AWE JUL 1922 .Pdf

See Page 76 for Our New Service of Prompt Replies

No. 4 SATURDAY, JULY 1, 1922 Price 3d

THE " LAST POST" BEING SOUNDED IN MARCONI HOUSE AND RADIATED BY WIRELESS TELEPHONY. THE OCCASION WAS THE UNVEILING IN MARCONI HOUSE OF A ROLL OF HONOUR ERECTED IN MEMORY OF THOSE OF THE MARCONI STAFFS WHO FELL IN THE WAR. CHIEF CONTENTS OF THIS NUMBER Page Page IS MARS TRYING TO COMMUNICATE ?63 PROBLEMS YET TO BE SOLVED. .72 FAULTS IN VALVE CIRCUITS . . 64 SOME AMERICAN IDEAS . 73 A "RIGGED -UP" TRANSMITTER AND STARTING WIRELESS 73 RECEIVER . . . . 65 MACHINE FOR WINDING HONEYCOMB CHOOSING YOUR AMPLIFIER . 74 COILS . . . .66 "MARCONI HOUSE 2L0 SPEAKING"74 HOW THE VALVE WORKS . . 67 TESTING YOUR 'PHONES . . . 74

THE "OFFICIAL" RECEIVING SET . 68 FREAK RESULTS . . . . 76 ELECTRICAL BENCHWORK : SIMPLE COMPETITIONS FOR ALL READERS 78 SOLDERING . . . 69 ERECTING AERIAL BY "TABERNACLE" METHOD . . . 70 and 71 Information Bureau, Radiograms, Club Doings, etc. C

emataut Wireless 62 JULY I, 1922

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and ER -dries No 4 July 1, 1922 Is Mars TryingtoCommunicate? THE possibility of definite attempts at Readers will find this an opportune article there seems to be no reason why corn communicationbeingmadefrom in view of the fact that Senalore Marconi, municarionshouldnotbeestablished. who has recently crossed the Atlantic on the other planets is so startling and captivat- steam yacht "Elletra,"iscredited by the The point where the first large element of ingtotheimaginationthatoneis American Press with having stated that he doubt enters is when we come to consider tempted to dwell on the conceivable re- would be at work all day Sunday, June 18th what power and what sensitivity would be sults-toletthe mind wander' along a (the day when Mars came closesttothe necessary. vista of fascinating "might -he's "-and to earth),inthehope of receiving wireless As Mars is our nearest neighbour and is messages from the planet.The Senatore is overlook the tremendous scientific improb- reported to have said : "I listened practically now passing as closetous as ourre- ability. all the time, day and night, for the fortnight spective orbits will allow, and as there When one remembers that. only thirty of the voyage, and had instruments ready to seems to be some reasonable chance of its yearsagothePhilosopher'sStone-to receive from anybody. SeveraltimesI being inhabited, apart from the general heard mysterious sounds, which I could not take but one of many similar instances- understand or explain, but I don't think considerationsalreadymentioned,we the quest of the ancient alchemists, was they came from Mars; in fact, I am not might examine the possibilities of Mars regarded as an amusing dream of a by- certain whether the Martians, are trying to being able to "ring us up.". gone age, and that to -day nothing is surer communicate.But I was there to do every- than that the -transmutation of the ele- thing possible to record any message sent. Strange Phenomena I shall continue to try to receive communica- First,though,letus recall what has mentsisan everyday occurrence,one tions,however slight,on the chance of success." already happened in the way of engaging hesitatestodismiss anyidea,however startling, without careful thought. the attention of wireless men in the matter. know nothing, compared with which the"Signals,"closely resemblingcertain People of Other Worlds. ether of space is as poor an agent for thelettersintheMorsecode,have been What assumptions, then, have we totransmission of messages as a messengerreceived simultaneously by stations as far make in order to justify us in assumingboy.We propose to weigh the possibili-apartasEngland and America.That that the ethereal disturbances which haveties in the balance of our present know-they were practically simultaneously re- given rise to so many conjectures are aledge as well as we are able, however, andceived is obviously no evidence as to their definite attempt on the part of thein-leave this promising line of speculationorigin, as the time taken to traverse the habitants of some other planet to get intofor a rainy day during the summer holi-Atlantic is only a fraction of a second. days. communicationwithus? Firstly,of But they were of uniform intensity.This course, that the other planets have intelli-Is It Possible? indicates either that their point of origin gent beings of a similar or higher state of It would appear that there is no actualwas somewhere on the earth on a longiti- knowledge of natural philosophy than ourimpossibility implied in the idea of inter-tude midway betweenthatofthe twe own, who,are sufficiently interested in ourplanetary conversations.Given a trans-stations, or that it was outside the earth small fragment of the universe to wish tomitter sufficiently powerful and a receiveraltogether andagreatdistanceaway. communicatewithus,orwho,whilesufficiently sensitive, Nature havingApparentlynoterrestialstationswere attempting to talk to some neighbours, arealready suppliedthe medium-laid theresponsible,soit seems highly probable unwittingly being overheard by us.On wires right up to the house, so to speak-that the latter alternative is correct. the face ofitthisisatleast possible, There remain two possible explanations for there seems to be no reason why our for the phenomenon even at that.Either planet should be unique in ,possessing in- INTER -STELLAR itwas-as most peoplewilldoubtless habitants.Surely other globes thrown off SPACE hope-a definite and intelligent attempt by our own or some other sun have been at communication, oritwas some acci- through a similar cycle of development, dental ethereal disturbance, say, on the which in due course has led to the evolu- sun or otherstar. Knowing as we do tionoflife and ultimatelyofrational how closelyelectronicdisturbancesare thinkingbeings.Whether suchaone connected with other waves, and that sun- actually exists and is within speaking dis- spots and the like frequently take place tance of us time alone can tell, but at PLANET -e- TRANSMITTING STATION simultaneously with magnetic storms on least the possibility cannot be ruled out. the earth, we must not dismiss this second Having granted this premise, the next possibility too hastily. - point is :Is there any limit set by natural Observation leads us to assume that the laws, of which we are cognisant, which ether of space isperfectly elastic.This makes the thing possible ?ant here we /// / means that when acertainamount of energyisexpended in producing vibra- must pause to remember that, far as our ATmoshiEsic / scientists have taken us along the path of BELT tions none of itisfrittered away as the ' knowledge, there are doubtless other and / waves pass onwards (asis the case with greater discoveries yet to be made.There Diagram Showing the Probable Effect of sound -wavesinair).The onlyreason may be some form of radiation, or even the Atmosphere on Wireless Waves that their intensity decreases as _they pro- some medium, of which weatpresent gressisthat they always tend to spread einoteitr Wtretess 64 JULY I,1922 out and so distribute their power over a Waves of short length would be mostampere to flow in the aerial.To do this larger area.Itis only when associatedsuitable for such a beam, as they do notwe must construct a transmitting station with matter-as itis in the earth's atmo-tend to spread out and form a sphericalhaving an aerial capable of dealing with, sphere-that absorption takes place andfront so much as larger ones.On theroughly, 4o kilowatts and needing genera- some work is expended on the medium.other hand, short waves spend themselvestors of about too h.p.Supposing Mars to lf, then, we could produce a wave withmuch more rapidlyinpassing throughbe 40,000,000 miles away, or 20,000 times either a straight or a converging front,planetary atmospheres. the width of the Atlantic, we begin to see and ensure that it keeps straight, we could howmanysuper -powerstationsthey transmit to any distance without limit andOnly 2,000,000 Horse-powerl would have to link up in order to reach without losing intensity or strength. These two considerations would lead usus; for ifit be assumed that the power In producing such a beam of waves thetoexpectthata medium wave -lengthrequired increases only as the first power planet's atmosphere would beof somewould be adopted by our Martian friends.ofthedistance,2,000,000horse -power slight assistance in the manner illustratedYet the signals so far received have beenwould be required. on p.63. The atmospheric belt wouldof exceptionally great wave -length. It may be objected that this is an unfair act somewhat as a convex lens and tend We may be able to form some idea ofcomparison, and the two cases are vitally to refract or bend the waves, owing to thethe power necessary and thedifficultiesdifferent.It is true, as already mentioned, lesser density of the outer layer.How-which ourplanetaryneighbours wouldthat in transmitting through the earth's ever,thisbelt only existsfof a smallhave to face'in their attempts to reach usatmosphere we havetocontendwith fraction of the distance the wave has toby considering the same problem on theabsorption, but then, on the other hand, traverse.Even supposingthetransmit-infinitely smaller scale on which it con-reflection and refraction by the rarefied ting aerial could be so arranged that afronts us when we wish to transmit acrossupper atmosphere assists us. The parallel or only slightly divergent beamthe2,000 odd .miles separating IrelandMartians, too, would probably be faced of waves was initially produced, the ten-and America. with much greater difficulties than we are dency to spread out into spherical waves The wave reaching the receiving stationin handling the necessarily high voltages, would come into play immediately itleftmust be of sufficient intensity to cause aowing to the rarefied nature of their whole the transmitter. currentofabout3omillionthsofanatmosphere. S. W. G. Enninnannrcnnacr=rrnrinnaninnnon=n=errnrom==nrrnnnrrinnrinn=mrrnnn=rinnrinnnr=nrin7 a uo a u 'FAULTS IN VALVE CIRCUITS Di EQZQZZUZIZG/G7GI;EZIG7L=1=77U:LL-:G:1ZIUG7Q1=Q2QQ2iLLIZIQQQZ11=GGJC12=CU.G1a7QQ2Cila7GIGI;Zi;11;706:liiCI FAULT S may be broadly divided into In tracing the cause of noise it is advis- (i) The first cause results in noises when two classes :(a) noises; (b) failure ofableto commence by testing the high-the valve or panel is tapped or vibrated, thesetto give signals.The first -men-tensionbattery,either by tryingiton and may be remedied by splaying out the tioned trouble is probably the more asser-another set or by trying another batterylegs of the valve. tive, anditiswith this class that this(known to be O.K.) on one's own set. The secondeffectcannot bestrictly article chiefly deals. When the insulation of the telephonecalled a noise.In a two -valveset,in When an amateur complains that hewinding has deteriorated, asitwillin which one valve is rectifier and the other gets noises in the telephones he is almosthigh -resistance telephones used in valve is low -frequencyamplifier, withthe circuits,loudcrack - 'phones in the latter circuit, if the filament ling noises result. current of the ampLifying valve is turned Telephonesmay beon nothing will be heard (except, possibly, tested on another seta slight hum due to adjacent A.C. mains). or by comparison withWhen the filament current for the rec- another pair on one'stifying valveisturned on, however, a own set. slight hissing sound is usually audible but The grid -leak is which does not interfere with reception. often asource of This hissing is caused by uneven electron noise.Once thetransmissionfrom thefilament. Itis trouble has beendifficulttoobtain a valve withoutthis tracedtothisitis effect, but the slight hissing is negligible. easily remedied. A good way oftracing the cause of The noises may benoise is to make up a circuit consisting of due to bad contact be-valve, telephones and high-tensionbat- tween theelementtery, the valve filament being lighted as and theterminals, usual.If there is no sound in the tele- withtheresultthat phonesthehigh-tensionbattery,tele- any vibration of thephones and valve are obviously all right, Example of Valve Panel with Three Valves valve panel, or evenand the fault must be searched for else- thebench,produceswhere.Other causes are faulty low -fre- invariably told that the cause isa badnoises which completely drown signals.quency transformers and condensers ! high-tension battery.The writer has beenThe noises produced by a faulty grid -leak Failure of the set to oscillate may be troubled with noises from many sourcesgreatlyresembleatmospherics,thatis, due to : (1) insufficienthigh-tension but not yet from high-tension batteries.sharp cracks followed by long-drawn-outsupply;(2) reaction coil leads reversed; Of course, noises are often due to badrustling noises. (3) reaction coil too small; (4) aerial short- high-tension batteries, but more often to Valves may produce noises :(1) by theing to earth; (5) no by-pass condensers pro- other causes.Common sources of troublelegs making bad contact in the sockets;videdacross telephones, high-tension are :(1)telephones,(2)gridleak,(3) (2) by uneven electron emission from thebattery,low -frequencytransformerpri- valves. filament. .naries. etc. B. J. A. JULY t,1922 65 e =deur Wireless amnrimnmnrrintrynrcrrnm=inarnarinrinnana=ritn===cininrinnannrirrinnrarirrnotntannTinTrnrnmnrimm=m O ti PP El E3 "Rigged-upATransmitter and Receiver E3 An Easily Improvised Set for Amusement and Practice El LCIIQQ=Z1072201aGQGJUGQUI=L:7CIGL'IUQL7OQUCQQGIQC7IZICIQZICIZIGQGGII;1=Q=ZZIZIZIZQQ1a:IfaILIZZGL=.11:717QCGI

the timeisfast passingconnection for the end of the winding onshowing that the apparatus consists of the ALTHOUGHwhen the very elementary experimentsthe magnet M.The secondstrip Eis loading coil (Fig. 4), the detector (Fig. 5), in wireless will present any novelty, quiteshorter than the other and also carries aandthetelephone condenser(Fig.6). a lot of entertainment may be secured in The loading coil(Fig.4)consists ofa theassembling and working of simple E wood base on which is mounted the in- apparatus such asisdescribedinthis ductance L c, wound with one layer of article, and which, as will be seen, requires No. 28 S.W.G. cotton -covered wire on a K the minimum of outlay and trouble to con- wooden bobbin measuring 2in.diameter struct. by 4% in. long and thoroughly soaked in The Transmitter.-Commencing with the shellac varnish after winding. transmitter, Fig. r shows the mechanism of The ends of the wire are securedto an electric bell which has been converted terminals at either end of the coil L c, in such a manner as to be capable of propa- 2 marked 5 and 6 respectively.The detector (Fig.5),consists of two essential parts, Fig. 1.-An Electric -bell Transmitter. thecrystalandthecopperpoint,the latter being provided with a means of terminal, shown at r.At the opposite end is a screw with the head filed flat to form a contact C, the screw on the knob K being treated in the same way.A small strip of paper may be gummed onthebase, between the terminals, rand 2, marked "battery," a second strip marked "aerial " Fig. 3.-Diagram of Simple Transmitter. being placed by terminal 4, and a third Fig. 5.-Detector. marked "earth " by terminal 3. gating ether waves over a distance of some A small adjusting screw S is mounted onadjustment. The crystalisa standard thirty yards. galena element and may be purchased for The small casting carrying the electro D E is. 6d. mounted in a brass cup. magnets M shouldberemovedbodily The brass cup D C is mounted on the and mounted on a wood base measuring base, as shown in Fig.5, and connected 6 in. long by 4% in. wide.The striking electrically with the terminal marked 8 by knob and wire should be removed from the means of a brassstripas usedinthe armature, which is then left as shown at C transmitting set.A small block of ebonite A, Fig.r.A bell should be chosen with, 1.1 orfibre H ismounted on the baseas Fig. 2.-Sending Key. fairly fine wire for the windings, as not shown andcarriesastripofspringy only will this take less current from thethe base on the opposite side of the arma-phosphor bronze r, which is fixed to the battery, but it will have a greater induc-ture A to the contact screw C S.This screwblock H by means of the terminal 7.A tive effect.The contact screw c Sisre-S serves to limit the amount of play on thesmall hole is drilled in the spring strip r moved from the dismantled bell and fixedarmature and also to prevent it sticking onabout half -way between the extreme end in the position shown in Fig.1. A stripthe poles of the magnet. and the inside edge of the block H.A of brass or copper is screwed on the base A two -volt battery or accumulator is nowscrew, either 4 or 6 B.A. thread, is screwed and holes drilled in it through which tworequired, and the transmitting set is corn -through the bottom of the base and passes terminals are screwed, as shown by r and 2, through the hole in the spring strip P.A the contact c S being screwed through the terminal nut T is screwed on about the third hole. the spring strip, as shown in Fig. 5, and A sending key is made up as show n in serves to adjust its position within certain

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10 PH [Fig. 4.-Loading Coil. Fig. 6.-Telephone Condenser. Fig. 2, and serves the purpose of making limits.A short length of No. 36 copper and breaking the battery circuit operating wire is soldered to a small screw j, which, the buzzer mechanism.It consists of twoFig. 7.-Di'agram of Simple Receiving Circuit.in turn, is carefully soldered to the spring brass strips D and E, D being drilled to strip P. Thecopperwireshouldbe take the terminal 3 at one end and a smallplete,theelectricalconnectionsbeingarranged to just rest lightly on the sur- knob K, of wood or ebonite, at the other. shown in Fig. 3. face of the galena D C, the fine adjustment It will be noticed that the brass strip D The Receiver.-The receiving station isbeing effected by means of the terminal is cut so as to form a lug F at right anglesa little more complicated than the trans-nut T. to its length.This serves the purpose of amitter, a reference to Fig.. 4,5, and 6 The telephone condenser is made up of Wireless 66 JULY I,1922 Qtrteteur twenty-five small sheets of tinfoil measur-best for him to purchase a head -gear readythe opposite end of the garden or some ing I% in. by u4 in. with a small strip leftmade or rewind a pair of ordinary re-thirty yards away, connection being made at one corner to form a lug, as shown inceivers himself. to terminals 5 on ,the loading coil.The Fig.6. Itisbuilt up by placing the Assuming that the reader has a pair ofearth connection is made to terminal 8 on strips of tinfoil, with pieces of waxed paperwireless receiversinhispossessionthe'the detector, the remaining portions of the in between, with the lugs alternately atreceiving set should be connected up asapparatus being wired up, as shown in one end and then at the other, as shown.shown in Fig. 7, the numbers on the con-Fig. 7. Itismost essentialthat the adjoiningnections corresponding to the numbers in The transmitting buzzer should now be pieces of tinfoil do not touch each otherthe sketches, while P H represents the tele-adjusted, by depressing the key K and electrically, and the waxed paper shouldphone head -gear. manipulating the screws s and c s until a therefore be cut larger all round than the Itis a good plan to mount the wholehigh-pitchednoteisobtained.Ifthe tinfoil. instrument on a wood base or in a smallground is damp and the aerial wire be When the condenser has been built upwooden containing case, terminals beingtouched with the bare hand a slight shock the ends of the tinfoil should be carefullyfitted to the outside for connection to theshould be felt. sealed together by means ofa blob ofaerial and earth, as shown in Fig. 7. An assistant should now be obtained to solder,twopiecesofcardboard being To test the apparatus, the transmittingoperate the sending key K, while the replaced on either side of the condenser andset should be taken out in the garden, theceiving setistuned up.The telephone a length of linen tape wound round to keepterminals marked s and 2 being connectedreceivers should be placed over the ears, the whole together.The condenser shouldto a battery or accumulator.The earththe tension screw T on the detector rotated then be immersed in the melted paraffinterminal 4 is connected to a short lengthslightly to vary the pressure of the copper wax and allowed to set in a solid block.of wire, the other rn3 of which should bepoint on the crystal, and the clear note of It may then be mounted on a small woodsoldered to a piece of brass strip measuringthe buzzer should then be heard clearly in base and the ends of thetinfoilplates12 in. long by 2 in. wide.This serves asthe 'phones. connectedtoterminals 9 andso. Thean earth connection, and should be buried By the way, the lightest possible con- condenserismounted onthebase byin some moist earth. tact is all that is necessary for the detec- means of two strips of fibre sheet, which The aerial is simply a to -ft.length oftor, the most delicate contact giving the have holes drilled at each end to takebellwire, one end being connectedto loudest signals. small wood screws. terminal 3,the other being joined to a The receiving set can now be moved The only remaining portion of the setshort length of cord and suspended fromfarther and farther away from the trans- required is the telephone head -gear, anda tree. mitteruntiltheresultsobtainedget the reader must decide whether it will be A similar aerial should he rigged up atunduly faint. A. W. HULBERT.

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Machine for Winding HoneycombCoils114111 w=outzuaJ000=u======zu=Q=1;ool;ziE=F.F=G7GZIQI=C;UlaQi1 THEfiddlingoperationofwindingor cam.This cam actuatesafeedingthe drum is in motion, the end of the wire honeycomb coils is reduced to a meredevice or finger which guides the wireis passed through the eye of the feeding mechanicaloperation by means oftheacross the face of the drum on .which thefinger and secured to the pin on the drum. Lokapcoil -winder, made byMitchell's coilis being wound, and to ensure thatThe fingers of the left hand should place a Electrical and Wireless, Limited, whichthe follower rod mantains contact with thetension on the wire to avoid kinks and to imparts a neatness and precision to thecam a return compression spring is fittedlock each layer to the one beneath it.One convolutions of the coils entirely unattain-to it.It is clear that a different cam isfinger of the left hand must also be pushed able by hand methods (see Fig. necessary for each width of coil, and a setagainst the follower rod to make sure that The mechanicalprincipleofthein - of three cams is provided for this purpose. "jumping" on the cam does not take place. Upon turning the handle it will be found that the wire is fed across the face much in the same way as cotton is fed across a bobbin on a sewing- machine, except, of course, that the coils follow a wavy path. When the coil has been wound to the size required, a blob of sealing -wax should be dropped on to the end of the wire and the end then cut off. To remove the coil from the drum, pieces of twine are passed through the four slots in tne face of the drum and tied round the coil.Unfasten the wire from the driving pin and slide the coil off.For safety, coils should be steeped inshellac and then thin d.

Fig. 1.-Honeycomb Coil in Fig. 2.-"Lokap" Honeycomb Coil Winder. Process of Winding LICENCES AT presentitisnot possible to obtain strument is briefly that of a drum rotated Fig. 2 shows the method of using thisthe necessary licence for wireless receiv- through bevel reduction gearing by meansinstrument.Having secured the machineing at the local post office.Before very> of a cranked handle.The shaft to whichto the bench, and arranged the bobbin oflong, however, it will be obtainable with- the handle is attached carries an eccentricwire so thatit may easily unwind whenout much formality. JULY I, 1922 67 emateur Wireles3 r mnmnn======rn=rimnrinninnna==nrmn=mri=rinninnimnain=mmn u L1

uEu HOW THE "VALVE" WORKS. -II aI uu CI u By Means of the Water Analogy We Further ExplainItsAction pi u a u a IiIGIOQZLICIQOU02021:1QQ=IUQZ1021ZIOGIQ2C7G7GG7PPGQPPZIGIGIUQUGILZIZICII7G1Q1;]GlI;C1=1:QUaLIZICIOCII=L7G7QCG11=Gil"

IT may be objected that the water analogyadditiontothis,it may be used as aThis, by varying the rate of circulation of used in the first article to illustrate thegenerator of electric oscillations of almostthe water, will in turn raise and depress working of the three -electrode valve didany frequency. the key Y.Only very slight movement of not take account of some of the properties Naturally such an adaptable piece ofx is needed tocontrol the speed of G, of the valve; for instance, the so-calledapparatus opens up a field of tremendous possibilities, and already there are many different ways in which itis being used either initsoriginal simple form or in some development worked out to fit some

P special purpose. functionsmen- Thethreeimportant RESULTING FLUCTUATIONS tioned above may, perhaps, be very simply orPLATE -CURRENT explained alonglinessimilartothose adopted in the previous article. F f_APOSITTVE NMI-PERO° Amplification. In Fig. z the key X isso arranged T -I A that a brake is kept lightly pressing on OSCILLATIONS INL a drum carried by the shaft of the small NEGATIVE HALT -PERIOD Fig. 2.-The Electrical Circuit for Amplification. variable speed motor B.By raising or de- Fig. 3.-Diagram showing Current Fluctuations. pressing the key the friction on the drum, "space charge."This is, of course, true.and therefore the speed of the motor, maya movement many times smaller in ex- It must be borne in mind, however, thatbe increased or decreased atwill. Thetent and power than the resulting move- an analogy, however useful it may provekey Y isattached to a vane inserted inment of Y. in assisting us to take a first grasp of athe piping of the water circuit.The vane It will be noted that the effort required complicatedtechnicalmatter,has com-is hinged at the bottom of its container into vary Y is drawn from the large motor A. pleted its purpose, when that understand-such a way that the flow of water whenThis is an important point, and enables ingisattainedandshouldthenbe circulating in the system tends to depressus, by making A sufficiently powerful, to dropped.If we attempt to push the com-the key, but is just balanced by the spring.reproduce the original alternations on a parison too far we are more than likelyIf the flow decreases, Y is raised by themuch larger scale and to operate instru- toget confusedor even erroneous im-spring, while if it increases Y is depressedments which those alternations would be pressions.When a man has obtained theby the increased pressure on the vane. incapable of doing if applied direct. So necessary confidence in the water which it Let ussetboth motors running andsmall, too, is the strength of the original is the purpose of swimming floats to give effort required at x that itis very him, he casts them aside as a hindrance little exhausted, and the extent or rather than an assistance. amplitude of the variations is very little reduced when that effortis put forth. Three Important Functions. CYLINDRICAL DRUM - P Wherever we erect an aerial,signals In the equivalent electrical cir- passinginalldirectionsimmediately cuit shown in Fig.2 the varying cause a number of high -frequency currents potential of the grid has the .same effect on the flow of electrons as to rush up and down it, and if we wish VARIABLE SPEED to interpret them we must install appara- 1,4o rwe the varying speed of G has on the tus to sift these currents out and reduce flow of water in Fig.1. It is first themtoair -vibrationsofaudiblefre- setat such a value as willnot quency.The frequency of the currents is affect that flow by means of the so high that even if they could be made battery B. Subse- quentlyitwillbe topassthroughapairoftelephone LIGHT SPRING receiversatallthey would be without subject to slight effect on the diaphragm. .The proCess of variations above obtaining vibrationsofspeech -frequency rKrr X Key Y and below this

fromcurrentsoscillatingatradio -fre- FIXED SPEED MOTOR value,imposedby quency is known as rectification, and the thehigh -frequency three -electrode valve may be made use of 1 `-' currentsoscillating as a rectifier.Some of the high -frequency Fig. 1.-A Water Analogy of Amplification, in the inductance L.' currents may be so weak astofailto These faint oscilla- operate the receiving apparatus, however,adjust the speed of B by electrical meanstions willbefaithfully reproduced on a and these must be magnified before use(not shown) until the fan G does not inter-much larger scale across the inductanceLi can be made of them.As an amplifier offere with the flow of water across thein the plate circuit, the necessary addi-, weak currents, both of radio and of speech valve.If now x is alternately, and verytional energy being drawn from the plate frequency, the valve has been found toslightly, raised and lowered, the speed ofbattery A. be so well adapted as almost to revolu-the fan G will be decreased and increased We may represent this process by the, tionise wireless in the last few years.Inin time with the alternations of pressure.diagrams in Fig.3, which also serve to, mateu r Wirelk5 68 JULY I. 1922 draw attention to the fact that, whereas Y. This is known as rectification, and ismechanical link between x and Y is the the incoming currents are oscillating (thatbrought about in the electrical circuit inreaction coil L, in Fig. 5.This forms one is, they flow one way round the circuit forFig. 2 by turning the selector switch tillwinding of a transformer,L, being the half a period and then reverse and flowcontact is made at -z on battery B, justother. Oscillationssetup,say,inL, as in the case of the hydraulic analogy wecause corresponding and magnified varia- reduced the speed of the fan G by means WAVES At AUDIO -FREQUENCY of the motor 13. The effect on incoming electrical oscil- lationsisillustratedinFig.4. The

WAVES Al RADIO -FREQUENCY essential difference between the resulting fluctuationsinFigs. 3and 4isthat, whereas in the former the average plate - current is practically constant and may he represented by the dotted straight line, in thelatteritincreasesslightlyfor each train of values, as is shown by the curved dotted lines.Thus the incoming currents

TIME oscillating at radio -frequency are rectified Fig. 4.-Effect of Rectification. into fluctuations of plate current, at audio - Fig. 5.-The Electrical Circuit for Reaction. or speech -frequency. the other way for the next half period) tions of the current in the plate circuit, of the resulting fluctuations of the plate cur-Reaction. which L, forms a part.These in turn re- rent are unidirectional. Having set our device running, as de-act on L3, and so the whole circuit becomes scribed under amplification,letuslinkthe seat of a continuous oscillation, the Rectification. up key Y mechanically with key x, so thatplatebatterysupplyingtherequisite Leaving A (Fig. i) running as before, letwhen Y is depressed by an increase in thepower.The applications of this principle, us decrease the speed of B by its electricalflow of water, x is depressed in turn by it.however, are beyond the scope ofthis control till G is only lust revolving.WithThus the fluctuations in the main circuitarticle. this adjustment any additional friction onreact sympathetically on the control and As mentioned in the first place, we can- the drum will stop the flow Of water inrender the model to a certain extent auto-not claim that the hydraulic analogy is a the main circuitaltogether,whereas amatic.When once it has been set goingworking model.It, will have served its decrease of friction will increase that flowit will continue to work indefinitely, thepurpose none the lessifithas enabled as before.Consequently only the positivenecessary energy being derived entirelyreaders to form a conception of the funda- halves of the alternations of pressure onfrom the motor A. mental principles underlying an extremely the key x will be reproduced on the key The electrical equivalent of theuseful piece of apparatus. SIGMA. Eneint-i===nnrinn=====tninnnn=nnn==ennerc======r3 u ul u ' a o t f ITS RANGE ; aLI u SPECIAL SWITCHES; EI U The "OfficiealReceiving' Set OTHER DETAILS. A U El A li:CIOQUGICII=C7G1=GICIG7GUIZIGIQCIGJQI;GIZ;71;laGLi1=7=1:7QOULZI=Gl2GLCGC771;i:QQ=1;CIL=GZZIQ;7Q.G7G;iaZQA1 ANUMBER of querieshasbeenhouses, these conditions confer great ad- Now inductance necessitatesa length asked concerning the receiving rangevantages. of wire, preferably in the form of turns; of the "official" receiving set described in (5) The efficiency of the receiving set.two turns,provided they arecloseto- the first number of "Amateur Wireless."This depends on (a) good insulation,(b) gether, give four times the inductance of It is impossible to state offhand what theproper adjustmentofdetector,and(c) one turn;three turnsgive nine times range of a set will be, for there are dif-good telephones. the inductance, and so on.Also the in- ferent factors that govern the operation. The only sound answer one can give is: ductance increasesin proportion tothe Briefly these are as stated below : Erect a set and discover for yourself what the range is.The knowledge that will be gained by experimenting will always be of AERIAL WIRE ,value. One or two correspondents have had difficulty in understanding the operation of the tens and units switch on the tuning inductance. In order thatsignals may be received,it must be remembered that WIRE TO the receiving set shall be in "tune" with TuNING INDUCTANCE WIRE TO EARTN the vibrations in the ether set up by the 2.-Detalls of Lightning Switch and Fig. 1.-Diagram of Oscillating Circuit. transmitting station.Assuming that the Connections. reader has a grasp of the meaning of the (1)The distanceofthetransmittingterms "inductance" and "capacity," whichsquare of the diameter of the turns in the station and its direction. have been explainedinthe elementarysame way.By having, say, roo turns of (z) The power used by the station; this,articles that have appeared, he will knowwire in a former (each turn being close of course, varies enormously. that to tune in stations of different wave-to its neighbour but well insulated from (3) The height and length of the re-lengths either the inductance or capacity,it), and having a slider, we can vary the ceiving aerial. orboth,oftheoscillatingcircuit(see inductance over a wide range, increasing (4) The position of the receiving station.Fig.r)must bealtered. The methodby a single turn at a time. The slider Ifitis on a hill or a level plain, andadopted in a simple setisto vary thehas certain disadvantages.It wears the is not sheltered by trees or neighbouringinductance. wire by constant rubbing and is liable to JULY I, 1922 mateur Wireless 69 short circuit two or more turns, which willof this switch the inductance is varied by The lightning switch is shown enlarged waste some of the energy.In order tocomparatively large amounts at a time.by Fig.2. A single -polechange -over overcome theseobjections,and alsoto To tune more closely the units switch isswitch isused.The aerial wire is con- make an inductancesuitableforpanelused, ten studs being connected tothenected to the arm. The lead to the tuning mounting, the turns are brought out tolast ten turns on the coil. inductance is connected to A and the earth two switches, one called the "tens switch" By using both switches togetheritis wire toB. When the set is in use the and the other the "units."Each stud onpossible to include any number of turnsswitch should be over to the left (A), and the tens switch has ten complete turns con-varying from one to the greatest numberwhen out of use it should be over to the nected to it,so that by moving the knobon the coil. right (a), thus earthing the aerial. onnnmn=rmnrinn=nrintnnnnnrrannnronnorrincrinm=rincnarrnnmtnrinnrinmarn=runinrnmernmminnriont E .130 BENcHwoRK SIMPLE P. vv. SOLDERING E 0 lEIGLIOGIGIGIGIOGIQL7GZIQL:IGIQUQG:100ZIQUG7GIGIGIUUUGULICIOULIQUI;100QQ=ZIGIUZIZIU=1;IZIULIGIOGJUQUQGIUGZIGIOQUGIUQL1il THE simple operation of soft solderingbut it cannot be used in electrical workever, adopted with instruments.Another enters largely into the construction ofbecauseitcorrodes quickly, and, more-method rarely used and notgenerally wireless apparatus, and thisarticleex- over, any spilt on the ebonite or wood willadopted is as shown at B, which isself- plains how it is done.It is only necessarypartially destroy their insulating proper- explanatory.When the jointis -twisted ties.You will find resin a safe flux, butup simply spread some flux on it,heat Fluxite may be used.Resin should bethe bit, and melt a little solder on to the powdered and sprinkled on the article. joint.Then "draw" the solder through Solder. Any very soft solder will do.I always use blowpipe solder because it melts at such a low temperature, and there is thus less risk of melting the shellac, etc., or charring the wood or other parts of the work.It is quite strong enough for the purpose.Certain combined solders and fluxes are on the market; and these are just as good. Heating the Bit. The bits may be heated in the kitchen fire, or, if the bit is quite small, even on a gas -ring.A gas -iron makes an ideal stove for lheating the bit.The bit must Fig. 1 Fig. 2 Fig. 3 not be allowed to get red hot, because the Figs. 1 to 3.-Three Types of Soldering Bits. copper burns away as well as the tinned Fig. 5.-Various Joints and Terminals. face: With a little experience you will to follow one or two simple rules, andbe able to judge the correct heat. and round the joint by keeping it pressed anybody can do it straight away. There is on to the work for a second or so.. no need to bother with the theory of theTinning the Bit I always like any terminal connection subject. Before we can actually solder it will beto look neat, and instead of just twisting necessary to tin the faces of the bit.This the wire round the contact screw I make Tools. is up terminal ends as shown in C (Fig. 5). is only takesa minute orso,andit Nothing much in the way of tools effected by heating the bit to the tempera- They are easily cut out of flat copper of required;asoldering -bitandanold about z6 gauge and bent to encircle the pocket-knife areallthatare necessary,ture at which it will be used, filing theflex; the end is,of course, stripped of and as there are no large pieces to befaces bright, and then melting a bead ofinsulation and the wires scraped bright soldered a small bit can be used; minesolder on to a piece of bright tinplate, on which some flux has been spread, and rub- with a pocket-knife.These ends are then weighs about 3oz.,and with thissize soldered to the flat part of the terminal, several joints can be made with one heat.bing each face of the bit on the tin soas shown.Plain wires may have ter- For getting in awkward places a hatchetthat a film of solder is spread on them. minals formed on them as shown by D bit will be handy, but most jobs can be (Fig. 5). done with any of the bits shown by Figs.Some Examples. Suppose you Ix ant to solder the ends of To solder the edges of two sheets of x to 3. Iuse the old pocket-knife for metal together,each of the contacting scraping the parts bright and clean, be-two pieces of wire together, all that it is edges must be tinned.If the edges are to cause solder won't "take " on greasy or overlap for in., the edge must be tinned dirty metal.A scraper can also be used for in.This is done by cleaning the for this purpose.A piece of clean tin- edges with emery cloth, spreading flux plate for use in retinning the bit should Fig. 4.-Simple Twisted Joint. along them, and melting a blob of solder always be handy. on to the point of the bit.This is then necessary to do is to scrape the ends withrubbed up and down the edges until a Flux. aknife(evennewwire must beso thin film of solderisspread alongit. A flux is necessary when soldering tocleaned), and twist the ends together as Having tinned both edges, they are fluxed make the metal chemically clean and alsoshown in Fig. 4.Sometimes the ends areandpressedtogetherwiththeheated to cause the solder to " flow " well intobound together with fine wire, as shown soldering -bit,when the solder will the joint.Spirits of salts is the best flux,at A (Fig. 5), but this method is rarely, if"sweat" through and make the joint.

