. for '0003 mid. for the same maximum wave -length as the valve set, * . * you will find it necessary to add a small loading coil c in series with the connection between the aerial' WIRELESS GEAR SUPPLIED D. N. (Harrogate).--lf I use my reaction terminal of the crystal set and the 'phone thminid coupled to the tuned anode coil or to an H.F. of the valve set. A coil suitable for lifts would be onej, ON DEFERRED PAY- of 40 turns, 24 D.C.C. on a cardboard spider former transformer, will I have to vary it at all when with 11 in. diameter centre and nine slots.If the MENTS-JUST A SMALL I change the wave -length ? telephones of the valve set are connected to the: In order to get the best out of your set you will find negative side of the H.T. battery, your best plan would -, DEPOSIT AND BALANCE this necessary, and you should have some method of bete short the 'phone terminals and connect the adding inductance to the reaction coil for use on the to the usual terminal, the H.T. + to the earth terminal IN MONTHLY PAYMENTS. high wave -lengths.For this purpose a little experi- of the crystaPset and the aerial of the crystal set to the: menting will he necessary before you find suitable H.T. + terminal of the valve set. In this 'ease it would values for the reaction coil and the added inductance. be necessary to remove the H.T.-by-pass condenser AN EXAMPLE OF VALUE OFFERED. -Usually about seventy or eighty turns of 38 S.W.G. from its position across the H.T. terminals. D.C.C. on a basket fonner,centre diameter 11 in.,will be * * a fairly approximate value for the reaction coil itself. This must not be taken as exact, as it will vary con- T..N. K. (Chatham).-It seems to me that Fellows Two -Valve Set. siderably with different. sets.The anode or trans- there is no reason why a large variety of 'vari- Absolutely Complete withBatteries. former will be found to be most suitable if wound able condensers should be made when itis basket fashion, and the two or three coils are mounted Aerial,Earth,Insulators, 'Phones, in a three -coil holder so that the coupling can easily evidently possible to arrive at any value by Valves. Tax Paid, B.B.C. Stamp. Pol- be varied at will. juggling two or three variables about with

ished Oak Case. Usual Price £15 I0s. * * * two or three fixed.One last point :Is it pos- R. D. K. (St. Albans).-Across which ter- sible to obtain small value variable condensers Cash £11, or £2 deposit and minals of my crystal set should I place a fixed by placing small fixed condensers in serieswith 9 monthly payments of 21 -. condenser large variables ? The point mentioned in thefirstpartof your A1901 mfd. fixed condenser can be placed across question certainly could apply 'to -the experimenter the 'phones and will often clarify signals considerably. but -would hardly be a convenient method to a) ply Best and Cheapest Wireless Supplies. Should you desire to increase the wave -length range to complete sets.The second part of your question of your set by about two hundred metres or so, a small brings to our mind a useful arrangement embodying fixed condenser may be placed across the aerial and If two condensers are THE SERVICE CO., LTD the principle in question. earth terminals, but a variable condenser is to be pre- placed in series the resultant capacity will he some 289-293, HIGH HOLBORN, LONDON, W.C.1 ferred in this respect, and '001is rather a 4arge thing less than the capacity of the smaller. Therefore capacity to use for such a purpose. withn variable condenser of '0003 mfd. With a switch TOWIRELESS EXPERIMENTERS. PATENT YOUR * * so that the smaller fixed condenser could be shorted INVENTIONS. when not required, the result would be that in the They may prove very valuable. Particulars and consult. "PIP" (Bridlington). --I intend making a latter. case there will be a variable capacity -of some- Monstree.BROWNE & CO.,Patentagents, valve set that may be used with the promised thing up to '001 mfd., but if tar: switch was opened, 9. Warwick Court, Holborn, London, W.C.1.Estab- " Home Constructor's Licence." Presumably and the small fixed condenser brought into series, the lished 1840. Telephone': Chancery 7547. greatest capacity value possible would be something I shall be able to make any set as long as it smaller than '0003 mkt.. 110023 to be precise. and the --Ni...Nr-MOUBLE YOUR SET%.,,"....,", does not cause trouble to my neighbours, and I adjustment of the variable e Mdenser will then be withthe" VARI-AERIAL." comprising: pay the necessary royalties.Can you recom- something up to '00023 mfd. That is an extreinely Long and Short Aerials,2Directional Loop useful method of obtaining very fine tuning.In the Aerials, 2 Loading Coils, 1 Minutely Critical mend a suitable two (or possibly three) valve first case the inductance is varied, and the capacity Variometer, Reaction Unit, and Regenerative set that will get all British broadcasting, Paris by means of the variable condenser with the small Vario.Complete in 3 Models: A. 2 ft., 21/-; and the Hague ? fixed condenser shortedThe latter value is brought B. 2 ft.6in.,25/-;C. 3 ft., 30 -.Packing, The accompanying circuit will enable you to hear down very low and the inductance increased. and then 1/-. Trade enquiries solicited.-Abbey Engi- all broadiasting, and should get Paris and the Hague the small fixed condenser is brought into series so that neering Co.(ScientificInstrument Section), quite clearly.Permitted inter -valve reaction is ob- a wide range of fine capacity tuning is available to 11 & 12, Great Sutton St.,Clerkenwell, E.C. tained by coupling the coil D to the tuned anode obtain the sharpest possible tuning. coil, marked C. The coils may be of the honeycomb What is a Vernier condenser ? type, and this type is to be preferred to the basket form, A variable condenser with a fine cog and screw The success of your instrument de- for these latter become too large and inefficient when adjustment for micrometer capacity tuning.The used on wave -lengths above about 3,000 metres. term is frequently applied in error to variable con- pends upon the Incomparable Crystal Under 3,000 metres you will find basket coils just as densers of small value owing to the fact that the good.The condenser across B should be of about function of these issimilar, butthe methal as '001 mfd. The others are all marked. Two coil holders detailed in answer to your first question. and placing " PLATINITE" of the double coil type will be found necessary.Po- For maximum efficency andettendedranp,e. tentiometer grid control of the H.F. valve can be them in parallel for the same purpose is different. Price1'-and 1'6. TRADE TERMS. employed if desired, the connections being shown in J. W. COX, M.P.S., MINERALOGIST, another diagram of this issue. C. A. B. (Pembroke).-Why is it that car- 732,StratfordRoad,BIRMINGHAM. borundum requires a voltage to be applied across it 'before it will operate successfully, unless the signals are very strong ? THE NEWTONIA WIRELESS FACTORY This is because carborundum differs from most FOR ALL WIRELESS PARTS AT FACTORY PRICES conductors of electricity in a very peculiar way. 13 15, WHITCOMB ST., W.C.2. If a graph is drawn plotting the voltage against the Regent 5469. LONDON. current, in an ordinary conductor it will be approxi- mately a straight line.This means that the current Beginner's Guide to Wireless increases an equal amount for each equal rise in Explains, in plain everyday language, everything voltage.In the case of carborundum, however, the you wish to know about Wireless Telegraphy. graph rises slowly in a straight line until it reaches a HOW TO ERECT, CONNECT, AND MAKE point called the " critical voltage," when it turns the apparatus required, and fullinstructions upwards and continues in a steep straight line.At for making coils, tuners, and complete valve thiscritical voltage the resistance of the crystal and crystalsets.Instructions and diagrams becomes less, and for the same increase in voltage we for a two -valve receiver are alone worth tour have a much larger increase in current.When a times cost of the book.112 pages, priceis., carborundum crystal is used for rectifying, it is placed post free.-SAXON RADIO CO.(Dept.14), " -VALVE-CRYST " (Brixton).-I , havea so that the aerial voltage will be added to that of a South Shore, Blackpool B.B.C. valve set and want to add it, to my battery which is always applying the critical voltage across the crystal.As soon as tide voltage is in- crystal set, but making as few alterations as creased by the slightest aerial voltage that caused possible. What is the best way to connect the by incoming waves-it causes a sudden increase in , two together ? current through the crystal..This sudden increase FOLLOW THE CROWD produces a sound in the 'phones, and thus the sinnals We presume that the B.B.C. set is a one -valve, are produced.If the crystal has not this critical BOUND EACH -DAY FOR with tuning coil, etc., enclosed, and that the crystal...voltage applied, the small extra -voltage from the set also has a tuning coil covering the same wave- aerial would only produce a very slight increase in lengths as the valve set.If it covers more-that is, current, which would not be enough to actuate the SPENCER'S STORES goes higher-so much the better. In the first place, the 'phones satisfactorily. grid, leak and condenker in the detector panel should * * 4-5, MASON'S AVENUE, bc!, shorted or removed, andthe grid of the valve BASINGHALL STREET, taken direct to the aerial terminal. Then. assuming F.C.(Harrow). -Why- isitthat upon LONDON, E.O. 2 :: that the 'phones are in series with the H.T. battery breaking a circuit in which there is a current and on the positive side, the by pass condenser across flowing, a spark appears at the break ? SPECIAL OFFER. the 'phone terminals should be removed, and the FR ENCH PHONES.-Guaranteed-18s, aerial and earth terminals of the crystal set connected This phenomenon is explained by what is called to the 'phone terminals of the valve panel.These are the self-induction of a circuit or conductor. When a PRICE LIST POST FREE. all tha alterations necessary, but in order to carry (Continued on page 704.) V

Popular WiAess Weekly, June 23rd, 1923 702

WIRELESS !WIRELESS! WIRELESS !and EVERYTHING for it We insiston being the

DON'T PAY MORE Cheapest in Great Britain. NOTE. We areexclusively WIRELESS NOT DABBLERS! Reliable goods at less than so-called Wholesale Prices (to the Public) " DON'T BE BLUFFED."

CANADIAN BRANDES HEAD- WASHERS, 4 B.A per doz.Id. SLIDER ROD,brass, 15 in.long, 1in. PHONES. stampedB.B.C.Ourprice WASHERS, 2 B.A per doz.lid. square, drilled each3111. perpair 22/6 FILAMENT RESISTANCES, smooth SLIDER KNOB each 2d. SoDPE HEADPHONES,4,000 ohms action, marvellous value 2 /ii SWITCHES ON EBONITE,S.P.S genuine,ourprice 15/8 -With engraved dials 2111 !!qualitythe best) -each THOMSON HOUSTON HEADPHONES, CONTACTSTUDS, with nuts and SWITCHES ON EBONITE, S.P D.T. (French) 4,000 ohms, our price 18 / 11 washers per doz.5d. (quality the best) . each1111 BROWN'S FEATHERWEIGHT HEAD- STOPS,with nuts per doz.7d. SWITCHES ON EBONITE,D.P.D.T. PHONES,4,000 ohms, our price 27/11 TERMINALS,withnut & washers, (quality the best) each219 each 16- 11d. & 2d. CONDENSER SPINDLES,allsizesin MARCONI R VALVES each 4d. BULLARD " ORA " VALVES 12 / 9 EBONITE KNOBS, 2 B.A , 2d., 3d., & stock, from eachlid. SPACING WASHERS, large per doz.25d. SCREWED ROD,2 B.A.,12in.long, DUTCH VALVES 8/3 SPACING WASHERS, small per doz.lid. each 3d. EDISW AN VALVES 12 / 3 CRYSTAL CUPS. 2 screw eachId. SCREWED ROD,A S.A.;12in,long, (All Guaranteed New). CRYSTAL CUPS. 4screw...... -.. _ each 2d. each- 256. L.F. TRANSFORMERS,Ratio 5 to1. FIXED CONDENSERS, till capacitics,each11(6. RUBBER -INSULATED LEADING -IN All guaranteed.(Postage1/.1each 11 / 3 EBONITE,cut to any size by machinery WIRE per yard116. CRYSTAL DETECTORS,Adjustable 1/35 while you wait per lb.316 INSULATORS,white reel, 2 in.,each CRYSTAL DETECTORS, enclosed in TELEPHONE TERMINALS,nuts & 11d. 'i per doz.1 / 4 Celluloidunbreakable case 2 / 3 washer. eachlid perdoz. 114 INSULATORS,whiteEgg, each2d., SWITCH ARMS,best makes 1 / 3 &91d. W. 0. TERMINALS, nuts & washer, per doz. 1;9 AERIAL WIRE,7/22, guaranteed bard - each2d . per doz.1 / 9 SPECIAL HERTZITE CRYSTAL, drawn copper, 100 ft.(postage1 / -1 2 / - PANEL BUSHES,drilled,each 11d., large piece each1016. CONDENSER VANES,fixed or moving, Per doz. 1 /4 WOUND INDUCTION COILS (Post - Perdo-, 31d. TOP CONDENSER,bushes,eachld.; 9c1.1. Real GoldCat'sWhiskers each 2d. per doz. I Id. a,12 x 4 9 x 4 8 a ly 6 a 36 a 2 per doz.1; BOTTOM CONDENSER,bushes,each 2/8 2,5 212 1 /II 1/8 CONDENSER SCALES. 0 to 180 eatM 316. 16 per doz..9d. TAPPED INDUCTANCE COILS,20 IVORINE LABEL SET, 12different VALVE LEGS,nut &washer, each 16.; tappings wound to 1,600 metres each2 / II readings ...... the sot71d per doz 10d. V ARIODIETERS(TubeType)complete BATTERIES, 41volt, 3d. each doz.2/9 VALVE PINS,nut & washer, each 16.; withknob 3 / 11 NUTS, 2 B.A per doz.24d. per doz. 9d. DOUBLE. 'RHONE CORDS,full length 1 141 NUTS, 4, 5, 6 & 8 B.A per doz.2d. PLUNGER SPRINGS, complete each16. BELL WIRE. 11,171 .4,,t,p,r,12 yds 6d. 44 ELKAY "WIRELESS CO., 225, Bishopsgate, London, E.C.2. Half -day closing, Saturdays. Trade Supplied -Accumulators charged on premises. Open Sunday: 11-2.30. Please remit ample postage. Note new Telephone No.: Central 8544.

"WIRELESS REVIEW AND SCIENCE WEEKLY." The New Compan;_on Journal to "Popular Wireless.V! On Sale every Tuesday Price3d.

" WirelessReview andScience Weekly -has the strongest advisory and contributing staffof any wireless and science journalinthe world. The chief Scientific Adviser is Sir Oliver Lodge, Every F.R.S., assisted by many famous experts. 91 article in " Wireless Review and Science Weekly bearsthehallmark ofauthorityand makes an instantaneous appeal to everyreader. Order Your Copy NOW ! 701 Popular Wireless Weekly, June 23rd, 11123. 11,111MalICIMINIM, RADIOTORI AL QUESTIONS AND ANSWERS. RECENT WIRELESS ELECTRADIX RADIOS (Continued from page 702.) Immediate Delivery INVENTIONS. current hasbeen flowing ina circuit, and the circuit from our Huge Stocks. is broken, the magnetic field that has been set up by The following abstracts are specially con- the current around the wire collapses.The collapse tributed by Mr.HaroldJ.C.Forrester, Everything from a Wave Meter to of this field will induce a voltage into the conductor, in the same way as the cutting of a coil by a mag- Fellow of the Chartered Institute of Patent an Earth Clip. netic field will induce an E.M.F. into that coil.For Agents, 88-90, Chancery Lane, W.C.2. an example, take an induction coil or a buzzer. The The best equipped City depot. sparking across the make and break is due to the COME AND SEE US. voltage induced in the coils by the collapse of the magnetic field around the windings.This induced 9, Colonial Avenue is first opening on voltage is always such that it tends to continue the Grant of the following Patents can be leftintheMinorics,nearAidgate flow of the original current, hence the extra voltage the full Station, Metropolitan Railway. causes the current to attempt the jump of the air opposed and printed copies of gap when the circuit is first broken. specifications purchased. LESLIE DIXON &Co..4 I:en 41G6 9, Colonial Avenue, London, E.1. " Q0ERY"(Harrow).-How is the inductance of a solenoid coil measured ?What data is 196,062.-BRITISH THOMSON- necessary ? HOUSTON CO., LTD.-SIGNALLING.- The inductance of a solenoid coil is measured in Hit it anywherel, terms of a unit called the " Henry," which is such High frequency signalling, in which dots that the application of a difference, of potential of and dashes are of similar length, but different one volt will cause a current change of one ampere in frequency,is effected by connecting the one second.The " microhenry:the one -millionth of a henry, is often used instead of the " henry." aerial to two different H.F. transformers, which is often too large.You will require to know either of which may have its secondary the diameter of the coil, the length and the number You want the best turns.The following formulais an approximate short circuited by a tapping key to allow CRYSTAL! method of calculating the inductance : the other to transmit alone.The aerial is No more searching for 4 rA x N' simultaneously tuned_ to the transmitted points-sensitive every- L X 10-' henries frequency and mechanical means may be where. Unaffected by provided for transmitting or receiving the moisture or) handling. When : signals. Mounted or Unmounted. A is the sectional area of the coil in sq. erns. I -each post free. Trade supplied. N is number of turns 1 is length of coil in centimetres : 196,085.-G.P. GRENFELL & J. THE THAMESMOUTH RADIOMFC. CO. L is the unknown inductance. ROBINSON.-DIRECTION FINDING.- SOUTHSEA AVENUE, LEIGH, ESSEX. Bearings may be gauged with ordinary To take an easy example : Given a coil of diameter 10 centimetres length receiving apparatus co-operating with a 100 centimetres and of 2,000 turns. rotating directional beam, distinctive signals BUY "AMAX" CRYSTALS. The sectional area is found by the formula : being given when at the cardinal points, RERTZITE. PERMANITE, TALITE,1/6 perbox. 'WC ELECTRONITE, ZINCITE,1/- perbox. GALENA, 22 either by the beam or another transmitter. BORNITE, SILICON, COPPER -PYRITES, 6d. per box. So that A = - X 5 X 5 sq, cuss. The bearings are estimated by observing WONDERFUL VALUE. 7 See thatour Amax " label is on the box, 550 time intervals or relative intensities. containing from 2 to 6largeCrystals. . A = - sq. eras. SOLD BY ALL DEALERS. Now substituting for the formula given above : 196,188.-A. W. KNIGHT.-INDUCT- THE AMAX CRYSTAL CO., 4 x 22 X 550 x 2000' Red Lion Rouse, Red Lion Ct., Fleet St., E.C.4. ANCE COILS.-A cylindricalinsulator 7 7 is split longitudinally and the two halves WIRELESS INVENTORS L = x 10 'henries are spring pressed apart to grip the inside 100 Fatents and Trade Marks, Advice Hand -book 1936000000 of a coil.The cylinderiseccentrically and Cons. free.-B.T.KING, Regd. Patent mounted upon a pin carried by a rotatable Agent (G.B. & U.S.A.), 146a, Queen Victoria 49 - henries St., E.C.4.'Phone: Central 682.38 yrs. refs. 10' pillar and the coupling between two or 1936 - more of such coils maybe varied,by rotating THE FAMOUS 4,000 OHMS L = henries the pillars. 49000 AVON" br 8z " -'039512 henries lELE.A.D1701-10NIE or 39,512 rnierohenries approx. 196,273.-MARCONI'S WIRELESS NEEDS NO BOOSTING. (For the sake of simplicity the correction factor TELEGRAPHCO., - LTD.-DUPLEX 0 CA (postfree) has been oinitte41.) SIGNALLING.-Two signals of different UTILITYCONCESSIONAIRESGa RADIO - CO.. ". HYDROMETER " (Totnes).-I have been frequencies received simultaneously may BANK CHAMBERS, HIGH HOLBORN. LONDON. W.C.I. advised by a friend not to rely upon my be passed over a single line, by connecting TRADE ENQUIRIES INVITER. voltmeter for testingthe conditions of to the aerial, circuit two detector sets which accumulators, but to use a hydrometer. deliver the signals at two audio frequencies Why is this?What should the hydro- (say 700 and 1,200).These are passed to meter give as a reading? Your friend is quite right.It is always best to filters of inductances in series and capacities test the conditionofcells'with a hydrometer, in shunt which cut out all frequencies above" because the density of the acidsolutionis the 850 for one, and below 1,050 for:the other, best indicator you can have as to the state of the accumulator.The more dense the solution is, the the signals then passing to the line. higher, the amount of charge in the cell, provided., of course,. that tireright strength of acid has been placed in the cells originally.A voltmeter, 196,295.-GES. FOR DRAHTLOSE however, may give a high reading even .when the TELEGRAPHIE. - TRANSMITTING. - cellsare run down.The voltageisthere, but there is no power behind it, and if you attempt to The grid circuit of a generating or power draw current, the voltage drops immediately. The valve has two branches, one containing a hydrometer readings on an average should be, fully condenser and couplingcoil.The other charged, about 1.215, and they should never be allowed to drop below about 1.18. A Hick's suction passesdirectcurrenttothefilament hydrometer is a very useful type to use with regard through an H.F.choke, and may con- to accumulators, and the reading is taken from modulator threecoloured beads, yellow,blue,and purple. tainasignalling key or a Yellow floats at 1.17, blue at 1.18, and purple at 1.2. having a condenser -resistance' shunt and a microphone to vary its grid potential. AshleyWireless CRYSTALEN Make your crystal as reliable as a valve 196,368,-S.R.MULLARD.--VALVES. Telephone Co Ltd. A little CRYSTALEN brushed over your The tension of a filament is adjusted and in- crystal will double the efficiency of your set by dicated by adjusting a spring which carries ogRenshaw St. Liverpool giving greater volume and quicker adjustment. Results wonderful. Price I - per bottle post free. a hook engaging thefilament and co- Sole (0) Avenis Testimonials may be seen at our Office.Obtain- operates with an indicator.The spring may able only from EVANS & BARRETT, 3, WARDOUR ST., LONDON, W.1. be helical and mounted with_ 'the indicator on the stem of the valve. Rift Julie 2:3111, 1923 POPULAR WIRELESS WEEKLY. 111

NOTICE to all engaged in "ENGINEERING

1.;tilt141

cmrarf COLL Dictionary LLUITRATIOLNICYCLOKIDIC DICTIONARY OF ENGINEERING ; CIVIL MECHANICAL ELECT RICAL MOTOR. ETCETC.. FREE. PART 1.

To extend the name of the Bennett College to everyone engaged inthe different branches of Engineering, we are, publishing an IllustratedDictionaryof Engineering,inabout24monthly parts.You rat have each inpnthly partns it Lumes out. FREE -3d. Postage only to pay. The Dictionary is free to those engaged in any of the I following trades: Engineering. Civil, Mechanical, Eleg.

trical,Structural,Motor, Sanitary,Boiler,Internal Combustion,Draughtsmanship,Marine,Shipbuilding. I NavalArchitecture,Building,Architecture,Quantity I Surveying, Aviation, Chemistry, Foundry Work, Metal- ! !orgy, Matriculation, Mining, Surveying and Levelling, 1 Telegraphy, Telephony, Wireless, and the conditions are i that you send your name and address, your age and 1 neenpation, with three penny stamps (to rover Postage/. We shall I writing your name and address very clearly. I hen place your name an our Free List and send you : I Part 1 atonce.The otherswillbe forwarded as . II. issued.Address your application fully to: I

I I I (Do not fail to give Department D 106, 1 (heparticularsre- . T4e hired and use The Bennett College, ! 6 -full add,...) this'Sheffield.

This is an excellent crystal receivingset,whichgives very good results on all wave lengths from 300 to1,500 metres, and is suitable for Perfect results receiving broadcasting from shipsandlong - distance with stations. The adjustments are simple and easily made, andthe Indoor Aerial silicon crystal detector well maintains its sensitive state. for No batteries are required. The set is sent out complete and includes 100 ft.coil of 7/22 stranded copper aerial wire, 2 shell insulators, and one pair 4,000 ohms double headphones. Z.1.12°6 Every set is tested and guaranteed to receiving broadcasting up to15 to 20 The Ceebee No. 3. miles, and Morse signals from much THIS highlyefficient instrumentis greater distance. given a most thorough test before the "FELLOCRYST " isBritish Made throughout. TRADE dispatch, and is guarantv.d to give Approved bythe B.B.C. and Postmaster General. perfectreceptionoverabroadcasting PRICE Complete- £3 : 15 : 6 SUPPLIED rang?.of 25 miles. Wonderfulresults Inclusive of all taxes. Postage 1:6 extra. can be heard at our Showrooms on this Extra 4,000 ohms double headphones...21 6 identical set attached to an Indoor Aerial. Inclusive of all taxes. Postage 1- Price £1:12: 6 including Ro rallies FELLOWS MAGNETO Co., Ltd. LONDON, N.W.10, Telegramq: FOWLER & BRIGDEN WILLESDEN The0-1. " QUIRMAG,'"PHONE, LONDON 1 30, Ruston Road, King's Cross, London, N.W.1. Phone .MUSEUM 4827. Amplify Your Crystal Reception

Low frequency amplification, added to a crystal receiving Set within its effective range, will increase the volume in accord- ance with the number of valves used for amplificAion, without producing distortion or detracting from the quality of reception. One valve will give comfortable telephonic reception while two or three valves will give excellent loud speaker reproduction.

[Pputo by swohle.

Mr. Tudor Davies, as Radolf in "La Baheme." kS,,p",:to Reproduced by exclusive permissionofthe, British NationalOperaCo.,1,1.1. VO-kitPV

/444% An ideal "STERLING "com- t=110t` bination for reception of the -1,'*141 gd'1011 opera .broadcast from Covent Summertime evening in the garlcn.Broadcast reception of Opera from Covent Garden Garden is with "STERLING" .No. 1 Crystal "StA,-2-ValVe L.P. Amplifier, and LOud. Speaker. No. R. 1200 "STERLING" No. 1 Crystal Set . £617 6 No.R., 1533 "STERLING" .Single Valve Low Frequency amplifier Unit £4 10 0 ' " R" Valve for Amplifier, extra. No. S 7221 6 volt, 20 amp. hour

Accumulator £1 196 66 volt High Tension Battery 150 No: R. .1284" STERLING "

Loud Speaker £6 2 6 If required in place of Single Valve Amplifier No. R 1537, Two Valve do. .. 132 0 No. R 1541, Three Valve do. .. £12 5 0

Will enable you to derive the greatest possible pleasure frJui 'listening -in' to GRAND OPERA AT COVENT CARDEN and will introduc..you to one of the highest forms of musical 'art.. You No. R 1533 No.12 1209 -will then be mare than ever anxious to hear the -actual performances. I Tobeobtained of all electrical dealers and stores. STERLING TELEPHONE AND ELECTRIC CO., LTD., Manufacturers of Telephones and Radio Apparatus, etc. (WHOLESALE ONLY). TELEPHONE HOUSE, 210-212, TOTTENHAM COURT ROAD, LONDON, W.I. Telephone: Museum 4144 (7 lines). Telegrams: " Cucumis, Wesdo, London." BIRMINGHAM: CARDIFF: MANCHESTER: NEWCASTLE -ON -TYNE: WORKS: 150, Edmund Street. 10, Park Place. 14, St. Peter's Square. 9, Clavering Place. Dagenham, Essex.

Printed and published every Friday by the proprietors The Atnalgaumted Press (1922), Ltd., The Fleetway House, Farringdon Street, London, E.C.4. Advertisement Offices! Messrs. J.II.Lile, Ltd.,4, Ludgate Circus,London, E.C.4.Registered as a newspaper and for transmission by Canadian Magazine Post.Subscription rates: Inland and Abroad,17/4per annum, 8/8 for six months.Sole agents for South Africa: The Central News Agency, Ltd.Sole agents for Australia and New Zealand: Messrs. Gordon & Gotch, Ltd.; and for Canada: The Imperial News Co. (Canada), Ltd. Saturday, June Urd 1921. 11,1t POPULAR WIRELESS WEEKLY, JUNE 30, 1923. REGISTERED AT THE G.P.O. AS A NEWSPAPER SPECIAL PICTORIAL NUMBER

^ z PRICE 3d. No. 57.Vol. III. SCIENTIFIC ADVISER: SIR OLIVER LODGE, F.R.S., D.Sc. June 30th, 1923.

This amateur station assembled by Mr. E. Clay, of Finchley, receivestelephony from America.

FEATURESIN THIS ISSUE. Communicating With Trains. Some Pictorial Valve -Crystal Circuits. A Super -Selective Receiver. Page of Practical Ideas. The New Eliminator. A Chat About Transformers. And articles by Sir J. Kenneth Mackenzie, Leslie McMichael, M.I.R.E., Rex Palmer (Director of the London Broadcasting Station), John Hope Fellows, etc. June 30th, 1923 ii POPULAR WIRELESS WEEKLY.

THE SUPER -SENSITIVE S. T. 100TWO -VALVE RECEIVER. For building this set obtain THE FAMOUS

The illustration showsoneof The complete set or components the Receivers built up in panel or individual parts can be sup- form. plied from stock.

L s.d. s. d. 1 5 -16th in. Thick Ebon- 1 100,000 Ohms Mullard ite Panel, drilled and Resistance, List No. 51 30 engraved - - 176 TRANSFORMERS atria -- Clips for above - 1 0 axtik-a.er COQ END rel JO MTh wooed 2 Variable Air Condensers Iratilue 1 '002 Fixed Condenser, '0005 mfd., List No. 15, List No. 18 - 30 at 211- each - -2 20 1 '0002 Fixed Condenser, 2 Audio Frequency Trans- List No. 16 - 26 formers, List No. 34, at 1 2 -Coil Holder- 126 25/- each - -2 100 1 Igranic Coil, No. 50 52 2 FilamentRheostats, 1 Igranic Coil, No. 75- 6 4 ohms, at 5- each- 100 5 10 Lacquered Terminals, 2 ValveHolders,List necessary screws, nuts, 26 No. 62, at 1:3 each- etc. - 36 1 R.I. Crystal Detector, 1 Mahogany Case- 12 0 with micrometer adjust- ment, in glass case - 86 8188

Our Components have 25 years' Radio Experience behind them. SEND FOR C 1 I11.0(, E TO -DAY. RADIO INSTRUMENTS, LTD.,12, Hyde Street, New Oxford Street, W.C.I. E.P.S. no.

-The "BROWN" HESTAVOX II LOUD SPEAKERS 2 -Valve Reaction Receiver with new improved Curved Horns THE requisites of a Loud Speaker are pure tone, clear articulation, and good volume ofsound. The BROWN Loud Speaker possesses all these qualities in a marked degree. Type H. z has been designed to meet home requirements, both as to volume of sound and price. PRICES H. 2 (Small), Low Resistance. H. 2 120 ohms, height 12 in.£3 0 0 (small H. 1 (Large), Low Resistance, 120 size). ohms, height 21 in. £6 5 0 Height High Resistances for either size, 2;6 to 5:- e xtra 12 in. THE BROWN MICROPHONE AMPLIFIER £5:6.6 This amplifiergives a magnification much greater than that obtained from a two -valve deposit secures immediate delivery of the above wonderful instrument, whichwillreceive ALL BritishBroadcast amplifier. Telephony, and is stamped B.B.C., and approved by P.M.G. Catalogue, post free, gives you details PRICES. The balanceis paidintwelve monthly instalments of of our Wireless Headphones, Loud Low Resistance (12o ohms input) £600 16/7 each on the usual hire purchase system, including Speakers ,Transformers &AmplifiersHigh'Resistance (2,000 ohtn. input) £6 26 Insurance. Wireless Receivers and Accessories to any value Attractive Showcard of Our Mandactures will be sent to all Retailers upon Request, arc supplied on the same terms. Sole Manufacturers: Write at one?. for Catalogue and Full Particulars. SUPPLIED THROUCH THE TRADE. WRITE FOR TERMS.

.1 London Offices and Showrooms (RETAIL ONLY), to which the Public I THE " HESTIA " ENGINEERING COMPANY''' are requested to address all orders if unable to obtain through locardealer : 32;Palmerston Road, Acton, London, W. 3. 19, MORTIMER STREET, LONDON; W.1. 1 minute South Acton Station. (N.L. or District Rlys.) Head Office and Works (Trade Only), Victoria Road, North Acton, W.3. Showrooms open g amt. -6 p.m. Telephone: Chiswick 586. "1;5 Popular Wireless Weekly, June 30th, 1923.. POPULAR WIRELESS

dune 30th, 1923. SCIENTIFIC ADVISER, SIR OLIVER LODGE, F.R.S., D.Sc. [Every Friday. TOPICAL NOTES AND NEWS.

B.B.C. Programmes. A New Set. Senatore Marconi. THE station Director of 2 L 0, Mr. Ilex Palmer, tells me that in the very near DR. LEE DE FOREST told me that he SENATORE MARCONI was very en- hopes to put a new three -valve dual thusiasticover theresultsofhis future he hopes to improve the pro- amplificationsetonthemarket recent tests.When I spoke to him grammes by fifty per cent. shortly. I understand that Elwells will the other day at Marconi House, he told probably have the matter in hand, and that me that he was extremely optimistic in re- The Licence Problem. the three valves will act as both high and spect of the new. method of wireless trans- IN spite of the delay in issuing the con- low frequency amplifiers, while rectification mission that he has been investigating. structor's licence, a large number of will be accomplished by means of a crystal. enthusiasts are getting busy, and theDr. de Forest claims that the set is quite craze of making one's own set is taking a Shakespearean Nights. free from distortion. firm hold. Amateurs realise that it is only a T WONDER why it isthat 2 L 0 have question of time, and that the licence is 1decided upon the drama to introduce their Shakespearean nights.Asthe sure 'to come in the end. WIRELESS REVIEW AND SCIENCE whole success of the venture depends upon WEEKLY " isTHE authoritativejournal Women's Radio Club. of wireless and popular science. No. 6will voice inflexion, the actors need to be very AWOMEN'S radio circle has recently contain many most interesting articles carefully chosen. written by leading authorities, and willbe * * been inaugurated.It has been in- on saleatallbookstalls and newsagents corporated with the Radio Society on Tuesday, July 3rd, price 3d. Lighter Plays. of Great Britain. ORDER YOUR COPY NOW! THE " Merchant of Venice," as broad- * * * cast a few nights ago, was very un- Aeroplane Wins. convincing inparts, and to those AN air express flew from London to Concerts for Holiday Makers. who did not know the play, and, therefore, Hythe last week, and arrived at IAM told that an enterprising firm are could not picture the scenes, it must have Hythe before a telephone call an-1sending cars fitted with six valve sets fallen rather flat.I think that a rather nouneing its departure from London. The and loud speakers to the seaside resorts lighter play or a comedy would meet with 'phone call was put in before the machineso that holiday-makers will not miss the more success.Still, wireless broadcasting left the ground.This could not happen broadcasting. is young, and we can -but learn by our ifwireless telephony were faults. used. * * * Musical Interludes. Next Week. THE musical interludes ARTICLES by Sir Oliver do a greatdeal to Lodge, F.R.S. (our brighten up the scents scientific adviser), and come as a welcome and Lt. -Col. Chet wode relief after some prolonged Crawley ; an interview with andintricatespeechor Senatore Marconi, in which dialogue. he describes the results of his latest experiments, and The " P.W."Combination severalotherimportant features will appear in next on week'sPOPULAR WIRELESS. ISeHLAVElistened -in * * * this remarkable instru- ment, and the results Dr. Lee de Forest. arereallyextraordinary, DURING a conversation but I have been sworn to with Dr. Lee de Forest secrecy with regard to the recently, duringhis nature of this wonderful set brief stay in untilsuch time London, he told be when the articles me that the concerning its reaction problem construction com- is far more acute mence to appear the States than in " P.W." is over here. * * * * * "Wireless Re-" to Guinea Pigs." view." EVERY time TO the impos- `! astation inglistof closes names form- own, all the radio ing the advisory up twiddle their staffof" Wire- ndensersa n d less Review and ueal like a lot Science Weekly " guinea -pip," has now beer, said Dr. de Radio progress in Japan.A ten-day wireless exhibition was recently held in Tokio.Tile photographs show (Continued on Forest. two sections of this, while above is a- reproduction of two pages from the Tokio " Radio Times." riage'70(i.) 700 Eopularl Wireless Weekly, June .301k 1923.

summer Night's Dream" shouldfollow Further Restrictions. NOTES AND NEWS. about three weeks later. JKNOW of other councils who have made (Continued from page 705.) 4i by-laws forwirelessapparatus,the Communication with Australia. . L.C.C. having demanded one pound added that of Prof. Einstein, the originator j UNDERSTANDthatbeforelong deposit before an aerial_ can be erected on their estates. of the theory of relativity.Truly, our IAustralia and the Dominions willbe * companion paper can claim to have the able tocommunicate directly with ' strongest editorial board ever formed. England by means of wireless.The most Quick Work. * * powerful station in the world is to be erected APLAYWRIGHT asked a friend whO Wireless Prosecution. in England, with the masts over 800 feet was about to sail to New York if he high. would take his new play to a well-; THE first prosecution ofits kind was known producer in New York. The friend,' before the Stipendiary Magistrate the who was also a producer, consented to do this. other day, when the captain of a Wireless By-laws. little errand, and asked if he might read the vessel was fined for failing to ensure that TAM told that the Wandsworth Borough play on the boat. Two days later came a hiswirelessoperatorkeptcontinuous 1Councilis taking drastic steps with radiogram from the Atlantic : " I'll buy the watch on board the ship whilst in Aus- tenants who do not obey the regulations play myself. What terms ? " tralian waters. regarding wireless aerials.One of the laws The message arrived at three -thirty, an * * is that the tenant has to depositten hour after despatch, and the recipient took Ellen Terry's Appeal. shillings, which is returnable when the said up his 'phone, called " Telegrams," and j AM receiving letters from all over the tenant gives up wireless. Also the apparatus dictated a reply. At five o'clock the answer A country in answer to the appeal for the must be removed, within one week on came -from the ship, sealing the AbRaligELain. Ellen Terry Blind Home, but I can still receipt of notice from the town council. do with many more,so don't fail to send your donation.It does not matter how small it is ;every little helps.

2 M G. HAVE received a letter from 2 M G, Istating that his call sign is being used by a person in Yorkshire.This is illegal, and 2 M G will report this to the P.M.G if the offender does not refrain from using other people's signs.I might say that the location of the person in question is known.

Scotland Yard's Wireless. SCOTLAND YARD has installed wireless on one oftheir wagons which is said to be the only one in the world capably of tekphdning while travelling at forty miles an hour.

A Novel Set. ONE of the neatest sets I have seen has beensentto me by a reader of POPULAR WIRELESS for test. It is a crystal slider set enclosed in a doll's piano. Aerial and earth terminals take the place of ;the usual candlesticks, and 'phone terminals are in the position usually occupied by the pedals.

The Internal Arrangements. THE keyboard has been replaced by a flat coil and a slider which is operated by opening the lid above the ` keys." Inside the piano is the crystal detector and wiring.Tested on my aerial the set gave wonderfully clearresults and was quite efficient some distance from 2 L 0, easily working two or three pairs of 'phones.

Held Over. OWING to pressure upon space it has not been possible to include the article By J. Hope Fellows in this issue, and it has been held over until next week. * Forthcoming Events. ''r HE Air Force Band are due to broad - 1cast from 2 L 0 on July 3rd, and Paul Specht and his band from the New Corner House on the 4th.On the 6th the Grenadier Guards will play, and " Romeo and Juliet " will be performed on either the 5th or10th, while" A Mid- Row 2 L O's band items are broadcast. Popular Wireless:Weekly, J4ne 80th,1923. 707

SIDE -LIGHTS ON THE INNER -WORKING OF 2 L 0 By REX F. PALMER (Director of the London Broadcasting Station). In this article " Uncle Rex " tells of the difficulties and criticism that await the organiser of Wireless Programmes.

HEX listeners -in sit down to enjoy their and those who prefer a jazz band to a ful card -index you ever saw-and you will -Wevening's entertainmentat home,_classical orchestra, or a learned lecture to a never really see this one, for its contents how little they think of all the work vocal solo, must bear in mind that the pro - might be either libellous or too laudatory. that has been done in order to arrange the gamine has been drawn to interest people A wonderful colour scheme has been adopted programme.The entertainment organiser of diverse tastes and to appeal to theso that at -a moment's notice a rainbow is always confronted by problems of which largest possible number of hearers.The combination of colours can be selected the public cannot possibly have any idea ; turn of each will come in good time ;and which will produce a perfectly balanced but the task before the organiser of an the fact that rather more than ninety per programme.There will be found violinists, ordinary entertainment is as nothing com- cent, of the letters which are received from violoncellists, and players on outlandish pared with the difficulties which beset the listeners -in, averaging about a hundred a instruments-such as the tom-tom or the man who is responsible for a broadcasting day, or more, express unqualified approval bagpipes ;while singers of all kinds, tenors, programme, every day of the year. of the existing arrangement of the items is sopranos, basses and contraltos are ready to Whenallthe most conclusive proof that the system of hand.Lectures off any subject can be con sid era tions programme -building which has been adopted produced at will from their own quarter, which have to be is sound.Of course, there are critics-and while humorous entertainers are constantly borne in mind are criticisms are always appreciated and care- popping out jack -in -the -box -wise from their taken into account, fully considered-but when, for example, hiding places. it will be clear that somebody writes to say that dance music n o programme should be cut out and more classic numbers Dealing the Cards. which mortal man included, there is sure to be somebody else By shuffling the cards and dealing theta could arrange can who suggests the exact reverse. as they come, an excellent programme in the possibly satisfy So whatisto be done ?Why, the raw is drawn up.But, then begins the real every one of the answer is simple, the present plan, always labour of organisation for the selected vast audience-an with modifications, must be continued while performers have to be secured,and v audience which is it continues to give pleasure to the majority hundred thousand other details have to lxe truly innumerable of those for whom the entertainment is thought of and arranged. -by whom it will provided, but when this ceases to be the When all this has been done, the organiser beheardinall case-and the letters are a fairly reliable " uncle Rex "- may think that his task has been accom- partsofthe Mr. Rex Palmer. indication of public opinion-it may be plished.Optimism of this kind is, however, country. taken for granted that another formula will not yet justifiable, for one soon realises that My sympathy, even as a member of thc be tried.There is nothing cut-and-dried responsibility does not end until the per- public, has always been with the enter- or hide -bound about the 'system,itis former is actually before the microphone. tainment provider.He has done his best, thoroughly elastic, and the fare provided Then, and not until then, the programme - poor chap-a poor best, mayhap, but still will always be in accordance with the wishes builder, being an acrobat, may pat himself his best-and he should be treated tenderly. of the majority ;for this is a thoroughly on the back and say, " Well done ; " for, The wind of criticism should be tempered democratic organisation. bar accidents, he will have arranged the to the shorn lamb, you know, and even programme and brought his team together, those who have paidfortheirplaces, Colour Scheme. and the rest is a matter which he cannot although they are rarely as exacting as the control.He can only hope that the in- deadhead occupants of free seats, should There is just one little point about which numerable listeners -in, seated in the com- be lenient.There is much to be said for a special word must be said.Broadcasting fort of their own homes-and ready to be the plea of the Fai West Saloon -keeper -7 is only in its infancy, and there is no know- kindly or severely critical, as the case may " Don't Shoot the bloke at the pianner, he's ing at present to what dimensions it will be-will be satisfied.And when he hcars doing his best." grow or in what direction it will develop. Already,however, one thing iscertain, that his end has been achieved, hew"....f Suiting Everybody. know that he has succeeded once more, and broadcasting is not ffing to be confined to he will feel amply rewarded for all -his labours. ' Now, to the uninitiated, it might seem thc provision of nothing but what may be that this is all a preamble-an " apeligia described as the lighter kind of entertain- pro vita sua "-to a confession that the ment or amusement.In the future it is Plenty of Variety. programmes which are broadcast froin the going to become a mighty force for the To have written lightly on this important London Station of the British Broadcasting spreading of knowledge and for interesting subject does not mean that the task is re- Company have not proved to be attractiNe. the faculties of the listeners.One word is garded flippantly, or' that the arrangement But This is not the case-in fact, those who to be shunned studiously-and that is a of programmes does not entail really hard have been responsible for the entertainment good adverb in this connection-" educa- work.Dozens of letters,for one reason feel that they may congratulate themselves tional."But wireless broadcasting is going or another, may have to be written before upon the success which has been obtained, to bring about a far reaching revolution, a an item on the programme is arranged ; and as shown by the immense number of letters revolution which has already begun in then, at the last moment, the absence or of congratulation which reach the offices educational methods ;and then it will be illness of a performer may cause a vacancy every day. found that education is not really anything which has to.he filled without an instant's But this is all an unwarrantable digres- to be afraid of, but that learning is the most delay. But all this is part of the day's work; sion from the point.This article isin- fascinatingformofentertainment and and the reward of popular appreciation, tended totelllisteners -in how the pro- amusement, and that learning in the wire- which is always so generously bestowed, is grammes which delight them in their hours less way is not all work but mostly play. more than a sufficient recompense. of rest are arranged by long hours of patient There, I knew it would happen !I am Some day, it may be possible to give a full toil-labour which becomesapleasure becoming lyrical, if not poetical.So I will description of your programme-as it ap- owing to the generous appreciation of the.now tell you all about the building of that pears to ma in the studio. But what I have vast audience.So to the matter in hand delightful programme about which you hive writtenisintendedto show that the with all seriousness. been thinking ever since you heard it. organiser of broadcasting programmes is not The first duty of a programme organiser The performers are selected from a vast likely to get into a groove or to suffer from is to realise that an audience numbering number of singers, instrumentalists, enter- lack of variety and excitement in his work. about a quarter of a million men, women, tainers, elocutionists, lecturers, and speakers So, now you know something about what and children has to be pleased.Obviously, -including experts on every conceivable has to be done when preparing the pro- -every item cannot make an equally strong subject-whose names, addresses, and tal- gramme you will hear when you next listen appeal to every member of this vast host ; ents are fully recorded in the most wonder. to " 2 L 0 calling." 708 Popular Wireless Weekly, June 30th, 1923.

means of the ordinary tuning arrangements on the receiver.It will be found, provided,' of course,that the receiver is sufficiently A SUPER -SELECTIVE RECEIVER. powerful for the purpose, 'that any other By J. F. STANLEY, B.Sc., A.C.G.I., F.R.A. station can now be picked up exactly as if An ingenious method of eliminating interference and permitting 2 L 0 did not exist at all. reception through jamming. The writer is situated four miles from the London station, but by using -the arrange- ment just described in conjunction with a 4 -valve set (1 H.F., 1 Det., 2 L.F.), all the NOWADAYS when a Londonerfirst the most successful of any, and gave truly other B.B.C. stations can be heard on the takes up wirelesshis main object satisfactoryresults. Thereisnothing loud speaker without the slighest trace of, is to receive the programmes trans- strictly new about the circuit, but so far as interference, while 2 L 0 is agitating the mittedfromtheLondonbroadcasting the writer is aware very few people have ether for all he is worth. station.So he probably makes or buys athought it worth trying out, and for that It will be obvious that the size of L is crystal or single -valve set, and is highly reason the following notes are put forward. not critical, since the circuit, C, L, is tuned pleased with the results obtained. Connected between the aerial and earth by means of the condenser, C.Hence any After a time he gets more ambitious, and terminals of the receiver (of the usual multi - values of C and L, which, in conjunction tries to receive some of the other broadcast- valve type) are a variable condenser, C, and with the capacity of the aerial, can be, ing stations, for which purpose he uses aan inductance coil,L, as shown in the tuned to the offending wave -length, will multi -valve set, and is greatly disappointed diagram. give the desired selective result. with the results obtained. He finds that he The coil, L, should be slightly larger than It will he found, however, that if L is can pick up some or all of the other broad-the tuning coil in the receiver, and the small and C large, the signal strength of casting stations, while the local station (in condenser, C, should be fairly small, say the other broadcastingstationswill be our case London) is silent, but that while .0003 or .0005 mfd. reduced somewhat.This difficultyis en- The method of operating the set is now tirely surmounted by making Las large as as follows : posSible and C as small as possible, under I. Tune -in the station it is desired to which circumstances this arrangement will eliminate (say 2 L 0) by means of the give every satisfaction. ordinarytuningarrangementsonthe receiver. No Trace of Interference. 2. Slowly rotate the knob of the con- No receiving set situated within a few, denser, C, until 2 L 0 disappears.If 2 L 0 miles of a powerful transmitting station is does not go, it indicates that the coil, L, really complete until it has been fitted with is not of the right value, and it should be an eliminator circuit " in this manner. changed for one slightly larger or smaller. The arrangement is, of course, applicable When the correct coil has been found, it will to any wave -length, and is not confined to be possible to tune 2 L 0 dead out by careful broadcasting stations. adjustment of C. By using suitable coils for L, any jamming 2 L 0 is working it is impossible to get rid station can be eliminated but so far the of him sufficiently to be able to tune -in any A Useful Addition. writer has not had much success with of the other stations satisfactorily. Now tune -in the station it is desired to powerful spark stations, since the tuning of:, At any rate, that is the conclusion the receive (say Birmingham or Manchester) by the latter is so flat -that total elimination is, writer came to after having tried all almost impossible.If L is wound with high - the usual so-called " selective " circuits, resistance wire, better results are obtained, for, although he could receive Glasgow but for C.W. and telephony L should have quite comfortably on a loud speaker a low ohmic resistance. (using four valves) when 2 L 0 was However, " this 'ere progress, it goes on," silent, yet when 2 L 0 started up these as Mrs. Wells remarked, and no doubt a two stations got hopelessly jammed. perfect spark eliminator willshortly be Something had to be done, and, after produced. There is no harm in hoping, trying various complicated arrangements anyway. the writer tried a circuit which he had at first thought too simple to be effective. However, this circuit proved to be by far MUSIC ON THE MOORS. An enterprising Bradford firm offers free listening - in to travellers on their charabancs.The apparatus employed was constructed entirely by Mr. J. Dobson, a member of the local wireless society, and consists of four valves 1 H.F. and 2 L.F., one of the latter being a " power " valve. Popular Wireless Weekly, June 301-1i, 1923. 709 PICTORIAL VALVE -CRYSTAL CIRCUITS. By OSWALD J. RANKIN. Showing how a crystal detector can be employed for rectification with valves introduced in amplifying capacities.