qb einaturwugss 70 71 Imateur Wireless Fr_nmarn=n=nnannmrinmr==m=m=nrinnctnnomrtn=rnanncmn=minnmaintann=nrirEcrirmn 7_,-nr_nr==nnna7rni=mmrnanfnmmmmmincrinnnntnnnmmmnimm=^^77

11 ERECTING AN AERIALBY THE "TABERNACLE" METHOD

11 don't putitinthe ground,touse an up again; it can hardly get too much of cement wall thicker at the bottom where same tension on them in a straight line. IJ Irishism.Make atabernacle,asitis this treatment. it will carry the long bolt and have to The free ends should now be bunched to- 1-1 called.Any well-appointed flagstaff will Thoroughly wet the wall that you are support the weight of the pole.Be care- gether and screwed up in the chuck of a Aerial " Don'ts " 11 show what thatis,but incase such a going to work upon.Take a length offul not to .get the cement in front of the carpenter'sbraceandtwistedtogether DoN'T run your aerial over a public thing is not in sight,it consists of three wood very slightly larger than the polepole, or you will not be able to take the while a fair tension is kept on the wires. highway;you will probably have to fl take it down. 11 If this is done carefully and the twisting thick planks of hard wood fastenedto- at the foot, and tack oiled paper, American dummy out and fix the permanent one in. Don't allow it to cross overhead wires ; gether to form a box without ends.Bury cloth, or even thin roofing felt,closely When thisstageisfinished you must slightly overdone, it will untwist a little there is always a risk of its falling on II this half -way down in an upright position, down on toitso thatitwill not drawleave it alone for at least fourteen days on being released, but exhibit no further to them, with perhaps disastrous results. and bolt the pole into the part which rises moisture from the cement when it is being -a month is bettercover it up so that tendency to come undone.Four stays- Don't neglect to include a lightning This piece ofneither sun nor frost can get at it, though back,front,andeachside-shouldbe protector or au earthing switch that will plastered in. put the earial to earth. woodis the"pattern"of rain and moist air will do no damage. provided. Don't forget that the insulation of the the foot of thepole, and then Two bolts, "rag bolts " for preference, Draw the pole to scale on a sheet of aerialis one of the most important when the cementis set itis;should be set well into the wall and the paper and measure along the base line the points if efficiency is desired. to be removedand leave a cement, near the top of the tabernacle, so distanceto the anchorage of thestays. Don't use insulators that are un- This will give the length of the latter to necessarily heavy. place for thepole to be set that an iron strap may be bolted over the Don't use any common bit of rope to in. pole to secure it when in position. scale. support the ends of the aerial. . Fastenthiswooden block Don't omit to make some provision on tothe wallinthe exactStaying the Mast. Anchorage. for the contraction of the aerial ropes positionthatthebottomof The photograph (Fig.5) shows a 3o -ft. Allsorts of devices are recommended that will take place in wet weather. Fig. 5.-Photograph showing Aerial Described Don't forget that soot on anin- the pole isto pole 2in. by 2in. for anchorage for stays, but in London and sulator makes an excellent conductor in this Article. occupy when with a small 18 -ft. fir most big towns itis very unlikely that a and that the efficiency of the set will erected.Take poleboltedtothe convenient fencepost or garden wall will suffer as a consequence. EVERYBODY now is putting up great care that top. Make a lead or not present itself.In the case illustrated Don't contemplateusingaframe aerials, and if everybody demands fir all the stays are attached to the house, aerialif you only have a crystal re- itisperfectly zinc cup to put over ceiving set. poles there will not be enough firpoles uprightall the top of the pole except the long one in front, which takes Don't try to economise by using a thin available for immediate needs. round. The to keep the wet out. the strain against the aerial and is made wire ,for the aerial. Thewriterhasusedandadvocated Fig. I.-Method Fig. 2.-Mast in " Tabernacle" block of wood Youhavealready off on to an old tree stump. A hard -wood Don't omit to clean the insulators something cheaper,lighter,andeasier, of Joining Masts. on Ground. should carry given the pole three stake driven into the ground a la tent - occasionally, especiallyifthe installa- and the photographs show that the height tionis near the sea or in a smoky a bolt, the coats of paint.Get peg will take a lot of beating. atmosphere. doesn't suffer; in fact, a 35 -ft.length of above the ground, keeping a clear 6 in. latterwell greased to a well -made galvan- It is the writer's opinion that a too -ft. Don't forget that the earth connection 2 in. by 2 in.is longer than the usual fir away from the surface of the soil with the prevent the cement stick- isedironpulley single -wireaerialisthebesttouse. is an important adjunct to the aerial. pole, and is also considerably easier to foot of your pole (see Fig. a). ingtoit,and threaded block with as large Short spans may make a double aerial Don't use very light supporting masts ; erect. If your poleisto go into a wall or throughitnearitsend a pulley as possible desirable, but a spreader thrashing about they bend too easily. a chimney you make your tabernacle of where its counterpart, the -3 in.in diameter in a gale might do damage.If you use The Wood to Use. iron and cement; that is all the difference, pole, will be hinged, so is not too large-so rope halyards hang a weight at one end Insulators.-Porcelain or ebonite.Quite First of all with regard to the wood : and the photograph(Fig.3)shows an that when the bolt is with- that the halyard good results are obtainable with insulators Go to a timberyard and ask to see some example of this construction.As it was drawn from the block and shall 'not be strained Pea made ofhard wood soakedinmelted long lengths of 2 in. by 2 in. wood without original, so far as the writer is concerned, inserted into the pole in round too small an RAG BOLTS paraffin wax. knots.Explain what you want it for and and has stood the test of time, he pro- position, the weight of the arc.Wire it firmly _ -4- Mast Stays.-Galvanised-ironorsteel why knots are ncr:-. desirable. poses to describe how it is done. pole will come upon the to the top of the pole 1.-- - wire, stranded or single. Pick out your piece of wood, but be T -4 - bolt and be held by the with stout soft cop- .L _ Leading -in Insulator.-Ebonite. L - careful to see that the knots are very few, Other Materials. cement tabernacle. Small per wire, but not so Shell Insulator. -- very small, and that none of them comes The materials must he good portland Severaldozen9 -in. Insulator. tightly that it cannot 1-4- Poic on the corners.Planeitup, or getit cement and the best washed builders' sand. nailsshouldbeworked accommodateitself planed just enough to get it smooth and The cement should not be too new and intothe brickworkofthewall on to the strain when the halyard pulls the T -4 - take off the sharp edges.Give three coats fiery, and certainly not too old and partly each side of the wooden block and lubri- aerial up tight.Now attach stays at every of lood paint, and you will have a cheap slaked.The sandshouldbe"sharp," cated,sotospeak,or,intechnical 15ft.all the way up, four stays at each -4 4 -- - and durable pole. thatis,gritty,clean and sharptothe language, grouted in, with some of the point.Two or three turns of thick soft Twenty-five to thirty feet in length is all touch, and not powdery and dusty when cement mixture, so that, rather than force*copper wire round the pole will do toI-- -:f --.--T - you are likely to get in one good piece, dry. the bricks apart when weight comes upon secure the stays, and then,if there is a ------so if you want a greater length two pieces Take equal parts of cement and sand them, the cemented nails will tend to hold chance of them slipping, a small tack or Fig. 4.-Method of Making Tabernacle must be joined.This unfortunately can- and mix them intimately while quite dry, themtogether morefirmlywhenset. staple will make them secure. on Wall. not be done by placing two ends together that is, so that no streak of sand or streak Keep the work well wetted all the time, No.16,18,or even 20 S.W.G. bronze and gluing them.You will want about of cement shows if the heap is cut into so asto wash the cement between the wire will be quite heavy enough to hold so as to keep the aerial taut and yet permit A 3 ft. overlap, and two 0 -in. bolts to bolt anywhere.Builderssay,turnitcom- bricks (see Fig.4). against any strain, and will not rust as the wet rope to contract without endanger- the fivo lengths together, as shown in the pletely over three times dry (perhaps ifI Get some stout iron wire, galvanised or might galvanised -ironwire.Be careful ing the structure. GAMMA. sketch, Fig.r. say,shuffle the cards three times dryI plain will do, and interweave itin any not to "kink " the wire or it will break. What looks particularly swagger up in shall be understood); moisten sparingly patterninand out amongst thenails, If a little more expense is not objected to, Materials for the Erection of Aerials.

the air is to plane off the edges of the top and gradually with cold water, mixing which should only project from the wall the top stays, particularly the one which IVood for Mast.-(a) Ash,(b)fir,(c) DI length gradually from bottom to top till the while and only giving enough water far enough to be flush with the front of the sets against the pull of the aerial, may be bamboo. the top is octagonal, that is, all the eight to make it cling together-the less water pole when in position. stranded with a carpenter's brace from Spreaders.-(a) Ash, (b) bamboo. sides you have made are of equal width. the better, so long asit just keeps from Take the cement mortar and work it in three lengths of single stay wire.To do Aerial and Lead-inWires.-(a).Stranded seven This givesit a graceful taper, makes it crumbling.Inthis stageitshould get amongst the nails and wirework and theI° this measure off,say,to per cent. more phosphor -bronze, saythree to A lighter at the top, and does not much re- two or three times as much mixing as it wetted wall tillitisa solid mass, and than the length the stay is to be and fasten strands of No. 20 gauge;(b)stranded copper wire; (c) No. 14 to 18 gauge single Fig. 3.-Photograph of Mast in Tabernacle El duce the strength. had before the water was added.As you trowel it off so thatitislevel with the one end of these wires to a nail.Now If you are setting this in the ground, take away a supply from the heap beat it frontofthedummy pole.Makethe run the three wires parallel and with the phosphor -bronze or copper wire. on Wall, einaturwugss 70 71 Imateur Wireless Fr_nmarn=n=nnannmrinmr==m=m=nrinnctnnomrtn=rnanncmn=minnmaintann=nrirEcrirmn 7_,-nr_nr==nnna7rni=mmrnanfnmmmmmincrinnnntnnnmmmnimm=^^77

11 ERECTING AN AERIALBY THE "TABERNACLE" METHOD

the air is to plane off the edges of the top and gradually with cold water, mixing which should only project from the wall the top stays, particularly the one which IVood for Mast.-(a) Ash,(b)fir,(c) DI length gradually from bottom to top till the while and only giving enough water far enough to be flush with the front of the sets against the pull of the aerial, may be bamboo. the top is octagonal, that is, all the eight to make it cling together-the less water pole when in position. stranded with a carpenter's brace from Spreaders.-(a) Ash, (b) bamboo. sides you have made are of equal width. the better, so long asit just keeps from Take the cement mortar and work it in three lengths of single stay wire.To do Aerial and Lead-inWires.-(a).Stranded seven This givesit a graceful taper, makes it crumbling.Inthis stageitshould get amongst the nails and wirework and theI° this measure off,say,to per cent. more phosphor -bronze, saythree to A lighter at the top, and does not much re- two or three times as much mixing as it wetted wall tillitisa solid mass, and than the length the stay is to be and fasten strands of No. 20 gauge;(b)stranded copper wire; (c) No. 14 to 18 gauge single Fig. 3.-Photograph of Mast in Tabernacle El duce the strength. had before the water was added.As you trowel it off so thatitislevel with the one end of these wires to a nail.Now If you are setting this in the ground, take away a supply from the heap beat it frontofthedummy pole.Makethe run the three wires parallel and with the phosphor -bronze or copper wire. on Wall, Otnateur Winless 72 JULY I,1922 E rronnritnommmerricrErninmnrmninmmmr2=ninnrimmmnonnnnrimm=crni-in===mrinthr7=n7r-rrat

Fliin PROBLEMS YET TO BE SOLVED ICI E l od Captain J. Hollingworth, M.A., indicates in this article what great fields of investigation still remain El a u :: for the wireless experimenter .. El '. 0 ID ,&,6=1=101;GICIQUZOCIIDGC11:11LIOOQUZIOGIGGIQQLZGQ(ZZZIOUDGIQUQCIGIGIOQQa:IG0301L1c.1Q=ILIZIGZUZCQQQL]i7ZUZGIZIUZIQQ1;1COI 'would probably not be far wrong totheory has been of enormous and vital im- High -frequency resistance is another big ITdescribe the difference between an en- portance,buttherearemany points,problem.It is not generally known that gineer and a layman by saying that the especiallyinthe operationof a valve,an inductance,especially a multi -layer latter is one who is aggrieved when a piecenot yet answered.The problem of radia-one, may easily have a high -frequency of apparatus does not work, whereas thetionthroughspace andtheeffectsof resistance of twenty times its continuous - former is agreeably surprised when it does.absorptionandreflectionarenotyetcurrent resistance. Instances of this could be multiplied from understood. any of our present-day mechanical aids to "Harmonics" partly, no doubt, due to aComplexity Twoproblemsbroughthomevery civilisation, The second general problem is one ofstrongly to the amateur are "jamming " flattering belief in the omnipotence of thecomplexity. Unlikeordinaryelectrical "expert," but much more to a lack of ap- and "harmonics." About the former there practice, in which in most cases a definiteis. no need to say anything; the latter is preciation of the complex problems in-circuit with only one degree of freedom is volved.Even among technical men them- yet another reminder of the fact that the being dealt with, practically all wirelessaerial circuit is not a simple one, but that selves, the field covered by their individualproblems are three-dimensional, and as experiences can only be so smallthat it contains inductance and capacity dis- such lead to the most elaborate mathemati-tributed throughout its length in varying they do not always fully appreciate thecal treatment.Simplification, adopted to problems confronting their colleagues. degrees.Such acircuit, when excited, abbreviate the mathematical work, oftenmay respond not only to the harmonics of In a comparatively young subject likeleads to results so different from. practice wireless telegraphy such ideas are very the exciting source, but also to the free as to be nearly worthless.To take anperiods of various sections of itself. prevalent; in fact, when discussing wire-example, the "simple oscillating circuit," less work with non -technical people I have As soon as the energy gets into the as generally dealt with, is supposed to con-ether,itpasses more from our control. heard the opinion expressed that since it issistof a "pure inductance," a "non -in- now commercially possible to send mes- Even if we knew, which we do not, the ductive resistance," and a "pure capacity "factors governing absorption and reflec- sages by wireless, what is there in the 'sub-all in series.In this form it yields to very ject to bother about further?Of course, tion,itisdifficult to see how we could simple analysis.But, as anybody who hascontrol them.Itis generally held that even the barest acquaintance with this fas-actually dealt with such circuits knows, cinating subject soon dispels such ideas, the electrical state of the upper layers of the inductance possesses both self -capacitythe atmosphere have a great bearing on but even then itisdifficult for anybodyand resistance, the resistance possesses in- who is not devoting his whole time to it these points, and, as we cannot get up ductance and capacity, and so on.Thethere to investigate them directly, it has to to appreciate the magnitude of the prob-behaviour of the circuit is also influenced lems still awaiting solution. be done in an indirect manner.One such by the proximity of other circuits, by themethod, now being employed, is to investi- earthing effects and many such details.So Leeway To be Made up gate the abnormal variations sometimes that while the simple circuit provides aoccurringindirectionalwirelesstele- Wirelesstelegraphy (including, offair description of the action taking place, course, telephony), besides being a youth- graphy, and, if possible, to deduce from any effort to base numerical results on itthese the nature of the electrical state in ful subject, has, due to outside circum-may easily lead to errors. stances, had rather an abnormal adoles the upper atmosphere capable of produc- cence.Its prime importance during theOverall Efficiency ing results like those actually observed. war caused a forced development, in which Another problem is that of overall effici-We have to deal with the ether as itis, the principal object was the production of ency.In a big transmitting station wenot as we should like it to be, and must sets which worked rather than the investi-think nothing of plant of several hundredhope that, even if we cannot control the gation of underlying principles, the latterkilowatts capacity, and are quite satisfiedether, we may be able to foretell its effect. only being touched where essential to theto receive at the far end about one mil-Atmospherics,X's,orstrayspresent former.Consequently there is now a con-lionth part of a watt.Compared with this,another big problem now being attacked. siderable leeway to be made up on thethe steam engineer with his boiler losses,Problems at the Receiving End theoretical side, or,in other words, thehis condensation losses and his other losses, At the receiving' end, the problems again reduction of the whole subject to a sys-usually considered so serious, appears abecome more of an instrumental nature, tematic form.Conditions very much re-genius.A large amount of the loss inand areconcerned with thedesignof semble the early days of electricalen- wireless work is, of course, inevitable fromefficientreceivers and amplifiers.Here, gineering before the theory of magneticthe nature of the case, but not all.A con-probably the chief enemy is stray capacity. and electric circuits was fully understood,siderable porton of the energy produced isWith the enormous frequencies used in and when the chief Abject of each maker ofused up in heating the transmitting induct-radio work the smallest capacity imagin- dynamos appeared to be to produce some-ance, the aerial stays_ and masts (ifofable makes itself felt; a mere rearrange- thing as unlike any of his competitors'metal) and the ground in the immediatement of the apparatus is often enough to machines as possible. neighbourhood.The last-namedisnow change completely the 'working.Mathe- Broadly speaking, an important problembeing tackled by the use of the counter-matical treatment is here of little help, of modern wireless is to reduce the subjectpoiseearth, a frame of wires stretchedand one can only fall back on experience. tosystematic and numerical form andunder the aerial; since it is now concludedIt is, in fact, a moot point how much of eliminate as far as possible the "trial andthat the majority of earthing losses aretheenergy of a radio -frequency trans- error " factor.Here we are at once met bydue to eddy currents surrounding the feetformer is transferred from the primary to twodifficulties. Thefirstisthat ourof the lines of force, rather than to any-thesecondaryelectro-magneticallyand fundamental principles are not in all casesthing of a purely ohmic natureat thehow much by capacity coupling. fully and accurately defined.The electronearth plates. In valves themselves, grid current is a JULY 1, 1922 73 QinatturWireless potentsourceoftrouble.If,assug-greater jamming than telegraphy, owing tnrcnrnmmarnmmorrnnt==ornotm gested in many text -books, the grid currentto the high damping of the oscillations C lc be actually reduced to zero by making theforming the carrier waves of the speech. grid sufficiently negative with regard toFor this reason short waves are the most Starting an thefilament,thevalve generallystopssuitable for telephonic purposes. hi workingaltogether. Itisone ofthe Instances of smaller problems connected reasons why the actual amplifying powerwiththe pure technique of the subject[11 Wireless.-IV of an amplifierisfrequently' not morecould be multiplied almost indefinitely, but El ill WUILQQI;Lli:JIZIQGGC:121;QGLGI;7QGIQQ1ZGUCl than ipercent.ofitsamplificationwhile extremely interesting and important deduced from sithple theoretical grounds.to those who are daily "up against." them,The Receiving Circuit. Although the losses in a valve may bethey do not possess the same importance FOR the moment letus assume that microscopic, the power available inthefor people concerned with the more general our aerial has been erected and the aerial is correspondingly small, and nonelines of the subject.Detailed descriptionearthconnectionmade. We cancon- must be wasted. of them is also very lengthy.Reviewingnect up our tuning device.The simplest Inwirelesstelephonythereappearsthe subject as a whole, one cannot but beform of tuner consists of a single -slide again the fundamental telephonic problem,led to the opinion that a vast amount oftuning inductanceas shown onp.74. namely, the undistorted transmission andwork lies in the consolidation of the groundIt will be noticed that the slider end of reception of the highly complex forms ofgained, and this will elucidate many out-the coilis connected to the earth.This speech waves.Italso causes somewhatstanding problems. J. H. is' a most important point, because when only a portion of the coilis in use the unused part should always be left nearest theearth end rather than the aerial end of the circuit. SOMEAMERICAN IDEAS We will remember that when we tune inasignal we findthat a very rapid alternating potential is set up across the inductance. However,thisisnot con- A Non -inductive Potentiometer simpledodge.Wind some No.28or No. 3o gauge wire into a coil sufficientlytinuous 'when itis produced by a spark NON -INDUCTIVE potentiometer station or telephony, and, therefore, we Amay be simply constructedinthe large tofit loosely over the secondary of the coupler, as indicated in the drawing.found that if we rectified this alternating manner shown in the accompanying illus- potential and passed this energy on to tration.The base is a neat piece of hard atelephonereceiverand obtainedan wood approximately 12in.by 2in. by audible note. 2% in.The slider rod is made from a As previously mentioned, one method piece ofM. -in.square brass rod, and is of detecting or rectifying this potential to in. in length.Holes are drilled near is by the use of a crystal detector.Per- each end so that brass screws will pass haps thesimplesttypeisthePerikon through, as shown.Two pieces of square Detector, which consists of two crystals, 54 -in. brass tube, each tin. long, are used a piece of zincite and a piece of bornite asthe supportsfor the sliderrod,as orcopperpyrites. Eachcrystal is TO NEGATIVE TO PLATE OF B - BATTERY mounted in a small metal cup by means CIRCUIT OF ALPIDiON .'i' TO PHONES of solder or Wood's Metal.One cup is fixed and the other is movable, so that the Increasing Loose -coupler Efficiency. pressurebetweenthecrystalscanbe varied.The crystals are only sensitive at The number of turns can best be deter-certain pressures, and therefore before it mined by experiment. Connect the ends ofis possible to receive a signal the detector the coil to the plate circuit of the valve,must be in a sensitive condition. one wire to the negative pole of the high- The telephones are connected in series A Non -inductive Potentiometer. tension battery, and the other to the re-withthedetector,bothbeing shunted ceivers.Application of this idea to theacross the active portionof the tuning shown.The resistance rod is a piece ofloose coupler really turns it into an induc-coil (see p.74). It will be noticed that graphite obtained by soaking a 4H draw-tive regenerative set.-Popular Mechanics.a condenser is shown connected across the ing pencil in hot water to loosen the glue telephones.This is not really an essen- and removing the wood protection.TwoTuning Coil Hints tial, but itis a great improvement.It small spring clips hold the graphite rodTo remove the insulation from the wireis usually known as a telephone or block- securely in place under the slider rod. Afasten two laths on one side of the tuninging condenser; we may best understand slider is made in the usual way.-Radiocoil, spaced in.apart, and scrape theits action by considering it as a kind of News. reservoir which stores up electricity during a signal.The condenser is usually A New Indoor Aerial made of either alternate sheets of tinfoil ACCORDING to Walter G. Voss in Radio and paper or copper foil and mica. News a.simple-substituteforthose The telephones are the only component amateurs who are unable to erect a suit- .....?"Nktkftwww of the receiver not yet considered.Tele- able aerial is simply to connect a wire' to phones foruse with acrystaldetector one of the terminals ofthe door bell. should be of the high -resistance type.A This, he states, provides an aerial extend- very good value for general use is 4,000 ing through the house which really gives Tuning Coil Hints. ohms, but higher values may be used if results. desired.Results will be very poor if the insulationaway by rubbinga woodenvalueis much lower than about 2,00C Increasing Loose -coupler Efficiencyblock covered with emery -cloth up and ohms. High -resistancetelephonesare THE efficiencyof thefamiliarloose down in the groove formed between themoreexpensivethanthoseoflowet coupler can be increased measurably by atwo laths.-Radio News. values, and they are usually more deli- eltritvtr Wireless 74 IULY I, 1922 cate.As an alternative to high -resistanceAdjusting the Detector. ircnnnnnamrrnorrnorriromeamarnrirn telephones, those of lower value may be A detector is usually adjusted by a test- usediftheyareconnected through aing buzzer.This- is exactly like an' elec- .EI transformer.A very usual value is12o tric bell with the hammer removed.Any " Marconi ordinary buzzer will answer the purpose,. 1:1[11:1 but itis much nicer to use one giving a House 2L0 very high note, that is, one with a very ine

small and light armature.The buzzer is .uuu connected to a battery and put some dis- . Speaking! tance from the receiver, preferably near the earth lead.The telephones are then uOUG1G101;l01:101:11;I0OGIOQUI;11;11;100GGLIG11;llil TUNING put on and the slideris moved to the COIL bottom of the coil so that nearly all the HULLO ! Hullo ! Hullo !Marconi coilis in circuit.The pressure between House 2 L 0speaking. Hullo ! the, crystals is varied until the note of theCaxton Hall !Hullo !2 B P.Marconi buzzer is heard in the telephones.TheHouse speaking.I have here a message buzzer is switched off, and everything isfrom the Archbishop of Canterbury to the then ready for receiving signals.TheseBishop of Willesden for transmission by EARTH wireless telephony from Marconi House to Connections of Simple Receiver. are tuned in by simply moving the sliding contact up and down the coil.When aCaxton Hall on the occasion of the Actors' ohms connectedtoasuitablydesigned signal is properly tuned in it is advisableChurch Union annual fete in aid of the telephone transformer, the high -resistanceto readjust the crystal detector, as some-children of travelling actors.The mes- winding of whichisconnectedinthe 'times a, slight alteration will give a loudersage is as follows : position usually occupied by the high -note than would be obtained with a buzzer MY DEAR BISHOP, --Please convey the resistance telephones. on that setting. PAUL D. TYERS. warmest expression of my goodwill for your efforts, and my hopes that, by 'the blessing of Almighty God, they may be rinnnrirrinnrinannEmmninnocommarinn=nraninnnrrnmrnm=nricrirring abundantly fruitful. Hullo, Caxton Hall !Marconi House El speaking. We now propose to give you a few musical items.The firstis a 'cello E ChoosingYour Ampliier El solo, by W. H. Squire. Ii1G11;1171MILLIGIQUOGIUGIOGlIQUOMZIMIZIOZIOUL:100Q0=0Q01;71QU=12=1;11:71:100G121 [her efollowedaremarkablyclear 'gramophone recordof W. H.Squire's AMATEURS are frequently at a lass tooscillating.The great disadvantage withsolo.] 1-1 decide what kind of an amplifier theyH.F. amplification is thatit only works Hullo, Caxton Hall !Our second item shall use.They may have had some ex-over the comparatively small band of wave-is a cornet solo, by C. Laycock, entitled perience with crystal or single -valve work-lengths for which the air -core transformer"Robin Adair." ing and wish to have louder signals, oris designed.This trouble can be overcome [This was equally clear and beautiful.] they may be beginners who are puzzled byby having the transformer windings tapped Hullo, Caxton Hall !Our third and last the variety of apparatus offered for sale. and the tappings taken from the switch,itemis" Dreamy Paradise," played on Three kinds of amplifiers are in commonthe latter being varied to suit the wave Hawaiian guitars. ' use-low-frequency,high -frequency,andlengths being received.A better method [This item was as unique asitwas resistance-and very often these are com-is to have a separate transformer for eachmelodious.] bined in a single receiver.° band of wave -lengths and plug in the one The message from the Archbishop of required. Canterbury to the Bishop of Willesden was Low -frequency. repeated, and afterwishingeverybody A low -frequency amplifier entails theResistance. "Good night" the speaker finished, and use of an iron -cored transformer for each The resistance amplifier is used like athe ether was still save for one or two stage of amplification, and is only of useH.F. amplifier for magnifying the receivedsolitary "spark" signals.Our home-made in a circuit after the received aerial cur-current before it is rectified.It is very use-crystal set had done well.-H. L. S. rent has been rectified either by a crystalful becauseitissuitable for all wave- or a valve.Its main advantage is that alengths over about r,000 metres.It almost single transformer is suitable for all wave-equals the L.F. amplifier in simplicity of lengths; adjustment of the apparatus isadjustment. thus fairly simple.If the rectified received A very good combination for long waves Testing Your 'Phones current is weak, a L.F. amplifier is notis a three -valve receiver having one re- THE test commonly used in the early very advantageous; loud signals are mag-sistance amplifier, one detector, and one days for receivers was made by means nified more (proportionately) than weakL.F.amplifier. Probably the best andof the handiest and weakest of batteries-a ones.Also a L.F. amplifier has a tendencysimplest single -valve amplifier to a'dd topenny and a two -shilling piece, between to pick up stray outside noises-both elec-an existing crystal or valve receiveris which a bit of moist paper was placed. trical and mechanical. No one living neartheL.F.,providingthedisadvantagesThe end of one wire from the 'phones was an electric tramway, or railway, or near amentioned are not experienced. connected to the " copper," and then the road over which there is much heavy traffic, For the enthusiastic instrument -makersilvercointouchedlightly(andre- should use a L.F. amplifier and experimenter the H.F. amplifier will' peatedly) with the end of the other wire. undoubtedly prove the most interesting. Nowadays a similar test is made with a High -frequency. L. A. W. single piece of sheet aluminium which A high -frequency amplifier is used to 0 should be damp.Simply connect one magnify the received current before itis Every Reader of " A.W," should have atwire of the 'phone to one end of the alu- rectified. Itdoesnotpickupstrayhand for reference a copy of the "Work"minium plate, and then touch the plate electrical disturbances unless the latter are Handbcok,"WirelessTelegraphyandwith the other wire, when, if the 'phone of high frequency, such as those caused'byTelephony : and How to Make the Appar- isproperly adjusted, each contact will your neighbour's valve receiver when it isatus," is. 6d. net. cause a click, in the 'phones. W. W. D. JULY 1,1922 75 makur Wtra2ss phone, but produces its tones more clearly and free from foreign vibrations. RADIOGRAMS Little or no information is yet available WOMEN areeligibleforthe Post-in any place of public amusement in theas to when the inception of the broadcast- master -General's certificate in wire-United Kingdom. By -a loud -speaking de-ing will take place.Apparently the cause less telegraphy. vice the audience will be enabled to obtain ofthedelayisbecause manufacturers all the advantages attaching to a wireless ofinstrumentshavenotyetagreed installation.It is hoped to give a publicupon a scheme which is to be submitted In recent tests on the Elletra a trans-demonstration within the next few weeks. to the Postmaster -General.The sugges- mission speed of too words per minute was tion has been made that the manufacturers attained. are unwilling to bear the annual cost of It is stated that a German scientist hasthe broadcasting stations, as it is estimated Obviously the future of the industry de-discovered a new attractive force whichthat the upkeep of each will be about pends to a great extent upon the steps isnon-magnetic, and yet which causes£20,000 a year: which are taken to regulate it. attraction between allmetals and even minerals.If any credence can be attached to the report it would seem that such a The proprietors of a well-known make A report is to hand that a Hungariandiscovery will find immediate applicationof cigarettes, in order to improve the con- engineer has invented a device for print-in wireless telegraphy and telephony. dition and comforts of their workers, have ingatlimited distances by current or installedafully -equipped receiving ap- wireless. paratus.Some years ago this same firm The papers say that a communicationerectedawirelessinstallation on their One result of the experiments conducted has been forwarded tothe Postmaster -factory and on one of their motor cars in on board Senatore Marconi's yacht theGeneral suggesting that the interests ofan endeavour to obtain direct communica- Elletra is considerable progress in the waythis new industry can best be safeguardedtion from traveller to factory at any and of eliminating static disturbances. by applying a condition, already requiredall times.The war prevented them pur- in allexisting contracts under the Postsuing this idea to a successful conclusion; Office-that only British -made apparatusbut itis a development that is nowadays The FederationofBritishIndustrieswill be utilised in its expansion. quite practicable. has had underconsiderationforsome time the scheme for wireless broadcasting Wireless receivers in newspaper offices recentlyoutlinedbythePostmaster - In thewirelessstationat Lyons two General. are not of much value, says a correspondent of the Newspaper World, the troublesystems of receiving high-speed messages being theconflicting electricalcurrentsare to be employed. -One is the method Wireless telephony has been establishedcaused by the presence of electric motors.of making a photographic record on a strip in The British West Indies between theWhen the mechanical work of the office is ofsensitisedpaper,andintheothgr Turks and Caicos Islands.Grand Turk finishedforthe dayexcellent wirelessmethod the message is taken on a special is now connected up with South Caicosresults can be obtained, but of course thathigh-speed gramophone.After the mes- and Salt Cay, distant twelve and eightis not when they are wanted. sage has been recorded on the disc the miles respectively. latter is placed in a machine running at much lower speed, and can then be tran- At a meeting of Hastings Town Council scribed by an operator.The reversof The Postal Authorities in this countrya proposal for a wireless set to be installed this system, can also be used in transmit- have decided to follow the example of theon the front was considered.It was esti-ting messages at speeds up to 15o words Washington Conference held recently. A mated that the cost would be ,too toper minute. meetingofexperts Istobecalledin Z3oo.The mayor said that he thought it London to settlethe question of wave-would be a good advertisement for the The most famous wireless station in the lengths, limitation of power and controltown and they might be ableto makeworld has been closed.Poldhu has sent generally. money out of it.The motion that the setits last message, and M P D, the famous be installed was adopted. call sign that has been heard for close on According to reports there is a " space twenty years, is to he heard no more. of territory" in California inside of which The Englishwirelessconcertstrans- The historicalsideofwirelesstele- wirelesstelephonemessagesabsolutelymitted each Tuesday evening from Writtle,graphywilleverbeconcernedwith disappear.So far as wireless is concernedEssex, now take place at 8 P.M. BritishPoldhu, forit was thefirsthigh -power itisa region of eternal silence. Some summer -time,ona wave -lengthof400 wireless station to be built, and from there sortofinvisiblebarrierintheethermetre; not at 7 P.M. on a wave -length ofthe first wireless message was sent across seems to barricade the wireless waves. boo metres, as hitherto. Amateurs through- theAtlanticona2,000metres wave- out the country are invited to send reportslengthon December 12, tom,toSt. John's, Newfoundland. A system of " ringing up " a station hason their reception, with criticism of the individual items, to the Writtle station. It has been found that the station has been invented by a French engineer.It several disadvantages, chief among them consists of sending a certain number of being its inaccessibility and the necessity signals in proper sequence (which actuate A special type of gramophone has beenof having long telegraphic lines over the relaysinthereceivingstation,these developedforproducingmusictobemost exposed parts of the Cornish coast. relays being such that they only respondbroadcasted.The tone chamber is larger The future uses of the station, it is ex- tosignals of correctsequenceandthan that of the ordinary gramophone, andpected, will be for experimental purposes, intervals. is supported on three posts which rest onthough this has not been definitely decided a sound box similar to the body of aup to the present.Its work is to be taken Messrs. Walturdaw have securedthe guitar.Itis claimed that this machineup by Clifden(onthewestcoastof rights of installing the " Marconiphone " is not only louder than the regular gramo-Ireland) with its call letters of M F T. emateur Wire145 76 JULY I, 1922 r nmnrrirmaranninnnaronornmernrrontorronnonarnmmtnncnnrinn======nmminnmf3