THERE islittle doubt that for good, arrangements. Two honeycomb coils, B, Fig. 2 shows a very useful valve -crystal clear signals without distortion there are mounted in a standard two -coil holder, combination in which the first valve acts as is, at present, no rectifying device to and each coil is shunted with a .0003 mfd. a H.F. amplifier, the crystal as the rectifier, equal a well -adjusted crystal.Possibly the variable condenser, so as to form a tuned and the second valve as a L.F. amplifier. best combination is a fine gold wire cat's - anode reactance coupling for the valves. The variometers, B and C, may be of the whisker pressing against a good specimen of The detector and telephones are connected standard type with ball rotor, or made up " hertzite " ;and next to this comes the across the plate circuit of the second valve in the usual way from honeycombcoils. Perikon combination, where a point of as shown.The .002 mfd. fixed condenser, The inductance value of each should be copper pyrites engages a flat surface of C, is provided to prevent the H.T. current identical. D -is a .001 mfd. fixed condenser zincite. The carborundum type has a from affecting the grid of the second valve. which shuns the primary winding of the reputation forreliability, and isa hot D is a grid resistance of about 2 megohm.s. L.F. intervalve transformer.This is an favourite amongst " old timers " ;but this requires a potential, which necessitates the use of a potentiometer and battery, and is therefore not very popular amongst " new timers," who are inclined to view the matter from an economic standpoint. There is a prevailing idea that a crystal detector is a troublesome piece of apparatus. This is purely a misconception. Any other piece of apparatus, however perfect, could become troublesome in the hands of a person possessed of very little skill or patience ; and let it be said at once that if any radio enthusiast does not possess a fair share of patience, then he had better give it up and go in for keeping rabbits or some -other simple hobby.In the right hands the crystal detector represents what is, probably the most important component used in radio consistent with cost and simplicity. For Weak Signals. The one real drawback is the fact that it will not amplify signals ;but we should consider that its duties are to rectify, and that although the valve will rectify also, it is decidedly more efficient in carrying out its @ L T @ H T duties as an amplifier, the purpose for which it was originally intended. If we employ a circuit embodying both we may lose a certain degree of reliability, but we are certainly gaining a few points as far as efficiency is concerned. 41. Apparently a few of our manufacturers have realised this, since there are some excellent crystal and valve combinations now on the market. The point is this : why waste that half an ampere of current on a rectifying valve when a crystal detector, which requires no upkeep, will perform the same duties in a much better way ?Con- sidering this, and also the initial cost of the. val4e, against the cost of the crystal detec- tor, crystal rectification appears to be a very attractive proposition. Fig. 1 shows a circuit employing two stages of H.F. ampli- ficationandcrystalrectification. This arrangement would be suitable where the signals were very weak, and in some cases for frame aerial reception. A Useful Combination. The receiving rangewillbe approxi- mately five times greater than by using the crystal set alone, and the volume of sound is also slightly increased.The aerial tuning arrangement may be modified, but, as pointed out in a previous article, if the circuit is new to the enthusiast, it is best to H T arrangethis as .simpleas possible and modify it, if desired, after becoming thor- oughly acquainted with the other tuning 710 PopularWireless Weekly, Julite 30th, 1923.

early morning watch," and, handing over the 'phones, he passes from the cabin. -LISTENING-IN"-BUT NOT TO BROADCASTING. Putting on the telephones, I settle down By A WIRELESS OPERATOR. to a six -hour vigil and reflect upon the vagaries of an operator's life.Six weeks ago I was sweltering under the hot sun of a Nigerian creek, with the bush spreading A.M. and several hundred miles from deck -houses and rigging, while the whole is over the decks.To -night I await the grey 2the nearest land.I have just been suffused with a ruby glow from two red dawn of the Newfoundland banks. called to go on - watch, and my first lamps which hang from the foremast, and thoughts are that a profound calm reigns this, coupled with the dead silence, lends outside in place of the ceaseless howling the scene a weird and almost uncanny NEXT WEEK. of a north-west gale and its attendant air. sounds of the creaking and straining of the there are several important features appear- Plenty of Variety. ing -in " POPULAR WIRELESS" which no vessel as she labours in heavy, seas. one interested in matters radio can afford More fully awake, Irealise that the At the foot of a companion. ladder I meet to miss.There will be a special Interview " racing" of the engines, caused by the an apprentice, whose breath freezes on his with SENATORE MARCONI, in which he describes the results ofhis latest experi- propellor being lifted clear of the water, is big coat. ments, articles by -Sir OliverLedgeF.R.S. absent, and then that the engines are Why is she stopped I ask. (our ScientificAdvieer), and MAGI: Chet- stoppedaltogether. A breakdown pro- "We've run into an icefield and there wode-Crawley (Deputy Inspector of Wheels bably.Anyway, I think to myself, better may be bergs about," he replies, and then : Telegraphy, C.P.O.).The latter deals with the ever -absorbing question of " Monopoly in to have an engine stoppage now than during " The first night we've had weathel to allow Wireless." the appalling weather of the last ten days. a little speed, too." ORDER YOUR COPY NOW! The sickening sleepiness that grips one And muttering things about the sea, and at 2 a.m. is worse this morning, as, the calm the North Atlantic in sea has allowed a real sleep for the first particular, he passes on time since leaving England ;but, once tofetchthe second turned out, the acute cold tends to banish officer's tea. sleep, and I am fully occupied in putting Running up the com- on as much clothes as possible in the least panion -ladderIenter possible time.The steam heater has been the wireless cabin. broken down for several days, and it is Under a shaded light useless to attempt to wash, for the -simple sitstheoperatoron reasonthat the water is frozen in the watch, writing inthe basin. log. Much doing ? "I Freezing Hard. ask. As I leave the cabin, the brass doorknob " Not much," he re- tends to stick to my fingers.Yes, the plies ; " but the old man mercury is lower than usual to -night. wants ice reports from On reaching deck an impressive scene eastboundships. By lies revealed.The ship is covered with a gum, I'm tired to -night; level mantle of snow, icicles hang from the you're welcome to the 5 C P the experimental station belonging to the Fellows Magneto Co., Ealing.

connect another of .0005 mfd.capacity capacity of0.01mfd., shunts the tele- PICTORIAL VALVE - across the aerial coil, R. A .001 mfd. fixed phonesandhigh-tension,,,hattcry.The condenser, D, is in shunt with the second- tuning of this circuit will be -fairly critical CRYSTAL CIRCUITS ary winding of the L.F. intervalve tran- until the operator is well acquainted with (Continued from page 109.) former ;and another, F, which has a the adjustments. excellent circuit for use in conjunction with the broadcasting.No variable condensers will be required unless the variometers are B replaced by ordinary tuning coils. Dual Amplification. A rather unusual circuitis shown in Fig. 3.Here the valve is made to function as a H.F. and L.F. amplifier simultaneously, rectificationbeing accomplished by the 'TT crystal detector.The results from this will be at least equal to two valves arranged in the ordinary way.In conventional circles it would no doubt be rated as a " freak," but this is not very disturbing when the actual results obtained leave nothing to be desired. -4'1"7"Tr06, The tuning coils, B and C, are identical, since both are tuned to the same frequency. These should be " a job "-Le., they should be constructed with the greatest care, the ends and the formers being made of ebonite if possible. A suitablesize coil for the broadcasting wave -lengths is 6 in, long by 31- in.in diameter, wound with No. 22 enamelled copper wire.The sliders should be of the best quality, and preferably of the flat. spring type.It will be necessary' to shunt the anode coil, C, with a .0003 mfd. ©L H variable condenser, and advantageous to' Popular .Wireless Weelly, hrne 30tli 711

EVERYTHING FOR WIRELESS POINTERS, BestIn Harrods Wireless Lounge (Second Floor) everything can be obtained by the amateur for building sets INSULATORS brass or aluminium.1 and conducting experiments, and wireless experts are always in attendance to give advice and information.Useful for many pur- r' centre. Each I D poses. Bobbin type.h 0 REACTANCE Weight, 2 ozs. Eac OD, FORMERS. Most Egg type. Weight C useful to experimenters. 2 ozs. Each UD. Inside diam. 3 ins. Out- Orderby Shell type. WeightEach 1 1/.. side diam; 4 ins. 7 /6 postif a 3i, ozs. Each II/ call is COIL HOLDERS impossible Speciallydesigned-to VOLTMETERS TELEPHONES. reduce capacity effects Pocket type. Most 0 in Mostefficient, reliable. Each U/ sensitive and SLIDER KNOBS reliable.2,000, way 13/6!;y11/- Useful when making own CONDENSER 4,000,or 8,000 DOUBLE POLE, DOUBLE THROW KNIFE Made from inductances. Smooth ohms. VANES. polished finish. SWITCH, mounted on china.Heavy22 S.W.G.Hard rolled Each 90. Per copper clips and blade.In- =/,..sheet,surfacematted GRID LEAK AND pairfj sulated handle. Each V and edges polished. CONDENSERS D.P. one way. Each 316 Fixed 1 Rotary 1 Splendidly made and per doz. I/per doz.I/I neatin appear- A I. HORNS for LOUD 91 SPEAKERS ance. Each Orders value E2 SEND FOR 22 incheshigh, e CONDENSERS Price Each U/ (Fixed).Made from and over sent FREE BOOK VARIABLE Curved Pattern 101 FULLY best quality Mica and post free Price EachI L. ILLtrs- INTER- , Copper Foil.All n TRATED Postage on each.. 9d- resistances. EachLI VALVE IVORINE SCALES COIL PLUGS REACTION UNIT Flat, semi -circular,for Fitted with brass inserts Condensers, V a r lo connection INTERVALVE REACTION UNIT ThisUnit willenormously and 1 /6 (shown on left) add to the efficiency of your meters,Couplers,etc. screw. EachI / Made from finest materials, instrument and may be safely Engravedblock, C CONTACT STUDS thisshort and long range used duringthe o*-r8o° EachUp, With nut- and washer. Unitis highly 00/ hoursofBroad- ... TELEPHONE Small 1/6 Large 2i. efficient. Each VW-/ casting. Each TRANSFORMERS TERMINALS Price from Each 93'4 SERIES PARALLEL EARTHING CLIPS Barrel type 2 B.A. 4d. SWITCHES Barrel type 4 B.A. 3d. on Ebonite These arewell tinned Telephone, Each 4d. LEADING -IN TUBES. Finest quality baseboard.4/6 to ensure certain Q W.P. type. Each 4d. obtainable.Various lengths. From2/6 Unmounted, includ- contact. Each OB. HARRODS Ltd Wireless Department 2nd Floorisig, dgst:r and 2/6 LONDON SW1 THE IlL1 IVA11111'11 sma 1111

-JVARIABLE PRECISION VARIABLE CONDENSERS get the BEST RESULTS from -a better Variometer your set. at a lower price. The ACME of FOR Broadcast reception there is no better tuner than a PEIZIPECTION Variometei. No Variable Condenser or coil with tap- SCIENTIFICALLY DESIGNED, pings is required.The tuning is simplicity itself-merely and no PANEL can beUPTO rotate the dialuntil the wanted wave -length is tuned in. But DATE without them. the Variometer must be a good one-a couple of lengths of Completely with cardboard tube are all right if you arewithin sight of 2 L 0, assembled but for real long-distance work you need a Vailo-bloc. KNOB and DIAL. Exclusive Features. ONE HOLE only for FIXING Internally wound stators with D.C.C. heavy copper wire. to PANEL.Large METAL to Smallest air gap of any Variometer yet manufactured METAL BEARINGS. -therefore high efficiency. Can be used as Variometer By their use BIG IMPROVE- or Vario-coupler by meansofashortbrassrod. MENTScanbemadeat Permanent strip contacts. SMALL COST. Wide bearingsguaranteedagainstwear.' MMMMMMM Can be inspected and purchased in LIVERPOOL at 00T -8/6 Well finished and solidly constructed Messrs. LEWIS'S LTD. 00075 8/ - in two patterns, complete with dial :- Wireless Department, a '0005 .. 7/-; No r.250-72o metres. STREET. '0003 .. 5/9 No. 2. 250'840 metres.1716 RAN ELAGH a '0002 ..5/ - Packing and Postage extra. VERNIER .. .. 4 / - One only, 9d. Two, 1/-. ---- PETO -SCOTT CO.,LTD., ObtainableObtainable through your dealer ordirectfrom :- Head Office : 64, High Holborn,W.C.I. JACKSON BROS. Demonstration Lounge : Condenser Specialists, 99, High Holborn,W.C,I. Branch (First Floor), 8, POLAND STREET, OXFORD STREET, 3,WellingtonStreet, or Strand, W.C.2. LONDON, W. 1. TRADE ENQUIRIES INVITED. Ad. 'Phone: Gerrard 6187 712 Popular Wire-Iss Weekly, Tune30th, 1923.

11 LISSEN RECENERATWE-REACTANCE (P. PATENT.) Common Causes ;II:

PROOF OF ITS SELECTIVITY.Itcuts out 2 L 0 from right close in, and brings in the other Broadcasting and Continental stations, of Distortionin 'II SENSITIVITY. Aerial and earth connections III can be dispensed with under many conditions. III REACTION IS NOT OBTAINED WITH A H.F. Amplifiers SWINGING COIL. Range 150 to 4.000 metres-REGENERATION Eliminated in "LISSEN" III OVER THE WHOLE RANGE. REACTANCE P. Patent) Price. - £2 -12.6 111 Blue print and instructions:with each. LISSEN The carrier wave on which telephony is trans - mattedis modulated intospeech frequencies ONE HOLE FIXING. (technically called "side bands "I.One of the 111 Tune witha LISSEN VERNIER CON- disadvantages of the tuned anode system of H.F. amplification is that it cannot amplify all these III DENSER (price 12, 6)-designed for fine tuning frequencies in the same proportion. This tends to in H.F. circuits. cause distortion. The LISSEN REACTANCE (Prow. Patent) method permits sharp tuning and yet III LISSEN REACTANCE (P. PATENT) allows the proportionate tuning of amplification of all the varying frequencies met with in tele- STILL TO BE USED phony. There is consequently no trace of distor- III Amplifies even loudsignals,and adds great tion with the LISSEN REACTANCE method. It range alicl power.Where aerial reaction is em- embodies all the advantages of the tuned anode III ployed, tune with a new LISSEN VERNIER- system and also particular advantages of its own. it is entirelysell -tunedif aerial reaction not used. Get the most out or the Ether by III using also the LISSENSTAT-the new device for 150 to 600 metres complete 27/6 perfect filament control-essential for tuning -in Id 150 to 10,000 metres complete..32/6 on long distance reception - itutilizes the Blue print shows two simple connections-easy tuning characteristics of the detector value- III Permits getting on the very spot for perfect to use-no switchto connect-no awkward reception-eachH.F. LISSEN ONE Value and the Detector Ills soldering-no complications. Valueshould haveLI SS E NST A T control. HOLE FIXING Price7, 6(Ready7days,order now). TUNING FOR EFFICIENCY.Features that make Any good Radio Dealer will show you these-if he cane the perfect tuner-great inductance with lowest H.F. not, take no substitute --send direct to factory, post free, resistance and least distributed capacity-no " dead end " losses-used with the Lissen REGENERA- DEALERS. - Please order a 'few days ahead, through TIVE -REACTANCE it will cut out 2 L 0-range factor or direct, 150 to 4,000 metres when tuned with a '0005 Con- denser (preferabry Lissen Mica Variable, 17:6)- this LISSEN tuner is quite different to the ordinary LISSEN COMPANY, plain, single layer inductance.It is complete with 8-16, WOODGER ROAD, GOLDHAWK ROAD, III 11 -point switch already mounted, there are no taps SHEPHERD'S BUSH, LONDON, W.12. to solder, no complications-usual LISSEN ONE 'Phone :1072 HAMMERSMITH. III HOLE FIXING-mounting isonly 2 minutes' N.B.-ClosetoGoldhawkRoadStation(Met.) Shepherd'sBush work.Length 4 ins., diameter 4 ins. (Central London), or Hammersmith Tithe. Buses No. 11 and 32, Price complete, 22/6. GET THE MOST OUT OF THE ETHER BY USING LISSEN EQUIPMENT. I, - - - - - _____------jj

THE BEST DIFFICULTY 13 "PTHLESBRITAIN'S OF MARVELLOUS EFFICIENCY CHARGING ACCUMULATORS MARVELLOUS PRICE IS EASILY 16/6',maPc.r OBVIATED Plus J./- extra for postage: j? YOU INSTALL Manufactured entirelyin our works, A Goswell Road and City Road, under mass production: hence the quality and -'4010011111101111111.TeaSEa4Z12. MARK price. We specialiseinthe manufacture of Precision Tools, stamped and turned CHARGING DYNAMO parts,inlargequantities.Sendus your enquiries. THIS IS NOT A TOY, BUT MADE FOR HARD We are experts in the production of WORK, AND CAN BE RECOMMENDED WITH Magnets of all shapes, and from Tung- ston or Chrome Steels. EVERY CONFIDENCE. SOLID BUILT-UP COMMUTATOR, MICA INSULATED, ADJUST SPECIFICATION. Case. Best hard Aluminium, solid Ear Caps.Solid ebonite of ample ABLE ROCKER,SPECIAL CARBON BRUSHES. drawn and accurately finished. sue, best, finish and correctly pro- Magnets. Latest type horseshoe insportuiracidio. OUTPUT : 1032 volts, 45 amps. pattern of finest Tungston Steel, re- This is a particular sulting in strong and permanent feature and receives careful atten- No. 64/1, Price 45/.., By Post 116 extra magnets. tion,finest materials only being used; Head Bands.Made from best Note : Size 71 ins. x 51 ins.x 41 ins. Weight 91 lbs. Core Pieces. Finest quality of quality Spring Steel, copper plated, special soft iron, with fibre insula- oxydized, and relieved, giving beau- OUR 100 -PAGE CATALOGUE ting cheeks. tiful finish. CONTAINING OVER12,000ILLUSTRATIONS Wire.Each earpiece is wound with bestEnglish Testing.Every earpiece is tested Post 3d. Free._r41. high conductivity, -thoroughly during, and after as- copper wire to 2,000 ohms by special sembly. machines. Finish & Workmanship.Of Diaphragms. Made from selected the best possible throughout. GRAFTON ELECTRIC COMPANY, iron, perfectly flat, to ensure perfect ASSEMBLY, By skilled labour under tone. expert supervision. 54, GRAFTON STREET, We agree to return cash in full if not satisfied, and TOTTENHAM COURT RD., GUARANTEE. returned to us undamaged, within 7 days. LONDOJ B. IL & Co. (Edward A. Boynton), Telephone MUSEUM 241. Works: SLOUGH. Admiralty & War Office Contractors. MANUFACTURERS OF WIRELESS Works :-167-173, Goswell Road, London, 'E.C.1.1-0, Goswell Place, London, E.C.1.361-363, City Road, London, E.C.1. GOODS FOR OVER 16 YEARS Telephone : Clerkenwell 6238. Offices :173, Goswell Road, London, E.C.1. Popular Wireless Wee,',./y, June C.:St!!, ID23. 7 A CHAT ABOUT TRANSFORMERS. By C. E. FIELD, B.Sc. This is the first of three articles, each complete in itself, dealing with the various types of transformers employed in wireless receiving sets.The author. in his usual interesting manner, combines both theory and constructional details. I. -GENERAL PRINCIPLES.

TO many of us there is an element of flow along the axis of both coils, but no can summarise the action briefly as follows : mystery about a transformer. It effect will be produced on the coil which is Alternatingvoltage. isappliedtothe appears in various parts of our re- not supplied with current.If, however, we primary windily. ;this drives an alternating ceiving sets, and takes a great variety of send an alternating current through the current througlithe winding, which, in turn, forms, and it is difficult sometimes to see first coil, it will produce an alternating flux causes an alternating magnetic flux to pass exactly what purpose it serves. Let us see, -that is, a flux which, after attaining its along the axis of both windings. The alter- first of all, what a transformer is, and how full value in one direction, falls to zero, natingfluxproducesinthe secondary it works, and then we will consider its rises to its full value in the opposite direc- winding an alternating voltage, which bears applications in wireless work. tion, and falls to zero again, repeating this to the applied voltage the ratio of the Most readers will be aware that when an cycle at the same frequency as that of the numbers of turns on the two windings. This electric current flows along a wire, the wire current producing it. ratio is called the " ratio of transformation," becomes surrounded by what is called a and a transformer is known as a " step-up " magnetic field.It is rather difficult to get a Concerning Ratio. or a " step-down " transformer, according mental picture of a magnetic field, but we We saw that when the flux through a as the secondary (output) voltage is greater can imagine it to be- a current of magnetism coil changes in value, a voltage is set up in or less than the. primary (input) voltage. flowing in circles round the wire. This the coil.This alternating flux produced by It must not be thought that when we " magneticcurrent "isreferredtoas the first coil, therefore, since it flows also increase voltage by means of a transformer " magnetic flux " in order to distinguish it we are getting something for nothing. We from electric current. are not, for if we connect the secondary (high -voltage) winding of a step-up trans- Production of Magnetic Flux. former to an electric circuit, the current As this magnetic flux is produced by the which flows will be decreased, compared with electric current in the wire,' its size and the primary current, in exactly the same direction of flow will depend upon the size ratio as the voltage was increased. and direction of the current. If the windings of a transformer are wound If, now, we bend the wire into the form round an iron core, a very much greater of a loop, it is -easy to see that all the flux amount of fluxis obtained for a given flowing round the wire must flow through winding, because iron isa much better the loop in one direction, while if the wire conductor of magnetic flux thanisair. is wound into a spiral the flux will pass Hence, by using an iron -core, the dimen- through each loop composing it,in tho sions of a transformer are very much re- same direction, and so will 'flow up thc duced, and for all ordinary purposes iron - centre of the spiral from end to end. Since coretransformersareinvariablyused. the flux flowing through the spiral is made

up of the sum of the. fluxes flowing through Three Principal Types. the individual loops, the total flux pro- These may be of two types, known respec- duced *will depend upon the number of tively as " open -core " and " closed -core " loops or turns of wire. ?PEN IRON -CORE (b) transformers.In the former type the iron We see then that when an electric current TYPE lies only along the axis of the windings, is sent round a spiral of wire, a magnetic and the flux must complete itscircuit flux is sent along the axis of the spiral. through the surrounding air.In the latter depending for its value upon the size of the type there is a complete iron circuit round electric current and the number of turns of the windings, so that the flux has an easy wire. The amount of flux also depends path for the whole of itscourse. Fig.I upon the diameter and length of the inside CLOSED shows diagrammatically the three principal of spiral, just as the flow of electricity in a FIG. I. IRON -CORE types of transformer-air-core, open iron - circuit depends upon the diameter and length TYPE core, and closed iron-core-the dotted lines of the wire of which the circuit is com- in all cases representing the path taken by posed.It has been found that if, by any THREE TYPES OF TRANSFORMER the magnetic flux. means, the amount of flux flowing through 0 In a wirelessreceivingcircuittrans- a -coil of wire is changed,, a voltage, or formers are used in conjunction with low - electrical pressure, is produced in each turn through the second coil, will produce in the resistance telephones, as couplings between of wire in the coil, the value of the voltage latter an alternating voltage, which will low -frequencyvalves,orascouplings depending upon the amount of flux chang- depend for its value upon the size of the between high -frequencyvalves. These ing in a given time. The voltages produced flux and the number of turns of wire in the three cases will be considered more in detail in the individual turns of wire all act in the in subsequent articles. same direction, so that the total voltage coil.If the number of turns in the second coil is equal to the number in the first coil, (To be continued.) across the ends of the whole coil depends it can be shown that the voltage produced upon the number of turns with which it is is the same as the voltage applied to the wound. firstcoilin order to send the current through it.If there are twice as many turns Readcrs are invited to submit The Transference of Energy on the second coil as on the first, the voltage Now let us see what happens when two produced will be twice as great as the vol- the results of their experiments coils of wire are placed end to end, or better tage applied ;in fact, the voltage will be in the form of short construc- one inside the other as in a loose altered in all cases in the exact ratio of the tional articles. If accepted Coupler, and an electric currentissent nunibers of turns on the two coils. for publication they willbe through one coil.If the current is supplied These two coils make up a transformer, from a battery, and so flows always in the of which they constitute respectively the paid for at our usual rates. same direction, a steady magnetic flux will primary and secondary windings, and we 714 Popular Wireless Weekly, June 30th, 1923.

absolutely - dead.-- Come- round another- eyening, old chap.. i'll-" Never Mind,"saidthe young man THEWRONG WAVE -LENGTH. cheerfully, rising and walking over 'to the It does not dO in these enlightened times to take ignorance on matters apparatus.He regarded the instruments wireless as granted when one entertains a stranger. with a certain languid interest.Then he . _ stopped, seemingly fascinated, at the switch which Henry had first exhibited to him. " VOU'RE fed up with wireless ? " said " I turn it -Z -like this-and those little globes Coming Through Fine ! 1Henry to the quiet young fellow light up." " Let me see,"he .said_ thoughtfully. - whom I bad brought - round to - A -waste of current," said the yo -!rig man " What did you tell me was the use of this dinner with him. pertinently. " A nice light evening like little,gadgethere ? ". Heclicked ...the Bored stiff," admitted the young man this, too." switch across with idle curiosity: " I dejectedly." They talk wireless all day at " On the :contrary," retorted Henry, in fancy " it the office-I simply can't get away from the' high, glee..".If they weren't alight, the Like a flash, Henry leapt into the'''fir. as wretched stuff." wireless fairies would never be able to see one possessed of an infernallegiori: " And I daresay," said my brother, " that their way in.Yom.ought to listen to Thiele . " Quick !Quick ! " lie jerked." Pint' not knowing too much about it all, you're William explaining it all to the -kiddies ! " - these headphones, man. It's coming thiOugh naturallya bit prejudiced." " Uncle William ? " repeated the 'young fine now.I 'must have had that aerial " I don't know too much' about it," -the man blankly. " You'll :hear him- presently," Henry switched off all the tithe.". other acknowledged." There's so much to . . learn, isn't there ? " explained.. He's the M.C. up -at the broad- I saw Henry in his garden the next evening. Henry laughed: casting station, you know." " Well," - he Said cheerktilly, I lancy He slipped a pair -of headphones over his I've 'altered your young' friend's opinie of " Oh well," he said kindly, ".there is, and ears,and turnedhisattention AO there isn't. But look hcre-my set's in tha wireless. He seemed 6- enjoy hiniself 4owing_bulbs. - next room-come along through and see it. mightily last night." " If you'll keep quite ,quiet for a minute He did," I agreed. And he' needs a Once.you. get a grip of things, you'll be as or two," he said, as if he were promising a ken as the rest. of us." little recreation; now arid again.ByJhe dog a biscuit to stop barking, " I'll see if I way," I added casually, "Aid Iniention to can get on to the London station for you." yon that he is-Uncle*William ' --'ofthe The pupil lit a cigarette and relapsed into Waste of Current ! broadcasting station ? " - The yang man smiled sceptically. When moody silence. For a full five minutes, not Henry bared his teeth with a horrible he saw the litter of paraphernalia that a sound was heard but theoccasional' and most unbrotherly expression. constituted Henry's receiver, his face fell a',click of a switch as Henry fumbled amongst " No",yott'. didn't I. he said savagely, full five points, with a tendency to go still' a forest of them. reaching :for a- briekbat ; And then :" Nothing yet;"reported and I haven't lower. seen. him since. e, Henry tensely. Henry caught his eye and roared. - " Crying before you're hurt," he chuckled, Ten more minutes passed indeathly " like the rest of them.Everybody, of silence. Wheless -Review course," he went on expansively, " knows "Can you hear anything ?" whispered the & Science Weekly" young man unsteadily. - what wireless . - No. 6 of this our authoritative com- " I'm afraid I don't," said the young man panion journal,willbe onsale on miserably: A Tense Moment. Tuesday. July 3rd, and will contain " NOM mind," encouraged Henry." It " Ssh-ssh-ssh !.'' came from a corner of among many other most interesting isn't really 'necessary.Now you see this Henry's mouth. "I'll -have it in a moment." features :- switchthing here ?That'stheaerial. " Good "saidtheOtherdoggedly, A specialinterviewwith SirJ.J. WitChL4 put it across like that."He lighting a large pipe, and subsiding into an Thomson, 0.M., F:11.S:', on "How moved a black lever by the window. " Now armchair. tke Electron was Discovered." it's on." Another ten minutes, entirely without " Utilising Nature'S Fortes." " What's on ? " demanded the other with incident, ticked slowly past.Then Henry " How to Make a Two -Valve interest. turned to his visitor. Broadcast Receiver." " The switch," said Henry cautiously. " It's no use trying to -night, I'm afraid" ORDER YOUR COPY NOW ! " Here's another switch," he continued. he apologised' at last. The thing seems

Wireless picnics will prove a very popular feature in the comingsummer months. This photograph shows a group of Cardonald youngsters being entertained with a 3 -valve loud -speaker set. Popular Wireless Weekly, June EQth, lcrn. Gamages Stocktaking Clearance of Wireless Sets and Sundries Heavy Surplus Stocks to be Sacrificed UNDER COST New and Perfect Goods. You Buy on the Money back Guarantee Post your order, or Come Early and Look over the Bargains MOVING COIL ADJU-STAILEI CRYSTAL DETECTOR (NRIIII London made.Base 31 x RELAY LOOSE I 3 x in. of Polished Ma-' A delicateinstrument hoganyqu, eredBurnished and movementofextreme COUPLER 1 Lac sensitivity.Of the mov- I Bras swork, ing coil type and provided Ebonite with a platinum circuit Knob. closer in place ot pointer. The contact screws are adjustable,and soar- ranged that the circuit closer can be set to move through an are ranging fromto less than;,, in. Can be used as an ordin- ary orpolarised relay where the greatest de- rapped gree of responsiveness ision Secondary, required. covering band of Special Offer of Wave -lengths 300 to 1,000 SALE metres. Undoubtedly the most efficient for shorter wave -1 BROWN'S PRICE 7/6 lengths, especially with crystal receivers.Estimated tol TYPE "A" Post V-. give at least 100/0 better results than the ordinary. tight" type.Especially effective when 'PHONES "$ONUS" UNIT VALVE PANELused with a Variable Condenser either in 35/1 (W.D.) Comprises Valve Hold- shunt or series. SALE PRICE Every pair tested. er, Filament Resistance. Post free Resistance 1,200 ohms. GridCondenserand Leak, 'Phone Condenser Usual and necessary terminal CONDENSERS. price forconnectionswith 1)-. A i r dielectric! 30:- positionsclearlyeng,rav- type. Faraday &ALE ed. Finished in polished House calibration! PRICE mahogany and ebonite Circular, ebonite! Post 6d. with heavy brass ter- top and bottom, Cords 3 6 per pair extra encased in cellud SALE Mid. Engraved THREE -COIL PRICE25 6 ivorinescale .1 Post 6d. Without 1 o n gl HOLDERS PANEL MOUNTING handle. Suitable for Honeycomb and mfds. I Burndept Coils. Beautifully CONDENSER SALE finished throughout. Skeleton Type. Accurate and PRICE , I SAPS CE- reliable. '00045 radii. .SALE PRICE Post- 6d. A .(1°9'5SALE ""9. PRICE10/6 BestQuality Geared '00045 mfds. Type. SALE PRICE OF/ 10/6 SALEPRICE '00008 (Verniei). Post Od Post Free. Post6d.27/6

Write for our 41111110 INTERVALVE TRANSFORMER SALE LIST DAMAGES Low -Fre- Post free. quency type highlyeffi- cient, small and com- CRYSTAL pact.Bath, suitable5 to: l .Very r panel Receiving mounting. SALE SET PRICE ATHOROUGHLY efficient instrument, P ,st6d. receiving telephony over a range 6f 25 miles with remarkable clarity. Neat and compact in polished mahogany cabinet with ebonite top. Timing inductance is tapped in four places, giving, in conjunction with the variable con- VALVE HOLDER Circular four pin type denser, a good range of tuning. Sen- asillustration,with sitive " cat's -whisker " type detector, wide base flange. fitted with the famous " Pecmanite " Made of solid polished ebonite, with four pins crystal.Complete as illustration. for making soldered SALE PRICE connections. Y e r y Carriage paid. usefulfor mounting EXTRAS:-'Phones, Sterling, 32/-;Brown's "F " type, 30/- ;purposes. Aerial Wire, 100 ft., 3/- ;Insulators,3d. eath; Earth Wire, 6d.SPECIAL SALE PRICE per yard; B.B.C. Tax, 7/6. 7,043(i. A. W. DAMAGE, Ltd.. HOLBORN, LONDON, E.C. 1. 716 Popular .file,elay,.July 304h, 1923.

AMPLION Buy your Loud Speaker where you see this sign.

ALFRED GRAHAM & COMPANY, Demonstrations at St. Andrew's Works, Crofton Park, our Showroom :: WORLDS STANDARD LONDON. S.E.4. 'Phone : Sydenham 2820/1/2. THE ALGRAPHONE THE 'Grains: Navalhada, Catgreen, London. SALON, SCOTLAND: '101. Mr. F. M. Milligan, 4 i*14...'"' 25 26, Savile Row, 25, Renfrew Street, GLASGOW. WIRELESS LOUD SPEAKER IRELAND: Regent Street, Mr. A. R. Munday, London, W.1. 41, Chichester Street, BELFAST. MANUFACTURED BY THE CANADA: REGENT 1075. Messrs. Burndept, of Canada, Ltd., PIONEERS IN LOUD SPEAKING 172, King Street West, Toronto. TELEPHONY.

THE LITTLE "TAY" HULLO !!! C.Q. WILL DAY 'CALLINGI Headphones 4,000w attention to some new lines which cannot FITS LIKE A GLOVE failto be of interest to all :- A NEW AMERICAN INTERVALVE TRANSFORMER. Perfect in its action Each pair carries and giving wonderful results ...... 22/6 each . . a guarantee . . A NEW CRYSTAL CUP instantly detachable 1/3. Carriage VARIABLE GRID LEAK, 1-5 Megohms and Paid PRICE 2216 detachable Condenser ...... 7/6 ,, Fromall WIRELESS SHOPS RESISTANCES, Wire Wound, paci,000 ohms 9,'- ,, or if any difficulty direct from the Sole Distributors- RESISTANCES, Wire Wound, 50,000 ohm; 6:- S.CORRE140, Gray's Inn Road, W.C.1. HAVING PURCHASED THE WHOLE OF A MANU- Tel. MUSEUM 2342. FACTURER'S STOCK OF GUARANTEED 7,22 HARD DRAWN AERIAL WIRE IN 100 Ff. HANKS, WE ARE ABLE TO OFFER THIS AT THE LOW PRICE OF 2/2 PER HANK OR 1 /1 1 FOR 50 HANKS AND UP. 40u-4 STAFFORD JUNIOR Sheet Ebonite, Grade A, cut to any size. 9,'6 Every requisite in Stock for Wireless. TRADE SUPPLIED. REVOLUTION INPRICE. These are only a few of our bargains.Do not fail to send WONDERFUL EFFICIENCY. for our Price List giving the lowest prices for the best 20 MILE RADIUS. quality goods.Postage on all goods extra. TUNING EFFECTED ON VARIOMETER Write for our new Catalogue, now ready. PRINCIPLE.NO SLIDING CONTACTS. MOUNTED ON EBONITE. Do not fail to try the NEW "DAYZITE," Regd. IMMEDIATE DELIVERY. The super marvel Crystal with Silver Detector Point at SEND 136 AND 1 /- FOR POSTAGE. 2,6 each, or mounted in Brass cup, 2,10, Postage 3d. extra. STAFFORD RADIO VALVE SETS. MOST EFFICIENT LOW PRICED SETS OFFERED. I VALVE SET WITH ACCESSORIESBY. INSTALMENTS, Vi 0 DOWN AND WILL DAY, LTD., BALANCE 1 WEEKLY. 199 Lisle St.,Leicester Sq., London,W.C.2 STAFFORD RADIO CO. LTD., 'Phone: Regent 4577. Telegrams : Titles, Westrand, Loudon. 150, SOUTHAMPTON ROW, LONDON,W.C.1. - - i'opulor Wirelesi Wc:ekty, June 30th, 1023. 717

perform the connection with any subscriber wished_for in the same manner as any other telephonestation. By a corresponding COMMUNICATING WITH TRAINS. switching they make connection between (By Dr. A. NEUBERGER, our Berlin Correspondent.) the waves coming from the train and the Although in Great Britain, on account of the comparatively short railway journeys common inter -urban telephone lines. that exist between the important towns, a means of communicating with trains is not felt to be very essential, it is a different matter in other countries, where Has its Disadvantages. a business man travelling by rail from one point to another may be cut off from There can be no doubt that the new the outside world for several days. How the Germans solved the problem by " train telephony," by which the under- means of a system of wired -wireless telephony is fully explained in the following standing is is a perfect one, represents an im- article. portant progress of traffic. Perhaps many a person will greet this wonderful triumph of modern science with AS soon as radio -telephony was success- its roof.This antenna consists of six paral- mixed feelings, as being so absolutely dis- fully accomplished, people began tolel wires that cover each of the two roofs, engaged from the ordinary surrounding; try telephonic communication froma length of 16 metres being obtained, so was a benefit to them.That is naturally trains.They succeeded, itis true, to athat the whole length of the wire is 192the reverse of the medal.But, -after all, certain extent, in speaking from the larger metres.The communication is carried outyou are not obliged to divulge the train stations to the train, but communicationby the usual apparatus in quite the same you intend to go in to your creditor or to your in the reverse direction failed.The cause of manner as from any ordinary telephone in mother-in-law. the failure was that the trains could notany house. The wireless carry the powerful apparatus necessary, andwaves pass from the antenna with small -powered plant it was impossible to the wires of the telegraph to transmit over large distances. that run along the railway. It was only by the construction of newThe waves do notenter amplifiers, that depend on the principle .ofinto . them,however,but cathode tubes, that success was achieved. only slip .along the surface These amplifiers are like electric lamps, and of the, wires and are not are exhausted as far as poSsible.Now, at disturbed bytelegraphic last, in Germany the first train haS been proL communication taking place sided with instruments that allow trans-in the wireat the same mission from the running train, and passen time. At Bergedorf, near gers on the train can receive calls during the Hamburg, and at Spandau, journey.Thetrialtrainruns between near Berlin, there are two Berlin and Hamburg, and was arranged by new offices that are called the society for radio -telegraphy, Dr. Erich " trainstations." They F. Huth at Berlin.The train is a D train, as corridor trains are called in Germany, in the midst of which there are two third-class cars. Both cars are used for usual communi- cation, taking passengers like any other car.Only one- ofthe compartments at the front has been fitted up as a wireless cabin.Here is the telephone in a telephone box, and at the side of it a room for the official that controls the apparatus. " Train Sltions." This official might be dispensed with a6 regards the wireless serviceitself,com- municationbeingaccomplishedwithout him.But his presenceisdesirablefor other reasons, especially for payment and for informing the passengers that are called for that they arewanted on the 'phone." On the roof of the two cars is the aerial, The two bottom photographs show the aerial in position consisting of a nuniber of arches on which on the roofs of the carriages.Above, a passenger being the proper sending wires and receiving "put through" by the attendant.Itis possible to obtain a call through any of the telephone exchanges wires are fastened.One of the cars has no by this means. telephonic apparatus atall,but is only carried along to prolong the aerial by using

It is interesting to note that all the ap- the whole of the wiring and assmibling, the paratus, even the 'phones, is made at thevarious parts being assembled -by one liand; A VISIT TO A RADIO G.R.C. works atHarlesden, no foreignthe wiring by another, and so on. And, apparatus being used,- and British labouragain, there is a special. section devoted to FACTORY. only being employed. First of all, we come the construction of variometers and vario- to the cabinet-making room, where the couplers. These are not wound on formers, cabinets are assembled, to be polished lateras is usual with this type of in.4trument; but . ATTRACTED by a large aerial on thein another department. are moulded and are -extremely light. and 4 roof of a factory bearing the name of are nevertheless quite as efficient as the more. 4 a well-known engineering firm, it was not long before I was in the presence of theDetection of Flaws. common type. ,.f. manager, who kindly offered to take me over After these cabinets have been varnished Later we came to a large shed where the t the works. The General Radio Company'san 1 highly polished and fitted with various metal turning is carried on.. -, apparatus is so well known to many peoplegadgets, they are passed on to have their There is a special X-ray installation for - that it should be interesting to read how it ebanite panels fitted. By this time the panelsthe detection of flaws, only perfect material iis made; and judging by the output, somehave been drilled, polished, lettered, and being used. The G:R.C. sets have, I note, eix hundred sets every week, the apparatus wired,allthe wiring,ofcourse,being been redesigned to give greater seleetivity, r must be giving entire satisfaction to the sal dered. and are tested at Harlesden to cut out Lon- Otielnan, of rourse, is not responsible fordon and receive other broadcasting stations. -public-. - 718 Popular Wireless Weekly, June 30th, 1022

WIRELESS !WIRELESS !WIRELESS !and EVERYTHING forit. We insiston being the DON'T PAY MORE Cheapest in Great Britain. NOTE. We areexclusively WIRELESSNOT DABBLERS! Reliable goods at less than so-called Wholesale Pioneers of -Prices (to the Public) " DON'T BE BLUFFED." Cheap Prices. CANADIAN BRANDES HEAD- WASHERS, 4 B.A, iierdoz.Id. SLIDER ROD, brass,13 in. long, in. PHONES, stamped B.B.C. Ourprice, WASHERS, 2 B.A... per doz.ltd. square,drilled - each 310.. per pair 1916 FILAMENT RESISTANCES,smooth SLIDER KNOB, ... each 20. SIDPE - HEADPHONES, 4,000ohms, action,marVellousvalue 2 / . SWITCHES ON EBONITE, S.P S 15 / 6 -With engraveddials 2/ 11 (quality the best) each 1'6 genNine, our price CONTACT STUDS, with nuts and "SWITCHES" ON EBONITE, S.P D.T. THOMSON HOUSTON HEADPHONES, washers Perdoz.5d. (quality the best) each 1 11 (Free el )4,000 ohms, our price - 18 / 11 STOPS, with nuts per doz.7d. SWITCHES ON EBONITE, D.P D.T. BROWN'S FEATHERWEIGHT HEAD- TERMINALS, withnut & washers, (quality the best) each 2; 9 PHONES, 4,000 ohms, our price 26 / 6 each Id., 1td. & 2d. CONDENSER SPINDLES, allsizesin MARCONI R. VALVES 12 / 3 EBONITE KNOBS, 2 B.A ,each 14d.,30.&4d. stock,from earlslid. MULLARD " ORA " VALVES 1219 SPACING WASHERS, large pet doz.21d. SCREWED ROD, 2 B.A., 12in.long, DUTCH VALVES 8 / 3 SPACING WASHERS, small per doz.11d. each 3d. EDISWAN VALVES 12 / 3 CRYSTAL CUPS, 2 screw eachld. SCREWED ROD, 4 B.A.,12in.long, (AllGuaranteed New). CRYSTAL CUPS, 4 screw each 2d. Carts 210. L.F. TRANSFORMERS, Ratio 5 to1. FIXED CONDENSERS, all capacities,each 110. RUBBER -INSULATED LEADING -IN Allguaranteed. (Postage1 / -) each11 / 3 EBONITE, cut to any size by machinery WIRE per yard lid. CRYSTAL DETECTORS, Adjustable- 1/3i while you watt perlb.3 / 6 INSULATORS, whitereel,2in.,each CRYSTAL DETECTORS,enclosed in TELEPHONE TERMINALS, nuts & lid per doz.114 glass case 216. 2 / 3, 1/11 washer, each1./jd per doz.1 / 4 INSULATORS,whiteEgg,each2d., SWITCH ARMS, best quality 91d. W. 0. TERMINALS, nuts& washer, - SPr ,toz 1 9

AERIAL WIRE. 7 / 22, guaranteed hard - cash 2d - ' Perdoz.1 / 9 ECIAL -HERTZITE - CRYSTAL, drawn topper, 100 ft.(postage 1 / .) 2 / - PANEL BUSHES,drilled,each1/0., large piece each 101,1. CONDENSER VANES, fixed or moving, per doz. - 1 / 4 WOUND INDUCTION- COILS (post- per doz 3td. TOP CONDENSER, bushes,each1d.; age9d.). Real Gold Cat's Whiskers earls2d. BOr doz. 11d. 12 x 49p4 8x2/6 x 3 6 x 2 Per doz. 118 TTOM CONDENSER, bushes, each 2/8 2 / 5 2/2 1/11 1/8 CONDENSER SCA LE g, 0 t6 180...each3td. ld per doz.9d.. TAPPED INDUCTANCE COILS, 20 IVORINE LABEL SET,12different VALVE LEGS, nut & washer, each Id.; tappings wound to 1,600 metres ...... each2 1 1 readit,9 theset7td. per doz. 10d VARIOMETERS (TubeType)complete

BATTERIES, /Itw, I , 3d. each doz.219 VALVE PINS, nut& washer, earls 10.; with knob 3.11 NUTS, 2 B.A. per doz.21d. perdoe 9d. DOUBLE 'PHONE. CORDS, full length1.41 NUTS, 4,5, 6J, 8 B.A...... per doz.20. PLUNGER SPRINGS, complete each 10. BELL WIRE,tinnedcopper, 12 yds... 60.