OUR INFORMATION BUREAU 1:1 Expert Replies to Readers' Questions. All Readers in Difficulty should Avail Themselves of This Free Service. Replies sent by Post when Stamped and Addressed Envelopes Accompany Queries LOUCCIZIGICLUIZLI21:2=0Q0:1;11ZIQGIOQUOGIGIUGIQUQ=CLIGLIQGC,Q00:7=UpZinQOUQGGICIGIGIQUCQUGUIZIQUZZQUGUuQUGIOClil Q.-I desire to know how to wire a single o The four large American C.W: stations- valve, L.P. amplifying panel so that it can Tuckerton (W G G), New Brunswick be usedinconjunction with an existing QUERIES ! detector panel of usual design without addi- (W I I),Annapolis(N S S),and Long tional batteries.-R.H. (II) SPECIAL ANNOUNCEMENT OF AN Island (W 0 K)-can nearly always be A.-The accompanying diagram shows a EXPEDITED SERVICE read at night under favourable conditions. suitablecircuitarrangement forthe L.F. ALWAYS mindful of our obligations to our Tuckerton comes in strongest, and on amplifyingpanel.T representsastep-up querists (and .we hope that every reader will oc- oneoccasion when they were working iron -core transformer (of the type known as casionally become a querist), we havemade special arrangements with a view to the improvement of Rome I read them for half an hour with- intervalve transformers), having its primary our Information Bureau, and we are now able to windingconnectedtothetwo terminals announce that, dating from the publication of this out interruption. marked " input " and shunted by a small issue, the bulk of toe queries that reach us will be answered on the day of their receipt.Putting it I was once able to receive New Bruns- fixed condenser having a capacity of,say, more definitely, our special aim will be this : In wick after P 0 Z (with whom they were .002 mfd.Ifthe detector panelitselfis the case of queries that reach us by the first post already provided with a telephone condenser, each day we shall do our best to send out expert working) had asked them to send v's be- replies by the evening of the same day.We this.002 mfd. condenser may be omitted. know that readers will greatly appreciate this cause they were receiving them badly. The " input " terminals are to be connected improved service, but its success will largely The Dutch concerts are clearly audible, depend on them.Let them write their queries as to the telephone terminals of the detector briefly as possible consistent with supplying all and on the new 400 -metre amateur wave- panel.When theamplifyingpanelisin the details required by our experts ;let their length telephony from at least six of the operation, the telephones (preferably having writing be plain and easily read ; let the questions a resistance, of say, 4,000 ohms) are to be be written on one side of the paper only ;and London amateur stations can be heard. connected to the two terminals marked " out- let a stamped and addressed envelope for the The valve I use is of the "soft" variety, put," across which it will be noticed there is replaccompany each quer . and in my opinion is equal to two of the another small fixed condenser of similar or0 0 hard R-type.-F. D. C. (Cambridge).

CORRESPONDENCE CLUB DOINGS Freak Results Wireless Society of Highgate (Affiliated with the Wireless Society of London). SIR,-I consider F. H. M.'s results, asHon. Sec.-MR. D. H. BADE, " Gatra," t3A, relatedin "AmateurWireless" forSedgemere Avente, East Finchley, N.2. 0 June 17, very good.Perhaps a few ofTHE second of the series of elementary lec- my own experiences may be of interest. tures on wireless was given at the Highgate Using a wire -bed mattress rolled up inLiterary and Scientific Institution on Friday evening, June i6th, by Mr. J. Stanley, B.Sc., a corner and a good crystal,I have noA.C.G.I., to an audience which again com- difficulty at night in copying many 600 -prised a Iarge number of visitors, including metre stations.At times even St. Marksseveral ladies. LT HT de la Mer, F F S(Marseilles), comes in Mr. Stanley went briefly over the theory of quite readable. the ether, showing that it possesses the pro- BATTERIES perties essential for wave motion -elasticity My outside aerial is a 4o -ft. twin aboutand inertia-and then took his hearers care- Diagram of Connections for Low -frequency 28 ft.high.On this, using the crystal,fully over the important subject of wave - Amplifying Valve. Madrid (E G C), Petrograd (P T G), andmotion generally, showing exactly what is Posen (P S 0) are readable.Six hundred-meant by wave -length and frequency.He slightly smaller capacity to that across the metre traffic comes in extremely well; allillustrated his remarks by analogies derived inputterminals. Rrepresentstheusual from the action of water waves, and led up filament rheostat and c and A the grid andthe British shore stations can be heard,to the fundamental equation forall wave anodesocketsrespectivelyofthevalve - nearly all of the French, Norwegian andmotion, that is, velocity = frequency x wave- holder.In order to permit the use of commonDanish, ,most of the German, Spanish, andlength.He then took up the 'question of L.T. and H.T. batteries it is necessary thatone or two Italian .stations.The longeroscillating current, showing how oscillations the telephone terminals of the detecting panel could be produced by the discharge of a con- are between the positive of the H.T. batteryranges are,of course, only obtained, atdenser through a circuit containing induct- and the anode.As many detecting panelsnight. ance, and how trains of oscillatory discharges are wired up with the telephone terminals There is no need to possess a valvecould be produced by the inclusion of a spark on the negative side of the H.T. battery, theamplifier toget stations on one's body.gap in such a circuit.The lecturer followed present panel should be examined and the by showing what was meant by the " imped- connections modified if found necessary. TheBy disconnecting the aerial and applyingance " of a circuit, and gave the formula for alteration in question will not interfere witha wet finger tothe aerial terminal F Lthis quality, and went on to point out how it the subsequent use of the detecting panelcan be heard.With the crystalthesefollowed from this that the wave -length of a alone if desired.-CAPACITY. "freaks" are, of course, -much more pro-circuit was dependent upon the inductance and Ovvvw-sa-wvneve nounced during the hours ofdarkness,capacity in that circuit. Finally he showed how, by application of People who are partly deaf can in someresults at times being scarcely believable.oscillating currents to open radiating circuits, cases use the telephone with ease.Wire--H. G. S. (-Wakefield). suchasordinarywirelessaerials,electro- less telephony is bringing a new hope to magnetic waves were set up in the ether and SIR,-Having read withmuch interestsent out into space.In conclusion, he showed the deaf.A caseismentioned inthethe letter of F. H. M. (Bexhill -on -Sea) inhow the different forms of aerials affected the Medical Press and Circular by Dr. Danthe issue for the 17th ult.I think thatshape of the waves produced and the direc- M'Kenzie of a man to whom the ordinarysome of my reception results might be oftional properties of the aerials.Mr. Stanley's electrical hearing aids were useless butinterest, though I should hardly call themremarks were illustrated throughout by excellent diagrams thrown on the screen, and who by wireless can hear the Dutch con- freak results.For some months past Ithis added considerably to the interest and certs more plainly than can an ordinaryhave been using a single -valve circuit onclearness of the lecture. person, the regulation double -wire aerial. (Continued on page 78.)

- JULY I, 1922 77 entateur WAS

RADIO TELEGRAPHY & TELEPHONY ALL YOUR REQUIREMENTS SUPPLIED FROM STOCK.

PULLEY BLOCKS,best galvanised, as illustrated, 2,1 post free. SPREADERS,finest stout ash, free from cracks, 6' x diam., 3/ - each.Carriage 6d. extra. AERIAL WIRES,best quality only supplied.Phosphor Bronze -7/2o, 18,'-;7:22, 13,/6;7/25, 7/,Copper -7/2o, 15/-; 7/22, 11/6; 7/25, All per xso' coil. SHELL INSULATORS. Green Porcelain, as illustrated,square, size weight "A," 4 ozs.Price 1/8 each.Size "B," 3" square, weight 6 ozs.Price 2/2 each. EGG INSULATORS. As illustrated, sizeti"x x ".Green porcelain.Price 9d. each.Postage extra. REEL INSULATORS. As illustrated,g"diam.,whiteporcelain,perdozen,2/3,postfree. H. T. BATTERY. 36 volt unit with tapping key 6 volts.Supplied complete with two plugs, 7/6.Postage extra.

LEAD-IN INSULATORS,as illustrated, 9" long, ; x a" long, 3/3.Postage 4d. extra.

32PAGE ILLUSTRATED CATALOGUE. 7d. Post Free. (Dept. 9), 236 HIGH HOLBORN, LONDON, W.C.1. RADIO SUPPLIES 'Phone-Museum 6894.

111 111=1111 1111111111 111111111111 11111111111 1111111111 MIMEO 11111111 ENE= =MR 11111111111 ELECTRADIX RADIOS. Marconi Trench Receivers (crystal), variable Condenser Inductance, Reactance, etc., £3 10/. each. Aerial Insulators, R.A.F., ebonite brass ring, 6d. each. Aerial Wire, 7/22 stranded H.D. copper, 71- per zoo ft. Aerial Pulleys.Duralumin with brass bushed wheel, Navy type ;small, 216; medium, 3/- ;large, 3/6 each. 1111111111111111111 111111111111111111 Aerial Lead-in Wire, rubber covered, 35/40, zz yards, if.. Earth Clips, 6d. each. Earth Spikes, 1/- each. Double 'Phone Cords, new, 316. Used.1/6 Earth Mats, 10/- each Plugs, sockets and cords of all kinds, solo Switches, A-E, 2/9 each. 1) 3 pair, ; twin, 1/6 ; 4 -way, H.T. Battery Boxes, polished mahog. Terminals, 3/- dozen. 6 plug sockets, 7'-. Condensers,2 M.F.,2/- ;4 M.F., 5/- ; Lightning Arresters, 2/6 each. Vernier for (panels, 4/9, 10/- and 11/6 Dewar Switches, for panel, 3/6. each.'ma Cabinet, 32/6. Fine Rheo- Wireless Head 'Phone Sets, Ex .W.D. stats for panels.Highest grade, 7'3; L.R., 10/- per pair,with!head,band and with Vernier extra lever, 8/ - cord. Single receivers L.R.. 4 6. New Receiver Amplifiers (Mk. z B)2valve delivery Marconi -Brown head phones Amplifiers,quite newguaranteed 51/- pair,2,0000 or4,000 ohms. £7 10/. Field Telephone Portable Sets, ex -Army, with roo yards insulated w:re and earth pikes, 27/6 per station or 50/- per pair. INSIST ON HAVING A Handiest Depot for City Buyerab LESLIE DIXON & Co., 9, Colonial Avenue, Minories, E.1 (Nr. Aldgate station). I FULLER"BLOCK"TYPE Wireless is attracting all men,The Amateur is entering ACCUMULATOR the field in great numbers, and he wants to know all FOR YOUR WIRELESS SET ! about it.He will require Materials, Parts, Tools,He The only Accumulator on the market that will hold its charge from 12 will also want to sell surplus material. to 18 months when not in use 4 -volt 40 amp, hours, £1 126, plus 1/3 carriage

6 -volt 40 £2 89, 1/6 " AMATEUR WIRELESS " Note :--These prices are 331% below those of the actual makers. is out to cater for this class of reader, who will be eager for knowledge and bargains,To meet him, use the Sale 8,000 Sold. 20,000 still in stock. and Exchange colums, which he is sure to search. Rate Descriptive and Instructive Pamphlet on request front- 3d. per word,3s. minimum, prepaid, Latest date The CITY ACCUMULATOR Co. (Dept. 14) Saturday mornings. 79 Mark Lane, E.C.3 (A7,19,M1;1) Address : ALSO SUPPLIED EY- The Advertisement Manager, Selfridge & Co., Ltd., Wireless Section ; A. W. Carnage, Ltd., "Amateur Wireless," Wireless Dept. ;Barnsley British Co-operative Society, La Belle Sauvage, Radio Section; Richford and Co., 153,Fleet Street, E.C.3. Ludgate Hill, London, 5.0.4. AGENTS WANTED IN ALL PARTS. emattur Wireless 78 JULY I, 1922

CLUB DOINGS (CO/1E0MM from page 76) Crosby, Waterloo and District The Hon. Sec. will be pleased to hear from Wireless Society COMPETITIONS FOR anyone interested.The Society has made arrangements to receive the Marconi concertHon. Sec.-S. FRITH,6, Cambridge Road, ALL READERS at the Highgate Literary and Scientific In-Crosby, Liverpool. stitution on Tuesdays at 8 P.M. during July,THE association'invites application for mem-THREE WIRELESS RECEIVING and anyone interested will be welcome onbership. SETS AS PRIZES these occasions. Stoke-on.Trent Wireless and Closing Date, Friday, July 7th Bradford Wireless Society Experimental Society WE offer as a prize in each of the - (Affiliated with Wireless Society of London).(Affiliated with the Wireless Society of London). following competitions a well -made Hon. Sec.-Ma. J. BEVER, 85, Emnt Lane,lion. Sec.-F. S. DINEs, 36o, Cobridge Road, wirelessreceivingset manufactured by Heaton, Bradford. Hanley. ON Thursday, June 15th, Mr. J. Gaskell gave oneorotherofouradvertisers,the A MEETING was held in the clubroom, atalectureand demonstrationonX-rays.approximate value of each set to be at, 7.45 P.M., on Friday, June 16th, when Mr. J.Questions were asked and answered regardingleast seven guineas. Bever gave his lecture on " General Wirelessthe relation of X-ray waves to wireless waves, Matters."This consisted in the main of a Rules.-The Editor'sdecisioninany description of his own four -valve set.Duringand comment was made upon the similarity the course of his remarks Mr. Bever madeof X-ray tubes and the thermionic tube. and every caseisfinal. Thereisno A corresponding section for members unableappeal from it.The copyright of all com- several references to the increasing number ofto attend the ordinary meetings has been people using valve sets, who not having theformed. petition efforts published by us will be necessary knowludge to operate them, cause ours. Allentriesto be in by Friday, interference by allowing their apparatus to The Leicester Radio and Scientific July 7, and to be addressed to oscillate unnecessarily.Mr. Bever's set was Society on view and was connected to the Society's (Affiliated With the Wireless Society of London). THE EDITOR, aerial.Excellent signals were obtained on "Amateur 'Wireless," short wave, including telephony from a localHon. Sec.-J. R. CRAWLEY, 269, Mere Road, station.The signalswereeasilyreadableLeicester. La Belle Sauvage, with the telephones lying on the table. THE monthly meeting of the society took place London, E.C.4. on Monday, June19th,atheadquarters. Sheffield and District Wireless The lecturer for the evening was the president Competition No.I. -A wirelesssetis Society of the Society, Mr. Cyril T. Atkinson, and theoffered for the best article of about 1,5oo CHANGE OF ADDRESS subject " Short-wave Reception." Mr. Atkin-words, written from your own personal son first of all pointed out the reasons for theknowledge and experience, and calculated ON and after June 23rd, 1922, the address ofspecial measures necessary for receiving short the Hon. Sec. will be :18, Linden Avenue,ether waves of below 30o metres, and thento help or interest your fellow amateurs. Woodseats, Sheffield. described step by step the various classes ofIllustrationswillin most cases bere- Hon. Ser.-LEONARD H. CaciwTHEE. gear and methods of construction.The lec-garded as a featureofmerit.Articles ture was illustrated by a number of pieces ofshould be written in simple language and PREPAID ADVERTISEMENTS. apparatus of the lecturer's own construction.be as bright and informative as possible, Wireless Apparatus-Complete or parts.Consulta- The Wallasey Wireless and and the subject may be anything that you tions.-Coy, 6, Cambridge Road, Crosby, Liverpool. [2 S Experimental Society think wireless amateurs would careto MorseCode.-Easilylearnedwiththe" Little (Affiliated to Wireless Society of London). read about. Should we publish any article Brick "(Prov.Pat.No.13,846)which sends messages and speed.Price complete, 6s.Full particu- Hon. Sec.-C. D. M. HAMII,TON, 24, Vaughanthat does not win the prize we shall pay lars,stampedenvelope. Obtainableonlyfrom Road, Wallasey. Grimshaw(Dept.A.W'.),LeghStreet,Golborne, for it. Lancs. 13 s AT the meeting of -the society held on Thursday, CompetitionNo.2. - Anothersetis MonthlyCompetition,Free. -4o -ft.aerialmast. June 15th, Mr S. J. Martin gave a most in- Particularsandlist,2d.-F.Armstrong,Wireless teresting lecture onthe " Theory and Con-offered for a brief description (with illus- Mast Works, Weybridge. [3 1 ZinciteBornitosupersensitivecrystals. Tested. struction of Simple Valve Sets.', tration if necessary).of the most novel and ,s.8d.per pair.-Wallace,113,St.James' Road, useful item in wireless apparatus-in its Tooting. [4 s Wireless.-Completesets. orspare parts. Every- design, material, make, electrical connec- thing the amateur needs.State your requirements. tions,etc.etc. The novelty must be Advice .free.-Davies, 73, Dale St., Liverpool. 15 s FORTHCOMING EVENTS Wireless.-Make your own apparatus;,8 connec- WirelessSociety of HullandDistrict.original-notcopiedfromanysource tiondiagrams. OS. 6d.-Edwards,38,Chancery Lane, W.C.2. [I r Julyso,7.30 p.m.Annual meeting forthe whatever. electionofofficers. Aftertheconclusionof Competition No. 3.-The third receiving the business therestofthe evening willbe S.W.C.ENAMELLED COPPER devoted to questions and answers. set will be presented for an ideal broad- No. 47 WI WirelessSocietyofHighgate. June3o, casting programme of twelve items.You From stock while it lasts, 40/- per lb., bobbins and post. 7.45p.m. Atthe age free.Cash with order.Reductions fos quantities. HighgateLiteraryand can enter for this competition on a penny J.JENKINS, 3, CLOAK LANE, E.C.4. Scientific Institution.Lecture (part III) by Mr. postcard.Simply write down in column J.Stanley :" Elementary Theory of Wireless form twelve items that you consider would TO WIRELESS EXPERIMENTERS. PATENT YOUR Telegraphy and Telephony." INVENTIONS. NewcastleandDistrictAmateurWireless make an ideal programme. They may prove very'valuable.Particulars and consulta. Association.July 3, 7.30 p.m.Annual general tints free.BROWNE & CO,Patent Agents, 9, Warwick Court, meeting for election of president and officers. Holborn, London, W.C.r.Est. 1830.Tel. Chancery 7947. Ilkley and District Wireless Society.July 4, When Will You 7.30 p.m.At the Regent Café, Con -pasture Road.Lecture and demonstration on short- UR CLASS ROTARY VARIABLE CONDENSERS. wave telephony reception. Send Your Effort ? ',.00s in Polished Cabinet, 4' X 4" X 4', Ebonite Top and Knob, Ivorine sc, o." -18o*, 16'8 Leeds and District Amateur Wireless Society. Ditto for Panel (scale extra) ...... 10/6July 8.Field day. '0004 inCylindricalBrassCase, Lacquer finish, Ebonite Top and Knob, Ivorine scale ; a very O a ANNOUNCEMENTS

handsome instrument ... .. 161 - Vanes, z/-; Spacers, 6d. doz. ; Ivorine Sale, 0°.1.80°, 1/6, post Catalogue of Wireless Apparatus and Parts. "Amateur Wireless andElectrics." Edited by free.Ebonite Knobs, 7d. each. Bernard E. Jones.Price Threepence.Published on WEATHERALL & Co., 28. Woodbridge Street, -The Economic Electric Limited, 303, EustonThursdays and bearing the date of Saturday imme- Clerkenvrell, London, E,C. Estab. over 20 3 ears. Road, London, N.W.r, has just issued a new diately following.Itwill be sent post free to any catalogue devoted entirely to wireless appara- partofthe world -3 months,4s.6d. ;6months, AERIAL WIRE,7 Strand22Gauge, 4'6 100ft. Ss.9d.;s2 months,17s.6d. Postal Orders, Post Leading -in Wire, high tension, heavily rubbered, 6d yd. tus and parts.The catalogue will provide aOffice Orders, or Cheques should be made payable Porcelain Insulators, Ring Type, a° diameter, 6d. each. useful reference for all those who are con-to the Proprietors, Cassell & Co. Ltd. Brass Rod, tsquare, /3" lengths ready drilled, 3d. each, structing apparatus, in addition to those who General Correspondence is to be brief and written on one sideof the paper only.All sketches and Contact Studs, large or small, with nuts & washers, 1./4 doz. are interested in complete sets, for every partdrawings to be on separate sheets. Condenser Parts and all Wireless Apparatus and and material used in wireless work is listed. Contributions are always welcome, will be promptly Sundries in Stock. In addition, the catalogue contains a. series of considered, and if used will be paid for. crystal and valve receiving circuit diagrams, Communications should be addressed, according to theirnature,toTheEditor,The Advertisement ATKINSON & HOOK and some general information on mattersManager or The Publisher, "Amateur Wireless," WIRELESS FACTORS, 25, Hamilton Road, WIMBLEDON. wireless. La Belie Sauvage, London, E.C.4. JULY 1,1922 79 emo tour Wireiess

sim IIIIII MI

.w ACCUMULATORS FOR WIRELESS 11111 In. ime 4 v.40 amp....18/6 6 v.40 amp. ...26/3 CQ Std bi 4 v.60 ...21/6 6 v.60 31/9 4 v.80 ...28/2 6 v.80 ...37/3 for ERICSSON PHONES 4v. 100 30/- 6 v. 100 41/6 SPEC IALS -2 volt 16 amp.Ebonite cases. -1 only, 3/9 post wHEN you instal your wireless set free. 2 or 3, 3/6 each, post free. 4 to 6, 3/ - -crystal or valve-you'll get each, carriage forward. maximum resultsifyoufitEricsson 4 volt 24 amp. in celluloid cases, absolutely new- Phones-clarity, sensitivity, strength of Postage 11, signals and absenceof " Specially only 11/9 each. suited to telephony. WE CAN SUPPLY THE HIGHEST QUALITY GUARANTEED Ericsson Phonesembodytheaccumulated ACCUMULATORS AT THE LOWEST POSSIBLE PRICES experienceoftelephone manufacture fora lee, CHURCH ST generation. KENDONG,NSIN, ' Easy to the head, light and comfortable.The F. YATES & SON, LO W.8TON. magnets never lose their strength and "shorts'! 'PhonePark 4276Write for lists, (One minute from Notting are non-existent. enclosing stamp to cover postage. Hill Gate Station). Write for Particulars TheBRITISH L.M.ERICSSON MANUFACTURING Co., Ltd. WHY NOT CONSTRUCT YOUR OWN SETS ? Head Office : 6o, Lincoln's Inn Fields, E.G.2 We can supply from Stock. A.E.C. and Telefunken Valves... 1'16 Crystals (Special Selected), Bor- Aerials, Stranded 7/o5 .0' ... 4/6 nite, Galena, Silicon, etc. ...6d. Egg Insulators (high insulation) 9d. Fusible Alloy (for fixing Crystals) ed.

Reel best quality... 4d. Inductance_ Tubes,sz in. x 3 in. ed. Filament Resistances, Flat ...1/6 12in. x 4 in. 9d. Lead -in -Insulators, Ebonite ... 2,6 Sq. Brass Red, (2 xx 9d. Ebonite Knobs, Drilled... Td. Enamelled Wire, .3gauge, lb....1/6 Switch Arms, Laminated 2/6 Sliders, Ebonite, with Plunger 1/- Condenser Vanes,Aluminium A to E Switches on Porcelain ... 2,9 (accurate size and gauge), per doz.1/6 Valve Holders(new improved type)1/9 Condenser Scales, Ivorine, 0/180°1/ - Detectors, Complete (2 Crystal) 8; - Transmitters with Cords... 51 - Studs with Two Nuts,per doz. 1:6 PANELS, TUNERS, HEADPHONES, etc. Postage extra. THE 499, GROVE GREEN RD., ESSEX WIRELESS CO., LEYTONSTONE, E.11. Telephones Telephone-- WANSTEAD 749. 0 min. from Station, G.E.R.) I IH He is Si 11111 le ER II IIel ga egg 'haphazard purchases till you have DON'T MAKE sent for our CATALOGUE of WIRELESS RADIO, ELECTRICAL & MECHANICAL SUPPLIES. INSTRUMENTS, Makeyour ownplant SCIENTIFIC SUPPLY STORES ACCESSORIES 1,11' 3. NEWINGTON CAUSEWAY, . and . 114.111 ottfittitokt, i i

LONDON, SE I'. MATERIALS s4J _ 44... f We st:ek everything for the Experimenter who wishes to build his own Set. ,t..'s;>°=j,.A.--...1 ,. = 111111 11:1111111r, '- 1.1 Z°;,a, ,.. 1[1.1 ',V Cid' FOR TOOL BARGAINS i." CALL or WRITE TO -DAY to ; .., Before buying elsewhere compare our prices. Remember, we have the Largest Stock of Tools to select from in London. We guarantee you satisfaction, so you can safely shop by post. Bargain List sent post Free. --for the construction and repair of DiPT. L W, 255-6,HICK HOLBORN, Electrical Installations, GEORGE ADAMS LONDON,W.C.L you cannot do better than use the tool SCIENTIFIC APPLIANCES that was designed for all such work, HENRY .1. DALE. W. HOLLINS. 11 0 29, Sicilian Avenue, Southampton Row, London, W.C.1, Me DRUMMOND 31 in. Top of Kingsway. In Centre of London. Corner of Bloomsbury Square. Screwcutting and Boring Lathe ELECTRICIANS. OPTICIANS.MECHANICIANS. Let us tell you about it.Send a card, or ACTUAL MANUFACTURERS at our Works, East Street, W.C., thus saving all intermediate profits. Post this coupon for id. (printed rate) The Store for all Electrical and Scientific Material WIRELESS &RADIO MATERIALS, VALVES. 'PHONES. PARTS and FITTINGS Call and see us. View our Show To DRUMMOND BROS. Ltd., Englewood Works, Guildford. Windows. Send for List post free 2d. Immense Stock constantly adding to, and Please send me full details of your 2 in., 4 in., and 3) In. lathes, Making ;Speolallyfor theAmateur to together with details of deferred payment system. Build up a Set Complete and Perfect. Splendid Value in EBONITE. BATTERIES. AERIALS. Second-hand Appliances Name INSULATED WIRES. CRYSTALS. ENGRAVED DISCS. MICA. HANDLES. Every Branch of Optical Address SWITCHES. TERMINALS. STUDS. and Applied Science Scientific Appliances, 11 & 29, Sicilian Avenue, London, W.C.1. (Imatzur Witness 80 JULY 1, 1922

All Wireless Amateurs should order a copy of this book To -day Absolutely Up -to -Date Wireless Telegraphy and Telephony And How to Make the Apparatus An Entirely New Work By E. Redpath NOTE ITS CONTENTS :

General Principles; Experiments ;Tuning and Resonance ;Transmission and Reception; Various Detectors ;Thermionic Valves as Detectors, Amplifiers and Generators ;Making Single -circuitReceiving Set, Short-wave Receiving Set, Valve Panel and a Five -valve Amplifier ;Wireless Telephony ;Arrangement and Erection of Aerials ;Index. 87 Illustrations I s. 6d. Net 'faille House of Cassell LA BELLE SAUVAGE, LONDON,E.C.4.

The Famous "WORK" Handbooks

Each 160 Pages. 1/6 net each ; .1/8 post free.