44ELKAY" WIRELESS 60.7 225, Bishopsgate, London, E C. 2. Half -day closing, Saturdays. Trade Supplied -Accumulators charged on premises. Open Sunday: 11-2.30. Please remit ample postage. Note new Telephone No.: Central 8544.

The ideal MAKE YOUR OWN E moonno=RECEIVING SET=amomnorz INSULATING VARNISH Th11111111111111111111111111111111111111111111111119111111111111111111111911111111111119T THE S.S. WIRELESS sets of parts com- 3HARDICOL prise everythingrequired, including SHELLAC INSULATIN G Inductances, Transformers, full-size Draw- ings showing top and underside of panels :: VARNISH CEMENT :: and position of every connecting wire. Guaranteed made from pure Shellac. A saturated solution in the cold.Perfect for all insulation work. Enquiries incited from the trade. 6d.and 1/- Bottles.Also in BULK. 2 -Valve (Low -frequency) Set - £3.10.0 HARDICOL ISOBTAINABLE FROM THE 2 -Valve (H.F. Reactance) Set-- -£4. 0.0 USUAL DEALERS AND THE MAKERS: 3 -Valve (1 H.F., 1 Det, IL.F,) Set -£6. 0.0 A. F. HARDING & CO., LTD., EXMOUTH ST., STEPNEY, E. 4 -Valve (1 H.F., I Det, 2 L.F.) Set-£8. 0.0 2 -Valve (note magnifier) Set -- -£3 .10.0 Carriage Paid CONTINENTAL SUPERSENSITIVE FEATHERWEIGHT PHONES Detailed List of parts THE FINEST PHONES FOR ALL-ROUND PURPOSES. EARPIECES CAN BE DETACHED INASECOND FOR on_application SINCLE USE. 4,000 OHM RESISTANCE, LAMINATED POLE PIECES;LEATHER COVERED HEADBANDS Broadcasting Variometer - - - - 9.0 FOR COMFORTABLE WEAR 15 6.PostageOd. Grid Leak and Condenser- - - - 3.6 AdjustablePattern, as Illustrated, 21;6. Postage 6d. Reactance :Transformers(Prov. Pat.) 4,000 ohm Phones, Brunel Type, 16.6. Postage 6d. 15.0 Scientific Basket Coils (set of sic) with Calibration Crystal Set Var. Tuning 40 miles re- Tables (suitableforall Broadcast Ware -lengths). ception guaranteed 15.0 150 to 4,000 Metres, 2,6. Postage 3(1. Post Free Coil Holders for Basket or Slab Coils, to flt in Stan- dard Plug-in Tuning Stands, 1'6 each.Postage 3d. 47 S.W.G. oz. Bobbins D.S.C., 1 0. Enam. 10d. Double quantity (Enam. only)1 6. Postage 2d. High -Tone Reed Type Buzzer, 2 9.Postage 6d. S. S. WIRELESS Co. Ltd, Grid Leaks, 2 meg., 9d. each. SPON END WORKS - - COVENTRY Fixed Condensers, all capacities, 1 0 each. Postage 2d. Enquiries Invited. Trade terms on application. Scientific Supply Stores, 'PHONE z HOP 4177. 8 & 126, Newington Causeway, S.E.1. illnion11innin111111111111111111111111111111111111111111111111111111111111111111111111111111111MWifila11l0 Popular Wireless Weekly. June 30th, 1923. 719

At a demonstration the other day, every- . thing claimed for the 3 E.V.C. was proved THE NEW ELIMINATOR thoroughly.At the showrooms, situated A. PORTABLE FOLDING Describing the wonderful " three electrode " about one mile from the London station, variable condenser, and how it eliminates a four -valve set was in operation, working a TABLE. " jamming." large, loud speaker at full power. Cuts Out " Statics." FOR some time a great deal of research work has been carried Out with a view In the ordinary course of events, it would THE illustrations show an ingenious new to eliminating interference of all kinds. be impossible to tune out 2 L 0 and receive folding table that should be useful to Amateurs living in London have been unable other stations, but with a variation of wireless operators, both amateur and to tune out the London station and receive about five degrees on this wonderful- instru- expert, as well as for a considerable variety ment Birmingham came through clearly and of other purposes.It can be made in any other broadcasting stations, whilst those without interference, and later a clear item size, ,but the standard size, when set up, situated in the other broadcasting centres from Cardiff. It has been tested with perfect measures 5 feet by 14 inches, and stands are similarly affected. results as near as ninety yards from 2 L 0. about 27 inches high.When folded the Not Fully Realised. Nearer than this, of course, results cannot overall measurements are 30 inches by 14 Perhaps the chief sufferers from inter- be expected to be good, as the wave has not inches by only 1 j inches, the legs folding ference are those situated on the coast, time to form properly, having to go a inside and flush with the table top. Thus quarterofitsown it occupies a minimum of space, and can be wave -length before conveniently carried, for instance, beneath being perfect. the cushions of a motor -car.From the As a static elimina- closed position it can be opened and set up tortheinstrument in two seconds, and folded again in four has been tested where seconds.There are no nuts or screws to conditions are reputed manipulate; and no loose parts to adjust. to be worst in this respect,namelyin For Many Purposes. Africa, and found to giveresults hitherto To prevent the two leaves of the table top unobtainable. from sagging where they are hinged at thecentre,alight,triangulartrussis. In the diagram a provided, which automatically opens as the method is shown leaves are hinged apart, and automatically whereby the 3 E.V.C. closes when they are brought together again. isconnectedto an The weight is less than 14 pounds. The table The Three Electrode Condenser. existing set for selec- should prove of great use for wireless sets -- tivity. especially when used out-of-doors-as well where it is almost impossible to tune out the This arrangement,' however, is only suit- as for picnics, in camp, for surveyors, and ships that vigorously transmit spark on 600 able in such eases where the desired station's shooting parties.It can be employed as a metres.There are many who have found wavelength is greater than the wave -lengths bed table, spanning right across a double it necessary to give up wireless altogether of the stations that are " jamming " ;a bed and resting on its legs on the floor. for this reason after having experimented different scheme being necessary in other can Also be used in a motor -car by leaving and utterly failed in cutting out thisin- cases.Itis,however, quitepossible to the legs: folded inside and spanning across terference. extend the usefulness of the three electrode in front of the back seats, the ends resting on The " Three Electrode " variable con- valve to the latter. the side doors of the car. denser (Messrs. Autoveyors, Ltd.) has been on the market for some six months now,

These photographs clearly show thethreepositions that should be taken when opening the portable folding 0 A table. 3 RECEIVER Z AE

X.To wave -length of offending signal. Z. As necessary to receive station desired. and judging by the complaints received dad..by POPULAR WIRELESS' -Of -people Such a table unti le to ..tune -out- various stations, the should prove veryuseful putt -have not yet fully realised the value forthose of this instrument. wireless amateurs The Eliminator, as it is called, is really who take capable of eliminating jamming, and is also part in out- of-doorde- very useful forcuttingoutstatics.It monstra- comprises three sections, each consisting of tions, i t s a tierof rotary or semi -rotary parallel compactness and adapta- plates of one-third disc area. bility will be apparent At a Demonstration. from the accompany- Whilst providing all the essentials of the ingphoto- ordinary two -electrode condenser, it has the Note the simplicity of the graphs. all-important addition of the coupling of the operations involved indicat- third electrode, which may be employed in a - ing the rapidity with which thbusand and one- applications. they can be carried out. Popular Wireless Weekly, June 30th, 1923.

Aneatlyarrangedtrans- SOME INTERESTING AMATEUR PHOTOGRAPHS. mitting and receiving station mounted on a desk.

A variometer crystal s e t built intoa cigar -box measuring 7" di" .< 3- by Mr. R. Bees- ! e y,of St. Bees School, Cumberland.

A home-made valve -crystal experimental set. An experimental unit system receiver with easily accessible wiring. Assembled byMr. G. Tombs, 78. Maldon Road, Brighton.

Another " cigar - box " receiver constructed, on lines suggested by arecentarticle in P. W.," by Mr. F. H. H. Peate," of 90,Port elet' Rd.,Stoneycroft,' Liverpool.

A crystal re- ceiver with tapped coils employ i n g alternative detectors. This neat - lookingset was made by Mr.M. Hirst.of 283, Rim - roseRoad, Bootle, Liv- erpool.

This highly efficient receiver brings in most of the B.B.C, stations on a frame aerial. Popular IV -if -class Weekly, June ;i'atii, 1923. ' 721.. WIRELESS WORRIES. By L. McMICHAEL, M.I.R.E. (Secretary of the Radio Society of Great Britain). This is the first of a short series of articles written specially fer " POPULAR WIRELESS " by Mr. McMichael, dealing with the problems that beset -the new recruits to the ever-increasing ranks of listeners -in. I. CHOOSING AND PURCHASING A SET.

ALTHOUGH wireless in this country is briefly the difference between crystal sets frequency amplifiers, - detector, and low - becoming increasingly popular every and valve sets of different sizes. frequency amplifiers.An excellent com- day, therearestillthousands of When voice energy is sent into the trans- bination of the functions of these valves people who have yet to hear a wireless con- mitting aerial of a broadcasting station, it is a four -valve set, where, as a rule, there -is cert, especially in the smaller towns and in is transformed, simply speaking, into wire- one high -frequency valve which magnifies the country districts. less waves. In order to hear this voice, it is the incoming signals, a detector, and two At the advent of something new and necessary to re -transform- these waves into low -frequency valves, which amplify the wonderful, the public, as typified by " the -speech, such as is heard in the headphones. -energy passing from the detector. man in the street," is strangely reserved in That. part of a wireless set which effects Points to Consider. its immediate adoption, whether it be some-, this transformation is called the " detector," - When -about to purchase a set the man thing merely useful or whether it be some- becauseit" detects "thewaves and in the street must satisfy himself as to thing which will give him pleasure and,changeS them back into audible and intelli exactly what type of set he requires by amusement at leisure, in the comfort of his - Bible sound. Therefore, every set must have answering the following questions : own home. a detector, one detector only being neces- (a)_Whith stations do I want to receive ? sary.The detector takes the form of a That is, is it the local broadcasting station Discussing Various Sett. crystal or a valve, and sets using a crystal only which will satisfy him, or does he Such has been the case at the coming of or one valve as detector are called crystal want to receive farther afield ? wireless.The whole country was taken sets and one -valve sets respectively. (b) How far do I want to receive? That is, by storm.People who had dabbled in Now, in order to magnify the sound which is he content with B.B.C. concerts or does he wireless before went wireless mad ;their the detector passes through, valves can want to 'receive Paris and The Hague as well ? enthusiasm was infectious, and spread to be used as low -frequency amplifiers. These (c) How far am Ifrom thenearest others, so that at the broadcasting station present .time there and, lastly, how are thousandso f niuch canI afford people who hold to spend ? licences to reeeivethe Havingsatisfied regular broadcast- himself on these ingentertainments, points,thepro- transmitted -through spectivebuyer the British Isles and should go to a good the Continent. firm and explain to But " the man in the salesmanexactly the street "-he still what he wants to holds back. H e is eceive,what volume almost afraid of that i s required, and a wizard wireless, and brief description of is still waiting for his the conditions of the neighbour to stretch localitywhere the a wire over his roof set is to be used. in proof that there is These facts help the a " wireless " in situ, salesman enormous- before he decides to ly to satisfy him in follow suitand add to every way with- an his own enjoyment instrument which by installing a wire- willanswer every lessset.Then h i s requirement. When difficulties c o m- this set has been found a demonstra- mence. He has This photograph, taken by Mr. G. W. Nicholls, of 331. Cavendish Road, Balham, S. W.12, shows the layout never heard awireless of a tapped coil crystal set. tion should be asked concert ; he does for, and this should not know what type of set he requires. He valves merely magnify or make loud signals enable the buyer to choose the instrument has heard his friends talk about licences, and which have already been detected by the which, from his own idea of finish, operation, it frightens him.How does he get a licence, detector valve or crystal. and results, will,best serve his purpose. and what kind does he want? He begins to Prospective buyers should clearly under- think that wireless is absolutely beyond The Use of Valves. stand that " wave -length" has no connec- him.Why ?Because he has not been When signalsare transmitted from a tion vdth distance in miles from a broad- educated to know the proper procedure to station the waves become weaker and casting station, and has no connection with follow in order to give himself quiet and weaker as they travel farther and farther the volume of sound obtainable from any well varied wireless enjoyment. away, or, as the radio engineer terms it, receiver. Distance from a broadcasting As far as " the man in the street " is con- they become attenuated. In order to magnify station, however, has a great deal of effect cerned, wireless did not come gradually. or strengthen these weak waves so that on the volume of sound to be obtained. It was thrust upon him well advanced, with the station appears to be near, valves can Therefore, if the proposed locality of the the inevitable result that he was absolutely be used as what is known as high -frequency receiver is,roughly speaking, more than bewildered. amplifiers.Used in this manner, the valve thirty miles from the nearest broadcasting station, itis always advisable to have at least ' Therefore, in order to guide him so that magnifies the incoming waves before; they he may enjoy the pleasures of listening -in, a reach the detector so as to make them one high -frequency valve in the receiver, for few remarks on the choice of a set, erection of easier to detect by the detector valve. this will strengthen the incoming waves. aerial, etc., will probably be helpful.Firstly, Thus we see that we can easily have a set (The next article will deal with the erection of however,- it will be advisable_ to explain with combinations of valves acting as high - the aerial.) 722 ;:cirelessII eckly, .1n 30th, 1923. MAKING WIRELESS POPULAR By Sir J. KENNETH MACKENZIE, Bart. Once the delights of broadcasting are extended to secluded " out-of-the-way " villages, wireless will gain a permanent position in the country as a " monotony breaker."This article discusses the possibilities of such an extension.

WIRELESS, or indeed even ordinary obtain the enjoyment of something they sets being used. So the question of making telegraphicandtelephonic, com- have only probably heard of in the way of reliable crystal sets capable of receiving over munication withtheouter world conceits, vocal and instrumental, to say a radius of a hundred miles or so must be does not seem to appeal to everybody. nothing of recitations or Grand Opera. One solved before such places as these can be There are folk who, happy in their own may try to explain to them what it is, but supplied with what would be most suitable. immediate surroundings, shrink from being only by actual experience gained through There is no doubt this difficulty will be brought into closer touch with strangers, hearing a good receiving set at work are overcome quicklyif - the progress made and have no desire for their isolation to be they likely to become eager to avail them-'during the past twelve months in wireless is disturbed or broken into unless and until selves of the 'opportunities now offered. To maintained, and new and extensive markets theirpersonalnecessities overcomethis effect this will require a more active pro- will then be open to those who can supply repugnance ;or the desire for exclusiveness paganda on the part of makers of radio them.I have in mind many villages in brought about by their location has been receiving sets, who now mainly rely on Devon and Cornwall where, such a method gradually removed by causes over which advertisements in the technical Press. of propaganda would yield much financial they have no control. To get such customers, travellers should profit to those who undertook it systemati- be employed who would tour, preferably by cally, as well as intellectual benefit to those Completely Isolated. car,throughoutlyingdistrictsofthe who would avail themselves of what was Such appears to be the ease at present country, and give evening exhibitions with offered them. with the 75 inhabitants of the lonely little a portable set in each village visited, either island ofSt. Kilda, who refused to take in the village school, or out of doors in the Opening for Young Men. advantage of the telegraph stationbuilt summer -time. They would explain how Nor need this be confined to villages only, there during the war e'by the Admiralty, simple a matter it is to erect and work a for, apart from the smaller towns, there are and even now have declined with thanks suitable set, how inexpensive such a thing is many country houses widely separated' from a wireless one which has beenoffered compared with the pleasure to be obtained each, other, to whose occupants should be them. One would have thought that people from it, and generally " spreaki the gospel " brought the knowledge of what pleasure and so completely cut off as they are from the of wireless to the advantage of all con- enjoyment they would derive from the rest of the world would have been glad to cerned.Nor need such a method of radio posseSsion of a wireless receiving set. If this get into touch with their fellow -creatures ; propaganda prove costly, as a small charge were done by the right kind of agent, one but such is evidently not the case, although or collection could be made at each such who was able to get into touch with such they have no other means of doing so village demonstration, and there is no doubt people privately, and who knew his work effectively.For the past nine months they that good audiences would be got wherever properly, it is certain much. good business have been completely isolated, no com- it were held. now lying begging would result.Here is an munication with the mainland having been opening for many young men at present possiblebecauseofweatherconditions. Joint Ownership. unemployed who socially. and technically This I can well understand, remembering But there is one difficulty to be con- should be capallie of .handling it properly. how, in the summer of 1884, when cruising sidered which may suggest itself, though, In the early days of electric lighting lunch off the west coast of Scotland in a friend's without doubt, it will not be long before it is profitable work was done On these lines with yacht, we thought we would go to St. Kilda overcome if it really exists.That is the regard to country houses, Wlitise owners had to, see the island and its inhabitants.Its question whether crystalsetscould be practically to be taught what if meant, and inhospitable, rocky coast -line looked drear employed for such purposes, and the use of convinced of the advantages'of that method enough as we approached, but the seas then valves not rendered obligatory, as may be of illumination before they would place an running madeallattempts at landing the case at present. order for an installation.The same thing impossible, and we had to return with our Not many villagers could afford valve applies to wireless now, though; of course, a curiosity unsatisfied. sets, nor be capable of using them efficiently practical demonstration is. ever 'go much It is probable, however, that their desire even were they able to buy them.Some more easy and simple. ' for seclusion from the rest of the world will have to give way to the necessities of others, for, owing to its situation, St. Kilda forms a The efficient receiving station assembled most usefulpoint from which weather by Mr. F. Worrall, of 51,- Bilden Street. reports can be received and notice given of Bolton.(Left) A closerviewofthe depressions approaching from the Atlantic. - tuning panel. Scope for Publicity. Whether due to innate " conservatism " and dialike of " new-fangled " inventions, ' to simple apathy, it is hard to say, but I have found in some parts of the country that the idea of wirelesS broadcasting does not appeal to some people, and more specially to the women folk; Wlio; 'one would have thought, would have been the firstto welcome such an opportunity for breaking the dullness 'and' monotony of their lit es. To most of the out-of-the-way villages of the United Kingdom the telephone has now kind of joint ownership might be ar- found its way, and facilities for communi- ranged, of course, and an efficient agent cating with neighbouring towns exist ; but might be able to do this on the spot they are chiefly used by visitors, and rarely with knowledge of the local conditions.' by the natives, and then only in cases of The mere fact of such villages being in sudden emergency. out-of-the-waydistrictspresupposes The fact seems to be that they do not the remoteness of any broadcasting understand what " broadcaSting 'means ; station, and consequently the neces- they have no idea of how simple it is to sity of sufficiently sensitive receiving 4

Popular Wireless Weekly, June 30th, 1923.' WIRELESS AT HOME, IN THE OPEN AIR, AND EVERYWHERE. call of the open air need not take you away THEfrom your Wireless pleasures. Add pleasure to pleasure take your Wireless:into the garden, on the river, in the forest, on picnic and holiday, any- where and everywhere. THE " FOREST " PORTABLE CRYSTAL RECEIVER has a guaranteed range of 3o miles from any Broadcasting Station, is highly efficient and can be carried with perfect ease in its neat and handsome -case.-Ready for use any time, anywhere, being only a matter of -seconds to fix the aerial to the nearest edge, bush or tree. Price, complete withaccessories,including , highly sensitive Headphones(4,000 ohms),

Aerial, Earth Wire and Insulators .. . Z3-12-6Post free. (All Royalties paid.)

Price Urithout accessories.. £2 - 7 - 6Post free. (All Royalties paid.) Passed by H.M. Postmaster -General (Reg. No. 82 7).

THE TRADE SUPPLIED Accumulators, H.T. Batteries, THE " FOREST " VARIOMETER. Headphones, Values, Ebonite, Brass Parts, etc., in stock for immediate Stoutly made, constructed of fibre tubing, this Variometer delivery. is the most practical one for making your own Receiver. Suitable for Crystal or Valve Receivers, having a wave- length range of 30o to 90o metres.

Complete with engraved dial and knob, ready for use.. ',rice8/6

Birth knob only .. 6/6 P,,tage 6d. extra.

THE " FOREST" L.F. AMPLIFIER. OUR GUARANTEE. (Passed by G.P.O.No. 3359.) Orders sent by post toill receive ourimmediate andcareful In handOrne polished mahogany case, with engraved attention.In the unlikely event ebonite panel. Guaranteed efficient. Added to your of dissatisfaction, money will Crystal or Valve Receiver, greatly increases the be refunded immediately. volume of sound. Extra units niay be added at will. Cheques, Postal Orders,etc., Maximum range and perfect reproduction guaranteed. should be made payable to "The Forest Radio Co.," end PRICE.. £2-5-O crossed "A -Co." Stamped I3.13.C. 10/. extra. Valve 157. extra. THE FOREST RADIO CO. WORKS: Blenheim Rd., N.22. SCIENTIFIC INSTRUMENT MAKERS, 'Phone: HORNSEY 3804. G.G.S. 'Phone:CITY 7134.71, FLEET STREET, LONDON, E.C.4.