Basket Making. With 151 Illustrations. Electric Primary Batteries.With 91 Illustrations. Pianos: Their Construction, Tuning, and Repair. BeehivesandBeekeepers'Appliances. With 155 Electro-plating.With 77 Illustrations. With 74 Illustrations. Illustrations. Fishing Rods and Tackle.With 199 Illustrations. Poultry Houses and Appliances.With 226 Illus- Bent Iron Work.Including ELEMENTARY ART METAL trations. WORK. With 269 Illustrations. Furniture Repairing.With 178 Illustrations. Pumps and Hydraulic Rams. With 171 Illustrations. Bookbinding. With 125 Illustrations. Gilding,Silvering andBronzing. With 27Illus- trations. Rustic Carpentry. With 194 Illustrations. Boot Making and Mending. Including REPAIRING, Sewing Machines: Their Construction, Adjustment, LASTING, and FINISHING.With 179 Illustrations. Glass Writing, Embossing and Fascia Work.With 129 Illustrations. and Repair.With 177 Illustrations. Building Model Boats.With 168 Illustrations. Soldering,Brazing and Welding. With 78Illus- Camera Making. With 245 Illustrations. Gramophones and Phonographs. With 103Illus- trations. trations. Clay Modelling and Plaster Casting.With 153 Illus- Household Repairs. Tailoring: How to Make and Mend Trousers, Vests, trations. With many Illustrations. and Coats.With 1S4 Illustrations. With 97 Illus-House Painting and Decorating.With 74illus- ClockCleaningandRepairing. trations. Taxidermy: Skinning, Mounting and Stuffing Birds, trations. Mammals, and Fish.With 100 Illustrations. Incubators and Chicken Rearers. With 124 Conjuring Apparatus.With 167 Illustrations. Illustrations. The Handyman's 1,000 Practical Receipts. Adjusting. With 79Illus- CycleRepairingand Induction Coils.With 82 Illustrations. Ticket -writing and Sign -painting. With 154 IL us-' trations. trations. Domestic Jobbing. With 157 Illustrations. Knotting and Splicing Ropes and Cordage.With 203 Illustrations. Tinplate Work. With 280 Illustrations. Dynamo andElectric -motorBuilding. With145 Toy Making. With 237 Illustrations. Illustrations. Lathes, Small.With 314 Illustrations. Magneto Repair and Adjustment. With 104 Illus- Watch Cleaning andRepairing. With 73Illus- Dynamo and MotorErectionand Management. trations. With 98 Illustrations. trations. Miniature Electric Light. Wireless Telegraphy and Telephony.With 100 MUs- Dynamos,Small. MAKING SMALL DYNAMOS AND With 141 Illustrations. trations. MOTORS. With 132 Illustrations. Model Aeroplanes.With 190 Illustrations. Wood Finishing.Comprising STAINING, VARNISHING, Electric Accumulators. With 57 Illustrations. Motor Cycles and Side -Cars.Wits 70 Illustrations. and POLISHING.With 12 Illustrations. With 134 Illustrations. Mounting and Framing Pictures. Electric Apparatus, Small. With 240 Illus. Workshop Appliances,Small. BUILDINGMACZNEs ElectricBellsandTelephones. With 144 Illus- Orations. AND APPLIANCES USED IN WOODWORKING AND METAL- trations. Oxy-acetylene Welding. With 43 Illustrations. WORKING. With 232 Illustrations. Electric Clocks.PRINCIPLES. CONSTRUCTION IND WORK- Patents, Designs and Trade Marks. Workshop Arithmetic. ING.With 213 Illustrations. Photography Simplified.With Frontispiece and 63 Workshop Hints for Metal Workers. With numer. Electric Lighting. With 65 Illustrations. Illustrations. ous Illustrations.

THE HOUSE OF CASSELL, LA BELLE SAUVAGE, LONDON, E.C.4

Printed and Published in England by CASSELL & COMPANY, LIMITED, Ludgate Hill, London, E.C.4. Sole Agent for South Africa, CENTRAL NEWS AGENCY, LIMITED. Saturday, July t,1922. 8 MAKE YOUR OWN ONE -VALVE SET (See pages 90 and 91)

Ind Electrics

No. 5 SATURL eiY, JULY 8, 1922 Price 3d

CHIEF FULLY CONTENTS ILLUSTRATED 1,1 \KING THE" WAVEVISIBLE (See p. 89)

Page Pag© WIRELESS AND TANKS . 83A SINGLE - VALVE RECEIVING THE " HON. SEC." : RUNNING A SET AND HOW TO MAKE IT . . . 90-92 WIRELESS CLUB . . 84 COIL MOUNTING SIMPLIFIED .84ELIMINATING THE AERIAL : " WIRED WIRELESS " . 93 TAPPING THE INDUCTANCE . 85 LIGHTNING PROTECTOR . . 93 WHAT WIRELESS TERMS MEAN 85 OUR INFORMATION BUREAU. 96 DRY CELLS AND THEIR WAYS 86 CONVERTING '7110NES . . 87 Radiograms, Correspondence, Club STARTING WIRELESS :THE Doings, Forthcoming Events, AERIAL AND EARTH .88 Three Prize Competitions. &akar 'Winless 82 JULY 8,1922

ECONOMIC LE CTRICLTD. (*M1TCHELFONES*1 I I Are not a spasmodic production to meet a sudden demand, but have been on the

If You Require market for over three months, and during NOTE this period 27,000 have been distributed Wireless 32 PACES AND to thetrade, and consequently we have OVER 200 not been able to offer them direct to the

ILLUSTRATIONS retail buyer. Apparatus INCLUDING 1000 per week are now available, and we announce

Send4d. CRYSTAL DELIVERY FROM STOCK To -dayforthe & VALVE RECEIVING You postyourorder,orcallatour " E.E.C." List CIRCUITS premises and get them at once.Think

OW' what this means to you-you, perhaps, who have been waiting and are stillwaiting. Standard resistance 4,000 ohms, double headgear with

WARNING ! double headstraps,comfortable,highlyefficient,

The wireless boom has been the signal for a number of in - and foolproof e x pe r enced andin some Instances, unscrupulous persons 351_ perpair.

to jump into the business. DEAL WITH A Special Terms to Traders and deliveries FIRM WHO KNOWS that will surprise you. " E.E.C." have26yearsElectrical MITCHELLS Electrical & Wireless Ltd., including:15 years Wireless Experience. Postal Address : McDermott Road, Peckham, S.E.15.

10, FITZROY NewShowrooms: Retail Address: 188. Rye Lane, Peckham, S.E.15. Head Office :

SQUARE, LONDON, Wi. 303, EUSTON ROAD, N.W.I. 'Phones: New Cross 1540/1641. Telephone : Branch Showrooms: MUSEUM 1055. TWICKENHAM. 1/430-GREAT BRITAIN'S GREATEST WIRELESS STORE-4)

r 1111111111111111111111111111

EQUIPMENT.IIIIIIIINIIIIIIIIIIIIIIIIit -FEDERAL JUNIOR AE EQUIPMENT I, 21/-:-moft. 7/22 AE EQUIPMENT II, 271-:-100ft. bare Copper Wire, a Reel Insulators, Earth 12/22 Enamelled Aerial Wire, a Shell Insu- - Clip, 4 yardsLead-in Wire, Aerial -earth lators, 4 yards Lead-in Wire, Earth Clip, CRYSTAL WIRELESS RECEIVERS Sweaddc.h, Lightning Arrester, Insulated Earth Aerial - earth Switch, Lightning Arrester, ILsulated Earth Lead. AE EQUIPMENT DELUXE,50/-:-200ft. 12./22 Enamelled Aerial Wire, a large Shell Insulators,8yards Lead-in Wite, large Earth Clip, superior Aerial -earth Switch, double Thousands of these instruments are in actual use length Insulated Earth Lead, Special Lightning Arrester.Carriage Paid. allover America to -day. G. D. HINKS, WIRELESS DEPT:, HARDINGTON, YEOVIL. 1111111118181111111111111111111811111111111111111 Write for lasts. (11111111011101111110111111101111111101011111 Complete withHighResistance Head- phones and Aerial Wire f Price £6 6s. TELEPHONE DOUBLE HEAD SETS. Suitableystalvaleor DELIVERY AT ONCE 2,000 Ohms, 3216 ;4,000 Ohms, 34/6.In stock. ONLY A LIMITED QUANTITY up your own receiving sets.Our price for compleie set of parts MAKE£1 le. carriage paid, comprising wound inductance with ebonite panel drilled for 20 studs, necessary studs, ebonite knobs, etc., crystal detector, HENRY J. BREWSTER & CO. terminals, wire for connecting.(No extrasto buy ;nothingtomake.) 11, QUEEN VICTORIA STREET, Stamp for List. LONDON, E.C.4 P. H. BOYS & CO., 187, Goswell Rd., London, E.C.1

THE WIRELESS CRYSTAL OF TO -DAYAND THEFUTURE The "HERTZITE " NEWTONIAN WIRELESS FACTORY SIMPLE TO .USE. NO BATTERY REQUIRED Price 2/6 post free for UNSOLICITEDTESTIMONIAL: any parts to make The piece of "FIertzits "'sent some time ago he.s given splendid results.Thin evening I heard hlozambique1,260 miles from Johannesburg) on C. PLEASS, Johannesburg up your own sets We can give you the best Wholesale Terms for all Crystals GOOD VALUE AND COMPETITIVE PRiCES " ORA " VALVES, 151- post free The Trade Supplied RUSSELL - SHAW 13-15, WHITCOMB ST., LONDON, S.W.2. 38, Great James Street, Bedford Row, W.C.1 Telephone: REGENT 643. (From Holborn through Broumlow Street, or Hand Court) 83

Etectrics No. 5 July 8, 19 22 WIRELESS AND TANKS ONE of the greatest problems of theTransmitter. tors to the other, and for cutting out the war was to find -a reliable means of At this time continuous -wave or valvecurrant from the dynamo. There was also communication between the front lines andtransmitters were not very efficient, andanautomaticmercurv-cupcut-out,but the rear during an attack, and until thewere found to be useless for tank work.owing to the rolling of the tank this was advent of the wireless tank in early 1917The Wilson transmitter was used, whichnever satisfactory, and itwas necessary it was usually quite impossible to tell howhas a high spark -frequency and emits afor one of the operators to keep one hand an attack was progressing until after thehigh, musical note.The make and breakon the dynamo switch and an eye on the inevitablecounter-attackhadquietenedof 36,000 per minute was driven by a smallvoltmeter. Itwasneverpossibleto down. With the ever-increasing numbermotor running at about 4,000 revolutionscharge for more than a few minutes at a of British offensives from early 1917 on-per minute.The normal input ofthistime,because,. thetankwas_ constantly wards it became essential that headquar-transmitter, using 30 volts, was about isostopping and starting, speeding up and tersshould know immediately of everywatts, but it was often necessary to trans-slowing down. 'Each time -the speed was fresh development in the attack in ordermit straight from the 8o -volt dynamo, andreduced, and the needle of the voltmeter to make preparations for further advancesthe input in this case was 400 watts.Thiscame near the safe charging point, the or to repel counter-attacks.It was this So -voltdynamo,drivenoff thetankdynamo switch had to be opened and then need for reliable information which ledengine, was normally used for chargingclosed again as soon as speed increased. the authorities to instruct Captain The result of this was that the accumula- ',W. R. H. Tingey to make experiments to tors .were never properly charged, and it ascertain if it was possible to employ tanks often became necessary to run the trans- as Wireless station carriers. mitter straight off the .dynamo NyiAll the There wee many difficulties in the way riskof burning outthesparkcoilor oftheirsuccessfuluse,-amongst them puncturing the condensers. being the impossibility of using the high aerials which were _necessary with spark Work'ng Range. transmitters ;the large mass of metal sur- In spite of the large power employed, it roundingtheapparatusandinclose was notpossibletoexceedaboutten proximity to the aerial ;the difficulty of miles range owing to the smallness of the receiving wireless signals on account of aerial and absorption of the transmitted internal noises in the tank; the. supply of power by the tank itself.At that time Diagramshowing the Method ofEreefng the power to the transmitter; and the danger high -frequency amplificationhadnot that the sparks from the transmitter might Aerial on a Tank. come into use .in the army; the low -fre- ignite the petrol fumes. two sets of accumulators for the transmit-quency amplifier used on the first wireless Six tanks were fitted with wireless atter and two sets for the lighting of thetanks hindered, rather than helped, the the tank workshops in France in May,cabin and the electric fans. reception of the rather weak signals picked 1917. The cabin was rendered almost up on the small aerial of "t soundproof by making its walls of twoReceiver. thicknesses of wood four inches apart, the The receiver was a Mark 1 t 1 tuner withPortable Instela'Ions space between being filled with sawdustvalve attachment, with internal alterations These tanks did good work at Ypres in and other packing. A small door led intoto bring the wave -length up to goo metresJuly to September, 1917, but it was soon the interiorof the tank for direct com-and also to permit of reaction being used.found that the wireless apparatus became munication with theobservationofficer, A three -valve low -frequency amplifier wasuseless when the tank itself was put out who had a table and chair, together withused in conjunction with the tuner, andof action.The remedy was to make the maps, telegraph forms, etc. both amplifier and tuner were run off the wirelessapparatusportable,sothatit same high-tension battery. could be removed from the tank when Aerial Systems. necessary and installed in a handy du The aerial consisted of eight strands ofCharging. - out or under any available cover.Po insulated electric lighting cable, arranged Charging was a very difficult operation.able installations were made in wooden in sets of four on cross -shaped spreadersThe useful life of a tank engine is limited,cupboards, using the same apparatus as asshown in the illustration.It was aboutandit- wasthereforean uneconomicaldescribed above. A large supply of ready - 20ft.long, supported at the front by ascheme to run a150 -horse -power enginecharged accumulators were taken on board to -ft.steel masf which could be raised orfor several hours solely to drive an 8o -the tank before going up into action. Two lowered from inside the tank.The aerialvolt dynamo for charging accumulators,3o -ft. masts and several spare aerials were was let down to supports at the back andso the charging had to be done while thecarried, and these were erected when the thencetothe instruments by means oftank was moving up the line to go intotank had gained its objective.Naturally, heavily -insulated high-tension cable:Theaction. A large charging board was fittedthe masts were very conspicuous, and the earth used was the tank itself, which, ofin the wireless cabin, with switches forstation came in for a lot of shelling in course, did not make for efficiency.. changing over from one set of -accumula-consequence. enulteur W4115 84 JULY 8,1922 The usual procedure was for one opera-ing months.These C.W. sets simplifiedprivately thinks that next time it will be tor toput the messages into code andmattersvery much; not only was thecheaper to give a donation I another to send the messages and keep anapparatus much smaller-both the trans- Of course, in addition to all this, there eye on the aerial ammeter.When themitter .and receiver were confined in oneis the usual routine work, such as writing needle of the ammeter dropped to zero hebox 15 in. square by 6 in. deep-but thereup minutes, circularising members (some knew that the aerial had been shot away,was no necessity fora large supply ofjob !) and general correspondence. and operator number three had to attendaccumulators.Six or eight accumulators And yet the secretary seems to thrive on tothe repairsto the aerial under veryfor the valve filaments were sufficient.forit. The Sunday morning visitor is greeted great risk.The average life of an aerialan action lasting three days.These setswith a smile, and alter treatment is sent undertheseconditionswasabouttenemployed one valve for transmitting andaway with a " Come again as soon as you minutes, and the masts after a day's worktwo forreceiving, the receivingvalveslike." Lecturersstillcontinuetobe looked very weird in their splints madebeing low -frequency transformer -coupled.worried and cajoled, the wiring diagrams from barbed-wirestakesand telephoneThey were very efficient.Using 600 voltsstill get out, and the queries are answered, cable. high-tension, a range of nearly zoo miles andthatspeciallittlejobyouhave was obtained with a set which followed theassigned for to -night is cheerfully put on Valve Transmitters. German retirement after the armistice, theone side when a member brings his set In the following spring valve transmit-apparatus in this case being carried in awhich is on strike. were installed, continuous -wave work,light car attached to the Armoured Car It is little wonder that there is no com- having made great strides in the p/eced-Squadron. P. S. B. petition for the position of "hon. sec." ters, L. J. W. 7,...... _. t sticky tape and Chatterton's compound. i You start tracing connections, eventually i finding, say, the primary of the intervalve i Coil Mounting The transformer has ceased to function.Well, thenthe ff favourite stand-by transformer on.Sec you have been saving for a rainy day is Simplified! rooted out and screwed and soldered intoii.,..111.4..11.011.41....10.1.44, 11,411.4,11.011.4.4,11..1111.1.11 position, and the signals roll in.Perhaps a valve filament is touching the grid in THE sketches,Figs. r to4,show a WHATEVER competition there maythe aforesaid member's set.He brings his simple method of mounting coils of the be for positions on the committee ofpanel, but no valves, and the set works,basket type.An ordinary ebonite valve any wireless club or society, it is perhapsusing thesecretary's.Back home goesbolder is used as a support, this being not a very remarkable fact that there isthe member and still no results. fitted to the panel in the ordinary manner. never any great rush when nominations Then the requests for wiring diagrams The leads from each of the coils are are invited for the position of hon. sec.and the numbers of turns ; and " Why will Two years' experience in such a- positionnot a resistance amplifier work on short have revealed the reason.Consider whatwave -lengths?" and "Is the three -coil sys- is required of this (to himself) importanttem better than the two -coil ?"And so person. on, day after day and week after week. In the first place, a secretary of a wire- Then there are the lectures. How many less society must possess a full knowledge membersrealisetheworkbehindthe of everything appertaining to the scienceneatly printed little syllabus issued at the from " How many turns on a honeycombbeginning of a session, the difficulties to re primary " to " the wave -length and callfind men to fit dates and dates to fit men, signofHonolulu."Ifshaky on anywhen you must meet the second and fourth query put before him, he must have theWednesday ?Do they realise the corre- Fig. 2.-Mounting capacityof making hisquestionerfeelspondence involved in fixing 'up the lec- for Fixed Coil. sure that the answer given is quite correctturers, and later on in finding out the and not to be challenged. apparatus required, the begging, borrow- Fig. 1.-Coils on He is expected to have the finest receiv-ing or otherwise acquiring such apparatus Holder. ing set of the club, and his door must bewithout expense (for most wireless ever open to any member who cares tosocietieshavetowatchthis),and the walk round at any time to see why his oneavoidance of the hundred and one hitches valve set will not get the Dutch concert. which always crop up on lecture nights ? He must 'be ready every club night to Then there isthe tradesmen's associa- hear, "1:n ! my set will not do anythingtion which wants a free lecture, or the but crackle;canIbringitround onbazaar committee who want a free side Sunday morning so that you can have a show.They suddenly realise that a wire- look at it and put it right for me ? " Of less society exists in the town and decide course he can, and Sunday morning comesto approach the secretary.For the credit and so does the aforesaid member with aof his club he decides to give the lecture home-made set with loose wires and shakyor run the side show, and it gets through. Fig. 3 -Coil on Fig. 4.-Holder connections, the whole held together withHe hasthepleasureand privilegeof Hinged Supports, with Coil on Base. carrying his apparatus to and from the lecture or bazaar room, generally assisted, soldered to two thick pieces of copper Every reader of " A. W." of course, by one or two members of thewire, and the latter are then put through should have at hand for reference a wireless club.When he gets his appara-the " spider holes " and twisted round, as copy of the " Work " Handbook, " Wire- tus back home he finds that a couple ofshown, so as to form plugs to fit the valve less Telegraphy and Telephony: and How valves have passedtheirlastelectron. sockets.The wire supports of the variable to Make the Apparatus," is. 6d. net. The nicely written vote of thanks he getscoils are bent round and two other pieces about a fortnightlater he frames, andattached to form a stiff hinge. K. U. JULY 8, 1922 85 entolcur Wireless it,...... Sts...... 40.1.61,111.10. I TAPPING THE INDUCTANCE COIL I

THEfollowingdescription,togetherend ofit.This procedureiscontinuedwinding), and these connections are taken with the illustrations, should enable theuntil the tube isfully wound to withinto a stud -switch, of which a very good amateur to make his own variable induc-about 1/2 in. of the other end, when the lastpattern is shown in Fig. 2.The number few turns must be secured with narrow bits of tape in exactly the same man- nerasatthebe- ginning. The next thing is tp scrape the insula- tionfromeachof the raised turns of wire just where they lieontheebonite strip. To each of these barespotsa short length of well insulated wire is soldered (as well as to each end, of Fig. 3.-Photograph of Wound Coil. Fig. 1.-Photograph showing Method of Making Tappings. course, of the whole tance at a very small cost. Aisastiff' and positions of the "tappings" can be cardboard tube about 4 in. in diameter and varied accordingtoindividualrequire- soin.to12in.long. Bisa strip of ments, there being no hard and fast rule. ebonite, or even of hard wood, the same This form of inductance will be found to length as the tube, and about14in. by have great advantages over the sliding .A in. cross section. contact form when home-made, as the latter The tube is wound with No. 22 gauge is liable to give a lot of trouble in the way copper wire, either enamelled or double - of faulty contact unless the workmanship cotton -covered, the winding being started is perfect.The method of mounting the about in. from one end.The first two tube is shown in the first illustration, the or three turns should be neatly secured by ends beingofebonite and hard wood. means of narrow tape tied in two or three When screwing the parts together the nar- places.After five turns lay the strip of row strip, with its connections, is turned ebonite on the coil so that the end just underneath,andthewiresaretaken projects beyond the last turn; the sixth through holes' inthe base,so that the turn obviously will be brought over the appearance of the finished inductance is strip.After another five turns on the tube very neat, as in Fig. 3.The switch can, the strip should be pushed along so that if - desired, be attached to one end of the number twelve will again come over the Fig. 2.-The Tuning Switch. completed inductance. PHEAUX.

WHAT WIRELESS TERMS MEAN. -IV Some Technical Words Explained as Correctly as Popular Language Allows VALVES, SOFT.-The typeof valve M UTUAL INDUCTION (SeeIn -the potential of which is thereby constantly used for reception does not need duction). - Theresultingeffectsin a state of change, these changes being to have so high a vacuum, and such valvesof induction by which the induced currentreflected in the plate circuit. are called " soft." The glass of these valvesthrows back and produces an effect on the small cylindrical plate of is clear, but appearance does not alwaysfirst coil and so on, thereby producing aPLATE.-Ametalsurroundingthegridand indicate a hard valve. " swinging " backwards and forwards offilament of a valve.It is connected to the current from coil to coil.This effectisleg of the valve marked " P " opposite to VALVES, HARD.-The glass chamberpresent whenever two coils are in electrical" G."The leg " P " is always set out of in which the parts of a valve arerelationship. square with the other legs to prevent any enclosed has nearly all the air removed. possibility of the valve being wrongly in- A hard valve implies a very minute amount GRID. -A mesh or spiral of wire sur-serted in the holder.The plate is connected of residual air.A very hard valve is neces- rounding the filament ofa valve.in the high-tension circuit of the receiver, sary in transmitting owing to the highIt is connected to the leg of the valveand is supplied with current from the high- voltage applied to the plate.Such valvesusually marked " G."The aerial circuittension battery.The changes in potential are not so suitable for reception, though theyof a receiver is connected to the grid of theof the grid are reflected in the plate circuit, can be used for the purpose.A hard valvefirst valve in a circuit.Currents strikingand the telephones being also in that cir- is frequently very black. the aerial are thus conveyed to the grid,cuit are thereby affected.

Eltliti,11:111',111111s ill 'III Hiil;[11 ill I!! 11111 i:11111111111ti iffi H111111111;11111E1 it 1111 11 I! lin 11,11 HI 111.1 11 II I!! 111:1 lilt 1111 r,;1111111211111,,,illittirIttu!rt,J1117.1T-1 Amateur Wireless 86 JULY 8, 1922

i DRY CELLS ANDTHEIR WAYS i k,...... a.to.....sr.oe.so.a.ts.rsr.a.sr..a.tr.a.s..ft.s*.v....t,.....a.o.a...oaa. .1...... 1..1 r.u. 11.114110,61111,.1.011.11.101.11.4...... ,...... 1.1,11014.11.1w41,4,11...110.0.1111.1...... rm....1...w... r...... 4,

WHEN the dry cell was invented, andBunsen and Grove, but they are almostthis article found a way of making such there were many inventors, not oneforgotten, whilst 'thousands of Leclanchecells return to better ways.He simply of the inventors imagined that it would becells are used every day. warmed them for an hour or two.He put used for the variety of purposes that itis Just as the original voltaic cell was thethem in the kitchen oven after the fire had to -day.The chief use of the dry cell is tomother of all the group that followed, sogone low and the oven was cold enough give little flashes of -light, sometimes for athe Leclanche cell is the mother of all dryfor his hand to bear and left them there secondortwo,sometimesforalittle cells. Itisjust aswell,therefore,to forthenight. Inthemorningthey longer, anditisalsolargely used forexamine some of the excellences and de-worked. Atfirsthe did not recognise wireless receiving sets. fects of the mother before discussing the what had happened inside the cell, so he Most readers have bought one of thoseuncertain temper of the daughter. tried the same treatment with some cells little three -celled batteries that are used A Leclanche cell has one pole of zincthat had become exhausted by use in a to give the energy for lighting up flash -and another of carbon, and the liquid be- flash -light.They refused to start working lamps. For a little while all has gonetween the two is a solution of ammoniumagain. right.Then, perhaps a week or so afterchloride inwater. The solution has a Before trying to understand the effect of the original purchase, the need for theslow action on zinc, but a coating of mer-heat on the cells we need to know exactly light, or perhaps the interest in the thing,cury prevents the zinc from wasting awaywhat the cells contain.The case of the has gone for the time and it has been put onthisaccount. When thepolesare cellis made of zinc, and this forms the away. When itistaken out again, itjoined up the zinc decomposes the am-negative pole.In the middle of the cell refuses to work. moniumsalt,formingzincchloride, isa rod of composition, mainly carbon The " refills," as they are called, costwhich dissolvesatonce, ammonia gas,with the necessary dioxide.The space be- very little, so as a rule you just buy a new which likewise goes into solution, and thetween the two isfilled with a paste of one and take no further trouble about it.old enemy hydrogen, which forms littlesome kind, flour paste, wood pulp, plaster- Perhaps that is the best thing to do. bubbles on the carbon plate. of-paris, sawdust-anything, in fact, that willabsorb thesolution and prevent it Bubbles. Getting Rid of the Bubbles. spilling.The pasteis,of course, satu- But thedrycellisagreatdevice. Of course, there is a device for gettingrated with ammonium chloride solution, There is no need to call it an invention.ride of these bubbles.Itconsists of aand usually a little zinc chloride is added The invention came a century or so ago,coating of manganese dioxide around theto keep the mass always damp. when men set themselves to clean up thecarbon.Manganese dioxide, however, is It was said somewhere near the begin- defects of the original voltaic cell.Voltabut a poor conductor itself, so the coatingning of thisarticlethat zinc and am- never dreamed of electric lights or wire-of the carbon plate is never made of themonium chloride have a slight action on less.He was happy enough with his ownpure substance, but has an admixture ofone another,even when no currentis discovery that a piece of zinc and a piecesomething such as finely divided carbonrunning.This is negligible in the mother of copper, when dipped into a solution ofto make it conduct.Whatever the com-cell, where the solution isfree to move, salt or acid, could send a current of elec-pound may be, it is the dioxide that burnsbut in the dry cell the layer of paste next tricitythroughawirethatconnectedup the hydrogen bubbles.Unfortunatelythe zinc gradually loses all its ammonium them.All the cells that have been madeit does this rather slowly, and if the cellchloride and, although there is plenty of sincethenarethedescendantsofthebe worked for more than thirty seconds or itleftin the cell,itdiffuses so slowly original one of Volta.The first users of soatatime,the hydrogenwillformthat the cell will not start.When the cell the voltaic cell soon found out its greatfaster than the dioxide can deal with itis warmed the paste is liquefied to some defect.They found that the copper poleand the current will begin to die away.extent and the ammonium salt findsits began to bubble all over with hydrogenIt only needs a moment or two of abso-way back to the exhausted layer and the gas.Sometimes the zinc pole got frothylute rest to allow the destruction of thecell is once more ready to start. -as well, and the froth consisted of hydro-hydrogen to catch up, and the cellis as gen bubbles, just like those on the otherfresh and ready for work as ever. Worn Cells. plate.The hydrogen bubbles proved to This property of quick, recovery is what It is very different with a cell- that has be exceedingly bad conductorsofelec-makes theLeclanchecellsoperfecta seemingly been worn out.Most ofus tricity.They have other evil propertiessource of power forelectricbells. Itshave had a battery in this state, and most which were not discovered until later, andother property of needing frequent restsof us have at some time or other pulled their power of stopping the current fromrules it out from all such sustained effortsone to pieces.We have seen the three flowing through the cell was quite enoughas are needed for keeping a small bulbsmall zinc cases inside and, -as likely as to set inventors the problem of getting ridconstantly alight. not, we have found one or more of the of them. All that has been said so far is commonzinc cases punctured as though it had been There is no need to tell of all the dif-knowledge, or at any rate most of it is toeatenawaybythechemicalinside. ferentcellsthatweredevisedimme-be found in the text -books, but we mustQuite naturally we have put down the diately. Mostreadersknowquitealook a little more deeply into the workingfailure of: the cell to the giving out of the number of them, but for the most partboth ofthe mother Leclanche and the zinc. they are only historical curiosities.They daughter dry cell before we find out the But a moment's thought ought to con- have nearly all been superseded by cellscause and cure of the daughter's ailments.vince us that there is plenty of zinc left, of the secondary or accumulator type. and a very slight knowledge of chemistry Reviving Dry Cells. enablesustocalculatethatfor every The Mother of Dry Cells. One of the worst defects of many drygrain of zinc we need nearly two grains of One, however-the Leclanche-remainscells is that they will not keep.It fre-ammonium chloride.As a matter of fact in constant use.In the early days it wasquently happens that cells that have beenwe Use a great deal more, because the considered to be a feeble thing comparedquitecarefullystoredforsixmonthssolution refuses to act when it falls below withthepowerfulnitricacidcellsof refuse to work. A friend of the writer of a certain strength. FRANK T. ADDYMAN. JULY 8,1922 87 ntattur Wireless

i I Converting 'Phones for Wireless .0. .IP.II.11..III.d..IIp.....II....otp...... ga.....,..,g...... ,...4

WITH a few exceptions,itis neces-figures in the sketch corresponding withfriendshasincreasedconsiderably,at sary that the telephone headgear forthe reference letters in Figs. f, 3, 3a and 4.least amongstthosewithreceiversto wireless work be wound to a high resist- It will be seen that with such a smallwind.The arrangement is clearly shown ance, anything from Soo to3,000 ohmscoil and with only a bent strip of metal Pin Fig. 4, E being a small electric motor per receiver being general.The state -to hold, winding the empty bobbin by hand would be an extremely awkward job; in fact,it would be almost an impossibility to wind the wire with sufficient evenness to get anything like the required amount on the coils. Again, the wire being so fine it is necessary to use great care to avoid breakage, which would mean starting all over again,

Fig. 1.-Diagram of Interior of Receiver. P Fig. 4.-Motor with Magnet Mountel. ment "high resistance" is perhaps apt to Fig. 2.-Wound Coil 4 or 6 volt, using current from an accu- misleadthereader ;whatisactually on Magnet. mulator and having a variable resistance meant, of course, is that the magnet coils inthecircuittoregulatethespeed. must be wound with a great number of Clamped to the end of the armature shaft turns of fine wire in order to produce a is a circular block of ebonite or fibreBon maximum magnetic effect with very little which the telephone coilCis mounted, current. The resultant resistance is, there- being secured in position by means of the fore, merely a necessary evil, unavoidable Figs. 3 and 3a.- clamping screw c S, which passes through in all magnetic devices which are more Magnet a n d the holes in the pole -piece P.It will be or less voltage operated. Spool Mounted noticed that the coil C is arranged to rotate Another point about wireless 'phones is for Wind ng. as near as possibleinthelineof the that the diaphragms are much thinner Figs armature shaft, so that, in spite of the coil than those used on ordinary commercial and also the coil being so small, it woulditself being rectangular in shape, it will telephones.This makes them more sensi- revolve with as little wobble as possible. tive to small variations in the magneticbe almost impossible to holditwithoutThis is very necessary, as any tendency of force from the coils.At the same time,getting cramp long enough to get all thethe coil to revolve eccentrically will tend the diaphragms are more easily damaged,wire on at once. to break the very fine wire.The ebonite currentcausingthemto There are several ways of getting over anexcessive this difficulty, with winding machines ofblock B is turned up in the lathe and a buckle. hole bored through whilst still in the chuck varioustypes, and the writer has tried them all with varying degrees of success.totake the armature spindle;this can Construction of Receivers. either bea good tightfitinthefirst Second-handreceivers,ofthetypeMost of them had the disadvantage that itinstance or the block may be clamped on known as watch -pattern, may be picked upwas necessary to have an assistant, either to turn the handle or to guide the wire; thethe shaft by means of a small set -screw, very cheaplyatmost largedealersin shown inFig.3a. A second clamping electricalsundries ;many oftheseare screw C Sis fitted,to hold the coil c in surplus Government instruments and well position for winding.This screw must be made.The general arrangement of a re- accurately positioned to ensure the coil c ceiver of this pattern is shown in Fig.1, running true.The best plan isto hold the ebonite earpiece and diaphragm having the coilin position and then mark the been removed. A permanent magnetht place for the screw by means of a scriber of semicircular shapeisscrewed to the passed through the hole in the pole -piece P. outer containing case, and mounted on the poles are two pole -piecesP,which are Revolving the Magnet. bent at right angles and carry the magnet Returning for the moment to the ques- windingsC. The ends of the windings tion of true and steady running, it is most are connected direct to the terminals T, important that the hole to take the arma- which pass through insulated bushes in ture spindle is accurately bored, and also the metal case and serve' to connect the that the armature spindle runs absolutely coils C with the main receiving instru- Complete Double Head -set. true, otherwise the coil c will wobble and ments. difficulty will be experienced, not only in The coilsC when removed from thetime taken to wind, even with practice,the wire continually breaking, but also in ordinary receiver will be found to contain wasconsiderable,andtheresultnotgetting it to fill in close to the cheeks of fairlythickwire,theresistancebeingentirelysatisfactory. Somelittletimethe coil.If the motor F.is of the type in about 3o ohms.The task, therefore, is toago, however, the idea occurred of usingwhich the armature shaft extends at lxith strip them and rewind with much finera small -power electric motor with the coilends, the opposite end to which the block B wire to a resistance of 2,000 ohms eachdirectly mounted on the armature shaft.is mounted may be used to carry a small receiver. Fig. a showsthegeneralThe result was entirelysuccessful, andknurled knob fitted with a short piece of appearance of the coil when wound, thefrom that day the writer's circle of wirelessbrass wire about in. in diameter to form etnoleur 14003 88 JULY 8.1922 ahandle.This will prove particularlywirerestinglig7ltlyacrossthesecondbrittle and liable to break.Having finally usefulforcontrolling the motor or forfinger of the right hand, the motor shouldconnected up to the terminals T the whole winding certain portions of thecoil bybe started on thefirstspeed, graduallyof the case should be filled with melted hand. increasingthespeedofthemotoras paraffin wax up to the level of the top of confidence is gained. the coils, the loose connecting wires will Winding. It is far better to go slow at first thanthus be firmly embedded and a break in the Withregardtothemostpracticalto risk breaking the wire when the coil iswire rendered almost impossible. method of winding the coils, the followingpartly wound and having to commence all - procedure is considered by the writer to beover again.Naturally, a little practice isDiaphragms. the most satisfactory : needed at first, but the knack of holding A special thin diaphragm should be pur- The motor should be connected up to theand guiding the wire is soon acquired, andchased in place of the comparatively thick accumulator and regulating resistance andafter a time it will be possible to wind aone originally fitted.The ear -piece is'then tested to see that itis in running order.coil and finish it off in fifteen minutes. screwed on; clamping the diaphragm in The block B is then permanently fixed to When the coilis almost full a singleposition, and the receivers are ready to the armature shaft and one of the coils tolayer of silk ribbon should be put on, the befittedwiththe headgear.This can be wound clamped in position and truedlast layer of the wire being wound overeasily be made from a length of old clock up.Somefairlythinshellacvarnishthis, leaving about six turns from the endmain -spring, the ends being softened, holes should be near at hand, together with aempty.The top layer is then held in posi-being punched or drilled in to take small strip of silk ribbon, this latter cut to thetion with the thumb and finger, while anscrews, with which to secure the spring to width of the inside of the coil: assistantquicklysoft -solders a shortthe back of the cases.With a little trouble A single layer of silk ribbon is stuck onlength of double -silk -covered No. 28 S.W.G.the ends of the spring can be slotted to the core of the coil with shellac varnish,wire to the winding.The last six turnstake the screws, so that an adjustment is , one layer of wire is then wound on andwill consist of thick wire, when the coilpossible to make the receivers adaptable to covered with a second layer of ribbonshould then be covered with two layers ofheads of various sizes.The only remain- soaked inshellac.The free end of theribbon and the whole thoroughly soakeding thingto be doneistoattach the wire is then carefully brought outside theinshellacvarnish and allowedtodryflexible leads to the instruments.These coil and secured to the clamping screwbefore touching again.The second coilleads may be ordinary silk flex of good C Sfor the time being.Itis taken forshould then be treated in the same way. quality.The wires should not be twisted granted, of course, that the sides of the together, however, as in ordinary practice, coil c are already insulated with varnishedAssembling. but should be quite separate.The two ribbon or paper; at the same time it is a When both coils are perfectly dry theyreceivers should be wired inseries and good plantostickasmallpieceof may be remounted on the magnet poles inthe two ends of the flexible leads can be varnished ribbon over the free end of thethe receiver case, and the winding con-soldered to terminaltags or plug wire, to insulateit from the subsequentnected to the terminals. connectors. layers of wire when these are wound on. It is a matter of 'opinion as to whether With alittle adjustment, the 'phones The main winding is now ready to start.the inside ends of the winding should beshould be as sensitive as a specially con- The bobbin on which the wire is purchasedconnected to leading -in wires of a stouterstructedpair of wireless receivers pur- should be mounted on a small brass rodgauge, some contending that the heat usedchased in the shop5, and will well repay so that itis free to rotate, and with thein soldering tends to make the fine wirethe trouble involved. A. \V. H.

THE AERIAL STARTING WIRELESS. V AND EARTH I 111.Vflo.. Designing and Erecting the Aerial. from trees as much as possible, and do nottypes respectively.When using these it SPEAKING generally, in order tore-letit run by the side of a building, asis advisable to use two or three at each ceive the most energy from an aerial,both these conditions tend to screen theend of the aerial in order to secure better it should be as long and as high as pos-aerial, thus decreasing its efficiency.It isinsulation.The method of joining is also sible.However, at the time of writingnot advisable to run an aerialparallelshown in Fig. 3. there are certain restrictions and regula-with telegraph wires or above a lead roof Referring to Fig. r, it4vill be seen that tions with regard to aerials.The ,Post-or guttering. at the top of the mast there is a small master -Generalstatesthatanamateur pulley which is used for hauling the aerial aerial must not be more than too ft. highinsulating the Aerial. wire up or down.Rope impregnated with and not more than tooft.long. If a The aerial only receives a very smallsome form of preservative is desirable, and double -wire aerialis used, the length ofamount of electrical energy, and thereforethe rope should he about twice the length wire allowed is extended to 14o ft._;this,every precaution must be taken to secureof the mast.Itis slipped through the ofcourse,includesthetotallengthofthe best possible insulation. A small leak-pulley before the mast is raised.In order wire-thatis,two wires70ft.,spacedage will affect the signal strength to ato prevent the mast from swaying in the - some distance apart.It should be remem-very marked degree.The two best aerialwind, and also to counterbalance the pull bered that these measurements include theinsulatorsare glazedporcelainandof the aerial wire, it is usual to fasten a length of the down lead to the receiver. ebonite.Some comparative tests made bynumber of stay wires to the top, and these Speaking broadly, one type of aerial isthe writer showed that the bestresultswires are very frequently insulated by in- just as efficient as the other, and thereforewere obtained with ebonite. serting a shell or reel insulator near the the form adopted will depend upon the An excellent insulator can be made fromtop and bottom of each, as shown in Fig. 1. available space.Fig.r shows one of thea 6 in.length of ebonite rod. A The down lead should be kept as far best arrangements for a single -wire aerial,small hole is drilled through each end foraway from the wall as possible.In Fig. and Fig. 2 a similar scheme for a twin -thepurposeofattachingthewire,as it, is brought into the house by means of a wire aerial.When determining the posi-shown in Fig. 3.Two forms of porcelainlong ebonite tube, which isfixed to the tion of an aerial, remember to keep it awayinsulators are known as the reel and shelltop of the window -frame.When erecting JULY 8.1922 89 (Intokur Wireless

To EAR Th FROMAERIAL FROM Jr -IL AERIAL

INSULATOR

STEEL GUY ROPE To TUNER TO EARTH ToTUNER B Fig. I.-Single-wire Aerial. Fig. 4.-Lightning Protector.

INSULATOR

ROPE SPREADER ToMAST HEAD AERIAL WIRE 60mr 6rfer

To HOUSE on MAST bY5ULA TOR3 LEAD-INWIRES NCl/ 10- FOoT LONG

LEAD-IN TUBE Fig. 3.-Insulators. Fig. 2.-Double-wire Aerial. an aerial the angle between the down leadThe ends of the wire are opened out andblades of the switch, as shown in Fig. 4 and the main part of the wire should be well "Finned.A small- part of the surfaceatB. The upper contacts are short cir- made as large as possible.Another pointof the pipe is scraped clean, and the endscuited and the lower ones are connected to bear in mind is that if one end of theof the wire are soldered to the pipe. tothe tuner.When the receiverisin aerial has to be higher than the other the use the switch is put into the lower posi- distant end should. always be made theEarth Plates. tion, thus connecting the aerial and earth higher. If a water pipe is unavailable, a metalto the tuner.It will be seen that when plate should be buried at least 4 ft. belowthe switchisin the upper position the A Twin Wire Aerial. the surface of the earth, and if possibleaerial is connected directly to earth, and To gain the advantage of two wires theydirectly under the aerial.Wire netting,at the same time the tuner is absolutely should be spaced apart, at a distance of atcopper gauze, and copper and zinc platesisolated. PAUL D. TYERS. least 6 ft.The spreaders are best made ofareallequally useful for earths.The 0 vs.".".\.w.n."."./0 bamboo on account of lightness.It will beplate should be at least 6 or 7ft.long noticed that the two wires must be insu-and about2or 3 ft. wide. A number ofMaking the "Wave" Visible 12or14s.w.G.) copper lated from each other until they merge to-thick(say No. ANinterestingexperimentforthose gether at the end of the down lead.Thewires are soldered to the earth plate, beingr -t who possess a spark coil is moment- method of insulation should be apparenttwisted together and brought to the re-arilytolight up an electriclamp by from Fig.z. ceiver.Since the plate is to be buried inwireless, that is to say by a wave from the thesoldered -connections are theearth, coilsituated atthefar end of a large Aerial Wire. liabletocorrode owingtoelectrolyticroom. Copper, phosphor -bronze, silicon -bronze, action.To prevent this it is essential to The ends of a coil of wire, consisting or aluminium wire rriay be used for anprotect the connections by well covering aerial.The wire should be of a fairlythem with paint or some insulating com- large gauge, say No. 16 S.W.G.Strandedpound.It should be remembered that the wire, such as 5/22, is the most suitable.more moisture there is in the ground the Aerial wire of this description may be pur-better will be the connection to the earth. chased in lengths of loo ft. or too ft. ;this is very often enamelled, which serves as aProtecting the Aerial from Lightning.. protection against corrosion. It will be obvious that an aerial will act more or less as a lightning conductor, The Earth Connection. and thereforeitisadvisabletoprotect Itisimportanttoobtain an efficientthe receiving apparatus during a storm. connection to the earth, and usually a mainThis is best accomplished by connecting water -pipe can be employed for the pur-a " micrometer spark gap "across the .pose.Connection should never be madeaerialand. earth.The arrangementis to a pipe containing screwed joints, suchshown at A (Fig.. 4), and it will be seen as a branch pipe to a cistern, neither onthat- itconsists of two very fine points any account should a gas:pipe be employed separated 'by a very short distance.One for the purpose.In arranging the positionis made adjustable, and the gap is set by Lighting a Lamp by Wireless. of thereceiver,itshould be placed asscrewing the points together until they near the earth connection as possible.A just touch, when the movable one is givenof about thirty turns, 20 in.in diameter, very long earth lead should be avoided.a fraction of a turn back until the con-are connected to a 32-c.p. lamp as shown Preferablyitshould . not be more thannection is broken. intheillustration. When thecoilis about 20ft.to25ft.Stranded copper An alternative plan is to use a double -operated and suitable adjustment made, wire may be used for the purpose, and itpole two-wayswitch. Theaerial andthe wave passing into space will cause the should be connected to the pipe as follows :earth are respectively connectedtothelamp to light up. W. W. D. Cm:deur Wireless 90 91 ematzur Wireless

A SINGLE -VALVE RECEIVING SET AND HOW TO MAKE ITI THE EDITOR'S INTRODUCTION THIS one -valve set has been specially designed (at the request of the Editor of " Amateur Wireless ") to follow on from the " Official " crystal set fully described and illustrated in the first number of thisojournal.The crystal set is being made by hundreds of our readers, and we trust that the present and rather more ambitious apparatus will be as welcome and as sucdessful. It will answer the needs of those readers (1) who live at some distance ft4om the broadcasting stations ;(2) whose space for aerials happens to be restricted ;or (3) who in general desire a more advanced type of receiving apparatus than the crystal set above referred to.

Photograph of Receiving Set with Crystal Detector and High - Photograph of Receiving Set with Valve as Detector and Low -frequency frequency Amplifier. Amplifier Combined.

AT the outsetit may be remarked that to make amplifier.In the Firstitamplifies B.A. (see Fig. SA).They can be ad- There are six pieces of mica i% in. byrin. and everything which appears in the accompanying theradio -frequencycurrentswhich justed by placing them in position and about 0.003 in. thick.The mica can be bought in drawings from the rough material would require a oscillate in the aerial circuit, and these pushing a valve right home. The nuts thick pieces and is split with a sharp penknife.The well-equipped workshop, but most, if not all, of the magnified currents are passed on to are then tightened up.If the valve thickness should be checked with a micrometer if parts which require special machining can be bought the detector circuit on the right. legs cannot be made at home they can possible, otherwise the only way to measure the ready made.Those who have already made a Fig.3 may help to explain the be bought for a few pence. thickness is to. cut up a piece into M.in.squares crystal set will not have had their labour in vain, meaning of the 'terms used.The top The legs and terminals should be with a sharp pair of scissors and pile thirty-four of jI for most of the apparatus can be used in the set to line represents two groups of high - polished and lacquered or they will theselittlesquarestogether,when theyshould be described.Those who have not made or used a frequency oscillations in the aerial cir- tho Cam quickly get dull on account of themeasure flu in. total thickness. crystal set are advised to do so before they attempt cuit.These may be supposed to have sulphurintheebonite. Afterthe A little over or under will not matter very much.

the valve set for two reasons.The firstis that it been considerably amplified (increased lI--1-Iii11111111111-' holes have been drilled the top can be Care should be taken to obtain the mica as clear as needs a little experience to know how to get the best in strength) by the valve.On passing a. ea finishedoff smooth with fine emery possible.It can usually be obtained in 2 in. squares, results from a home-made set, and the second that through the detector circuit they are cloth, and a little oil rubbed over the and two of these should be ample for the purpose. the mere use of a crystal set will thoroughly instil deformed in shape Lo be something Fig. 2 surface will give a good colour. The tinfoil is cut up into six strips 2 in. by in. into the mind of the amateur that he must have all like the second line, and the effect The wooden part is made out of two and a hole punched A in. frorn`the end of each one. his apparatus thoroughly efficient. producedinthe telephone may be Fig. 2.-(above) Valve as Detector and solid pieces of mahogany or teak (or Copper foilis better than tin because itwill not One can sometimes afford to be a little wasteful likened to the third line oscillations, Low -frequency Amplifier Combined. soft wood wil do) TI in. and Y4. in. tear so easily, but tinfoil will answer quite well. when signals are amplified, but when itis impos- hence the term audio -frequency.In thick respectively.Some of the thick The "leak" is made of a piece of sheet fibre or sible to put more energy into the telephones than is Fig.tthe valve magnifies the radio - Fig. 6.-(right) Layout of Valve Panel. piece has to be carved away to leave ebonite in. by y4.in., with two holes made at received by the aerial, which is the case of the crystal frequency current and allows it to pass Cab of pore Ebanile shr,r room for the terminals, valve legs and each end2Y4, in.apart.Fibreispreferable;if set, much will be learnt of the advantages of keeping on to the detector, and in Fig. 2 the Fig. 6 connecting wires, this, of course, being ebonite is usedit must be roughened with emery - insulation and apparatus up to the mark. valve performs the two operations of High- o)1radio -frequency done when all the parts are assembled cloth.A thick line with an H B pencil is drawn amplifying and rectifying together. oscillations(too rapid to on the ebonite panel.If the maker is from one hole to the other, and the pencil is well The Circuits. ailed telephones). good at engraving he can mark the rubbed in round the holes, as shown in the drawing, Figs.r and z show alternative circuits which will Apparatus. letters to the terminals of the plate, to make good contact with the clamping nuts.The give good results if the instructions are carried out The apparatus needed forcircuit grid and filament, but otherwise they Rectified 4..oscalationsob- in full.In both these circuits the valve acts as an No. r comprises : E- tamed' with detector. should be stamped on or marked in I. A complete receiving set. ink on the wood underneath.The 2. An additional aerial tuning in- connections of the terminals to the ductance. Low- eraudio -frequency valve should 'be made with No. 20 3. A valve holder. <_oscillatio.^-producedin gauge bare copper wire. A little piece 4. Batory Bt of 4 volts and battery iMt.phones. of rubber tubing should be slipped over 0®o B2 of 30-40 volts. Fig. 3.-Diagrammatic Repre- Fig. 7.-Diagram of Con- sentation of Oscillations. nections of Valve Panel. theplateconnection which hasto For circuit No. 2 : cross one of the filament wires. I. Aerial tuning inductance. advantage that it can be vefy easily and finished off smooth with an iron 2. A valve holder. converted to a "regenerative circuit.' smoothing plane set very fine.Fail- Grid Condenser and Leak.

Photograph of Receiving Set with Crystal Detector and High - Photograph of Receiving Set with Valve as Detector and Low -frequency frequency Amplifier. Amplifier Combined.

- 3. Batteries Br and Bz. ing that, a "dreadnough" file will cut The next piece of apparatus is the , 4. Telephones with condenser. Valve Panel. it better than any other.Fig. 6 shows grid condenser and leak, which will be 5. Grid condenser C and grid leak L. The valve panelisillustrated by the layout of the holes.The four needed for circuit.No. 2.These are 0 0 If the amateur has already two tun- Figs. 4 to 8.The top is made of aholes for the valve legs should be shown in the diagrams Figs. 9 to 13, ing inductancesitwould needless piece of ebonite 4 in. by a% in. by.4., marked out very carefully; they are andalsointhe photograph. The work to fit up circuit No. 1, but if he in. thick; in. thickness would drilled A-in.in diameter so as tocondenser is made up of copper or Fig. 4 Fig. 5 Fig. 1.-Valve as High -frequency Amplifier vv'th has not, it might be easier to adoptdo, but the thicker material will be allow a little play for adjusting the tinfoil,bothof which can be pur- Figs. 4 and 5.-Plan and Side Elevation of Valve Crystal Detector. circuit No. 2; the latter also has the stronger.The edges can be trued up valve legs, which are screwed No. 4 chasedfromanyelectricalstores. Panel. , *.- . 'mu emcdettrWistiRs3 92 JULY 8, 1922 box for the leak should bemade of hardfifty hours; a'good cell has a total capacitytension battery, so that there is no need wood if possible.It is easiest to make itof 7o ampere -hours.If not used too oftento have new cells for the purpose if old solid and carve the centre out like thethey would perhaps last for three monthsones can be obtained.An alternative is valve panel, the bottom piece being gluedor more, and when unfit for this purposemade up of three units of eleven cells; on.A piece of wood or, better, ebonitethey can be added tothe high-tensionthese units can be purchased for about 5s. V in. thick is cut to the same size as thebattery. each.Also twelve to fifteen pocket lamp leak; this is to clamp the condenser down A40 -ampere -hour4 -voltaccumulatorbatteries (3% volt) might be used.It has with.The terminals should be as shownwill cost about 25, and must be chargedalready been stated that if dry cells are in the drawing, with nuts and washers. every month whether itis in use or not.used for lighting the filament they can The condenser can now be assembled..The cost of charging usually depends onbe passed on for this service when they First the terminals are pushed throughthe conscience of whoever does the job.are too old for the former. the holes in the lid of the box, then theIt will probably be about 2s.per time. When using old cells care should be condenser is assembled in the followingOf course, if more than one valve is usedtaken from time to time to see that the order :a piece of copper foil on one ter-it would pay to have the accumulator be-voltage of any 'cell does not fall below minal, a piece of mica, a piece of foil oncause of the extra current consumed., Ao.7 volt.The battery should be carefully the other terminal, a piece of mica, andbig disadvantage of accumulators thatinsulated.It may rest upon glass plates, so on.These must be carefully laid on,they are messy and not easily portable. such as old photographic negatives, and one exactly over the other.When the It will be noticed that no filament re-preferably it should be enclosed in a box. last piece of foilis in place the ebonitesistanceis included in the apparatus orOperation. strip should be pushed over the terminalsdiagramofconnections. When using Having now described all the apparatus and then the fibre with the pencil markaccumulators the writer considers thatit which is needed, a few words on the work- outwards.Washers and nuts are used to isnot worth the extra cost and troubleing of the set may not be out of place. Always take the valve out of the holder when making connections.If you accidentally connect the high-tension battery acrossthe filamentitwill be a costly mistake. To further obviate accidents a piece of Fig. 9 % ampere fuse wire may .be connected in series with the H.T. battery.No. r circuit will need two inductances; these should

Fig. 11 t6 dm - Fig. 10 --r Figs.. 9 and 10.-Case for Grid Leak and Condenser. 96%I k---1 pencilline Fig 8a.-Valve Leg. be about the same size, and when every- O ?loco17g.x/' thing is connected up and you are listening for signals you should tune both circuits at once. Copper Stele 2 c3 34 In circuit No. 2 only ,one inductance is used.The grid condenser is taken out Fig. 12 Fig 13.-Constructional Details of ofitsbox. When signalsareheard Figs. 11 and la-Elevation and Under Plan of Grid Leak. Condenser. thicken the pencil line on the- grid leak and the signals should gradually become clamp the whole tightly together.Theto have a 6 -volt battery and variable re-stronger.If too much pencil has been capacity of the condenser should be aboutsistance. A 4 -volt battery can be con-added it can be rubbed out.As it may .0003 microfarads and theresistance ofnected straight on to the filament of thetake a little time to adjust the leak it the leak z,000,000 ohms.The condenservalve without the least danger of burningshould be- done when a station is transmit- will not need any adjustment once itisout, whereas one has to be careful with ating for a long time; for instance, the put together, as it will be approximately6 -volt battery.When using dry cellsit Parisweather reportorthe Admiralty of the stated value -ifit has been madewould be worth while including a rheo-signals. When the leak is finally adjusted properly, but the leak will have to bestat, but instead a short piece of resistanceit is put back in the box and the edges are adjusted when thesetisinuse. Thewire could be inserted as' a connection tosealed round with paraffin wax to prevent method will be described later. get over the difficulty. the ingress of moisture. Inthisconnectionthewriter would J. F. S. Batteries emphasise the need fora voltmeterif o Thelow-tensionbatterynextclaimsvalves are used.It should preferably read A perhaps unusual source of noise in attention. Thisisneeded tolighttheup to 6 volts.It should also be used toa receiving set was the presence of spiders' filament of- the valve, which may be ancheck the voltage across the filament inwebs on the aerial.This particular aerial M or R type.These valves take a currentorder to see that it never exceeds 4.5 was low atthe house end, and during of about y. amp.The two most suitable The high-tension battery niay be ob-last August a quantity of spiders' webs sourcesofcurrentare accumulators ortainedina number of ways.In theappeared on the insulators, etc.The first dry cells, and if there is any difficulty inwriter'scaseitconsistsof about thirtyintimation of these was that signals were getting accumulators charged, the writerdiscarded electric -belldrycells.Whenvery weak, and the set would not oscillate wouldcertainlyrecommenddrycells.the voltage of a celldrops belowta aboveabout5,200metres. EVentually The initial cost of four good cells (theyholeisdrilledin the top and alittlethis was found to be due -tothe webs, must be large ones) will be aboutits.water added; this usually freshens it up.which caused fiendiSh noises in the tele- These should easily have a life of aboutVe.ry little current is taken from the high-phones when thea'erial swung about at all. JULY .8, 1922 93 Omatcur Wireless IIII i ELIMINATING THE AERIAL The Squier System of " Wired Wireless " i 1

T isevident even to those who up topower line in various ways; the preferredalternating -current arc -lights would Ithe present have only taken a super-arrangement used at present is shown in"hum" at the pitch of the circuit which ficial interest in wireless that one of thethe -illustration.In this method of con-supplied them.Someone proposed that a most desirable objects to be achieved isnection- the danger of short circuiting thetelephone transmitter should be connected the elimination of the aerial.The aerialmains is entirely avoided, the condensersto a city's arc -fighting system to broadcast is the one inconvenient component of thebetween the mains acting as a by-pass forpolice calls, news of robberies, etc.The receiving set.True, with a valve ampli-thehigh -frequencycurrentsonly,per-difficulty, however, was that the arc -light fying set_ frame aerials can be used, butmitting the power current, direct, or alter-was not asufficiently"loud -speaking" then not everyone can afford such sets,nating, butof low frequency,toflow receiver to be heard above street traffic, so and, moreover, many would not have thealong the mains.For the wireless cur-nothing ever came oftheidea, The technical ability necessary for their opera- rentsthe two mains areconnected inproblem of putting on another stream of tion.Obviously, the type of instrumentparallel and used as one conductor, the"talk"withoutinterferencewasonly that would be ideal for those whose chiefground being the return conductor.Goodsolved when a reliable method was found interest in wireless telegraphy is simplyresults are also obtained by connectingfor using a high -frequency electric current the broadcasting reception would be onethe transmitters and receivers between theas a "carrier." of the simplest nature and would not, re-mains, suitably protected by condensers to 0\-15."5./WINIVNIVNIC) quire an aerial. keep the large power current from passing To this public wireless is a means to anthrough the wireless apparatus, but the TWO KINKS end and, providing that broadcasted pro-arrangement indicated above is more suit-A CONDENSER HINT grammes could be received successfully, able. IN the construction of small fixed con- their care is not whether the ether is the densers difficulty is often experienced in conveying medium or whether wires areIts Advantages. The advantagesofthelinewirelessmaking connection to the tinfoil sheets.A used for transmission.In the latter case simple and effective Method is to use ordi- the installation of transmitting wires ormethod of broadcasting are many.In the firstplace, the ether channels used for f linesis,of course, out of the question. But if use could be made of existing wires,wirelessbroadcastingarelimited,and say the lighting mains which are noweven the few wave channels which are available for broadcasting can be more CONOC,40 general in all towns of any size, and this Condenser Plates Held by Eyelet. without affecting their ordinary use, a veryprofitablyemployedforsuchwireless useful object will have been attained. activities where ether wireless is the onlynary eyelets to fasten the plates together. That thisis a possibility of the nearor best method of communication.AlsoIf several condensers are made of uniform sincethereisnowirelessinterferencedimensions they areeasily interchange- futureis proved by a demonstration re-caused ,by broadcasting on power or light- centlygiveninAmericabyGeneral able.The method of application is illus- ing circuits, any number of wave channelstrated above. A. M. George 0.Squier, Chief SignalOfficermay be employed and, therefore, multi- U.S.A., of the application of his systemplying the possible number of stations that LIGHTNING PROTECTOR f wired wireless."An American con-can be operated on tile same line.It is AVERY efficientlightningprotector conceivable that in every community we can be made from a thin sheetof PJWCP mica and two discarded carbon brushes MAINS may haveseveraltransmittingstations operating at the same time, but each on asuch as are used on electric motors and dynamos. rooktopurrat aunts different wave -length and supplying different services.One might be used ex- Drill a hole in the mica about -A--in. clusively for music, another for currentdiameter and oneina brush the same EARTH EARTIS news, and still another for educational in- CARSON Suitable Connections for the "Wired Wireless"formation, etc. System. A suitable plug connection in the light ',OLDER temporary gives an account of the demon-socket is all that will be required, so that A 5 SPRING stration. "Radio Broadcast,"the paperwherever the light circuits extend, which referred to, says: is nearly universal these days, "wireless" broadcasting may be received. General Squier's Wired System. It is hard to realise at this moment the la i5 GeneralSquier hasdemonstrated ex-vast possibilities of this method of broad- perimentally in his laboratories that itis casting, but judging from the universal WOOD BADE entirely feasible and practical to transmitinterest in the preliminary announcement Lightning Protector. high -frequency -current telephony overin the press,itisa fair guess that thediameter but in.deep, andfillthis power lines and electric light circuits, and-system will come into general use veryhole with softsolder. Then place the for it to be.received by a large number ofquickly. brushes together with the mica between, people by connecting receivers at various There is nothing new in this idea;it care being taken to ensure that the hole points on the line, the connection beingoccurred to many people years ago, butinthe micaisopposite tothesolder. made by a suitable plug in any lightits fulfilment was just out of reach.ForMount the protector on a well -varnished socket. instance,it was found thatif telephoneboard, and fasten with clips.One of the The transmitters or receivers are of thecurrents were passed through an electricbrushes should be connected to the aerial, usualtypes now employed forwirelessarc the original sound would be repro-,the other (containing the solder) should telephony and may be connected to theduced audibly, just as the old-fashionedbe connected to earth. J. -L. niateur Wireless 94 JULY 8,1922 imagination to see a future Derby photo- graphed, wirelessed from the course by a super -directional transmitter, received and RADIOGRAMS projected on the screen of a cinema ten minutes later ! Wirelesspartiesare being organisedwards switches itself off until the next one now. is due.Of course, time switches are not Speculating as to the future of the wire- new, for they have been in use for electric lessindustry a writerinthe "Sunday lighting,etc.,for some time, butthis One broadcasting station in New York Chronicle" uses the gramophone for pur- appears to be the first attempt to applyposes of comparison.According tothis sends out no fewer than ten musical pro-them to wireless. grammes a day. writerthereareroughlytwomillion gramophonesinuseinthiscountry. Every year about i5o,000 gramophones are Three Continental wireless services are A great number of schools are takingsold to the public, of which roughly 25 now being conducted simultaneously fromup- the subject of wireless, and are accord-percent.are made completeinthis the Ongar Marconi stations. ingly installing suitable apparatus.Twocountry, 5opercent.containforeign recent additions are the Lowestoft Centralmechanism, and 25 per cent. are imported SchoolandtheschoolatGrayswood,from the Continent. The capital employed The European wireless weather report,Surrey.In the latter two pupils are de-in the industryisabout ,5,000,000for transmitted dailyat11.30 a.m.(Green-tailed each morning to take the time signalmanufacture and Li,000,coo for wholesale wich Mean Time) from the Eiffel Tower;from Paris, and to adjust the school clockdistribution.The number of people em- is now being supplemented by data fromaccordingly.The daily weather report isployed in the industry is, roughly, io,000, America. also received each day from the Air Minis-and the number of dealers who handle try's station at Kingsway House. A wire-gramophones8,000. Every yearabout less lesson is given each week to a large The Almanzorarecently,whensixty Lio,000,000 worth of gramophones are sold miles north of Fernando Noronha, ex-class of scholars, all of whom can "listenthroughout the land. changed wireless signals with Cape Town,in" simultaneously by means of a loud Assuming, therefore, that there are as speaker. a distance of 3,457 miles, thus constituting many people willing to buy wireless sets a wireless record for the South Atlantic. as there aretobuy gramophones,this country ought to be able to absorb two According tothelatest reports broad-million sets.If the average investment Radio House, Wilson Street, Finsburycasting is delayed for three reasons whichon every set were only Zs, the total in- Square, E.C., is the newest sending stationmay be summed up as follows : vestment would be Z;to,000,000.Ifthe The station is Differences have arisen in regard to thecountry could absorb these two million re- of the Marconi Company. erection of the broadcasting stations. forthecontrolofthe new stationat ceivers in a period of five years this would A continuous wave issent out Manufacturersdesire protection formean an average of of new from Ongar, and that wave is interruptedBritish -made wirelesssets. They arguebusiness each year with employment for at Radio House. that hardship will be involvedif,afterseveral thousand people, and that is a very they have incurred heavy expenses in themoderate estimate. erectionofthebroadcastingstations, "Fire" in an editorial says :The fireforeignmanufacturersareallowedto flood the market with receiving sets. hazards of the country are likely to be " Wireless in the Tropics."-With reference considerably increased by the broadcasting The special machinery and apparatusto the photographs used in a recent issue to of wireless news and the installation ofrequire a considerable time for construc-illustrate this article, Mr. Chatwin asks us to thousands of receiving sets by amateurs.tion and installation. state that these were taken by Mr. J. A. It is thought improbable that there willCooper, A.M.I.E.E., who has a collection of It is well to be forearmed, because care- photographsillustratingtheEastAfrican lessness or ignorance in the setting up ofbe much further delay. campaign from 1916 to 1918. an installation and use thereof may cause Itisunderstood that the majority of .much fire damage, and at the least inter-the broadcasting firms are in favour of an ;ferewithfire -alarmsthathaveabove-increase in the cost of the licence, and it ground wiring. is proposed that the suggestion should be put before the Postmaster -General.Itis CORRESPONDENCE suggested that the extra fee should be Considerable acceleration of the com- los.6d., making the total yearly cost to Can any Reader Kindly Explain ? mercial wireless service existing betweenthe amateur £1 is. England and Spain has been secured by SIR,-In all the text -books I have read service from Ihave been informed that the medium the recent transfer of this through which the electro-magnetic waves thePoldhustationto a new Marconi station at Ongar.Under the new condi- Some little time ago a technical journal(used in wireless) travel is the same as that devoted considerable space to a method ofof light.This medium is called ether and tions messagestoSpain, marked "Via Inis all-pervading.Below is a rough table Marconi,"insteadof being relayed bytransmitting photographs by wireless. long land line circuits to Cornwall, areits present form the system is rather in-of wave -lengths radiated in this ether. transmitted direct by distant control fromvolved; at the same time, considering the X-rays, about 2.5 millionths of an inch. Radio House, Wilson Street, E.C., to thevast strides made in the past few years it Actinic rays of maximum intensity,to receiving station in Spain. is quite within the bounds of reason that amillionths of an inch. method of broadcasting photographs may be Heat rays of maximum intensity, about evolved shortly which will enable pictures15 millionths of an inch. An entirely new automatic receiveris of, say, a big fight, race meeting or other Electricrays,shortest measured, 0.24 claimed to have been invented by a New-public functionto be flashed from the in. ;as usedinwireless, about 300ft. castle engineer.The apparatus is tunednearest broadcasting station to be pickedto 50,000 ft. to a certain station, and it switches itselfup by any private station equipped with Itisquite commonly understood that on at certain times of the day in anticipa-suitable reception apparatus. the velocity of the above waves are all the tion of scheduled transmissions, and after- Itonly needsasmallflightofthesame, namely, approximately 186,000 miles