---GRIFFIN WIRELESS SUPPLIES Co. -- 80, Newington Causeway, /ifyoulave NOT - Hop 1806. LONDON, a VALVE SET S.T. 100 CIRCUIT. adopt the next best and The above can be seen, heard and explained in our showrooms. use All Components for this circuit in Stock. CRYSTAL. DETECTORS, VARIOUS, surplus A\ supply Bargain 2/.carte SCIENTII CRYSTALS ROTARY SERIES, PAR.ALLEll, SWITCHE'S for Panel mtg. .. 2/8each 1V6 each or 3 for 44- post free. TELEPHONE PLUGS & JACKS* for Panel mtg.2/6 each CRYSTAL SETS, various, 21/-. 2716. 35/-,40/- & 45/ - SCIENTIFIC METALS C? urp (md2 ) LimitedStock. Rare iN'ieis Specialists WATCH OUR WEEKLY SNIPS. IMPERIAL HOUSE . KINGSWAY. No Junk --All Quality Goods --No Rubbish. 7-7617ePh072e REGENT 3420. Expert .1 dr ice Free. I,-f Y , 7q4 Pnpiitgi. Wireless Jane 30th, 1023. BROADCASTING TRANSMISSIONS. In the following programmes full details of the Continental transmissions are included so that possessors of suitable receiving sets can take advantage of the many interesting items that these stations broadcast. From an educational point of view such material is invaluable, more especially for such amateurs that may be studying one or other of the Continental languages. GREAT BRITAIN. Hours of We ve-lengt h Station. Call Sign. Transmission. Items Transmitted. in Metros. Remarks. London ...2 L 0 Usually -5.30-11 p.m. . Musical Items, News, etc. 369 Every Weekday.

Newcastle ..5N0 Pt 5.30-11 p.m. . 91 0/ tf 400 91

385 Manchester.. ..2 Z Y 5.30-11 p.m. . 1 91 PP 99 425 Birmingham...... 5 I T 5.30-11 p.m. .. 91 91 49 91 .. 09

415 99 Glasgow .. 5 S C 5.30-11 p.m. 19 IP 04 /0 353 Cardiff.. . .5 W A 5.30-11 p.m. t1 11 tt .. BELGIUM

Brussels (1) B A V 11 a.m. (G.M.T.)..Weather report .. .. 1100..Working days. 3.50 p.m...... Aeroplane traffic . 1100 ..Every day 8 p.m... ..Concert .. .. 1100..Tuesday & Thursday

6 p.m. .. ..Concert .. .. 1100..Sunday HOLLAND

The Hague.. PCGG 3-5 p.m. (G.M.T.) ..Concert . 1050 Sunday. 8.40-9.40 p.m. ..Concert 1050 Monday & Thursday The Hague.. PCUU 7.45-10 p.m. ....Concert 1050 -Tuesday. (Laborat ori urn Heussen) .9.40-10.40 a.m. .. ' 1050 Sunday.

The Hague (Volthuyzen) PCKK . 8.40-11.40 p.m. Various 1050 Friday. Ymuiden (Middelraad) PCMM 8.40-11.40 p.m. ..Concert . 1050 Saturday. Amsterdam P A 5 8.10-11.10 p.m. ..Concert and News 1050 Wednesday. FRANCE Lavallois-Perret (Radiola) SFR 2-3 p.m. (F.S.T.) Music .. 1780 .Sunday. 12.45-1.45 p.m...News and Concert ..

5.5 p.m. .. Stock Exchange News 1780..Every day.

..Instrumental music .. 1780 ' 8.45 co.m. General News.. .. 1780 .. PP 9.30-10.30 p.m. Vocal and instrumental concert ..1780 St Paris (2) (Eiffenower) F L 6.40 a.m... .. Weather Forecast .. _ 2600 11.15 a.m. .. Weather Forecast. 2600 . 3.30 p.m. ....Stock Exchange News .. _ 2600 . 6.20 p.m...... Weather Forecast, Concert.... 2600 90 10.10 p.m. .. Weather Forecast.. ..2600 Ecole Suporieure des P.T.T. 7.45-10 p.m. ....Radio Concerts .. 450 TuesLy, Thursday, 2.30-7.30 p.m. Radio Concerts 450 "Saturday. Radio -Riviera (Nice) 11 a.m... 0 4 News, Concert .. 480 Every day. 5-6 p.m. .. ..News, instrumental Concert.... 460 , 9-10 p.m. . ..Latest News. Conceit .. 460 Lyons (La Dona) Y N 0 6 0. 10.45-11.45 a.m...Concert .. .. 3200..Every day 3-3.35 p.m.....Financial News and Aviation Reports 3200 . a Pt GERMANY, CZECHO-SLOVAKIA, AND SWITZERLAND

Berlin...... L P ..7-8 a.m. (G.M.T.)..Financial News, etc. .... 2800 Every, day. (fionigswusterhausen) 11-12.30 a.m. 4-5.30 p.m.....Financial News, etc...... 280Q Eberswalde .. . .. 6.30-7.30 p.m. ..Concert -...... 2930 ThurZay. 4-.7 p.m...... Lectures and Concert. -. .... 2950 Sunday. Prague .. . ..P R G ..7-11 a.m. and.3 p.m.Weather News, General News..... 1800 90 9, a.m.-2 p.m. & 9 p.m. Concert ...... -.. 4500 Geneva ...... 5-6 p.m...... Concert ...... 1200 04 Lausanne ...... H B 2 ..5-6 p.m...... Concert ...... - Every day. The British Broadcasting Stations transmit on Sundays between 8.30 and 10.30m. and at varying times during weekday mornings and afternoons.The programmes appearing in the daily Press should be consulted for full details. (1) If, at the indicated times, a station has to receive or transmit service communications, the weather transmission willytake place after these communications.Tuesday :Operatic selection on the gramophone.Thursday :Various on gramophone.Sundays :Various by artistes. (2) Special concerts given during the evening are announced in the course of the preceding transmissions.

There is a distinct advantage in the H.T. An interesting catalogue of complete sets battery with replaceable units over theand high-class accessories has been dis- CatalbOues ordinary type, and all amateurs should maketributed to some4,500clientsby L. a point of seeing J. F. Smith's new leaflet McMichael, Ltd. They have also published describing the " Sure-a-Lite Everlasting "a leaflet descriptive of the new " Eiffel Bak Reviews batteries. Tower " Wireless Masts. * * * Another unit H.T. battery lately placed The Electrical Depot,. Ltd., have placed on the market is the " Seddon." With theon the market a very neat little battery ordinary type of H.T. if one section goes charging panel, the " Cressall."By means dead the whole battery is practically useless, of this instrument accumulators can be so it will not be long before this type of easily charged at home off the D.C. Mains. MANY causes of failure have been traced battery is universally used. * * to faulty connections so Fluxite, Ltd., Ashdown, Ltd, have forwarded us an have placed on the market a very handy We have received from G.W.T., Ltd., two interesting brochure descriptiveoftheir little soldering set, entirely complete in itself, interesting leaflets. The first deals with the B.B.C. valve sets. These instruments, while which should find its way to every wireless repairofwirelessvalves and ordinary giving maximum results, are perfect in work- den. This set is very reasonably priced, andelectric light lamps, and the second with anmanship and detail. The catalogue ends up by the use of this solder ,a, home-made setefficient little rectifier, and a very excellent with a list of broadcasting stations and a has a much greater chance of functioning transformer, by means of which all accumu-,complete list of the Moise. alphabet, figures, first time than if wires are loosely connected. lators can be charged at home. and punctuation Popular Wireless Weekly, June 30th, 19,23.

The Best Finish for Radio Cabinets With Johnson's Wood Dye you can finish the cabinet of your Radio Outfit as well as an expert cabinet maker, and in any colour you wish, to harmonise with your other furniture.It comes in fifteendifferent beautiful shades,allof which can be lightened ordarkened-fulldirectionsoneverylabel.Johnson's Wood Dye iseasy to apply. Itpenetratps deeply and brings out the beauty of the grain without raising it-it dries in four hours. JOHNSON'S WOOD DYE isused and recommended by most cabinet makers.They know thatthereisnothing that can equalitfor a rich, 'everlasting finish. JOHNSON'S FREEBOOK ON POLISHING WAX WOODFINISHING An occasional application of Johnson's Polishing Wax To allwho write for over the finish of Radio Cabinets, whether bought sets it, we will gladly send c/Ae or home-made, will always keep them looking new, and our illustrated book gives a beautiful polish that will not collect dust or show PROPER finger prints.It will improve greatly the appearance of onthe Proper Treat, .,REATMEN all cabinets. mentofWoods. It FOR fl-°°1IS explains how to obtain vsfOODWP"- Renovates Ebonite the best possible finish Fuitc4ITURE Johnson's Prepared Wax isan idealpreparation for on allkinds of wood. restoring ebonite panels and other instrument boards and itwill be a great as used on wireless receiving sets.Furthermore, panels help toallthose 'who treated with Johnson's Prepared Wax resist acid fumes &AON 11 el 2 given off from the low-tension battery, and prevents that are making their own S .0AOtiliSON outfits. lheWodlinichutylwesnEtTON M ODE I. thick film of acid which you have no doubt noticed cover- ESoT OR ing the whole of the ebonite panel, and causes a terrific W leakage and bad results. ,1 Give Johnson's Prepared Wax a trial.You will be sur- 1 S. C. JOHNSON & SONS, LTD. prised at the wonderful clean appearance it gives, and the " The Wood Fihishihg better results you will get. (Dept. P.W. 6), West Drayton, Middlesex. Dear Sirs, Will you please send me your illustrated book, which S. C. JOHNSON & SON, LTD., explains the best way for finishing Radio Cabinets. "The Wood Finishing Authorities," My Name WEST DRAYTON, MIDDLESEX. My Address 733 Popular Wireless Weckly, Jiine30th, 1923. "WIRELESS REVIEW AND SCIENCE WEEKLY "

No. 5 of our great companion journalis now on sale, price 3d.In it will be found an important announcement concerning Professor Albert the famous originatorof the theoryofRelativity, and one of the world's greatestphysicists.Professor Einstein has accepted the post of Chief Physics Consultant to" Wireless Review and Science Weekly "-a suresignof the esteeminwhich the journalisheld by scientists.

No.5alsocontainsarticlesby ProfessorA.0.Rankine,D.Sc., Dr. N. W. McLachlan, M.I.E.E.,andMr.P.J.Risdon,F.R.S.A. A splendidlongillustratedarticleontheHelicopter formsanotherattractive feature.

No. 6 of " Wireless Review and Science Weekly " willbe on sale Tuesday, and will contain a very important interview with Sir J. J. Thomson, 0.M., F.R.S., the Master of Trinity, Cambridge, and discoverer of the Electron.

SirJosephtellsthefascinatingstoryofthisdiscoveryinlanguage everyone can understand and appreciate.

Futureattractionswillincludearticlesby Sir Ronald Ross; K.C.M.G., F.R.S.,the world famous medico -scientist, whoseresearchesintothecause , , andcureofmalaria have earned him thegratitudeofthe world. Other articles by SirOliver Lodge,Professor J. Arthur Thomson, Captain Round, Sir Frank Dyson, and Professor Einstein willappearinfutureissues.

ORDER YOUR COPY NOW and becomearegular subscriber to the most authoritative and most popular Wireless andScience Magazine inthe world. " Wireless Review and Science Weekly " has taken premier place and standsalone, unique and unchallenged. Remember: EVERY TUESDAY. PRICE 3d. Popular Wireless Weekly, June 30th, 1923.

PRACTICAL IDEAS FOR THEAMATEUR.

This is the height of D above the surface CALCULATING THE at which the measurements were taken, so TERMINAL you must add the height of the table and the HEIGHT OF AN AERIAL. thickness of the book. Supposing they were CONNECTIONS. 2 ft. 6 in. and 1 in. respectively, then the P. the angles in one triangle are equal total height above ground level of your 1to the angles of another triangle, then aerial would be 32 ft. 7 in. WHEN wiring up a set the problem of the triangles are similar and their soldering connections to terminals corresponding sides are proportional." is often one that gives a great deal of trouble, and there is usually some refractory This geometrical proposition enables you FILAMENT RESISTANCE Point at which the folder refuses to take. to calculate the height of your aerial quite Again, when connections easily. FOR CONTROLLING are made by In Fig. 1 the small triangle A, B, C, is giving the wire a turn round the shank of similar to the large triangle, A, D, E ; conse- TWO VALVES. the terminal and se-. quently, if D represents, say, the chimney curing with a lock - to which you wish to attach your aerial you nut,asshownin It can form the triangle A, B, C, and calculate THE sketch explains the idea without an Fig.2, the applica- the length of the line D, E, representing the elaborate description.The principle tion of heat due to height of your aerial. points in its favour being : soldering usually has 1. The saving of space on one's valve a slackening effect, panel. and one is faced with Obtaining Measurements. the difficulty of being There are many simple ways of forming unable to tighten up the small triangle. Two rulers or sticks satisfactorily. The writer offers our the following method, which was found to I give greater ease and certainty, as well as FIG I making a much neater and workmanlike job, together with another advantage mentioned later.

Two -Way Connections. 2. Costs less to manufacture .one resist- Drill a small hole about a4 in. india., ance of this type than two single valve or larger if necessary to suit the wire in use, resistances. aboutin. deep, as shown in Fig. 1.Next Rail contact arm iscontrolled by a bare and clean the wire, applying a little separate ebonite knob, and the contact arms

held on a table will serve for the lines A, B and B, C, the table top forming the line A, C ;but perhaps the simplest method is as are insulated from each other by an ebonite follows : Place a large,stiff covered book on a bush. table and hold a ruler upright by its side. FIG. 2. FIG 3. Raise the cover of the book until, when Neater Connections. looking along it from the back, it is in line One of the screws securing the resistance withthepoint D (your chimney,for unit to the panel is extended and acts as a flux in the shape of powdered resin or instance). Observe the distance between stop for both contact arms in theoff Fluxite.After heating the soldering-iror the fly -leafof the book and the point position. and loading with solder,rub the wire where the cover intersects the ruler-this through the solder and an efficient tinning is the line B, C.Measure from the back kill result. of the book to the edge of the ruler, which Add flux to the hole in . terminal and will give you the line A, C. apply the iron ;with very little trouble the All you have to do now is to measure hole willfill with solder, and while in a the distance from the back of the book to molten state insert wire and hold in place the base of the chimney, and you have the until set. line A, E, and all the figures necessary for It will be seen from Fig. 1, which shows your calculations. the finished article, that any slackening of The formula is :AC : AE :: BC: DE. the terminal can be adjusted without dis-

Supposing BC was 6 in. (ita foot), AC 8 in. turbing the connection.: (1 of a foot), and AE 40 feet, then Brassstripsare used to ...collectthe A two-way connection is simply made by : 40 :: : DE, currentfromthecontactarms,thus twisting the two wires together, as shown So that DE=40 xx 1, or 30 feet. avoiding any trailing wires. in Fig. 3, and proceeding as before. Popular Wireless Weekly, June 30th, 1923.

receive broadcasting from America, lectured on " The Reception of American Broadcasting." Sec., Mr.. C. H. P. Nutter, F.R.A. (5 D B). irecess Radio Corner, 243a, Se!hurst Road, Norwood Junction, S.E. 25. .The Beckenham and District Radio Society. Club A very successful meeting of the above society was held at ManoeHouse, the new headquarters, on Thursday, May 31st. at 8.15 p.m.The new set under construction was brought along, so eport that members might help; and also note progress made. Sec., Mr. J. F. Butterfield,10, The Close, The Editor will be pleased to publish concise reports of meetings of Wireless clubs and Elmers End, Beckenham. associations, reserving the right to curtail the report if necessary.Hon. secretaries are Reports sent High Wycombe and District Radio Society.* reminded that reports should be sent in as soon after a meeting as possible. The first summer meeting of the society was in cannot appear in this paper in less than ten days after receipt of same.An asterisk held at Polmark, Naphill,the stationof a denotes affiliation with the Radio Society of Great Britain. member (Mr. K. H. Milner), and proved an unqualified success. Tottenham Wireless Society. a welcome to new members, briefly outlined the '2 0 D (Mr. E. J. Simmonds, Gerrards Cross) The meeting of the above society, held on object of the society, and pointed out that kindly provided a transmisaion, and the scien- Wednesday, June 13th, was devoted to the throughamateureffortsmanyimportant tific department of the Royal Grammar School, demonstration of members' instruments. discoveries in the field of wireless telegraphy under Mr. J. Hum, demonstrated transmission A number of sets were displayed and tested, may happen. and reception on the O.T.C. Mark III. Trench ranging from a one to a five -valveR.I. set, Hon. sec.; G. J. Price, 22, Honor Oak Park,set. including the society set. S.E. 23. Hon. see., A. C'. Yates, 30, High Street, High Interestingresults were obtained from a Wycombe. Flewellingcircuit and from an interference Leyton Radio Association* eliminator. At the fifteenth meeting of this association The Thornton Heath Radio Society. Arrangements are being made to set aside an instructive discourse on Cabinet Construction A very successful preliminary meeting was one meeting per month for further ditiplays. by the treasurer, followed by the demonstration held on Tuesday evening; June 5t11,- forthe Those interested in wireless will be assured of Mr. A: T. Billingsley's3 -valveunitset, purpose of forming a radio society in this district. of a hearty welcome at any of the society's entertained the members. Officers were elected, a committee appointed, and preliminary arrangements made. Meetings will he held fortnightly and member. ship is extended to all ladies and gentlemen interested. Communications should be addressed to the Hon. see., R.S. Keeler, 72, Bensham Manor Road, Thornton Heath. TheLeedsandDistrictAmateurWireless Society. An instructional meeting was held on May 25th, Mr. T. Brown Thomson lecturing upon " The Electron Theory." The thiriy--,ixth general meeting was held on Interior of. wireless controlled model boat.Towards the bow can be seen the coherer and relay ;in Jane 1st. Air. A. F. Carter, A.M.I.E.E. presiding. the centre the selector, accumulator, rudder controls, switches, etc. During the _course of society business, the hon. sec: announced that application had been made for transmitting and receiving licences, and that meetings, there still being plenty of room for - Forthcoming attractionsinclude apublic apparatus would very shortly be placed at the new members. night, and lectures on Fixed Condenser Making, disposal of the members.Mr.S.Kniveton, Hon. sec., Mr. S. J. Clyde, 137, Winctielsea Restoring Dry Batteries, Copper Plating, The F.R.Met.Soc., then delivered a very instruc- Road, Bruce Grove, Tottenham, N. 17. Flewelling Circuit, and.Grid Leaks. tivepaper entitled" Wireless and Weather New members or any wanting further par- Forecasting." . Streatham Radio Society* ticulars apply to Sec., Capt. H. Thorley, C.A., Hon. sec., D. E. Pettigrew, 37, Mexborough On June 13th the chairman. Mr. H. Bevan Church Army Social Centre, Goldsmith Road, Avenue; Chapeltown Road, Leeds. Swift, A.M.I.E.E., gave a most interesting lec- Leyton, E. 10. ture on " The Romance of Radio."Dealing The Sydenham and Forest Hill Radio Society. with the history of transmission- and reception Newport and District Radio Association. An interesting lecture was given on May 4th in its early days, the lecturer -described the At a general meeting of the association held before the above society by S. C. Tucker, Esq. various kinds ofdetectors and transmitters on June 7th, Mr. G. Betts lectured on " A Simple (vice-president of the society), starting with an used and demonstrated on the blackboard the Crystal Circuit." ordinary crystal set, and using a galvimometer circuits then in vogue.After describing the Hon. sec., H. W. Winslow, 3, Dock Street, in place of the headphones to show how it was Poulsen arc method, electrolytic, chemical, and Newport. possible to get the most sensitive spot on the crystal detectors, he mentioned the first recep- crystal before fitting headphones. tion of music, by means of radio, in his experience. Radio Association.South Norwood and District May 28th, 1923.A lecture was given on This was the melody, " I dreamt- I dwelt in Branch. Elementary Electricity by W. V. Pegden, Esq. marble halls," sent by means of a tithed buzzer A meeting of the above society was held at (chairman). to each note. Shortly afterwards, the music from H.Q. on Thursday, May 31st, when Mr. J. H. D. Hon. sec., M. E. Hampshire, 139, Sydenhani a gramophone record was transmitted through Ridley, one of the first British experimenters to Road, S.E. 26. the medium of the singing arc lamp.Dwelling on the possibilitiesofradio,the chairman considered that the transmission of vision and power would soon be accomplished on the large scale. Hon.sec..S.C. Newton. A.M.I.E.E.,5, Pendennis Road, Streatham, S.W. 16.

North London Wireless Association * The evening of the 132nd meeting was set aside for general discussion among members. Many interesting questions were asked and answered. The experiment proved so successful that it is intended to keep regular evenings for exchange of views and solving the many problems en- countered by amateurs. Hon. sec., Mr. J. C. Lane. Physics Theatre. Northern Polytechnicli4itute, Holloway Road,

Honor Oak Park Radio Society. The society held its second meeting on June 13th, at St. Augustine'a Hall, Honor Oak Park. Mr. R. Fuller. of3. Leinster Square, Rattle:lines,Dublin,carrying outmanoeuvres with hiswireless The chairman (Mr. W.' J. Pollard), in giving controlled model electric launch. Popular Wireless Weekly, June 30th, 1923. 729

and now. .let us haveQuality THIS insistentdemand comes from thousands of experimenters who now, after the first few months' experience of inferior " parts,'are realising that they must havedependable,guaranteed Components...goods - with a name behind them. Itisthis demand forQualitythat is causing the greatly increased popularity of Woodhall-Wireless Components in allparts of the country ... They are goods designed, manufactured, and guaranteed by a Firm who embody precision, efficiency, andvalue, in each of their products. WOODHALL Guaranteed Variable Condensers Assembled complete as shown, with aluminium end- plates and ebonite bushes, for panel mounting.Ad- justable bearing, accurate And spacing; aluminium 22 gauge vanes ;attached to panel by drilling one hole only. P 114 5 plates ... 5 6

P115 9 6 -

P 11615 66

P 11725 8 -

P 11831 ... 86

P 11943 10 6

P 120 57 ...12 - Knob and Dial 1/9 extra.

I WOODHALL IGuar- anteed Moulded

40- Variometers Extremely close coupling (approx.1 -16th between wind- rT'o produce a loud speaker ings).Internal winding 'firTalf fixed by special process. 1- which is worthy of the Eliminates dead-end effect and artisteswho nightly rapacitylosses. W,L. with 100 ft. aerial. 250 / 750 metres. broadcast has been our am- For A.T.I. as supplied, or can be used with small basket -coilin bition- A loud speaker series for anode tuning induct- which reproduces the fulness ance. Withmassiveebonite knob and terminals, as shown. of the violin, the delicacy Bracketsmoveableforpanel of the flute, the blare of the or table mounting. trombone and the charac- I WOODHALL IGuaranteed teristic quality of the voice, that has been our ambition Paxolin Variometers and that is the guaranteed Constructed ofPaxolin tubing (not performance of cardboard) ;equal to ebonite inin- eulation, and more rigid.The walls allow close coupling, and the bearings are accurate and robust. Wound with S.C. wire ; attached to panel by drilling one hole only; complete with terminals, and fatted 0/9 Loud -Speakers with knob and dial. :74 Obtain one from your usual I s -s stores,electricianorwireless dealer, and judge for yourself. We are confident your verdict a Trade will be enquiries invited.