JULY 8, 1922 95 entattur ittrelesS per second, .hence the argument that theenthusiasts I find they are just as much in medium must be the same for each.Now,the dark.I would be greatly obliged if CLUB DOINGS thevelocityof soundis much smaller,you would insert this query in your thost The Hackney and District Radio being 11,120 ft. per second, the medium forhelpful journal and let myself and others Society sound -waves beingair.An experimenthave the benefit of other readers' scientificHon. Sec.-E. R. WALKER, 48, Dagniar Road, proving that the medium for sound wavesknowledge.-G. B. (Sacriston). South Hackney, E.g. THE third meeting of the above Society took and the medium for waves oflight are place on June 22nd at III, Chatsworth Road, entirely different is easily demonstrated by Freak Results Clapton, at 8 p.m. theclassicalexperiment of placing an SIR,-F. H. MPs letter on freak results A meeting, to be held on July 7th, will be electric -bell under the bell -jar receiver ofhas greatly interested me, as only the otheropen to the general public.An elementary an air pump and removing the air.Upon lecture on the " Principles of Wireless " will day I had a similar experience of receiv-be given, terminating by the reception of the circuit being closed the trembler of theing signals without an aerial.Iuse atelephony and music.The apparatus to be bellis seen to vibrate, proving that theone -valve set, and was in the act of dis-used will consist chiefly of units made by medium of light which allows us visionconnecting the outside aerial and changingmembers. stillexists within the bell -jar; also thatover to a hore-made frame inside whenBirmingham Experimental Wireless the sides of the vessel are transparent toI heard signals, my hand touching the end Club the waves of light.One cannot, however,of the aerial wire (not the terminal).This (Affiliated with the Wireless Society of London). hear the action of the trembler because,so interested me that Icalled my friendHon. Sec.-MR. rRANK. S. ADAMS, III), Ivor theairbeing withdrawn,thereisno in, and signals were still heard when heRoad, Sparkhill, Birmingham. medium for the sound -waves to travel in.touched the aerial wire.This seems re-AT a meeting held at Digbeth Institute on My difficulty, which I would like ex-markable, as neither of us had any con-Friday, June r6th, a lecture was given by plained, can be very clearly presented bynection with the apparatus.Can anyoneS. H. V. Abbott, Esq , on " Wireless at Sea " Mr. Abbott described wireless systems and changing the substance of the bell walls.account for this?Another little experi-methods since the earliest days of marine Instead of glassletit be porcelain (anment was receiving telephony from Mar-wireless.An interesting programme of lec- insulator), or any substance opaque to lightconi House withasimplecrystalset, tures,discussions,and demonstrations has waves. We can now neither hear nor seeusing- the above -mentioned frame aerial.been arranged, for the summer months. the action of the trembler blade, but if weMy station is only about 2% miles fromLeeds and District Amateur Wireless haveasensitivedetectorofelectricalMarconi House, which may account for oscillations placed outside of the jar wethis, but the frameis a very primitive Society (Affiliated with the Wireless Society of London). can easily detect these oscillations causedaffair,consisting of two pieces of woodHon. D. E. PETTIGREW, 37, Mex- by the spark at the trembler blade. I (4 ft. by 4 in. by q. in.) made in the shapeborough Avenue, Chapeltown Road, Leeds. thinkthisprovesthatelectro-magneticof a cross and wound with fourteen turnsA GENERAL meeting was held on Friday, waves do not follow the laws which governof No. 2S enamelled wire.No other insu-June 23rd, at the Leed§ University.It had been found impossible to arrange a discussion light waves.By thisexperimentitis lation is used.The frame is hidden awayon " Direction Finding," as scheduled in the shown thatelectro-magnetic waves willin adirtylittleoffice in the city, withsyllabus, but Mr. G. P. Kendall, B.Sc. (Vice - pass through interveningobjects whichhigh buildings all round and a P.O. tele-President) had offered to describe his four - are impervious to light waves. My diffi-graph pole on the roof. valve receiver. cultyisinsatisfyingmyselfthatthe set ,works This set, Mr. Kendall explained, was still I may say that my valve in the experimental stage, being assembled in medium for light and wireless transmis-very well on this small frame.-L. P. S.the well-known 50 -watt trench -set cabinet, and sion is the same.At present I cannot be- (City). (Continued in second column of next page) lieve it and wish it could be made clear. Referring to the table of wave -lengths, I can understand X-rays passing through substance because they are so minute.All eibstances,itisgenerally agreed upon, are made up of molecules separated by "P 0 Z" spaces which are filled with ether.If this is so one has no difficulty in realising the probability of X-rayswavescreeping through these spaces between the molecules.However, wireless waves are very largeandcouldnotpossiblycreep through.I am aware that wireless waves can be distorted, but even this fact does not help us to an easy solution of the above experiment. At the present day when signals can be readily heard without an outside aerial, the apparatus being totally enclosed within four walls of a room in the centre of a house,itisnot to be wondered at my doubting the assumption that the medium for light waves and the medium for electro-magneticwavesareidenticallythe same. The waves of light from the sun do not travel all around the earth's surface.In the case of wireless transmission, however, the electro-magnetic waves are well known to follow the earth's surface. All this may be very easily explained. I have never had it made clear to me, and One of the great German stations which amateurs are constantly hearing.In addition upon asking quite a number of wireless to much Press work it transmits time signals and weather obse, atiors. Omntair winless 95 JULY 8, 1922 OUR INFORMATION BUREAU Expert Replies to Readers' Questions.Hundreds of Replies are sent by Post. TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES Write distinctly, give all necessary details and keep to the point.Ask one Question at a time-never more than two.Send a Stamped and Addressed Envelope. Send the Coupon cut from page 98. 0.111.111.11.1 - ./"."14.11.611AW ...... 111. Range of Apparatus other end is then twisted.This may be doneheld on June toth at the Signal Corps Head- Q.-Please say what signals could be re-in various ways, the best being to fasten it inquarters, to hear a paper by Mr. W. J. Feather- ceived by means of the receiving apparatusthe cli-uck of a drill brace, and rotate it untilstone, entitled " Miscellaneous Subjects Re- as described on p.10 of the first issue ofit is evenly twisted all the way along.Thelating to Wireless."The lecturer gave a clear AMATEUR WIRELESSiferectedatLuton.wire should be pulled tightallthe time.description of the various detectors (past and -F.H. (26) When finished, unwind a little to take thepresent), and explained the various uses to A.-The receiving set referredto, whenspring out of the wire, and coil it up carefully.which a relay could be put.He exhibited a used in conjunction with the usual " amateur "The stranded wire may now be wound on thegood type of this latter piece of apparatus. aerial should prove capable of tuning in wave-inductance.To keep the turns from touchingMr. G. H. Strong (President), who occupied lengths from about 150 to about 700 metres.one another, a ball of fine string is wound onthe chair, proposed a vote of thanks, which ,Therefore, in the first instance signals can beat the same time side by side with the wire.was seconded by Mr.C. Dyson (another received from stations which employ wavesThe whole can then be varnished with shellacpioneer). Fourteen newmemberswere between these limits.These will include shipsand baked dry.(2) The connections to theelected.Intending members should get in and coast stations (on 600 metres), amateurcrystal were quite clearly shown in the draw-touch with the Hon. Sec. transmitting stations (180 metres), telephoneing.The aerial wireis connected to one Stockton - on -Tees and District stations (amateurs on 18o and 440 metres,switch 'arm and the crystal itself.The pointer proposed new broadcasting stations on 35otouching the crystalisconnected to one Amateur Wireless Society to 425 metres), and a few ship and shoreterminal of the telephones.The other tele-Hon. Sec.-Ma. W. F. WooD,4,Birkley stations working on 300 -metre waves.Thisphone terminalisconnected to the otherSquare, Norton, Stockton-on-Tees. is quite a fair selection, but it must be remem-switch arm and toearth.Use siliconorTins society is only a month old, but is one bered that the question of range must beFrench galena. of the largest in the district, having close upon considered, and this is a most difficult matter eighty members.Permanent rooms have been to estimate, depending upon several factors SHORT ANSWERS taken in the Malleable Workmen's Institute, such as (r) the power employed by the dis- Amateur (Cheshire). - (I) Coloured polishNorton Road, with the use monthly,for tant transmitting station ;(2) the height andmay possibly act as a conductor and " short "lectures, etc., of the large concert hall.An efficiency of the receivingaerial ; (3)the'your detector.Use insulating varnish overaerial is being arranged for, and considerable efficiency and sensitivityofthe receiving"wood(2) One layer only.(3) Clean off insula- apparatus has been placed at the disposal of apparatus ;and (4) the very important ques-tion only on the surface edge of the wire ; brushthe members. tion of the skill of the receiving operator.Itthe coil in the direction of the " lay " of coil A Club official will be in attendance in the isconsidered, however, that, with a goodafterwards to remove dust, etc.(4) A pocket -rooms every evening. aerial, average care in the construction andlamp battery will last longer than a Leclanche, The membership is open to persons of any use of the apparatus and the use of really goodcell,and would not run down so quicklyage, including ladies.The general meetings telephonereceivers,thesignalsreceivableowing to high resistance of potentiometer.take place on the second Thursday in every shouldinclude" spark "telegraphyfromVoltage is required, not current. (276) month. shipping and several English coast stations W. H. H. (Macclesfield).-You should cer- as mentioned above, together with telephonetainly be able to receive over a longer range of Wireless Society of Highgate (speech, music, etc.) from one or two of thewaves, but it would not increase or decrease (Affiliated with the Wireless Society of London). nearest of the proposed new broadcastingyour reception of signals over long distances.Hon. Sec.-Ma. D. H. EADE, " Gatra," 13A, stations.With regard to this latter, however,Wave -length has nothing whatever to do withSedgemere Avenue, East Finchley, N.2. it must be understood that until the stations.distances in miles.Other instruments do not,MR. J. STANLEY, B.Sc., A.C.G Igave the actually commence operationsitis impos-iieed. altering. (166) third of his series of lectures on the 'elementary sible to state with any degree of accuracy theory of wireless telegraphy and telephony justat what distancetheir transmissions on Friday, June 23rd.After briefly alluding Cum DOINGS (ontinued from page g5) to the different types of aerials and indicating should be receivable upon a crystal receiving the functions of the earth connection, Mr. set.-CAPAcITv. utilising some of this set's components.TheStanley went on to deal with tuned circuits Gauge of Wire for Inductance first valve functions at radio frequency havingHe showed how, by coupling a coil in an Q.-(i) Would it be possible to use No. 36potentiometer grid control, and isdirectlyoscillatory circuit with a coil in another cir- s.w.c. bare copper wire for the " Official " re-coupled by means of reactance -capacity orcuit,oscillations could be induced inthe ceiving set described in No. r, as I have plentyresistance -capacity methods to the grid ofsecondcircuit,and that these oscillations on hand ?(2) The method of wiring up thethe rectifier, which functions on the grid condenser system.The setisprovided withwould have maximum strength when the crystal detector is not quite plain to me. Willmagnetic regeneration taken from the platenatural frequency of the second circuit was von kindly give me some information, and also,side of the rectifier to the aerial circuit,,,whichthe same as the natural frequency of the first what is the best crystal to use ?-A. E. S.will provide for the reception of continuouscircuit.He pointed out that by this means (194) energy could be transferred from one circuit A.-(i) No. 36 s.w.c. wire is too small towaves if the coupling be tight enough to setto another, the amount of energy transferred use as a single wire for an inductance coil ofup self -oscillation or autodyning. Two stagesbeing largely governed by the tightness of the low wave -length.No. 26 wire has a crossof low -frequency magnification follow, andcouplingbetweenthe .coils.MrStanley sectional area of .00025 sq. in., whereas No. 36by means of a plug -and -jack combination,showed that the closed circuit coupled.to an has an area of only .000045 sq. in.However,the telephoner or loud -speaker may be placedaerial circuit is such an arrangement, and, if five strands of No. 36 were twisted togetherin the plate circuit of either the rectifier, thesince in this ease it is desired to radiate as they would give the same area as one strandfirst L F valve or the second L F valve.Themuch energy as possible from the aerial, he of No. 26.Stranded wire has the advantagereceiver uses valves and will function on alldealt with various methods employed in prac- over single wire that there is greater surfacewave -lengths, being very useful for telephonytice to prevent the energy transferred from the for the same cross-sectional area, and as 'high -reception.Theoretical and practical diagramsclosed circuit to the aerial circuit being re - frequency currents flow chiefly at the surfaceof the scheme of connections were explainedtransferred back to the dosed circuit, mention- of a wire, and not uniformly all through asbriefly but clearly by the lecturer. ing in particular the rotary and quenched direct currents do, the stranded wire will offer Wireless Society of Hull and spark gaps. He then passed on to consider ,less resistance.To strand the wire a clear the receiving station, and showed how electro- space of about too ft long will be- required. District magnetic waves impirging on the receiving The wire should be laid out straight on theHon. Sec.-H. NICHTscAr,rts, 16, Portobelloaerial produced oscillations in the aerial cir- ground in five pieces of exactly the sameStreet, Holderness Road, Hull. cuit, and that these oscillations would be of length.The ends are twisted together, andTHERE was a,large attendance of members atmaximum strength when the receiving aerial one end is fastened to a firm object.Thethe monthly meeting of the above Society,was tuned to the same frequency as the trans- JULY 8,1922 97 entattur Wudtss We can supply YOU with ALL Build Your Own Sets ! We are the PIONEER FIRM to specialise in sets of parts for any type of Wireless? Apparatus. All PANELS are drilled and tapped ready to receive fittings. COMPONENT PARTS All FITTINGS are ready made. All YOU DO is assemble and connect up. for your wireless setstraight from stock BLUE PRINTS and INSTRUCTIONS are supplied. Please mention "Amateur Wireless" and send 6d. stamps right now for our 24 -Pagel If you wish to savemoney, send forour Illustrated Catalogue " A/W " with list of Transmitting Stations. Complete List TRADE SUPPLIED CONDENSER VALUE Complete Sets of Parts for VARIABLE Aerial Wire, 7/22 bare copper stranded in 100 ft. hanks 5/6 per hank CONDENSER ready to assemble Ring Pattern Insulator, 2 in. by 1 in., S in. hole ... 6d. each. No Drilling or Fitting -required. in. sq. Section Brass Rod for Sliders, cut in 13 in. lengths, *0015 '001 *0(05 1003 '0002 '0001 and drilled each end ready for fixing 8d. each. 27/- 21/- 14/- 11/- Inductance slider complete with plunger 8/- 71 - Cardboard Cylinder? 12 in. by 4 in. diameter 10d. each. Cabinets : No. 24 enamelled wire, H.C., true to gauge ... 2/8 per lb. 419 416 4/3 4/- 3.9 2/9 Large or small Condenser Plates (Aluminium) ... 1/8 doz. The above are supplied with Ivorine-Scale for Panel mounting or Ebonite top 89' x 41" fo Large Spacer Washers for condensers, cut true to 1,000 of an box mounting. We can substitute Ebonite Bevelled dial in place of scale for 3/6 extra. Small spacer washers Ditto .... 6d. doz. PLEASE STATE WHICH YOU REQUIRE. Ivonne Scales... 11- each. Condenser Box in Polished Oak or Mahogany, 31 in. by 83 in. by 2 in. 5/. each. '0003 mf. Condenser complete -assembled in polished mahog- PARTS FOR TUNING COILS any or oak boxes 17/6 each. IMPREGNATED TUBES, 3', 1/9 ; 4', 1/9 ;5'. 213, perfectly round, per ft. All necessary parts for above condenser -no drilling or fitting SLIDERS, fitted with 14' square brass rod and terminal, 2/3. required, but unassembled 15/- each. ENAMELLED WIRE, per lb., 22 gauge, 31- ; 24 gauge, 34 ; 26 gauge, 3/9. Ditto, but without box ... 111- each. CRYSTAL DETECTORS, 3/6.CRYSTALS, Galena, Bornite, Carborundum, 9d. per Ditto, but without ebonite top, and box suitable for panel packet. mounting 10/- each. Crystal detector, mounted on Ebonite, complete with Crystalel- each. Large or Small Contact Studs 1 /- doz. COMPLETE SETS OF PARTS Valve Legs, complete with nut and washer ... Sd. each. to build the following : SHORT WAVE TUNER with switch, studs, wire, ete., 18/6 ; Cabinet, 416. Instrument Wire at Rock -bottom Prices SINGLE VALVE RECEIVER, 15/9 ; Cabinet, 3/6 extra. Send for particulars of our Unit System Complete Sets or Parts.By this System you can build a most powerful 5- or 7 -valve set in easy stages.Each unit is complete to J. B. BOWER & CO., Ltd., itself, and can be added to at will. CALL AT HOLBORN AND HEAR SETS DEMONSTRATED WIRELESS MANUFACTURERS, 15, Kingston Road, WIMBLEDON, S.W.19. PETO SCOTT (The Condenser King); Works: MERTON. 7, FEATHERSTONE BUILDINGS, HIGH HOLBORN, 'Phone: WIMBLEDON 1030. LONDON, W.C.1.(Turn up by No. 63.) Also at Stores: 17, Frome Road, Wood

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9 "SECONDS OUT OF THE RING Quality that will not be counted out. One Trial willconvince yon. Aerial Wire, 7/zz's Enamelled Hard Drawn Copper, 6/ -Ivorine Scales.o to 180P. Engraved (not printed), 1/2 VALVE PANELS. Single valve.Mahogany case. Baize - per too tt. each. covered base, ebonite top. Containing grid, leak Aerial Insulators, Shell typezIt in. x al in., green, 1/6 each.Ivorine Tablets.Set of 6, 9d. and condenser, telephone condenser. Filament vt Reel type, 3 in. diam., white, 6ad. each.Knobs. Ebonite. 14in.diameter. Superiorfinish. resistance, and with terminals to allow the addi- Batteries.For H.T.Make your own.Flash Lamp Knurled, 8d. each. tion of extra panels.A beautiful piece of work- Batteries, 5/- doz. LOUD SPEAKERS.Marked efficiency.4000 ohms, manship.Price, 296 each. Battery Cases. Mahogany, Terminals for tapping, fitted £2 each. SUPERIOR QUALITY WIRE. British Made. 13/- each. Mica.Pure Ruby.Pieces, 3 in, X 3 in. X .002 in. thick. All whe wound free. Post extra. Buzzers for Morse practice. 3/- each. 6d. each. Condensers. Fixed. Exceptional quality. TerminalParaffin Wax, 1'- per lb. S.W.G. Single connections : from *000t to *oot, 2/9 each. Resistance Wires. " " brand. 22'S(1 ohm per S.C.C. D.C.C. Silk D. SilkEnamelled Condenser Vanes.Not rubbish.Best Aluminium, 1/- yard), 24's (II ohms per yard), and 28's, enamelled doz. (4 ohms per yard), 2d. per yard. Condenser Spacing Washers. Accurate.Small,4d. Switch Arms. Exceptionally strong and well made, 3 leaf. 12 III, 4/- 5/4 doz.;large, 8d. doz. 2/6 each. 14 1/It 2/- 41" 514 Condenser Screwed Rod. Brass,12 in, lengths, 2 B.A.,TELEPHONES.Our Speciality.A much needed 16 21- 2/1 4/2 5/6 rho 9d. each.4 B.A., 6d. each. want. A sensitive light and comfortable head -set at the 18 zlx 2/2 4/4 516 Contact Studs.Large, well finished, 2/- doz. right price.In huge demand.Complete with cords. 20 z/z 2/3 4/8 6fe 2/6 Copper Foil Sheets.9 in. x'3 in.,6d. each 140 ohms, 27/-; 4,000 ohms, 30/-; 8,000 ohms, 32/6 22 216 2/11 51- 68 218 Ebonite.Best quality.Any size,oil or sheet, 5/- per lb. each. 24 31,- 316 5/6 741 2/8 Filament Resistances. For panel mounting. A speciality.Terminals. A very neat wireless terminal. Polished, 26 317 411 6/8 8/2 3/2 41- each. complete with nut and washer, 2/6 dozen. 28 4/4 417 712 9/- 3/6 Grid Leaks.Exceptional quality.All tested. TerminalTerminals to fit flash lamps refil contacts, with slot and 30 516 8/- 101- 3/10 connections, 2/6 each. screw, 2/- dozen. 6/- 2 32 7/3 13/- 4/2 Inductance Tubes.12 in. long.Specially imp'egnated. Tin Foil. Free from lead. Sheets, 26 in. by 13 in.,4d.each. 34 7/- 813 i9i//o 141- 4/4 o in., Ed. ,3 in., 7d. ; in.,Sd.;4 in., 10d. ;4i in.,Valve Sockets.With nut and washer.Fine finish, set 36 8/8 5012 141- 15/6 4)8 1/ 4; 5 in., 1/2 ;6 in., 1 6 each. of four, 10d. 38 x1/3 13/2 161- 5/3 Inductance Sliders.Polished Ebonite,in. square hole,Valve Holders.Best quality ebonite, 1/6 each. 40 151- 181- 18/6 246 616 6d. each. Valves.Zenith, 4 pin vertical filament, 10/8 each. 42 2713 211- 3116 341' 91- Insulating Tubing, 6d. per yard. Mullard, 15/- each.Marconi -Osram, 26/6 each, I Carriage extra.PI ease remit ample postage, balance returned.Orders over 42 carriage paid.Money back if not satisfied.

Cent. J. L. CARTWRIGHT & Co., Manufacturing Electrical Dept. A, 130/132, London Road, Manchester. [G"'"'s:PI durum, Special Terms to the Trade. Agents Wanted : Agents names will be included in our advertisements. M.acheater. mateur Wirdess 98 JULY 8, 1922

He pointed out the various directfrommanufacturers. Staterequirements, mitting station. quotations per return.Box No. 2, Amateur Wireless. methods of increasing or decreasing the natural High Grade Variable Condensers, ebonite top and COMPETITIONS FOR frequency of an aerial by suitable combinationsknob engraved ivorine scale, 00-180, .0005 in polished of inductance coils and condensers.At thecabinet ins.6d., or in cylindrical brass tube, as.; ALL READERS dittofor panel mounting withscale,125. ;crystal conclusion of the lecture, the whole of which detector on ebonite base with ball and socket adjust- was followedwithgreatinterestbythe ment, 5s. 6d. ;post free.-Weatherall & Co.festal,. THREE WIRELESS RECEIVING audience, a cordial vote of thanks was given over zo years), 28, Woodbridge Street, Clerkenwell, to Mr Stanley. London, s SETS AS PRIZES The South London Wireless and THE BEST BOOK ON Scientific Club WIRELESS FOR AMATEURS. Closing Date, Friday, July 7th (Affiliated with the Wireless Society of London) How to make and use a Wireless Valve Receiver Set, by-- Day after Publication of this Issuo. StJohn's Institute, Larcom Street, S.E.I7, E. K. Spiegelhaler. This book has been specially written REcExTIN Mr. Walsh gave a very interestingfor Amateurs in Wireless.Clear Constructional details lecture on high frequency, accompanied by accompanied by 24 very practical illustrations are given, WE offer as a prize in each of the whichwillenable theoperatortobuildhis own set following competitions a well -made practical demonstrations with a ro-in. spark economically and to workitsuccessfully when made. coil, glass -plate condensers, Oudin coils, etc., Price 3/6 ti t.Send P.O. for a copy. wirelessreceivingsetmanufactured by besides furnishing very interesting data re- E. & F. N. SPON, Ltd., 57, Haymarket, London, S.W.1. one. orotherofouradvertisers,the garding the construction of this type of transmission apparatus. approximate value of each setto be at This lecture was followed by one by Mr. FROM STOCK least seven guineas. INSTRUMcErthisWIESout foreference. Wilkinson on " Cinematography," with special 8.W.G.S.C.C. S.S.C. 0.8.C. EN. Rules. -The Editor'sdecisioninany reference to kinematics.Having dealt with 41/- the projection, manufacture, and taking of the 47 110/- 120/- and every caseisfinal. Thereisno 46 97/- 107/- 26/- appeal from it.The copyright of all com- cinematograph film, he then dealt with the 45 64/- 80/- 20/- theory of light rays. 44 50/- 66/- 16/- petition efforts published by us will be 43 40/- 52/- 13/- ours. Allentriesto be in by Friday, FORTHCOMING EVENTS 42 31/- 33/- 9/- July 7, and to be addressed to 41 30/- 32/- 8/- Ilkley and District Wireless Society.July 5, 40 14/- 17/- 18/- 22/- 6/6 THE EDITOR, 7.30 p.m., Committee meeting ;8 p.m., lecture 39 12/6 15/- 17/- 21/3 6/- "Amateur Wireless," and demonstration on " Short-wave Telephony 38 11/- 13/- 16/- 19/- 5/3 Reception." 37 1* 12/- 14/6 17/3 4/11 La Belle Sauvage, Leeds and District Amateur Wireless Society. 13/9 15/- 4/8 July 14, 8 p.m.I.ecture by Mr. D. E. Petti- 36 8/6 10/- London, E.C.4. grew on " Maritime Radio Communication." 35 7/9 9/3 12/9 14/- 4/6 34 6/10 8/- 11/3 13/9 4/4 Competition No.I. -A wirelesssetis TELEPHONY TRANSMISSIONS 33 6/2 7/6 10/6 13/- 4/3 The Hague, Holland (POGO).1,070 metres. 32 5/10 7/2 9/1 12/10 4/2 offered for the best article of about 1,500 July 9, 3to 5 p.m. 31 5/6 6/10 8/9 11/6 4/- words, written from your own personal ' Writtle (2MT).400 metres.July it, 8 p.m. 30 5/- 5/4 719 9/103/10 knowledge and experience, and calculated EiffelTower (FL). 2,600metres. Each 29 4/9 5/- 7/6 9/6 3/8 afternoon (Saturdays and Sundays excepted). to help or interest your fellow amateurs. 28 4/3 4/6 7/2 9/- 3/6 Illustrationswill 27 4/2 4/5 7/- 8/6 3/5 in most cases be regarded as a featureof merit.Articles PREPAID ADVERTISEMENTS. Other Sizes on Application. MonthlyCompetition,Free. -4o -ft.aerialmast. AERIALS, 7 22 . ft should be written in simple language and Particularsandlist,2d. -F.Armstrong,Wireless FINE WINE- SUPPLIa.100 .' 61- Mast Works, Weybridge. [3 r be as bright and informative as possible, Receiving Sets, " A.T.M." crystal, complete, readyA. E. DAVIS, 41, 3.trinttir8.rad,and the subject may be anything that you for fixing; guaranteed; £4 ios.-Turner, below. DoubleHeadphones,2,000 megohms,complete, AERIAL WIRE, 7 Strand 22 Gauge, 46 100 ft, thinkwireless amateurs would careto 325.6d. -Turner, 79, Playford Road, London, N.4. [8 r Leading -in Wire, high tension, heavily rubbered, 6d yd. read about. Should we publish any article Newtonian WirelessFactory. -2,000 telephonere- Porcelain Insulators, Ring Type, 2' diameter, 6d. each. that does not win the prize we shall pay ceivers, single 215., cords 1s. 6d.; double, with head Brass Rod, Isquare, 13 lengths ready drilled, 13d. each. band, 40s.-13-15, Whitcomb Street, W.C.2.Regent Contact Studs, large or small, with nuts & washers,114 doz. for it. 643. Condenser Parts and all Wireless Apparatus and Newtonian Wireless Factory. -Reelinsulators, Sundries in Stock. CompetitionNo.2. - Anothersetis samples, 6d. each; condenser plates, 3d. pair; crys- Male for Price List. Terms cash with order. Postage extra offered for a brief description (with illus- tal cups, 4d. each; ebonite inductance sliders,iod. each; 3 by 12 spiralwoundtubes,9d.each; ATKINSON & HOOK, tration if necessary) of the most novel and shellacinsulating varnish,iod.per bottle;square WIRELESS FACTORS, 52, Hamilton Road, WIMBLEDON. rods, drilled, 13 in. long, 6d. each. -13-15, Whitcomb useful item. in wireless apparatus -in its Street, W.C.2.Regent 643. design, material, make, electrical connec- Newtonian Wireless Factory. -Complete crystal set for making up your own apparatus, comprising all tions,etc.etc. The novelty must be materialsand2,00n-olimreceiver,reducedprice, original -notcopiedfromanysource 435. 6d. ;carriage,zs.-13-15,WhitcombStreet, REILESS- W.C.2.Regent 643 - whatever. Agencies wanted for supplies for cash for amateur FOR THE HOME wireless outfits.First-class position, largest city in By Norman P. Hinton, B.Sc. Competition No. 3. -The third receiving Scotland. -Apply Box r, c/o " Amateur Wireless," La set will be presented for an ideal broad- Belle Sauvage, Ludgate Hill, E.C.4. [7 r Written by an Expert for the Amateur. Filament Resistances, 4s. ;radial switches, ebonite casting programme of twelve items.You mounted, 5 -way 5s., to -way 7s. ;switch arm, 2s. 6d. ; A complete guile for all who contemplate installing wire. mounted knifeswitch,S.P.,2s.3d. Post free.- less apparatus.It tells how to install the apparatus, gives can enter for this competition on a penny Micklewright,Ltd.,Manufacturers, Perivale Lane, advice on its selection and purchase, and explains every- postcard.Simply write down in column Alperton, Middlesex. [6 s thing in a manner quite easily understood by the beginner Ratchet Wheels for electric clocks, 30, 4o, 6o teeth,-everything that will smooth the way for the amateur and form twelve items that you consider would 25. 2d. -Wm. Bristow, 166, Pavilion Road, S.W.i. [2 5 help him to grasp the main principles of wireless, so as to Always Get it from K.E.W.S.-Crystal receivers, be able to receive messages, has been included. Well bound make an ideal programme. 1:25s.;crystal detectors, 6s. ;24S.W.G. enamelled and illustrated -a book you will want to keep. wire, 2s. 8d. per lb. ;aerial, enamel, d.c.c. and s.c.c. wire, valves, terminals and all accessories stocked. Price 2,%. net, of all Booksellers Revised list with full particulars of our unit system, Published PITMAN'S, PARKER STREET, ANNOUNCEMENTS WirelessService,io,Glen- by RINGSWAY, stamp. -Inquiries K.E. " Amateur Wireless andElectrics." Editedby view Road, Lewisham, S.E.i3. [8s Bernard E. Jones.Price Threepence.Published on For Sale. -Double headreceiver, 6o ohms, Thursdays and bearing the dale of Saturday imme. (Brown's),price.£1. -Scott,io,HamiltonRoad, diately following.It will be sent post tree to any Oxford. [o s partoftheworld -3 months,4s.6d. ;6 months, LightningProtectors. -Don't takeunnecessary 8s.9d. ;12 months,17s.6d. Postal Orders, Post riskswith your buildings and your receiver.Use Jefferson's improved broadcasting type.Substantial Office Orders, or Cheques should be made payable insulation,completewithbase,terminals,fixing to the Proprietors, Cassell & Co. Ltd. screwsanddirections,as.ad.,postfree. -From General Correspondence is to be brief and written Cyril P. Jefferson, 3A, Golders Way, London, N.W. on one side of the paper only.All sketches and [to s drawings to be on separate sheets. Wireless. -Complete sets or' spare parts.Every- Contributions are always welcome, will be promptly thing the amateur needs.State your requirements. considered, and if used will be paid for. Advice free. -Davies, 75, Dale St., Liverpool. [13 s Communications should be addressed, according to Manufacturers' Notice. -Wireless dealers, retailers theirnature,to TheEditor, The Advertisement and manufacturers ofsets can obtain immediately Querist's Coupon Available until Manager or The Publisher, "Amateur Wireless;' deliveryofallpartstotheirownspecifications Saturday, July 15, 1922 La Belle Sausage, London, E.C.4. JULY 8, 1922 9y Amateur litriziRss