TheI WOODHALL Filament Rheostat A more efficient rheostat at little more than the price of the old style.Spring plunger contact; smooth and constant.7 ohms resistance ; winding mount- ed on core;-off " position ; two terminals ; engraved dial and 11 The Telephone knob.Attached to panel by drilling one hole only. 5/6 Manufacturing Co., :4 Limited Woodhall-Wireless Components of all kinds are stocked by London Showrooms: leading Wireless Dealers and Factors. Ask your DealerforWoof:hall-Wireless Components.Ifhedoesnotstork_ 68, Newman St., Oxford order direct by post from us: and if you give your Dealer'sname and address "True Music" St., London, W. 1 we supply goods post free. Money back in 7 days ifdissatisfied. PRICE £6 10s, 91 The Woodhall-Wireless Manfg. Co., coirmaiorm.avacu.armaos,,,t.00,,,t.amolagar 15, FURN IVAL STREET, LONDON, E.C.4. Telephone: Holborn 5919. Radio Call Letters 2 11 P. Popular Wireless Weeklg, June, 301A, 1923.

The circuit is by no means perfected as yet, and you -Aral find the tuning very critical. The position of the reaction Coilis also very' Critical, while thetwo variable leaks should be carefully adjusted for best RADIOTORIAL results.Up to, the present the shrill, high-pitched whistle has not been entirely eliminated, and so a certain amount of distortion of speed is bound to All Editorial Communications to be addressed The Editor, POPULAR occur.For C.W. reception the circuit is very good, but altogether the set is well worth a little time and WIRELESS, The Fleetway House, "Farringdon Street, London, E.C.4. trouble, as it is a most interesting circuit. You may find that a variometer placed in series with the reac- tion coil will assist in tuning out the whistle, though it nmy cause a slight diminution of signal strength At the moment of writing no details are to hand in before you are able to cut out distortion. As regards respect of the activities of the committee of learned valves, the ordinary It type will be quite suitable. gentlemen who are presumed to be investigating the position of broadcasting, more particularly in respect (Bexhill). -- What size of litences.The decisions arrived at by this com- "HONEYCOMB" mittee may be momentous, startling facts may be former, number of spokes, wire and turns; etc., brought tolight,beneath its seeming tranqUillity. shall I require for honeycomb coils for primary, Revolutionary: fire may be seething, but in the interim secondary, -anode, and reactance to tune to the wireless" pirates "areincreasinginnumbers, amateurs are throwing all prospective ideas of " con- broadcasting ? structor's " licences to the board and openly and Wind the coils with 26 D.C.C. on formers 2 in. defiantly hoisting the radio "skull and crossbones." diameter, with 15 spokes each side and I in. in width. These officially appointed commiees do not seem to Primary, 50 turns;secondary, 75 turns;anode, hurry themselves- possibly they adopt the relativists' 75-100 turns reactance.50 turns. Note that view of time snd regard just a few weeks, a few months, honeycomb coils are the subject of letters patent, and or a few years, as but a few moments relatively to the A. P. (Rugby).-Can you give me details of permission should. be obtained from the patentees, significance of the results achieved. the Flewelling Super Circuit ? before constructing. One cannot criticise their actions because one knows nothing of what is proceeding behind the stout walls of official silence, but it is to be hoped that shortly the F. S. N. (Booker).-What do you consider committee will issue forth from its dignified seclusion the best single -valve circuit for use in conjunc- and lay before the P.M.G. decisions worthy of the time they are taking to prepare.Time is money to both the tion with a loose coupler? Can I use a variable Poet Office and the B.B.C., and both interests are losing grid leak ? heavilyduring this quite, in my opinion, avoidable delay,in issuing a licence suitable for the man who desires to construct his own set. THE EDITOR.

Owingtotheenormousnumber ofqueries received daily from readers of POPULAR WIRELESS, I have temporarily decided to limit the number of questions sent in by one reader to three.Readers are asked to keep their questions as'short and as concise as possible in order that the minimum of delay can be exercised in answer. ing queries.Until further notice three questions from one reader will be the limit for one letter. ....FLEWELLING SUPER -REGENERATIVE CIACUIT All questions should be addressed to POPULAR WIRELESS Queries Department, Room 138, Fleet. The diagram shows the connections of this circuit way House, FarrIngdan Street, London, E.C.4. and the condenser valites.The aerial should be a Readers are requested to send the necessary small, straight wire of about 4 ft. in length. DonotuSe This circuit should give good results with the loose postage for reply. the ordinary outside aerial, as the set reacts very coupler.The '0005- condenser in series with the strongly and will cause interference over considerable aerial may, of course, be omitted, as a slider is used distances. for tuning.If you intend keeping to the same circuit The Editor desires to direct the attention of The bank of '006 mfd. condensers should receive and using the seine valve, a variable grid leak will be his readers to jhe fart that, as much of the in- attention, asthesecondensersshouldbe. fairly unnecessary, but this type of leak is very useful when formation given in the columns of this paper accurately made. Experiments should be carried out, the valves arc being constantly changed, as different using different capacities, however, for we have found valves usually need different values of leaks:" This is of a technical nature and concerns the most that sometimes a larger condenser across the leak is circuit sometimes works gratewell when the high- recent developmentsin time Radio world, desirable. The coils have 125 and 70 turns, as shown, the 70 -turn coil being tapped at 20, 30, 40, 50, and, tension battery is cut out. some of the arrangements and specialities * described may bethesubjectofLetters 60 turns.A former of 3 in. diameter will be quite suitable and the coil should be wound with stout D. S. (Croydon).-Can an, ordinary two; Patent, and the amateur and trader would wire, say, 18 or 20 D.C.C., or enamelled. The reaction elide coil be used in conjunction with a valve be well advised to obtain permission of the coil can be of the spider variety, rotating inside or up patentees to use the patents before doing so. against the other coil. (Continued on page 732.)

CHASING AWAY THE " LIMEHOUSE BLUES." Popular Wireless Weekly, Ji'ine 30th, 1923. '731

Price List of Units NOT the least of the advantages of Peto-Scott for home construction. Standardised Radio Units is thatitenables No. 1. Tuner Unit .. 27,6 No. 2. CondenserUnit 42i- a man to gain a wealth of useful experience No.3. H.F. Amp.Unit 13,6 No. 4 Detector Unit 17:6 while he is assembling them. No. 5. L.F.Amp.Unit 33 6 Mr. James H. Falconer, of Kew, S.W., writes : " It is solely No, 6. Crystal Detector owing to the instruction I have received from assembling these Sets Unit .. 15'6 of Parts that I now understand the principles of Wireless and am No. 7. " Reactode " Unit .. 28,6 able to go ahead and experiment a bit on my own." Cabinets for1,3,4,5,6&7 3,6 If you, too, want to build a splendid Three -Valve Set like for No. 2.. 7; - Mr. Falconer's at a moderate cost and learn the principles of Wire- Postage. 95. per Unitextra, less at the same time, send 6d. for a copy of -Radio -a 24 -page but paid over £2. Booklet fully illustrated with photographs and diagrams. PETO-SCOTT CO., Ltd., P. Weullington St., Strand, W.C.S. 64,High Holborn,W.C.11)9;"'iVi'''At,Vorli)°,n4?'1'i.

ACCUMULATORS SPECIAL OFFER AT --DEPENDABLE--/ REDUCED PRICES Popular Type. Clear Celluloid Cases. Volt-IgnitionAct.A.R. RADIO SERVICE O. age.Cap. Amps. Price Vrrtrr.a Cap. ALL Aerial Wire, 7/22 bare copper stranded, 100 ft.26 1000 4 71 8 9/111 Insulators. Reel, 1J,d. Egg 3d. Shell, 6d. 1310 4 20 10 1211 ; 1/6 1315 4 30 15 14/1.1J WIRELESS Variometers,silk wound, fitted with Ebonite 1320 4 40 20 Dial Knob...... 46 1330 4 60 30 Willi2/3 ACCES- Crystal Receiving Set, Variometer tuning...100 1340 4 80 40 29/- E P R 1420 6 40 20 , unassembled70 27/6I2,6 SORIES f ACCUMULATORS 1430 6 60 30 33/9 ' Crystal Detectors on Ebonite base 3/-&2/- have 1440 6 80 40 3/6 1450 100 50 KEPT 9, f f Glass covered ... 36 20 YEARS' Oojah Basket Coils, set of 7, 150-4,000 metres50 REPUTATION IN Slab 8, 150-26,000 76 Accumulators RICHFORD & Co., charged on the STOCK. Basket Coils, our specialline,setof6, premises day and 153, FLEET ST., LONDON, E.C.4 170-3,500 m. night. Telephone :Holborn 5126. Estab. 1876. Coil Holders, 3 -way tExtraordinary value I " 2- I66 Intervalve Transformers, not rubbish 12/-32,6,16/6 Valves, soft, Dutch, ideal for detecting ... 106 MARRO1STITE CRYSTAL hard, amplification... 116 Tested and guaranteed. Amplion Loud Speakers upwards from 2 126 NICAYIKO1STITE CRYSTAL' VariableCondensers, For Panel Mounting. In Celluloid Case Use with any wire contact. '001 12,6 15/- '0005 ... 10/6 13/- MAIEZIKOINTITE CRYSTA.Z. '0003 ... 9/6 11/- Sensitive in every spot. , HEADPHONES- IVI.A.RICOMITE CRYSTAL "SLOPE " 4,000 ohms 1008,000 ohms 12 6 Supplied in sealed boxes.only.

"BRITISH" 4,000 1008,000 12 6

"BRUNET" 4,000 126Pival 1 MARKONITE CRYSTAL 2 6 No battery needed. Trial box containing two crystals post free for. 2s. WATERLOO ELECTRIC Co. Ltd., TRADE. Ask for Catalogue. All crystals supplied byweight. 129, Waterloo Rd., London, S.E.1 ROSE BROS. ElectricalCo.,Ltd., HOP 5649. Closed on Thurs. r p.m. Sat. 9 p.m.Other nights, 8 p.m. LONDON : GLASGOW : CATALOGUES FREE. 25-27, Milton St., E.C. 2. I 194a, St. Vincent St. Popular Wi'reless Weekly, June 30th, 1023. RADIOTORIAL QUESTIONS AND ANSWERS. (Continued from page 730.)

as detector ?I only want to get London. I may mention that the coil is giving quite satisfactory results with a crystal receiver. I intend using a Cossor valve. What plate and filament voltage willit take ?Can I use ordinary torch batteries connected in parallel for either "filament or plate supply ?I should prefer a. circuit that does not contain any variable condenser. -What is the probable range and cost of such a receiver ?What is the- best circuit to use, cutting out all un- necessary apparatus ?Shall I be able to use it under the new home constructor's licence when it is issued ?When is .this licence to be issued ? A two -slidecoil should give quite satisfactory results at your range.You will get London broad- casting,and probably Croydon aeroplanetraffic telephony, if your coil will tune up to 900 metres. You may also hear some local amateurs on the 400 - metre band of wave -lengths.The Cossor valve takes 31 to 4 volts on the filament and 20-80 volts on the plate.You cannot use torch or any dry batteries for the filament unless you usea Dull emitter type of valve.Torch batteries connected in series (notparallel)will make quite an efficientH.T. The cost will be about £3, excluding aerial, -coil, and 'phones, which you doubtless already have.You will be able to use this set with the home constructor's licence as far as reaction is concerned. We cannot say when the new licence is to be issued. As regards the circuit you wish to use, the following connections will be quite O.K. :Aerial to one slider, end of coil to earth second slider to grid leak and condenser of valve ;the grid leak and condenser to grid of valve ; plate of the valve to 'phones and 'phones to H.T. + : H.T. -to L.T. +, L.T. - to earth.Also L.T. + to the centre of the filament resistance and the end of the resistance wire to filament. The other side of the filament, of course, goes to L.T.

P. S. N. (Latchmere).-I have a three -valve set,onedetector and two low -frequency amplifiers.When I switch on the two -valve amplifier it becomes very noisy, and sets up a howl which I cannot prevent unless I reduce my high-tension currentto practically nil. the heart of This stops the howling, but signals die away. How can I prevent this ?I am using separate high-tension batteries. As the two -valve amplifier is run- from a separate the Circuit. high-tension battery, see what happens when the negative of this battery is connected to earth.If this fails try reversing the connections to the primary windings of the transformers, one at a time.It is WHICHEVER type of Circuit you are using worth trying to earth the iron cores of the trans- -singlevalve-notemagnifier-high- formers.If the above suggestions fail to stop the frequencyamplification, howling, disconnect the windings of the secondary orthemost transformerfromthelow-tensionnegative,or intricate reflex Circuit, you cannot use a better positive, as the case may be, and connect them to the Valve than a COSSOR. negative pole of a four and a half volt pocket -lamp battery.Connect the positive of this pocket -lamp battery to the negative of the low-tension battery. Its unique construction is wholly responsible for In this manner the grids are always given a fairly its loud and clear speech, absolutely strong negative potential, which should certainly - free from prevent the amplifier from breaking into continual distortion and microphonic noises. self -oscillation. Five experimenters out ofevery sixare now standardising onthe COSSOR for reception Q. P. R. (Coventry).-What is meant by work under difficultconditions.Why not be absorption modulation ? The term' absorption modulation refers to the guided by their experiences and let your next process of varying the amplitude of a radio -frequency Valve be a COSSOR-the improved working of alternating current in accordance with any desired your Set will surprise you , wave form.It is accomplished by systematically absorbing energy from the A.C. circuit in an element of a circuit which serves as a conveniently variable resistance. This will be more clearly understood if all Sold by all dealers in example is used, for instance, using the plate circuit of a three -electrode valve as a variable resistance, WirelessComponents and varying such resistance by means of suitable and manufactured by: voltages impressed on the grid, or by coupling such 1 5l a variable resistance to the aerial circuit of the COSSOR VALVE CD., LIO. transmitting set. Highbury Grove, N.5. \ CH. * * " AERIAL " (Morecambe).-How can I cal- culate the effective height of my aerial The effective height of an aerial is the product. of Rzot462.6 theform factor, and theheight from the earth to the highest point of the aerial. The effective height of the aerial can be determined by measuringH,the Gilbert Ad. average height of the main elevated portion of the aerial ;calculating C, the capacity of the same portion, disregarding the effects of the masts, trees, (Continued on page 734.) Popular Wireless Weekly, June 30th, 1923. 733

ThisisthepopularMarconiphone V 2,which bringsall BritishBroadcasting Stations withinrange ofany partofthecountry. The signature " G. Marconi "on the caseattestsits perfection of work- manshipandabsolutereliability.

The 0 Vo"1 Ma'GOAL T'rtuniph ofSthentaster aZind

,14 Yourlocaldealercan 44.40714. supplyyou. In case THE MARCONIPHONE V2 ofdifficultyapply to:- MARCONI'S WIRELESS TELEGRAPH COMPANY, LIMITED Marconiphone Department, Marconi House, Strand, London, W C. 2

HeadgearTelephones. THE NEW IMPROVED MITCHELLPHONES F,SiniAg3 AT GREATLY REDUCED PRICES.

WITH Leather Covered Headbands. WITH NON- ADJUSTABLE ADJUSTABLE eie" MAGNETS MAGNETS (illustrated) Onlythebestproductsmillgive you reallysat)sfm iccy resultsinWireless.Hereis a briefselectionofthe best obtainable.Note the prices : SUPER -ANTENNA: 3d. per yard -7/25 best tinned copper 19/6 wire, heavily insulated. 25/- I've Pair, " Autoveyors " SUPER. - CRYSTALS & SUPER, TENTACLES. Specially selected and tested on long-range Per Parr telephony by experts. SUPER -CRYSTALS: Volumite, 2/6; Talite, Hertsite, 2 / 3; Zincite,Permanite,Tellurium,2/-;Selenium,Molt bdini t e, 1 /6;IronPyrites,1/-;Bornito,Gelena,Carborundum, Swivel EarpieceS, Silicon, . 6d.: Graphite, 3d. fit comfortably SUPER -TENTACLES. Iridia Platinum, 1/3: Gold,1/-; to the ear Thumb and Finger Silver, Tungsten, Aluminium, Nickel Chrome, Nickel Copper, Sliding Adjustment. German Silver, 3d.; Zinc, 2d.; Copper, Brass, Steel, Lead, ld. FILTIEONS (Paid.), 5 /- each. A variable Grid leak ensuring precision control of Detector Valves. YILTRON COMBINATION (Patd.), 10 /- each. A variable NEW REVISED Grid leak coupled with a variable Grid condenser. EDITION Or CHICCO " LIGHTNING & STATIC DISCHARGER WIRELESS (Regd.), 5/- each. A complete protector which may be fitted CATALOGUE NOW to any set in two minutes and needs no further attention. READY. GREATLY " Autoveyors " SPECIAL PORTABLE LOOP AERIAL, REDUCED PRICES OF Adjustable Magnets for 10/each.Designed for outdoor, picnic, or river use. SETS AND maximum sensitivity, WESTERN ELECTRIC PRODUCTS: ACCESSORIES. Headphones, 4,000 ohms, E111210. Crystal Sete, with Headphones, £4/2/6. PRICE SIXPENCE. Loud Speaking Equipment, £3610/0. Can be supplied immediately from stock. Sterling Crystal Set, with 4,000 ohms.Headphones, £6/ 17, (' FOR SENSITI VI IY AND CLEARNESS OF TONE, THEY EVEN Npraitrox Loud Speakers and Amplifiers at revised s. SURPASS 1HE OLD TYPE MITCHELLPHONES WHICH THEY Cheques and Postai Orders should be crossed and made Pay- SUPERSEDE. SEE THEM AT able to: MITCHEL-1:S wELiERECLTECSALLATNDiD AUTOVEYORS LTD. McDERMOTT ROAD, PECKHAM, S.E.15. Radio Engineers and Contractors. WEST END SHOWROOMS: 84 VICTORIA STREET, LONDON, S.W.1. Write for Catalogue, the most comprehensive 2, GERRARD PLACE, W.I,(opposite Shaftesbury Theatre.) list; inthe -Wireless Trade, Post Free, 3d. 'Wireless Weekly Aerie 30tk, 1923.

..u.le RADIOTORI AL The same applies to the owners of the B.B.C. licence who grumble. These things KEEN PRICES QUESTIONS AND ANSWERS. are " on tap " every night, and the trouble SYDNEY JONES & CO., is that listeners won't give themselves a I203,SHAFTESBURY AVENUE, (Continued horn page 732.) chance. Instead of listening twice per week, LONDON, W.C.2.(Near Princes Theatre) some of them are doing their best to qualify screening effects, and suspension; and measuring CO, for corn plasters on their ears, through the actual capacity of the aerial at low frequency.

INVITE The formula for the effective height is then listening for about three hours each night of ! TRADE ENQUIRIES FOR Cs the week, to the same " theatres."They TERMINALS : NUTS : SCREWS : WASHERS EH = H, - are just suffering from surfeit of " too much CRYSTAL DETECTORS :EBONITE KNOBS OF C * . * of a good thing." ALL TYPES : ALL PARTS FOR WIRELESS The fault of the B.B.C.is that they SETS : HEADPHONES - BRUNET AND PIVAL " ST. GEORGE " (Missenden).-What is a re- jector circuit, and to what use is it put ?Can haven't taken this point fully into account. I BUYTHERIGHT QUALITY I use wood or slate for a panel in place of If they try the system of allotting to each AT THE RIGHT PRICE ebonite ? night a certain class of music, then those who Send or Call for List.Phone: Gerrard 7441 A rejector circuit is a tuned circuit composed of an like Greig, Chopin, etc., can feast them- inductance and a variable condenser, which is shunted selves once per week on -Mondays ;others Mini El=f across a portion of the receiving circuit.The circuit YOU CAN ASSEMBLE YOUR SET is so tuned that it will not respond to the desired who like being " whirled into happiness " with the certainty of success if youget aRadias outfit. signals, but will act as a by-pass to all other signals could have such a feast each Tuesday, etc. ; Ion may adopt the unit principle of building up an Ex- of near wave -length which would be likely to cause this would ensure a certain amount of fresh- tensibleExperimentalSystem,or interference.Two or three rejector circuits can be select acombinedSet to suityour included in the receiving circuit so as to cut out in- ness and eagerness.I very much admire localityandtaste.Everythingis terference as completely as possible. saanyd otniraiianggramj aonudrboilta: We do not advise the use of either wood or slate the principle of the " P.W." editorial staff RAD/Ax eaci!ottailnlevdalgueona cave as a substitute for ebonite. though they may give onthesesubjects,becausetheygive splendidsevic t1 quite satisfactory resultsif treated wellfirst.In equal publicity toallcorners, and as a E costs 30113. Ask for our catalogue the case of the wood, it should be dried in the oven, linitgaLsTallfinj,111;geoliouse, being left there for a few days to do away with any " Readers' Parliament " I think " P. W." is Percy St., Tottenham Court Rd., London, W.1. possible dampness.It should then be removed and second to none. allowed to soak in paraffin wax for several hours. This completes the treatment of the wood.Slate Yours faithfully, advertisements should also be well dried, and should be coated with EDWARD A. ARNOLD. WHENreplying to a thin layer of shellac.The shellac helps to prevent 4, Steele Road, pleasemention "Popular any moisture from condensing on the surface of the Wireless" to ensure prompt attention. slate.The slate is preferable to the wood. especially West Ham, E.15. for use as valve panels.In any case, the expense saved by using woodwill not compensate for the loss of efficiency that is likely to occur. To the Editor, POPULAR WIRELESS. BRUNT Sir,-In a recent issue of " P. W.," Mr. P; HEADPHONES 22, 6. B. L. N. (Canterbury).-How can I find the Morris writes criticising the Sunday broad- sensitive pojnt on my crystal set with the aid casting programmes, decrying the brevity TRADE511LUPPLIMID, of a buzzer ? of the entertainment provided, and pointing The two terminals of the buzzer are attached by S.CORRE, 140, Gray's Inn Road, W.C.1. short lengths of wire to a dry battery of about 4l volts. out what he considers to be the need for. Tel.:Museun? 2342. As soon as the buzzer is operating well, connect a " an interlude of a jolly, rollicking order." short length of Insulated copper wire to the terminal of the buzzer, say about three feet, 'and hang it On behalf of the manylisteners -in " whc over the back of a chair, or anywhere convenient. sincerely appreciate the distinction made THE NEWTONIA WIRELESS FACTORY Now place the 'phones on your head, and the buzzing FOR ALL WIRELESS PARTS AT FACTORY PRICES should be heard in them.Adjust the crystal until by the British Broadcasting Company be- 13/15, WHITCOMB ST., W.C.2. the loudest buzzing is obtained.It is not necessary tween their Sunday and week -day pro- Regent 6469. LONDON. to vary the tuning of the set in any way. The buzzer grammes, may I suggest that one evening in should be about three or four feet away from the set. --Beginner's Guide to Wireless Another method is to place a coil-spider-web type- seven devoted solely to music of the higher ExplOns, in plain everyday language, everything in series with the buzzer and the battery, and to order cannot be considered excessive, and you wish to know about Wireless Telegraphy. couple the coil closely to the aerial tuning inductance. does much towards raising the standard of HOW TO ERECT, CONNECT, AND MAKE This will introduce H.F. impulses into the receiving the apparatus required, and full instructions set, and the crystal can then he adjusted as before. musical taste throughout many sactions of for making coils, tuners, and complete valve the community, at the same time giving and crtstal sets.Instructions and diagrams for a two -valve receiver are alone worth four genuine pleasure to all music -lovers. times cost of the book.112 pages, price Is., Surely, with the excellent broadcasting post free.-SAXONRADIO CO.(Dept.14), which provides us with so much variety each SouthShore, Blackpool ORPESPONDENCE evening, we can rest content with a curtailed programme of really good music on one Hertzite. Electronite, Permanite, Talite, Zincite, Copper -Pyrites, Galena, Bornite, day of the week, simultanedusly permitting Silicon,etc. Wholesale only.Delivery from stock. -THEAMAX CRYSTAL CO., Red Lion the staff of the B.B.C. a few hours additional House, Red Lion Court. Fleet Street, E.C.4. relaxation on a day primarily intended for rest. To the Editor, POPULAR WIRELESS. Yours faithfully, Sir: 1 have read the majority of opinions Er STANLEY SKIPPER (Capt.). on the B.B.C. programmes, and feel fairly well convinced that ninety per cent. of the To the Editor, POPULAR WIRELESS. trouble is the fault of the complaining lis- Sir,-Might we ask through your paper, teners -in. Some years ago a friend of mine if something could not be done with regard received aninvitation from his brother to Sunday evening broadcasting ;the pre- (the manager of a West -End theatre) to sent transmission is very little, one hour " trot along when he liked " and enjoy a and a half, of which about fifteen minutes free stall. More fortunate than many he also news items, and fifteen to thirty minutes received the " open sesame " to a cinema. talk by the preacher ;there is not much left For the first month he could always be for music. Sunday evening isthe one found at one or the other after 8 p.m. evening at home for many thousands of Suddenly one evening he changed his mind business people, when the family is gathered about the merit of West -End theatres, ex- together and friends drop in.A full even- pressing them as giving very monotonous ing programme would be very acceptable. AshleyWireless programmes. I suggested that he would be The percentage of church -going people is doing a wise thing to give them a rest, but very small, and there is very little doing TelephoneCo.L-td. coming from the land of .Haggis and whisky on Sunday evening. The B.B.C. might easily 69RenshawSt. Liverpool he couldn't see the logic of missing some- close down, in turns, one or two week thing for nothing, the consequence is, that nights, and give their staffs a night off, this Sole Aienis you couldn't get him inside of any sort of wouldnot only give them arestbut theatre now without the assistance of a stout rope. (Continued art page 736.) Poppldr, ireless\ Wedgy, 3Otk 1923. 735

ifill1111,0;-'EVERYBODY91WA FA ha Mb - EJ FA hA E2 WA Ka ALL GOODS ORDERED BY POST haFA WA US VARIABLE CONDENSERS must be accompanied by the Correct PA ha PA Post Prices marked on each article. RAWA ASSEMBLED AS ILLUSTRATED U2 The quality and value given do not PA Drilled Ebonite Ends to fix yourself 11- perPair extra U2 permit of them being sent otherwise. UMWA WA Approx. Cap. No. of U2 in Mfd. Plates Price. No rubbishy catch lines here. All RA Ka real value for money. PLEASE NOTE, W A FA FA '001 57' 6/6 F US RA Fa Rubber Lead-in Wire (good), 12 yds., 1/9.By post, 2/6. WA Bell Wire, 12 yds., 8d.Bypost,1/. dozen. k2 Twin Flex, 12 yds., 1/9.By post, 2/- dozen. WA FA '0005 294/6 ILA k2 Switch Arms, 10d.,1/-, 113, 1/6.Post, 6d. each extra. WA Ka ha Rotax Accumulators, 4 v. 40amp.,171.. Carriage, 2/-WA WA LA ha KA FA '0003 19 3/3 Fix:daeh.Condensers.Good value. 11d.,1/3. .Post,6d..ha Ka each extra. PA U2 H.T. Batteries, 60 volt, 9f,Carriage, 2/-each. RA PA ha H.T. Batteries, 15 volt, 2'6.Carriage,1/.. each. MA VA '0002 13 2/6 Ebonite Valve Holders,10d.,1/.,1/3. Post,6d. each LAA ha P PA extra. ka LA Basket Coils, " Oojah,"setof 7,5/-.By post,6/.set. RA MA UM Basket Coils, 2/8 and 3;6set.Post, 6d. extra. RA PA '0001 7 2/3 Insulated Sleeving, 5d. and 6d. length. KA US RA FA Crystals (Mounted), II ertzite, By post, 1,'6. U2 Crystal Detectors, on ebonite, 1/5.By post, 21, RA FR ha US Perikon Detectors, enclosed with 2 crystals, 2/4.By FA FA Vernier... 31/9 post, 3;'3. UM kV RA Perikon Detectors, suit expensive set, 3/9.Bypost,4/6. hi/ WA PA KA Enclosed Detectors, 1/8,2/9,3/6,3/9. Post,1/.. each ha nn NOT THROWN TOGETHER. extra. FA MN Valve Pins, slotted, 7d. doz.By post, 1/.. UM &A FA FA Aluminium Vanes,,22 gauge, 5d. doz.By post, 9d. doz. h a US COMPLETELY ASSEMBLED AS SHOWN Coilson RA Tapped Ebonite,10 tappings, broadcasting US k2 size, price 2/6.Post, 1/- each extra. RA FA h al Ka .001 8/- S.P.D.T. Switches on Ebonite, 1/9, 2/6 each.Post, 9d. FA FA D.P.D.T. t, 2/6,3/6 each.Post, 9d. U4 RA .0005 Accumulators, 6 v.60a.,absolutelythe best,35/.. U2 5/11 Carriage, 2/., extra. FA Pa U M Slider Knob and Plunger, 3d.By post, 7d. each. PA PR .0003 4/11 Terminals, W.O., Telephone, P.O.and allpatterns, MA h2 WA including nuts and washers, not junk, 2for 31d. Wel MA PA ha *0002 3/11 1/6 doz.By post, 1/. doz. extra. ha Aerial Wire, 100 ft., 7/22", 2/13.By post, 3/3 hank. an as WA Transformers, very best,25/, Also12;6 U2 .0001 3/6 Intervalve RA WA each, 16/-' 20/-each.Post,1/-each extra. k4 KS Knobs, bushed 2 B.A. (best), 3d. each.By post, 7d. PA WA Vernier ha hS 3/3 3 Way .CoilHolders, Ebonite and brassfittings,718. PA Post, Vs earn extra. Ka kAPA - , 'La FA Dubilier Condensers, at usual prices. PR an ALL ORDERS BY POST MUST BE Telephone Transformers (R.I.),20/.Post,1/6. Ka FA ACCOMPANIED by1/3 per set EXTRA. H.T. Batteries, 30 volt, 4/6; 30 volt, 5/-.Post, 1/. each ON WA extra. WAWM !LA - OTHERWISE NOT EXECUTED - ha FA Telephone Leads, long,1/-.Post, Gd. extra. FA !LA PR Filament Resistances,1/6,1/8,2/.,2/6,3/.Post,Gd. k2 U2 each extra. be Transformers,L.F.(RadioInstruments,Ltd.), ha7,4 25', MA Post, 1/-. FR UA hA FA " BRUNET " FRENCH PHONES RA ka D.C.C. WIRE STOCKED ha 7A BEWARE OF IMITATIONS WA U4 22, 24, 26, 28gauge. hA PA haRA 4,000 ohms (different headbands) (post 1 /6 pr.) 22/6 and 25;- kA

11RA21 haWA RA B.B.C. Phones, best quality . . (post 1/6 pr.) 17/- and 19/6 RA U2 &A PA TO CALLERS ! WA h2 T.M.C., 4,000 ohms, stamped B.B.C. (post 116 pr.) 24/6 pair. LA WA hA (Phones supplied by T.M.C. themselves, taken from expensive sets to clear.) sell everything you want for your haFR RA PA ka To callers t121 RA WONDERFUL PHONES, double receivers, By post home - madeSets. No junk. No WA MA UA PA 6,000 ohms, very loud 18/11 20/6 WA ka tiL2 FA cheap job lines.All low in price, RA U2 They want some beating for Value ha PA FA UA but first-class quality. ha VA WA 01*7 SAL INLYRO.11.-IF AND ST-T141:11A.11" FA U4 Ka TRADE SUPPLIED FR h 2FA SPECIAL CHEAP PRICES TO CALLERS U4 P A PA UA &A FA FR LA hA FA PR 112 L111111111111111111111111111111111e ha FA FA hA U4 PA k4PA Phone : GERRARD 4637 ka ...L.'. Right Opposite RR gl RA kn t)101314 9 to fl;f. k4 RA M. RAYMOND FS LA FA F-= DALY'S RA ka = Saturdays - 9 to 8 p.m. = IFS Sundays 11 to 2 p.m. =h2 144 GalleryDoor Ez- RA as 27, LISLE STREET, W.C.2 Ka FA PA! hA iTililliillnililiiiiii11111111111g ha, WA FA PAPAPAPARAPAPARAWAR2PAPAPARAPAPAPAPAFAVARAPAPAPAEAPARAPAPAPAPARAPARAPAMAFAVARAPARALA PAPAPARRRAPAPNIMAPA PAR2 APAPARA RAPAPAPAPAPAPT,eH hakahahahAhahakahah IShAhAKSkahAhAhahilhahahahaha AftahahahahldhahAhAhahahahahAhahahakahAKAhAhAhAhahahahah hahAKAhAhahatah4h4hahaka, 1923, 736 Popular Wireless Weekly, June 30th, CORRESPONDkNCE. WAVEOLA WIRELESS HORN (Continued from page 734.) RECENT WIRELESS rat. 178147-20. The LATEST INVENTIONS. and BEST. would save expenses and give those with The only scientific more powerful sets a chance to get other The following abstracts are specially con- sound chamber yet tributed by Mr.Harold J.C.Forrester, produced. Has stations. I have spoken to many " listeners - Fellow of the Chartered Institute of Patent been tested by 411 in," and I can assure you this is a very the leading wireless Agents, 88-90, Chancery Lane, W.C.2. 'expertsandad- popular opinion. mitted to be super- M.0. Ross. iortoallother types. Nodis- Birmingham. tortion:Enuncia- Grant of the following Patents can be tion perfect. Price : Depot: - The Editor, POPULAR WIRELESS. opposed and printed copies ofthe full 142, CRAY'SINN RD., Sir,-How long is radio going to emulate specifications purchased. ::LONDON, W.C.1. 30'- Rip van Winkle ?We flatter ourselves Phone: 311,etlio we are modern, alive ;in our secret souls we consider we are brainy. What happens ? 196,453.-A. P.WELCH.-TRANS- Whilst our accredited agents, the B.B.C.,FORMERS.-Abox ofmagnetic mate- ELECTRADIX RADIOS put up a good fight, we switch over torial having the sides stiffened with ribs " stand by " and wait. inside and out forms the return path for ImmediateDelivery Sooner or later we shall have to either the magnetic field.The internal ribs sup- from our Huge Stocks. learn Morse or hack up the B.B.C.The port the core and winding, and the box latter is easier, more pleasant, and alto- may be filled with wax and provided with Everything from a Wave Meter to gether better.I'm conservative enough to terminals and with lugs for screwing down an Earth Clip. hate " direct action " and boycotts, butto a baseboard. The best equipped City depot. it's got. to be done in self-preservation, and COME AND SEE US. the sooner we begin the better,before 9, Colonial Avenueis first opening on " Uncle " Arthur and his merry men die 196,561.-BRITISH T H O M SO N- leftinthe Minories,near.Aldgate of broken hearts. We are a goodly number, H OUSTONCO.,MAINS.-TD.-H.F. SIGNAL- Station, Metropolitan Railway. and can affect box-office returns and music LING OVER H.F.currents sales, either for good or evil, by supporting are superposed on power conductors and LESLIE DIXON&Co. Avenueii4166 or not supporting certain firms and societies supplied to consumers who, in order to 9, Colonial Avenue,London, E.1. just in the same measure of reasonablehear news, etc., merely connect to a lamp dealing as they hand out to us.Put thesocket a system of condensers and induct- RADIO REPAIRS ances for blocking the power currents and Re -winding 'Rhones,I20ohms,5 6 per pair: " listeners -in" cipher on goods from firms 4.000. 10,6 per pair. Low -Frequency who allow their samples to be broadcasted, a detector and telephones for receiving the Transformers.7 6. any Ratio. Condensers, and make a black list of those who try carrier currents.Step-down transformers Sets, anything Wireless, Estimates. Repairs tested for signals before returning. to starve us out. When commerce realisesmay be provided between the feeders and RETAIL WIRELESS. that it is a paying proposition to be civilthe consumer's leads, and any consumer 8.The Arcade. PENZANCE. to radio, then shall we get a wondrous can be excluded by inserting choke coils. civility ; and we can do it if we only goThe system may further permit telephonic to those theatres who let us hear part of communication between consumers. FOLLOW THE CROWD their show, and buy the music that bears BOUND EACH DAY FOR the name of firms who are pally to us. 196,595.-SOC. ANON. POUR We do not expect to get ".ovrt for nowt," L'EXPLOITATIONDES PROCEDES SPENCER'S STORES - but we want. reasonable treatment to ourM. LEBLANC-VICKERS.-VALVES.- 4-5, MASON'S AVENUE, supply stores, the B.B.C.The cheapestSufficient gas is present to allow an ionic BASINGHALL STREET, advert. in the world and a good,honest discharge, the cathode is maintained incan- LONDON, E.C. 2 : proposition to those who avail themselvesdescent, and a source of constant potential SPECIAL OFFER. of broadcasting their goods, and all we equal to that required to produce a discharge FRENCH PHONES-Guaranteed-12/6: . get is the frozen mitt. between cathode and anode is placed between PRICE LIST POST FREE. The Queen's Hall affair shows us thethe grid and anode to maintain the grid spirit .3veare up against, and ought to relatively negative. TO WIRELESSINVENTIONS. EXPERIMENTERS. PATENT YOUR prove conclusively that it's no use arguing They mar prove very valuable. Particulars and consults. unless we have weight behindit ;.for bons1.ce. BROWNE &CO.,PatentAgent 196,610.-WESTERN ELECTRIC 9,Warwick Court, Holborn, London, W.C.1. Estab- surely no firm can claim copyright of the Halted 1940. Telephone :Chancery 7547. words of our Royal Family.Let's get CO., LTD.-GENERATORS-A set for together arid show them that we resentgenerating stable oscillations without har- A Book Bargain monies 'comprises a back -coupled generating Technical Electricity. CrDai'idge and Hutchinson unfairtreatment,and don't mean to Gives a thorough acquaintance with the elements swallow it.Let it be as business -like as valve and three amplifiers. The back - of Practical Electrical Engineering based on sound they please, so long as it is reasonable. coupling circuit contains a blocking con- scientific principles, One of the best introductions denser and variable resistance, whereby the to the subject. Show our appreciation of the B.B.C., and Published 716, Our bargain price 3'., post free. say in no doubtful terms that radio will operation of the generating valve is confined Mention offer 12o. back them up in the fight to the last man to the straight portion of its characteristic FO YL ES, 121; Charing Cross Road, London. curve, and over -load prevented. The Immense stock (secondhand and new) all subjects. and the smallest crystal set. - Meanwhile, Messrs. Chappell might do filaments of *he generator and first amplifier -ACCUMULATORS worse than study heraldry.The motto ofare in series and shunted by an equal Brand new, best British make, at the Prince of Wales would be awfully goodresistance so that the amplifier grid voltage much lower prices than elsewhere advice to them, before next they attempt is determined by the generator filament SMYTH, LTD., 53, MUSEUM ST.,BLOOMSBURY,W.C. to stand between his Royal Highness andpotential. the public who love him. PLEASE Yours faithfully, 196,613.-N. R. LINSE.-REGULAT- JERSAISE. ING SWITCHES.-A pairof resistances Besuretomention Croft Cottage, or impedances each have a ring of studs "POPULAR WIRELESS" Gorey, Jersey. arranged in the usual manner, and the When communicating switch of one is mounted upon a notched plate which is moved one step each time the withAdvertisers A SPECIALINTERVIEW WITH switch of the second makesacomplete SENATORE MARCONI WILL revolution.The two may thus be suitably THANKS! APPEAR IN NEXT WEEK'S combined to form a unit capable of fine "POPULAR WIRELESS." adjustment. R, June 3014 1023 POPULAR WIRELESS WEEKLY. iii

3R0CAST:NG NOTICE to all engaged in ENGINEERING1

Dictionary

DICTIONARY OF ENGINEERING CIVILMECHANICAL. ELECTRICALmotOR.Etc ETC_ FREE. PART1.

To extend the name of the Bennett College to everyone engaged inthe different branches of Engineering, we arepublishing anIllustratedDictionaryof Engineering, in about 24 monthly parts.Yuu can have each monthly part as it comes out. FREE -3d. Postage only to pay. The Dictionary is free to those engaged in any of the feaLOCRYsi following tradesEngineering, Civil, Mechanical, Elec- trical,Structural,Motor, Sanitary,Boiler,Internal Combustion,Draughtsmanship,Marine,Shipbuilding, NavalArchitecture,Building,Architecture,Quantity Surveying, Aviation, Chemistry, Foundry Work, Metal- lurgy, Matriculation, Mining, Surveying and Levelling, SUPER Telegraphy, Telephony, Wireless, and the conditions are that you send your name and address, your age and occupation, with three penny stamps (to cover postage), writing your name and address very clearly.We shall then place your name on our Free List and send you Part 1 atonce.The otherswillbe forwarded as issued.Address your application fully to: (Do not fail to give Department D 106, THIS isahigh- theparticularsre- , quire() and use this The Bennett College, I grade Crystal i--full address.) Detector es- Sheffield. pecially designed for receivingbroadcast- ing, and complies withallregulations. Beautifully pure clear speech and music are SOLDER OR SORROW received, and as many WHICH is it to be? asthreepairs of fLUXIT The Wireless aspirant Fellows 4,000 ohms MPLItizs whoissatisfiedinleaving LDERie double headphones the connections of his aerials andsetterminalstolook can be simultaneously afterthemselvesbyjust used. twistingthemtogetheris The " FELLOCRYST SUPER " is mounted in a asking fortrouble. Apart front the untidy appearance, highly polished oak cabinet and is sent out complete careless connections are going with 100 ft. coil of 7/22 stranded copper aerial wire, to roWer-the efficiency of the twoshellinsulatorsand onepair4,000 ohms finestreceivingsetinthe world. SOLDERING will make doubly sure of them, and, incidentally, double headphones, and is British Made Through- FLUXITE will make sure of the soldering.Soldering ischild's play out.Fully approved by the Postmaster -General and when you've a tin of FLUXITE at hand to help you, or, better still, a the British Broadcasting Company. complete Soldering Set that we have had specially prepared for the con- venience of customers.Ask your Ironmonger or Hardware Dealer to PRICE COMPLETE £4 - 15-6. show you the neat little inclusive of all taxes. Postage 2/- each. Additional Double Headphones -- 216 (4,000 ohms) inclusive of all taxes. Postage1/. SOLDERING SET Itisperfectly simple to use, and FELLOWS MAGNETO Co., Ltd. will last for years in constant use. LONDON, N.W.10. It contains a special " small -space " Solderingiron,withnon -heating - Telephone Telegrams - metal handle, a Pocket Blowlamp. WILLESDEN 1560.1 "QUIXMAG," PHONE, LONDON FLUXITE, Solder,etc., and full instructions.Price 7/6 sample Set, FLUXITEpost paid, United Kingdom. icreeyyoofc(agewof SIMPLIFIES SOLDERING All Hardware and Ironmongery Stores sell FLUXITE in tins, price 8c1., L4, & 2,8. For the tool -kitof your car or Buy a Tin To -day. motor -cycle,orany soldering P/ jobs about the home. FLUXITE LTD., 324 Bevington St., Bermondsey, England EDISWAN!

ci

VALITS GLI

Noiseless 0 O Sensitive C.)

THE IDEAL LOUD SPEAKER be FOR OPEN AIR USE, RENDER- /Robust ING THE MOST DELICATE There is no better Valve INTONATIONS WITH A for wireless work than the Ediswan Type A.R. It is 0 VOLUME SUFFICIENTLY silent working, sensitive, YET and essentially strong. It ba PENE,TRA.TIVE, gives high amplification, a, WITHOUT DISTORTION, isvery compact, and extremely economical fl3 is the in current consumption. This Valve-made by the makers of the world- famous Ediswan Electric Lamps-has been specially II designed for operation on low plate voltages and is -particularly recommended for amateur work. WHAT USERS SAY :-Atypical example ofthe z splendid results constantly being brought to our notice:- O " Dear Sirs, Dudley, 1-6-1923.. Last December I purchased -one of your A.R. type receiving 0 LOUD SPEAKER Valves, and I could not wish for abetter Valve.My set is a home Made, -suite ValVe,varionteter tuned. My aerial is IS ft. high amti r soft. long,with this I can receive Glasgow, 25omiles distance, New- castle, Manchester, London, Cardiff, Birmingham rs miles away. Reproduces Radio music _ We have had' very considerable experience in the de- 0

velopment and manufacture of the Thermionic Valve. The ; with a fidelity comparable first ex,perigients in, connection with investigation of the CII ""Edison'Effect," on which -the working of a valve depends, ra were carried out at our Ponders End Works by Prof. J. A. Fleming, who was the Companys "Scientific: Adviser. to that of "STERLING " f:4 Head Telephones. - 1 I PRICE 15s_ DESCRIPTIVE LEAFLETS FREE ON REQUEST; PRICES: Also manufacturers of complete Receiving Sets, Accessories, 120 ohms 2,000 ohms and H.T. and L.T. Batteries. Z6 - 0 - 0 Z6 - 2 - 6 Ash your, usual Dealer, and if unable to supply send us a post card with .his name and address. - - Obtainable from all electrical dealers and stores. THE - EDISON SWAN ELECTRIC CO., LTD., STERLING TELEPHONE & ELECTRIC Co., Ltd., Contractors to H.M. Admiralty, War Office, Royal Air Force Manufacturers of Ts:en/tones and Radio Apparatus, etc. '

I - (WHOLESALE 'ONLY). -. 123/5, Queen Victoria St., E.C.4, -=-- Telephone House, 210-212, Tottenham Court Road, London, w.1. and 71, Victoria Street, S.W.1. = Telephone: Telegrams : = - -WORKS t PONDERS END, MIDDLESEX. =.- Museum 4144 (7 lines). "Cucumis, Wesdo, London." 77, Branches in all Principal towns = BIRMINGHAM: CARDIFF: MANCHESTER: = 150, Edhsund Street. 10, Park Place. 14, St. Peter'S Square. = = NEWCASTLE -ON -TYNE: ' WORKS: t -._-_ Dagenham, Essex. =------_ 9, Clavering Place. - : ThilliiIIIIIIIIIIIIIIIH1111111111111111111[1111111111111IiiIHIIIIIIIIIIIIIIIIIHM-.;

Printed and published every Friday by the proprietors The Amalgamated Press(1922), Ltd., The Fleetway House, Farringdon Street, London, E.C.4. Advertisement.Offices: Messrs. J. H. Life, Ltd.,4, Ludgate Circus,London, E.C.4.Registered as a newspaper and for -transmission -by Canadian.Magaatue.- Post.Subscription rates: Inland.and Abroad, 17/4 per annum, 8/8, for six months.Sole agents for South Africa: The Central News Agency, Ltd..- Sober agents for Australia and New Zealand: Messrs. Gordon & Gotch, Ltd.; andfor Canada: The Imperial News Co. (Canada), Ltd. Saturday, June 30th, 1923. RtR