III IM MN " 11811 1111111111- MEI OUR POLICY IS TOLIVE QUICK DELIVERY & SATISFACTION im i Condenser Vanes, Aluminium (accu- A to E Switches on Porcelain ...2;9 CQ Std bi rate size and gauge), per doz.1/8 Valve Holders Screwed Legs & a Nuts Do., Large Spacers (true to 'poor'), eadi1/6 per doz, Bd. Crystals (special selected), Bornite 6d. for ERICSSON PHONES Do., Small Spacers (true to .000r") Carborundum, Silicon, C. Pyrites per doz. 4d. Etc., Etc.,6d. Do., Scales Ivorine calk° each...1/- Crystal Cups, Brass with Fixing WHEN you instal your wireless set Do., Ebonite Tops and Bottoms Screw 6d. -crystal or valve-you'll get (bushed)1'3 Fusible Alloy (for fixing crystals) 6d. maximum resultsifyoufitEricsson Aerial Wire Stranded 7/25 roo'...4/8 Inductance Tubes If x 3' ...6d. Do., Egg Insulators (high insulation) 9d. Phones-clarity, sensitivity, strength of v) 12' X 4' ...9d. Do., keel best quality 4d. Sliders Ebonite with Plunger ...1 - signals and absence of " click." Specially Ebonite Knobs, Fluted Top (drilled) 7d. A.E.G. & TelefunkenValves,tested 10,6 suited to telephony. Genuine " Hellesen"Batteries. New Enamelled Wire, 23 gauge, i lb. 1/6 36v H.T. EricssonPhonesembodytheaccumulated Unit with Wander Plug 8/8 Sq. Brass Rod, le X e X V... 9d. experienceoftelephone manufacture fora Tuners,Headgear, Transformers, etc.Postage extra.Advice given with pleasure. generation. THE bhowronms Easy to the head, light and comfortable.The magnets never losetheir strength and " shorts " ESSEX WIRELESS CO.499, GROVE GREEN RD., arenon-existent. (Wholesale ltetxit.l LEYTONSTONE, E.1 I . Write for Particulars Telephone-VVANSTEAD 748. (1 min. from Station, G.E.R.) TheBRITISH L. M.ERICSSON MANUFACTURING Co., Ltd. WE OFFER Head Office: 6o, Lincoln's Inn Fields, E.C. 2 PROMPT DELIVERY OF COMPLETE SETS and ALL AMATEURS' NEEDS SETS OF PARTS to build your own Valve Panels, Condenser Panels,VariableCondensers,etc.etc. AerialWire,Insulators,FilamentRheostats,Accumulators,H.T. Batteries,ValveHolders,Switches,Knobs, Terminals,etc.etc. Ebonite Sheet Rod and Tube; cut or in bulk. TRADE SUPPLIED ; CATALOGUE (now due from press), 4e1. Showrooms open q mm. till 7 p.m., where you can "listen in" and inspect our latest productions. Telephones The" H.B. " RADIOEQUIPMENT COMPANY, HEAD OFFICES AND SHOWROOMS, 109, HIGH ROAD, KILBURN, N.W.6. Bus Services: 8, 16, 28 and 51 pass door. 3 mins. Kilburn Park aria(Bakeries Rly.) l III UM I= IIIII II11 *FOR WIRELESS 4 Build your own Wireless Set. We can supply allparts from a Crystaltoa Complete Set. DAVIS & TIMMINS LISTSFREE w."."-fs-rwes.n..n.".n.wN PROMPT DELIVERIES LIMITED Try- ELECTRICAL SUPPLY STORES, 5, Albert Terrace, King Cross, HALIFAX. 34a, York Road, King's Cross, N.1

haphazard purchases till you have DON'T MAKE sent for our CATALOGUE of SCREWS and TERMINALS WIRELESS for WIRELESS SETS. I RADIO. ELECTRICAL &MECHANICALSUPPLIES. INSTRUMENTS, SCIENTIFIC SUPPLY'STORES ACCESSORIES 8, NEWI$CTON CAUSEWAY, . and . :: ASK FOR ILLUSTRATED LISTS. :: LONDON, SE I. MATERIALS We stock everything for the Experimenter who wishes to build his own Set.

191, BISHOPSGATE, E.C.2. SCIENTIFIC APPLIANCES Near Liverpool St. Station. HENRYJ. DALE. W, HOLLINS. C. S. SWAN9 'PHONE :BISHOPSGATE 1155. 11 II29, Sicilian Avenue, Southampton Row, London, W.C.I. 15 Volt H.T. Units ..3/3 Leading In Tubes 13d. to 2/6 Filament Switchesfor Panel Microphoneswithreplaceable Top ofKingsway. In Centre of London. Corner of Bloomsbury Square. Mounting 3/9 Insets 2/8 Crld & Hocking Condensers 2/6 & 3/ - CrystalsIn cups .. 9d. ELECTRICIANS.OPTICIANS. MECHANICIANS. Aerial Insulators 8d. A. Type ValveHolders .. 1 9 ACTUAL MANUFACTURERS at our Works, East Street, W.C., thus saving all intermediate profits. New & Ex -Government Wireless Apparatus in Stock The Store for all Electrical and Scientific Material WIRELESS & RADIO MATERIALS, VALVES. 'PHONES. Call and see as. View our Show PARTS and FITTINGS Windows. Send for List post free 2d. THAT BOOK YOU WANT Immense Stock constantly adding to, and ON WIRELESS OR ANY OTHER TECHNICALSUBJECT Making; Speciallyfor theAmateur to Splendid Value in ;!'oyles have it or will quickly obtain it. Build up a Set Complete and Perfect. 1,000,000 Vols. (Second-hand and New) on Techni- EBONITE. BATTERIES. AERIALS. Seeond-hand Appliances cal and every other conceivable subject instock. INSULATED WIRES. CRYSTALS. Books sentonapproval.Write for Catalogue lot (free) mentioning ENGRAVED DISCS. MICA. HANDLES. Every Branch of Optical ,requirements.Books Purchased. SWITCHES. TERMINALS. STUDS. and AppliedSc ience FOYLES,121, Charing Cross Rd., London. Scientific Appliances, 11 & 29, Sicilian Avenue, London, W.C.1. Wireless r 100 JULY 8,1922

Universal Electric Supply g HEADQUARTERS ' 4 BROWN STREET Telephone ONE DOOR FROM MARK ET5e 644.664Are 34,29 CITY 1892 -. MANCHESTER FOR 0.P.Q,Box No.tn. WIRELESS SUPPLIES In addition to our own wide range of" WirelessSpecialities we carry stocks and can give prompt deliveries of the Leading British Makes. Send your Inquiries. Large Illustrated Catalogue, post Free 6d.

CONDENSER UNIT INDUCTANCE TUBES CONDENSER PARTS AERIAL WIRE BLOCKING BROWN'S LOW FREQUENCY and CLIPS Impregeated FIXED and MOVING Per loufeet. CONDENSER, 5/. LOUD SPEAKER, INTER -VALVE Length 12 in. VANES 3'- 3/20 ..4/- 7/22 .. 5/- GRID LEAK, 3/. TRANSFORMER Simple mid eff1 ient. Dia. 2/19 .. 6/6 3/18 .. 6/6 Type 11.2.. £13 0 0 1105to 0003 laid.,3/ - Dia. CENTRE ROD. 41 in. PLUG CONNECTER, Wound with 20,000 turns ..64 4 .. 1/- 46 ech 7/2o .. 7/6 2 -Pin, 1/6 HIGH-TENSION of wire,each layer spaced Set of 3 =mute Ion REGULATING SCREW Ebonite Base, 12/6 3 ..8d 5 .. DA' LAMINATED SINGLE RECEIVER, BATTERIES, and insulated from the .. 10d a..2/. SWITCH ARMS 2/6 1/. 1.5 volts .. 3/6 next. Approximate re- Sit val lies can be ob- EBONITE KNOBS with head band 6 cord tained simply by lift-SMALL CONDENSERSVALVE SOCKET. 1/9 120 0111115 .. Variabm Type,36 volts,sistancePrimary, zsoo *00044 3/4 1.- and 1/6 ing one end of any VALVE SOCKET 500 27/6 Tappings every 3 Secondary, so,000. Ofsni 3/0 INSULITE SLIDERS 1/. Cu ri dens .r. TERMINALS 1,000 30/- volts. 7/6 Ratio, 1.3.E170. 6d, ANODE RESISTANCE 1/3 per set of 4 KNAPE SWITCHES 2.000 3 ACCUMULATORS Fitted in polished maho- LEADING -IN TUBES 3/6 S.P. 1 tray .. 1/9 /4000 0111 Is.. CONTACT STUDS, DOUBLE RECEIVERVolta Amps gany CASK. with 4 termin- S.P. Simi:chi. 3 in. 7d , 0 in. 20111 01 3/6 Smallsize, 2,- dozen. 2/4with head band 6 cord 4 40 ..28/-als in polished engraved D.P. 1 3/9 113. 213,15 in, 4/- VARIABLE 1,000 °lobs - 4 panel. £1120. 6d. ANODE RESISTANCELare 35/- 60 ..35/- Eel/5 3 in. 7d 1l ,,r', 1/6, 2,000 ., .. 37/6 6 40 . 42/- 20,000 to Ili ,000 001uS, AERIAL INSULATOR GRID CONDENSER FILAMENT RHEOSTAT 101 in. 2/4. 4,000 0 60 .. 132/ - 7/6 la in., 1/32i in., 2/6 and LEAK, 7/6 7/6 REGULATING RESISTANCE CRYSTAL DETECTOR SKELETON BUZZER VOLE% DRY BATTERIES Lowest prices. Mounted on white porcelain base. Mounted on polished Prompt deliveries. Particularly suitable for varying filament hard-, ood base,Single British Made.Most current in Wireless Receiving Sets. Silk, Cotton and powerful of all Dry Cup Enamelled Wires. Batteries. Recommend - TYPT, Send your inquiries. e d for the illumination of 6L 6d. Wireless Valves. On s. d. polisll- Volex Giant,volt, 11 6 edEbo- 6 16 6 Aero 4.,16 6 nite

6 23 0 Base,

Emperal, a 27 6 Estrerrie;y sensitive for 70. 6d. Crystal pesting. l'ost Free. Price 22, 6d

......

Wireless is attracting all- men.The Amateur is entering the field in great numbers, and he wants to know all about it. He will require Material, Parts, Tools. He will also want to sell surplus- material. " Amateur Wireless" is out to cater for this class of reader, who will beeager for knowledge and bargains. To meet him, use the Sale and Exchange columns, wax which he is sure to search. Rate 3d. per word, 3s. minimum, prepaid. Latest date Saturday mornings.

3- ADDRESS: THE ADVERTISEMENT MANAGER "AMATEUR WIRELESS," 5 LA BELLE SAUVAGE, LUDGATE HILL LONDON, E.C.4.

0,-nr.,,Intasnmnanannnrommezonmononannamontmamonnanonannomononameerzramanramonsimn8D

Printed and Published in England by CASSELL & COMPANY, LIMITED, LudgateHill, London,E.C.4.Sole Agent for South Africa, 'crrriv.i. NO IT'S AGENCY, LIMITED. Saturday, July8,1923t 101

How Wireless Telephony is Made Possible (Pages 110-112)

No. SATURDAY, JULY 15, 1922 Price 3d

Wirelessatthe The Apparatus Westminster City here shown is used School, where mes- in conjunction with sages from Belein, aFrame Aerial South America, 40inchessquare 5,000 miles distant, wound with60 have been received. turns of wire.

Wireless Class at Westminster City School NOTE THE CONTENTS OF THIS NUMBER Plenty of Illustrations Pae Page FORTUNES AWAITING THE INVENTOR 103 HOW WIRELESS TELEPHONY IS MADE A WELL -MADE CRYSTAL DETECTOR 104 POSSIBLE : The Underlying Principles PRACTICAL WORKING WITH VALVES 105 cf the Telephony Transmitter 110-112 A COMBINED CRYSTAL AND VALVE A WINDER FOR CYLINDRICAL COILS 109 RECEIVER ...... 106 CONSTANT HIGH-TENSION BATTERY 109 EFFICIENT EARTH CONNECTIONS . 106 THE WIRING OF AERIAL INSULATORS 107 CAUSES OF WEAK RECEPTION . .112 STARTING WIRELESS :MAKING A MOUNTING COILS . . . . . 114 SIMPLE CRYSTAL RECEIVER. . 108 SIGNALS FROM MARS . . . . 116 Radiograms, Information Bureau, Club Doings, Forthcoming Events, Correspondence, etc. ernateur Wirdess 102 JULY 15, 1922

IEC1ONOMIC. LE CTRI LTD. (1VIITCHELFONES4) I Are not a spasmodic production to meet a sudden demand, but have been on the n If You Require market for over three months, and during NOTE this period 27,000 have been distributed Wireless 32 PACES AND to thetrade, and consequently we have OVER 200 not been able to offer them direct to the ILLUSTRATIONS Apparatus n retail buyer. INCLUDING 1000 per week are now available, and we announce

Send4d. CRYSTAL To -dayforthe & VALVE DELIVERY FROM STOCK RECEIVI NG You postyourorder,orcallatour "E.E.C."List CIRCUITS premises and get them at once.Think

what this means to you-you, perhaps, who have been waiting and are stillwaiting.

Standard resistance 4,000 ohms, double headgear with WARNING! double headstraps,comfortable,highlyefficient,

The wireless boom has been the signal for a number ofin- and foolproof experienced, andIn some Instances, unscrupulous persons 35/..per pair. to jump into the business. DEAL WITH A Special Terms to Traders and deliveries FIRM WHO KNOWS that will surprise you. E.E.C. have 25 years Electrical MITCHELLS Electrical & Wireless Ltd., including 15 years Wireless Experience. Postal Address : McDermott Road, Peckham, 5.8.15. Retail Address :188. Head Office :10, FITZROY New Showrooms : Rye Lane, Peckham, S.E.15. SQUARE, LONIWN, 303, EUSTON ROAD, 'Phones: New Cross 1540/1541.

Branch She-, : Trunk 1/4).GREATBRITAIN'S GREATEST WIRELESS STORE-4)

COLLOY WIRELESS INSTALLATIONS FREEDemonstrationin your home ifin London ELECTRADIX RADIOS area.Let our expert call and advise you. We instill free Brown -Marconi 'Phones. 3,060 ohms,AerialLead-in Wire, rubber covered and give working instruction. Provinces, stamp for list. 51/- per pair ;(000 ohms, 52/- per 3500, 12 yards, 3/-. pair.Complete with cord and tags.Aerial Pulleys.Duralinnin with brass All component parts stocked at lowest prices Delivery from stock. bushed wheel, small 210; medium 3/-, Brown'sL.R. 120 ohm phones with large 3/6 each. ' cords, 37/6 per pair. Earth Clips, Gd. eaeb. 4, CLONMELL ROAD, S. TOTTEN HAM Head 'Phones. S.M. 12/6 per pair,Earth Spikes, 1/- each. with cords. Earth Mats, to/- each. New Single Receivers.1,500 ohms inA. to E. Switch on porcelain base, 2/9. IF YOU REQUIRE THEBEST-INSTRUMENT series, 10/- per pair. N.W.O. D.C.C. D. S.C. ENA.ls IT. L.R. Single Receivers,4/6 each. 22 4/0 6/6 Cords. New, ss 5/0 weArgiaols8,0auLteadtozapecLeviemse,sda.nd Double Telephone 16 516 FAit 819 3/6 each ; Used, 176 each. 28 8/0 1110 4/8 Field Telephone Sets. Portable, ex -AerialInsulators.R.A.P. type with BO 8,6 12'O 62 11/3 33[6 la Best ElastankLin 7/25 Mt Copper. Army, with 100 yards insulated wire, brass ring, light andistrong,0d. each. 64 14/0 15/0 6/6 9/0 per 100 fk. 2716 per station ;60/- per pair. Lightning arresters, 2/6 88 16/6 20/0 7/0 Portable Telephone Sets.Wall type, as 1a/0 27/41 9/0 PrPrices et per pound-Reets A Postage Fre e in polished hard -wood box, magnetoCondensers from 010 to 37/6, all brand ring, quite new, 301- per station. new. CODING & CO., 9, GRDSVENOR RD., TUNBRIDGE WELLS, KENT. Breast Plate Transmitter in ease, 17162 M.F, Condensers, 1/2 each. each. 4 M.F. 51 - Receiving Sets.Trench pattern, cali-Switches.8 -way lever for A.T.I., 11/ - brated Receivers, 651- to 65/- each. each. THE WIRELESS CRYSTAL OF TO -DAY AND THE FUTURE Dewar Lever for panel, 3/8.SO amp. Ditto., with transmitter, £5 each. D.P., 16,- each. Mark 2.B. Receiving Sets, perfectly newTransformers.Telephone, 15/6, Inter - and guaranteed, £7 10/-. valve, 211, Crystal Detectors, 71- each. H.T. Battery Boxes, polished mahogany, "HERTZITE" For Aerials. 7122, stranded copper aerial 6 plug sockets, 7/ - wire, 7/- per 100 ft. Pole Finding Paper, ed. per book. SIMPLE TO USE. NO BATTERY REQUIRED DYNAMOS, MOTORS. CABLES and ALL Price 2/6 post free ELECTRICAL and WIRELESS APPARATUS Mounted' in our Patent Detector, 5/9, post free THE HANDIEST DEPOT FOR CITY BUYERS We can give the best Wholesale Terms for all Crystals BRITISH "R" VALVES 271-."ORA" VALVES 15/- LESLIE DIXON & CO. H.T. Batteries, tapped :-15 volt, 4/- ; 36 volt, 8/-. 9, COLONIAL AVENUE 4 volt Batteries, 6/9 doz., post free MINORIES,-E.C.1 RUSSELL - SHAW (Close to Aldgate Station, Metropolitan Railway) 38, Great James Street, Bedford Row, W.C.1 0 ;

Fortunes Awaiting the , Inventor ? Substitute for the Valve :: New Circuits : Loud Speakers, etc. MANY of the epoch-making inventionscan be increased.This isa line whichSecrecy. by which the world has ,benefitedwill appeal to many since it involves very A further necessity to the commercial have been due to the efforts of dabblers inlittle expense; the cost is a vast amount ofdevelopment of wireless telephony is some science.The prizes in the field of inven-patient endeavour. method of making conversation unheard tion are always more plentiful when a sub- except by the person to whom litis ad- ject is in its infancy, and in this respectAtmospherics. dressed, or, in other. words, attain the same wireless is peculiar, for few subjects have The elimination of atmospherics also re-amount of secrecy as is obtainable on ,the had such rapid development: At the samequires much researchandoffers _greatland -line telephone.A great deal of -re- time, however, itis evident to the mostreward.Everyone who has used a receiversearch is going on with reference to the casual observer that only the fringe hasknowsofthedisturbingeffectofthedirecting of ether'waves- to definite points been touched upon. various cracklings, etc., caused by atmo- sothatunauthorisedpersons may not Discovery is not always the perquisitespheric disturbances.In commercial wire-listen in to any communitations1 of the highly -trained mind, as a study ofless,particularlyintropicalcountries, A necessary: corollary to Ibis .secrecy is manyoftheimportantinventionsofthese disturbances necessitate the expendi-a device which will enable any definite the world will show, and it is the purposeture of a vast amount of energy in orderwireless station to be called uFr at will. of 'this article to indicate to the ordinaryto communicate over short distances.TheAt present there is no device in ekistence amateur some matters that require eluci-atmospherics are a terrible inconvenience,which will enable an exchange to operate dation and improvement which are quite.and a great reward awaits the inventorwith a number of subscribers on its switch- within his scope and, possibly, capability.of a device that will entirely eliminateboard.The method now involves either them. aconstantwatch being maintainedor A Substitute for the Valve. attention at definite times when stations Perhaps the most imperative needis Telephony. ,can communicate.It is qiiite obviouS that the discovery of an efficient substitute for Then in the matter of telephony there asimpledeviceisnecessarythatwill valve detector, or, failing that, a sub-is a number 'of devices required, the in-enable either a wireless exchange to be stitute for the incandescent filament whichventing of which will undoubtedly be tooperated or at least which will enable two istheall-important partofthevalve.the pecuniary advantage of the inventor. stationsto work without- the' danger of The valve itself, wonderful though itis, Firstly, there is duplex telephony.Insignals from any other stations operating is really a very inefficient device studied-wirelesstelephonyitwillhavebeenit and causing false alarms. from the point of view of energy consump-noticed that "cross talk," such as takes tion or the relationship of the input to theplace on the land -line telephone, does notLoud Speakers. output.There are, no doubt, many sub-occur.If two stations are working one From the amateur point of view the stances yet to be discovered suitable forwith the other, the first station has a fewinvention of a goOd cheap loud -Speaking the purpose of detection in wireless reminutes' talk, changes over from send- todevice is a great. necessity.There are, of ceivers beside which the valve will be areceive (the same aerial is Used for send-course, a number of such appliances on puny implement. ing and receiving, the connections fromthe market, but few of them utilise any of But to take the valve as itis, the ques-thetransmitter and the receiver beingthe well-known acousticeffects whereby tion of a substitute for the electron -givingeffected by switches or other means asamplification of sound can be obtained at filament commands the attention of all,desired), and the other station makes what-little or no cost.The present devices are, particularly from the point of obtainingever replyisnecessary. This fromain the main, large -editionsof ordinary something which would give off electronscommercial point of view is a great dis-telephone receivers, or they operate on a without the relatively huge consumptionadvantage; it is often very necessary thatsystem that simply eats, upenergy with no ofelectricalenergyasinthe presentone should be able tointerrupt a con-corresponding increase in the volume of valve. versation, apart from the time which issound.Few of them are anywhere near It has to be admitted that research onlost. acoustically perfect. these lines is limited to a very few, but The present line of research on this sub- There are, of course,' one hundred and there is every chance of the amateur light-jectrunsonwhatisknownastheone devices which are necessary and to ing on some substance or combination of"quiescent aerial," that is, an aerial_ frorriwhich the budding inventor can "apply his substances whichwillgivethedesiredwhich radiation only takesplace whentalents.The few particularisedinthe result. speech or sounds are made in the micro-foregoing remarks are matters requiring phone and which eliminates, the carrierthe Urgent attention of every investigator New Circuits. wave sent out -by many of the presentand experimenter. Another good field for ,the efforts of thesystems.Another method involves the use A final word.Protect all ideas which fortune-hunting amateur is that of devls-of relays automatically to change over theyou think are' of any Value at all after they ing new circuits by which the sensitivityconnections of aerial and earth when ithave received the consideration of a good or the amplification properties of the valve'Is desired either to Send or receive. reliable patent agent. T. B. T. emattur ittraess 104 JULY 15, 1922

A We Crystal Detector

THE detector shown by the photographshort stud projecting /ziin.screwed in.than to turn the screws down from the (Fig. 1) and in elevation and plan byThe other is drilled in. and fitted withsolid. Fig.2 will interest those who have thean ebonite bush at the bottom (not shown The bridge for the ball and Socket joint' time and inclination to make apparatus ofin the drawing) for the terminal which is(Fig. 7) is made from %-in. by 34 -in. brass the best materials and pleasing design..connected to the crystal cup.The ter-strip, drilled out with a /-in. hole in the Doubtless a detector giving just as goodminal base of ebonite (Fig. 4) is held incentre, and countersunk withalarger results as the one here described could beplace by the two terminals, the left handdrill to take the ball.The strip which made in half the time, but there is a goodone being screwed on to the stud. holds the ball:in place must be very care- deal to be said for making something that Fig.5 shows the arrangement of thefully bent so as to get the holes in the is worth looking at when itis finished. crystal cup.It is insulated from the base'correct position.It is best to turn the ball Every amateur has his own particular first and fit the joint to it afterwards. A crystal or combination of crystals that he gauge for testing the roundness of the ball swears by, and thisdetector will work can be made by drilling a /-in. hole in a equally well with silicon or treated galena, piece of sheet metal and cutting out a and with a little modification it could be section of the curve. As will be seen from used with zincite and bornite.The writer the assembly view a small terminal nut is has always used silicon, chiefly because it used finally to adjust the tightness of the is easy to obtain a good sample and be- joint. cause it does not need a potentiometer and Fig.8 shows the constructionof the dry cell. " point."Itis made from No. 3 B.A. The base of the detector in the writer's tappedrod,andhasa/-in.ebonite 4case was made from an iron chuck plate sphere at one end.The other endis casting which happened to be about the -drilled out with a hole for a short rightsize. A brasscasting would do distance.The rod should be a fairly tight fitin the hole through the ball, but pot too tight or the ball itself will turn.A gramophone needle is then solderedin position as shown.A piece of fine steel

Fig. 1.-Crystal Detector Complete.

Ebonite

Fig. 5 Fig, 4 Figs. 4 and 5.-Details of. Terminals, Base and Fig. 2.-Elevation and Plan of Detector. Crystal Detector. Fig. 3.-Details of Cast-iron Base. equallywell,orbetter,and couldbeby two ebonite bushes which are clampedwire is wound on the end of a egs in. drill, finished all over and polished.It is ad-together with the nut and washer at theand when this is allowed to spring it will visable to have a heavy base as it preventsbottom, a short piece of copper strip beingbe found to make a good tight fit on the thedetectorgetting outof adjustmentsoldered to the washer and carried underneedle.The end of the wire can then be owing to vibration.The iron casting wasthe right-hand terminal.The cup is madebent to point along the axis of the needle. turned up tothe dimensions shown infrom a piece of %-in. brass rod drilled outThe object of the needle is to prevent the Fig. 3 and polished only on the boss, theas shown, and the crystal is fixed in placecoiledspringbeing damagedifitis rest being enamelled black; three 'smallwith Wood's metal. screwed down too far.Very good results ebonite studs were fastened in the bottom The pillars(Fig.6)are made fromcan be obtained by bending the point of for it to stand upon.The two holes for0 -in. brass rod.It is probably quicker' tothespring back onitself,thatis,U- the terminals are made in. apart.One drillout holesinthe end and soldershaped, as a very sharp point is not the is drilled and tapped No. 3 B.A., and apieces of No. 3 B.A. tapped rod in placebest for a silicon detector. JULY 15, 1922 105 (Imateur WireteSS The bridge and crystal cup are all en-a %-in. hole in the centre.The side and It must not be forgotten that note ampli- closed in a clear celluloid cover.This cantoparecementedintoabrassringfication is useless as an attempt to make be made by bending a piece of -kin. sheet(Fig.9). Itis possible to make quite aextremely weak signals audible, and unless celluloid round a 1g -in. diameter former, good ring by bending a piece of -A-in.their initial value is such that they can be allowing aat -in. overlap which can besquare brass rod round a former and mak-heard with one valve the note amplifica- tionwillnot help matters much.The function of a note amplifier is to increase 000001101ESOOLI the value of signals which are already strong enough to be audible in the telephones and to enable a loud speaker to Fig. 6 be used.The construction of an amplifier for radio -frequency currents-that is, the magnification of extremely weak and other- wiseinaudiblesignals-isadifficult matter.Here again one stage of radio. IPA bire %f frig in frequency amplification is usually not very difficult, but two or more stages involve much patience and experimental work to &' obtain balance between the valves. Fig. 9 6,1111W,ffig"'"ZiffesMIIIIM A Simple Valve Equipment. A very suitable equipment may consist Figs. 6,7 and 8.-Details ofof aset comprising one radio -frequency Ellgill411111113 Pillars, Framework and Point.stage having a tuned plate circuit, one Fig. 9.-Brass Ring for Cover.rectifying valve with magnetic reaction t;31.nrly Sala) circuit, and one note magnifier. A set of 11 4 this description, when using transformers Fig. 7 Fig. 8 of the plug type, is capable of giving results which are quite loud enough for all cemented up with celluloid solution.The ingalapjoint. The joint should bepractical purposes when used with head side is made of a piece of celluloid 2yi. in.bound up with wire and well soldered. telephones, and without the many difficul- by 6 in., and the top is a I Win. disc with J. F. S. ties experienced when many valves are used. The writer has experimented during the ************************

last few months with an amplifier which has four radio -frequency, one rectifying,

and two audio -frequency stages, and as a PRACTICAL WORKING result has obtained considerable experience HINTS AND of what not to do in the construction and USEFUL NOTES I operation of such a receiver.The advan- WITH VALVES. tage of having three or four stages of radio -frequency magnificationis that the THE' wireless amateur is a person whohour being twelve miles away, the "swish-set need not have tuned -plate circuits, and dabbles more or less sincerely with aning"duetooscillationwasdistinctlymagnetic or capacity reactionis seldom audible. necessary, although these features are an art which is extremely complex and need- advantagesometimesandshouldbe ingmuchknowledge,experienceand Even those experimenters who have a fair knowledge of physics and electricityarranged for even if not used. A pbtentio- patience. The word "amateur" covers meter is necessary in order to control the many kindsof eiperimenters, from theshould not attempt to walk before they can university professor down to those who docrawl.The writer found this out to theoscillation of the set. not know the elementary principles of acost of much material and wasted labour An old rule, usually found to be ccrrect, most fascinating and instructive hobby.and strongly recommends anyone com-is, "Plan your work, then work to your All classes of experimenter are useful tomencing first to work with a one -valve set.plan," but in radio -frequency working this the community and should be encouragedAfter a few weeks further valves can berule must not be too slavishly followed, as much as possible, but it should alwaysadded without having to scrap parts. as invariably a set which operates quite be remembered that those who do not fully well when roughly coupled up on the Adding Valves. bench entirely refuses to work when put understand the apparatus can cause con- in a neat box and decently connected up. siderableannoyanCetoothersinthe It is a recognised fact that any addition district through allowing their receivingof amplifying valves should atfirst beOne of the causes of this trouble is due oscillationmade as note magnifiers.The reason forto effects between the transformers, valves, instrumentstoapproach the etc., and can be overcome to a great ex- point. thisisthat note -amplifying valves have thetransformersconstructedwithirontent by taking great care when planning "Swishing" of a 12 -mile Distant Station.cores, and then windings have no need toto keep the many connections as far apart As an example covering this point, abe tuned to any frequency or wave -length,and as short as possible, and arranging the recent experience of the writer's may bewhereas radio -frequency transformers areradio -frequencytransformersatright angles to each other so that the lines of mentioned.A portable set was fixed upalmost invariably arranged effectively to in a position about twelve miles from atransfer the energy at one wave -lengthforce do notintersect each othermore than can be avoided. A. F. C. largetownwhich,ofcourse,haditsonly.Littledifficulty isexperienced in amateur wireless society, and an attemptadding two valves to the initial rectifying made to hear "The Dutchman" with avalve, but theaddition of a third stage is" WORK," the weekly journalforamateur sometimes difficult owing to howling of themechanics (3d weekly), this week contains seven -valvereceiver. No difficulty was articles on Chemical Rectifiers, Whitemetalling experienced in hearing our, good friend,valves, which isoften caused by inter -Bearings. A Gramophone Stand and Recorl but, in spite of our nearest wireless neigh -oscillation between the valves. Cabinet, Small Bench Drilling Machine, etc. etc. (Inv:7km- Wirers 106 JULY 15, 1922

4.4,0***************v

A Combined Crystal and Valve Receiver

THE receiver about to be described isdiameteris now passed through thein-'phoneswilldo as wellifa telephone not new, butisonly known to theductance coilin the space left betweentransformer is inserted between the 'phone! moreadvancedexperimenter,andits turns12and13,and thecoillashedand 'phone terminals. many advantages are unknown to the new- securelyto the brass rod by means of When testing thereceiver make sure comer in the wireless field.It is as easyadhesive tape.A hard -wood or ebonite to make asa simple one -valve receiverknob is fastened to the end of the brass rod so that the reaction coil can be rotated inside the inductance coil(Fig.3). A variablecondenserofabout.oco5 '111 micro -farad capacity is connected between the aerial end of the inductance (A) and the handle of the seven -point switch, and the 6 2 3 4 5 6 7 tuner is complete.

1.-Inductance Coil. Fig. 2.-Reaction Coil The complete receiver is shown in the diagram Fig. 4.It will be seen that the to a person of ordinary ability. Brieflyaerial is joined to the inductance coil at Fig. 3.-End and Side Views of Mounted the receiver consists of a valve used as an the end nearest to No.rtapping.The Reaction Coil Fitted in Inductance Coil. amplifier ofradio -frequencyoscillations,earth is connected to the atm of the seven - in conjunction with a crystal used as apoint switch, and the variable condenserthat the crystal is correctly adjusted, then detector or rectifier. isplaced between the aerial and earth.rotate the reaction coil; at the same time The Tuner. The grid of the valve (G) is connected totap the aerial terminal with the finger.If An ebonite or prepared cardboard cylin-the aerial terminal through a grid leakclicks are heard in the 'phones each time the aerial terminal is touched the receiver der 4in.long by 3in.in diameter isand condenser (c), which may be omitted wound with forty turns of No. zo double -with verylittledetriment to the signalis ready to receive signals.If no click is cotton -covered copper wire, tapped off tostrength.If used, the grid leak should beheard reverse the connections to the re- a seven -point switch from the followingof two megohms resistance and the gridactioncoil;thiswillgivethedesired result. turns :6,1'2,18, 24, 3o, 36 and 4o.Be-condenser of .003 micro -farad capacity. tween turns 12 and 13 a space of ytin. One connectionofthereactioncoil With careful adjustment of the crystal is left as shown in Fig. 1. (which is, of course, inside the inductancethe strength of signals will be from zoo coil) is connected to the plate of the valveper cent. to 300 per cent. louder than those Reaction Coil. (n), and the other connection is taken toobtained when usingthevalvealone. This is a basket -wound coil of No. 26the telephone terminal which is nearest toAnother advantage of this circuit is that single -cotton -covered copper wire woundthe positive terminal of the high-tensionby simply switching off the filament cur- on a cork rin. in diameter with thirteenbattery (M).Take careful note of this partrent signals can still be received on the pieces of cycle -wheel spoke or blanket pinsofthecircuit. A connectionistakencrystal.This is an asset when the filament spaced equally round itscircumference. from this telephone terminal to the posi-battery runs down in the middle of an in- tive of the high-tension battery, and theteresting transmission. P. T. B. negativeofthehigh-tension batteryis connected to the negative of the filament......

battery (H).It will be noticed that the . negatives of both batteries are joined to

the earth terminal (E). .Efficient Earth. , N The Crystal Detector.

Now for the crystal detector (x).The Connections writer is using a galena crystal with gold . point contact, but a perikon or any other...... crystalcombinationgives equally good TOO greatan importance cannot be results.Itis advisable to use a crystal attached to the earth connection for - Fig. 4.-Diagram of Connections for Completewhich does not require an applied voltagewireless work, as should this not be reli- Receiver. through a potentiometer. A connection isable and thoroughly well made in every taken from the plate of the valve (P) torespect itis impossible, even with instru- The wireissimply wound in and outone terminal of the crystal detector(lc). ments of the highest grade, to get any- round the spokes (Fig. 2) until the coil isThe other terminal of the crystal is joinedthing like first-rate efficiency out of your just of sufficient diameter to rotate insideto the telephone terminal opposite to the station.Therefore, even as the strictest theinductancecoilwithouttouching.one which is connected to the reaction coil. attention must be paid to the insulation of When the reaction coil is wound, leaveA fixed condenser (N) of about .or micro -the aerial so must equal attention be paid about 6 in. of loose wire at each end forfarad capacity placed across the 'phonesto the good contact of the earth connec- connections, and soak the coil in a bathand high-tension battery as shown willtion.There are several forms of earths 11# of melted paraffin wax. When the wax isimprove results.The valve filamentis used in wireless work, but allare not just about toset, remove the coil and-supplied from.a 6 -volt accumulatorsuited to the convenience of the everyday allow it to harden.Afterwards the spokesthrough avariableresistance(j)of 5 class of amateur, who naturally requires can be withdrawn and thecork takenohms. to secure the maximum of efficiency with away. Telephones of from 4,000 to 8,000 ohmsthe minimum of inconvenience and ex- A piece of brass rod r,in. long and in.total resistance should be used, or r2o-ohmvense in the matter of installation. JULY 15, 1922 107 Cr Ws Good earth connections can be obtainedshould bedrilled and tapped yt.in. fromfast the earth lead.First place the drilled by spreading out wire netting over the sur-each endtotake two metal screws aspiece of brass on top of the other, then face of the soil, or a metal plate 3ft. insert the two screws in the holes.Now square, having theearth lead securely laythe brassstrips on thewater -pipe soldered to it, can be buried to a consider- where cleaned, holding them firmlyin able depth in fairly moist soil. position with one hand, the piece with The earthlead,which, by the way, the screws being uppermost as shown in should be as stout and short as possible, Fig.r.The earth wire, after being well may be taken to a water -pipe, preferably cleaned, should now be bound round over to the water -main on the road side of the Fig. 1.-Plates on Pipe. the brass pieces between the screws and input tap.However, this is not essential round the pipe, say about half a dozen so long as the connection is made to the times, after which it should be twisted and cold -waterpipe,, anditcanevenbe Fig. 2.-Component Parts of Plates. soldered at the point Et (see Fig. 3). attached to the pipe over a sink or in the All that is necessary to add the required bathroom. tension in order to ensure perfect contact Having decided upon the pipetobe isgently to tighten up the two screws. used, a portion of this, say about 1% in. This will have the effect of forcing the wide, must be thoroughly cleaned until two brass pieces apart, and as the wire quite bright by means of a piece of emery - passes over the top plate and under the cloth (see A, Fig. x.).It is now necessary water -pipe it will be strained and pulled toensurethatthewire when twisted tight up against the pipe.It is, of course, roundthepipewillbequitetight, not necessary to put too much strain on, thus making good contact.This is very only just sufficient to secure good contact. important, otherwise disappointment will The bottom plateservestoprotect the water -pipe from being punctured by the arise due to noises when receiving and Fig. 3.-Finished Earth Connection. failure of signals in some instances.A screws as they are tightened up. good contact can be made quite easily by On no account should gas -pipes be used securing two' piecespfflatbrass, eachshown in Fig. 2.The screws need be nofor this purpose, as apart from being in- measuring s% in. long by in. wide andlonger than % in. efficient they are dangerous in the event about /Liin.thick.One of these pieces Having done this, all is ready to makeof lightning. D. F. U...... : .

: Insulators : The Wiring of Aerial ...... THE shell -type insulator is quite a goodinsulator ishere shown properly wired;small bobbin insulators as indicated in the pattern for use in amateur aerial con-the substance of the porcelain is in com-photograph; a chain of four of these will

struction, as it is light ;at the same timepression,so that even should the insu-give insulation sufficient for the most ex- it presents a considerable area of glazedlator be shattered the wires would link upacting requirements. porcelain between the wires itis desiredtogether and the assembly toinsulate. Further, not being reticu-not come down.This,if lated, or containing recesses, itis gener-fatal to the proper use of ally kept fairly clean by the rain when ittheaerial as suchon is up in the air and out of reach of pocket -account of loss of insula- handkerchiefs and dusters. tion,isa considerationif The insulator is so simple in design thatstays have to be insulated it would be thought to be obvious how toby means of porcelain insu- Ilse it to the best advantage.In the pho-lators, as the loss of a stay tograph the firstshell insulator is wiredmight resultinthe mast wrongly.First of all, the wires are sofalling.It will be seen that disposed that the insulator is under ten-the single wireiscarried sion, and thisis not the best stress forstraight on after it 'emerges porcelain. from the hole in the insu- If the insulator were to break the con-lator, and the free end is struction would part and let the wholebroughtbackandcoiled thing down. Also the single wire is shownround this, so that all the juste roughly twisted; that isto say, thetwisting is done on the end main wire is twisted and contorted justof the wire whichisnot as much as the tail or free end.' Everyonestressed.In the case of the %rho has had to put up thin wires understrandedwiresthe wrong any considerablestrain knows that anyand the right way is shown. mechanical twist or kink is dangerous inItisbad practice justto Shell Insulator Shell Insulator Bobbin a single wire under tension,while thetwist up the end round the Incorrectly Wired. Correctly Wired. Insulators. slightest "nick" in the surfaceisfatal.run of the wire as shown The way to avoid this danger is to allowon theleft. The cable should be un- Ebonite is sometimes used for aerial in- the run of the wire to remain as straightstranded and each wire bound round allsulation, but, generally speaking, its use as possible, whilst the tail end is coiledthe rest tillall the loose ends are usedis not to be advocated.Eyes are provided, round several times as indicated in theup. Ifshellinsulatorsaredifficulttoand itis simply a matter of passing the photograph next on the right.This shellobtain, a "shackle " can easily be made fromwire through. S. W. G. entatPur Wireless 108 JULY IS. 1922 0 0 0 4. 4. 40 44 0 4 0 0 0 *0 . 0 0 . 0 1 WIRELESS. VI A SIMPLE di

STARTING CRYSTALRECEIVER 0* *40 0* *0 .0 0 4 0*** .40*. 0 0 .. 0 04) 'THE reader will now understand thattube.This will be understood by refer-and the ends of the winding are brought Ithe essential components of the receiverence to Fig.2, and it will be seen thatthrough theholesinthe wooden disc, are the tuning coil, the detector, and thethey are afterwards secured by small brassbeing connected to the back of the ter- telephones.It is not advisable to attemptscrews passed through the sidesof theminals.Thus the winding does not come the manufacture of the latter unless he is tube.The end pieces are made from anyintoelectricalcontactwitheitherthe askilledinstrument maker and has ahard wood, and should be about 4% in.cylinder or wooden ends and discs at any large number of tools at his disposal. Thesquare and 34 in. thick.These are fixedpoint;this,of course, ensures the best other items can be made very simply fromto the discs by brass screws after the coilpossible insulation.Having reached this has been wound. stage the end pieces can be screwed to the wooden discs, thus firmly fixing the coil. VVinding the Coil. When winding a very, large coilitis The Sliding Contact. usual to arrange some form of winding The slider may be made if desired, but apparatus, butitis unnecessary inthisas itis a standard detail it can be pur- case.Referring to Fig. 1, about 6 in. ofchased for about a shilling.It consists of Fig 1.-Method of Fixing Winding. free end of the wire is passed down holea piece of moulded ebonite containing a No.1,up hole No.2, and down holespring and brass plunger which makes materials in the hands of almost any ex-No.3,the end being put through thecontact on the winding of the coil.Usu- perimenter. loop which has been formed inside theally the slider is made to fit a square tube between holes No.i and No. 2.Itbrass rod, as shown in the diagram.A The Tuning Inductance. will be found that this willfix the endpiece of square biass rodiscut about We will remember that the longer theof the wire quite firmly.The winding is7 in. long (that is, the length of the tube wave -length the greater is the amount ofthenstarted,makingeachturncloseand end pieces), and a hole is drilled in inductance required to tune it in.There-against the other.It is essential to keepeach end to take a small terminal screw. fore, before we make our tuning coil, wethe wire fairly tight, but not so tight asTwo pieces of ebonite are next prepared. must decide over what range of wave-to strain it.When the other end of theThese should be made abouttin. long lengths we desire to tune.It is impossiblecoil is reached the wire is fastened off inand i4 in. thick.The width is that of the to wind up one coilto receiveall end piece, the ebonite being fixed to wave -lengths. tore- For example, femora EaON I 17 this as shown in Fig. 3.It will be ceive400metreswave -lengthwe No noticed that a hole is drilled in the might require about twenty turns of middle of the ebonite, a small part of wire on a certain size tube, while to the end piece being cut away to accom- receive23,000 metres on the same %ra CARDBOARD modate the head of the terminal screw. size tube we should require thousands The screw is put through the ebonite, of turns.Obviously we must use one --111711 passed through the hole in the square coil for short wave -lengths and another brass, and the two parts of the ter- for longer wave -lengths, wound pos- minal are screwed up tightly.The sibly with rather finer wire on a larger Fig. 2.-Half Section of Tuning Coil. same process is repeated at the other diameter cylinder.Perhaps the best end of the square brass, and the pieces range of our first coil would be from abouta similar manner to the first turn.Theof ebonite are then screwed to the ends. 35o metres to 600 metres when used withbest wire is double -silk covered, but this, Two terminalsareconnectedtothe the aerials previously described. of course, is rather expensive, and cotton -slider rod, whereas only one is needed. or enamel -covered may be substituted.ItThis makes the appearance of the coil sym- Construction of the Tuner. shouldberememberedthatenamelledmetrical, and the additional terminal may The coil will be wound on a cylinder wireisthinner thansilk -covered, andsometimes be of use in different circuits. 6 in. long and 3 in. in diameter.Card-therefore if thisis employed more turns The coilis now complete with the ex - board postage tubes are very suitable forwill be required to fill the winding space, the purposeifthey are previously pre-withaconsequentincreaseinthein- pared.A 6 in. length is cut off with aductance of the coil.It is not very usual saw and the surface and ends are carefullyto use silk --or cotton -covered wire with a smoothedwithveryfineglass-paper.sliding contact, but this may be done if Three small holes are drilled in each endthewindingisgivenathincoatof of the tube in the position shown in Fig. x.shellac. The tube is then heated in an oven to Fig. 3.-Method of Fixing Slider Rod to End drive out any absorbed moisture, and whileMounting the Coil. Piece. itisstill hot itis given a coat of thick Although a connection is only requiredception of the winding contact; where the shellac varnish.This is prepared by dis-to one end of the winding, it is useful toslider touches the winding the insulation solving shellac in methylated spirits.Thebring both ends to terminals for use inmust be removed.Thisisbest accom- tube should be heated and varnished atother circuits.A hole about3q in.inplished by, rubbing it with a piece of very least three times. diameter is made in the centre of eachfineglass-paper,usingtheedgeofa Wooden ends are fixed to the cylinder,wooden disc and end piece.Two squaresstraight piece of wood as a guide, so that which serve as a support for the slider,of ebonite about in.long are placeda neat line of bare copper wire appears. as follows : Two wooden discs about in. over the holes in the end pieces, beingOnly just sufficient insulation should be thick are cut out with a fretsaw of suchfixedwith small brassscrewsateachremoved to ensure the slider making an size as tightly to fit into the ends of thecorner.A terminal is mounted on each,efficient contact. PAUL D. TIERS. JULY 15, 1922 109 Ontateur Wes

A Winder for Cylindrical Coils 4.404

...... THE photograph(Fig.i)and sketchhave two sets of cones as shown in the A problem that soon presents itselfis (Fig.2)illustrate a simple machinephotograph; a single cone can be madethat of fixing the end of the wire to the which has been designed for winding cylin-to suit the diameters mentioned.It willformer at the commencement and the com- drical inductances of different sizes. be seen that increase in the diameter ofpletion of the winding.This can easily The object of having a machine forthe cones will necessitate increase in thebe accomplished by drilling a couple of winding coils is twofold :first, it ensures abearing height; this explains the blocksholes at the point where the end of the better finish, since the turns are naturallyshown under the bearings in the photo-wire is to lie.The holes should be only at right angles to the axis of the coil andgraph; in the sketch the blocks are, ofslightly larger than the diameter of the itiseasytoobtainatight windingcourse, dispensed with. wire, and the wire should be passed in and throughout, secondly, the time required to A few washers 'at the handle end of theout of these and then run off round the wind the coil is reduced to a few minutes.spindle and a fairly strong spring at the former. Nothing elaborate is required to obtainother end complete this useful appliance. If tappings are required on the coil they the taut wire; a pile of books placed be- To wind a coil, first remove the bearing tween the wire bobbin and the machineand cone at the end away from the handle, is all that is required. slip on the former on which the coil is to The base A(Fig.2)ofthe machinebe wound, put the cone on again, then a should be of soft wood, so that the spindlewasher, spring, another washer, then the bearings B and c are readily screwed intobearing; push the bearing along until the any suitable position for any size of former. The bearings are made from i-in. by flat iron bent as shown and drilled to re- ceivethescrewsandspindle. The spindle is a length of mild steel rod N. in. Fig. 1 in diameter, screwed at the handle end Fig. 1.-Photograph of in.Whitworth. The length can 'be made to suit the longest coil likely to be Winding Machine. requited; a good length should be chosen, Fig. 2.-Details of say t8 in., as the extra length is not in Winder the way.The handle is made from i-in. Fig. 2 by `3-in.iron and a knob rescued from the " junk heap "; both ends of the ironspring is well compressed, and screw itcan be twisted loops, made as the winding are tapped and nuts areused on both dawn.It will be found that the former isis done by taking a turn round a match sides. nowtightlygrippedbetweenthe twoand giving it one or two turns. A wedge The cones n are turned in a lathe and cones. It should be mentioned that thecan be made to fit between the cone and will take any coil from Iin. to 6 in. dia-cone near the handle should be a tight fitbase to hold the coil while this is being meter inside.It is not really necessary toon the spindle: done. J. R. H.

......

. A Constant High-tension Battery

00000* tf .6.464.44 .9 0 ,t 40**400 c>0 THE battery to be described is designed Bend a piece of the zinc into the formsulphate crystals to cover the coil of wire. to give about 3o volts, which issuffi- shown in Fig. 2.Solder a small connect-Treat each of the test tubes in a similar cient to work most valves, but it can being wire to the top.Place the wire andfashion. added to if a higher voltage is required. A stand similar to an egg -stand may be made for them, or they may be slung Zinc VALK together with wire. Materials. RUNIC' Thirty 6 -in.test tubes aboutI in.in VALVE The "cells"should be connectedin diameter(obtainableat most chemists); RUBBER series; that is, the + (copper) connection 3oft.No. 20 S.W.G. bare copper wire; SOLDER( D CONNECTION ZINC of one cell joined to the - (zinc) connec- 3o pieces valve rubber 4in.long; 30 SOLUTION tion of the next, and so on. pieces zinc 4Y2 in. long by in. wide Each cell will give aboutIvolt, and COIL Of by -3-1, in. thick; a solution of zinc sulphate COPPER WIRE ^ the current will remain constant for a long (as used in Daniell cells); a small quan- ZINC time. M. S. B. tity of sulphate crystals. COPPIA 501,nATE CRYSTALS Ors."."."./%1Ws.PArk"e Fig. 1 Fig. 2 Fig. 3 Construction. Fig. 1.-Insulated Fig. 2.-Zinc Fig. 3.-Cora- "AMATEURS desiring to understand the Take a piece of the copper wiretft.Copper Element. Element. plete Cell. principles of the subject and to make their long and twist about half ofitinto a own apparatus could not wish for any- coil(Fig.t).Insulate the straight partzinc into a tube as shown in Fig. 3.Fillthing better."This is what "Electricity" of the wire with a pieceof the valvethe tube half -way with a solution of zincsaysofthe Handbook "Wireless Tele- rubber as shown. sulphate and then put in enough coppergraphy and Telephony." einakur Wtretess 110 111 entatturWtivigss

4 et Aerial Inductance Tuned Condenser Coupling

Aerial Ammeter Tuned Tuning Condenser An article in whichan expert describes Reaction CottBuzzer Switch How Wireless Telephony

clearlyandexplicitlytheunderlying

principles is Made Possible of the telephony transmitter

IN attempting toset out a simple ex- of ordinary breathing.These impulses sound -waves coming from thespeaker's This condition of affairsis created in planation of the apparently mysterious orwavesspreadoutwardsfromthe throat have in this way been translatedthe ether by means of the power valve "mechanism" by meansofwhichthe speaker'smouththroughtheairand into corresponding charges ofelectrical shown on the left of Fig. 2.High-tension humanvoice is transmittedthrough finallystrikeagainsttheearsofthe energy.The medium of transmission has current at 600 volts pressureisfedto "space"-that is,without theassistance the plate of the valve from the generator. listener, through which they are conveyed been changed; insteadof theresultant eitherofwiresoranyotherobvious to the brain. effect travelling at the rate of sound -waves The plate and grid of the valve are retro- medium-it will be found most helpful In the gramophone the human voice is through the air (34o metres per second) it activelycoupled throughthe .reactance

in the first place to consider briefly other mechanicallycopied andrepeated. In moves forward about one million times coil, so that the valve is caused to "oscil- O known methods of speech -transmission in making a record the interrupted gushes of faster-that is, at the velocity of the elec- late."A steady supply of high -frequency order to trace step by step the progress of air from the speaker's throat are directed tric current, which is the same as that of current of constant amplitude is thereby invention leading tothefinalachieve- against a flexible diaphragm, causingit fed into the aerial, and is thence radiated light.

ment of wireless telephony. tovibratesympathetically. A pointed The current variationssocreated are outwards in all directions in the form of

needle on the reverse side of the diaphragm induced into the line wire and finally pass, ether waves of constant and regular form. The Link or Medium. reflects these vibrations is the tracing it at the receiving end, through a coil wound We have now existing in the ether a

Itisascientificdoctrine, which may makes upon a revolving wax cylinder. round the poles of a permanent magnet, condition that is analogous to that of a safely be taken for granted, that there is I Dubilier Sendreceitv Morse -key Headifeleph,on In reproducing from the record a needle where they give rise to precisely similar steady current flowing in the microphone Condenser Switch no such thing as what is called "action is forced to traverse the serrated path of Three Transmitting changes in the strength of the magnetic circuit of an ordinary line telephone trans- Lattice Panel Valves at a distance."In other words, if a dis- the previously made tracing, and inso field.The magnetic fluctuations in turn mitter.The main difference lies in the turbance of some sort or other gives rise doing imparts corresponding vibrations to react upon the metal diaphragm of thefact that the energy concerned is in the toa corresponding effect some distance the sounding diaphragm.These vibra- Combined Telegraphy and Telephony Transmitting and Receiving Station telephone and cause it to vibrate in such formofhigh -frequencyalternations,or away, there must be an intervening link tions are transmitted to the layers of air a fashion that it creates air waves corre- waves in the ether,instead of being a or medium connecting the disturbance and adjacent to the diaphragm and, spreading to thoseoriginally constant and uni-directional current in a spondingexactly the resultingeffect. For example, the outwards, reach theearsofallwithin withthefactthatlightreachesus less" energy.It should be borne in mind applied to the microphone at the trans- metallic circuit.

cause or origin of ordinary speech lies in range of the instrument. not onlyfrom the sun, whichissome that electric effects always travel at the mitter end.The receiver diaphragm is It will be remembered, however, that jn theactionsof the vocalcordsinthe no,000,000milesaway,butalsofrom same speed,whether they pass over a held close to the ears, which receives the order to make thedirect current carry human larynx.As the breath is expelled Air as a Medium. thestars, which are inconceivably more metallic conductor of any kind or whether air waves and interprets them as speech speech -formvariationsthemicrophone from the speaker's lungsitisthrottled In the casessofar considered atmo- distant,andbecauseofcertainother they are radiated "wirelessly" through the in the ordinary way. was used, and, in effect, this caused the or interrupted in such a manner thatit spheric air is the connecting link between good and sufficient reasons, we are forced ether. This velocity of travel is 300,000,000 We are now ready to investigate the sound -waves frontthethroat to release

emerges in gushes or waves of differing the transmitter and receiver.It is a well- tothe conclusion that there must exist metrespersecond,andisdetermined working of the wireless telephony trans- more or less energy or current in the whole frequencies instead of in the steady flow known fact that if an alarm clock is care- some all-pervading medium by means of solely by the inherent properties (elasticity mitter, and we shallfindthatitisa of the circuit by varying its resistance. fully suspended inside a which such light -energy is propagated.It and inertia) of the ether, and not in any developmentof natural glass vessel, which is then has further been firmly established that degree by the properties of any particular the cases that have just

C.W .transmission graduallyexhaustedby this medium, which we call the ether, is conductor. been considered. A -1111'11111111,11'1i11111',1111,Ii1111,1111 from Power Valve. means of an air pump, the alsothe ' vehicle wherebyallelectrical It should be borne in *'

(Constant frequency sound of the bell grows effects are manifested.In other words, The Microphone. mind that,as previously AERIAL 11111111111111111111111111111ithilil and amplitude.) fainterandfainter,and if an electrical disturbance at any point Returning to the case of ordinary wirestate d,analternating finally, as a high degree gives rise to a corresponding effect at some telephony, the action of the transmitting electriccurrent when of

of vacuum is reached, can distant point, the connecting link betwvtx end is due to the effect of air waves from sufficiently high frequency no longer be heard. the two is the ether. the throat beating upon a microphone inis no longer held or bound The next stage to con- When one is dealing with the case of a serted in series with an electric battery. to the metallic conductor, All . hb ee I11 I 111111111 C.W . as Modulated wozoNoNe by the Control Valve. sider is the ordinary line steady direct current through a wire it is The microphone consists merely of a box butspreadsoutwards TRANV-ORmER frequencies I;'Iii,l'Ilii10111,11111,1,1,' uIl Speech telephone,andhere we true that the metallic path is the mnin containing carbon granules, which, itis therefrom in all directions CnOrct have been imposed begintoapproach more focusoftheelectric energy.But the found, offer a lesser or greater resistance through the ether in the con (same frequency but 1111111111'1111,1111111'1111111,111111' varying amplitudes). closelytothe conditions surroundingetherisalsolargelycon- tothepassageoftheelectriccurrent form of waves or ripples that exist in wireless tele- of electro-magnetic energy. flap .110'i cerned.In the case, however, of alter- according as they are pressed more or less TENS.Or. GENERATOR phony. 'Firstandfore- nating currents, particularly those of hi,:h tightly together.One end of the box is If, therefore, we feed to MICROPHONE

most, we are no longer frequency, the metallic path becomes'of closed by a flexible diaphragm which is an aerial a constant sup- concerned with air as the less importance-it isthen more in the vibrated by the impact of the sound waves ply of such high -frequency ResultantRectified Current from A on mediumoftransmission, nature of a path of least resistance through emitted by the throat of the speaker. current,thataerialwill the receiving' phones; butinstead we haveto the ether.In other words, the wire acts The result is that the pressure between become thecentreofa no effect. deal with electricity. merely to focus the direction of the mov- the carbon granules varies with the cor- sphereofenergy -ripples LeorrtnsionSUPPLY T. VALVEFILAMENTS AND Nevertheless, when we ing current. responding movement of the flexible dia- intheether,justasa AERIAL AMMETER MICROPHONECIRCUIT

have adjusted ourselves to Finally, if the frequency becomes high phragm, and the battery current reacts to point on the surface of a EAR TN ResultantRectified the new medium it will be the variation of resistance thus interposed pondwillbecomethe enough theelectrical energy no longer Current from a on found that the "mechan- finds the wire the most convenient path, inthecircuit. Insteadofremaining centre of an area of con- the receiving' phones; Fig. 2.-Diagram of Two -valve Telephony Transmitter ism" involvedisclosely provided speech effect. and, therefore,it commences to rad;,01 steady, the current flows in irregular quan- tinuousripples, as Used on Aircraft. analogous to that already all titiesor "gushes" corresponding to the that a constant supply of Fig. 1.-Diagrammatic Representation outwards in directions through the described. ether itself.This is the condition that ex- sound waves imposed upon the diaphragm. stonesaredroppedinto of Telephony Waves.

Because we arefaced ists when an aerial is transmitting "wire- The original air -pressure variations orthe pond at that point. a. einakur Wtretess 110 111 entatturWtivigss

4 et Aerial Inductance Tuned Condenser Coupling

Aerial Ammeter Tuned Tuning Condenser An article in whichan expert describes Reaction CottBuzzer Switch How Wireless Telephony

clearlyandexplicitlytheunderlying

principles is Made Possible of the telephony transmitter

ment of wireless telephony. tovibratesympathetically. A pointed The current variationssocreated are outwards in all directions in the form of

Because we arefaced ists when an aerial is transmitting "wire- The original air -pressure variations orthe pond at that point. a. stin trur Witttes5 112 JULY IS. 1922 Ifone considers the natureofetherpower valve soastocarry the sound -the plate circuit of the power valve, as waves alittlereflection will show, thatwaves to be transmitted. will be evident upon consideration of the energy -variations can be imparted to such There are many ways of doing this, butdiagram. a "current" simply by varying the ampli-in the transmitting set shown in Fig.2, The effect of this is to vary the ampli- tudeofthewaves. Thegreaterthewhich is a simplified diagram of a two- -tude of the continuous waves emitted by amplitude of each wave the more electricvalve transmitter, the "amplitude" varia-the power valve to an extent and for a energy it carries, and vice versa. tions are imposed by means of a secondperiod determined by the value and dura- The diagram A, rig.1, shows a steadyvalve Failed the "control." tion of the extra voltages derived from stream of continuous waves of constant the choke coil-thatis,originally from amplitude, whilst B shows theeffect ofThe Control Valve. - the microphone. varying the amplitude of such waves by The message to be transmitted is spoken In other words, the action of the control means of impressed speech, the frequencyinto the microphone, and in the ordinaryvalve is to increase or diminish, in sym- of the waves (thatis,the number con-way sets up variations in the steady cur-pathy with the action of the microphone, tained in unit distance) being the same inrent flowing in its circuit.These varia-the originally constant supply of high- both instances. tions are applied across the microphonetension voltage appliedto, the plateof At the receiving end the dictator willtransformer shown on to the grid of thethe power valve from the generator.In simply wipe out the lower half of eachcontrol valve, giving rise to correspondingconsequence,the normal supplytothe wave, with theresult thatinAitherealterations of the grid potential. aerial of uniform oscillations, representing will exist a steady current in the 'phones In the ordinary way these grid changesa constant emission of power at a steady as shown, giving rise to no audible effect;are reflected as current variations in therate,ischanged, in sympathy with the whilst in Br the telephone diaphragm willplate circuit,but on a magnified scalevariations of the high-tension voltage, into be vibrated in accordance with the irregu-owing to the amplifying action of the valve. anirregularormodulatedsupplyof lar currentindicated and will produce A choke coilis,however, inserted aspower, which constantly varies in accord- corresponding sound -waves. shown in the plate circuit of the controlance with the air waves impressed upon The final part of the problem then re-valye, and as a resultthe, plate -currentthe microphone.The electric power so solvesitselfinto finding the most con-variationsare unabletopass, butareemittedis subsequentlyrectifiedand venient method of varying the amplitudereflected back as corresponding voltageappears as speech in the telephones of of - the continuous waves emitted by thevariations, which in turn are applied tothe receiving set. 1. J. HONAN.

o o.

000440o

Weak Reception::Some Afterthoughts

......

N -the article on weak reception in No. 3ohms). So small is this capacity that largeUnwanted Leaks. 1the effect of stray capacity on simplemetal terminals or long wire leads may The grid leak should have a value not crystalreceivingsetswasconsidered.have quite considerable values, and suchmuch greater or less than that already Most amateurs who have commenced withincidental condensers as these would formgiven, and care should be taken that there such a set will sooner or later wish tomight seriously impair the operation of theare no unwanted leaks on the apparatus. increase their range of reception by con-valve.This -possibility would be betterWe, are rather liable to look upon the structing a valve set.One of the mostappreciated, perhaps, if we remember thatebonite mountings of terminals and the satisfactory simple circuitsofthistype300 micro -faradsisthe capacity of twocotton -covering of wire, to take two ex- metal plates, roughly 4 in. byamples at random, as being true insulators V 2 in., and separated by a piece-that is, as offering an infinite resistance SECONDARY of thick, brown paper.It isto the passage of the current.This is by WRONG unlikely that pieces of metalno means ,true.Two terminals close to- PRIMA

WINDI thissizewillfigure in thegether on a piece of moist or slightly dirty GRID connections between the grid Comxrumi:1 TELEPHONE ebonite, or two cotton -covered wires lying C bk and the grid condenser, whereacross one another, particularly as cotton TRANSFORMER they would do most harm, butalways holds a certain amount of moisture GRID the writer has heard of a setunless it has been carefully impregnated LEA., giving trouble becausethewith shellacor some similar insulating wire forming this connectionvarnish, may have a leakage path between E was unnecessarily long andthem of only a few thousand ohms.This ran close to an earth wire.should be particularly borne in mind when This point is not so likely toarranging apparatus compactly on panels arise where the receiving setor in boxes. An Efficient Valve Circuit is permanentlyarranged in In the set illustrated two or three pos- box form, but the amateursible, sources of trouble are avoided by who prefers to make up ausing the telephone transformer shown, is shown here, and probably many readersmore temporary set, so that he may tryand these should be considered when it is are engaged on or are considering thewhat our American friends call a varietydecided whether itis worth while con- prospect of making such.Itis now in-of "hook-ups," usually has his apparatusstructing or buying such a transformer. tended to point out how likely sources ofscattered about somewhat, and he wouldIf the 'phones, which should, of course, trouble may be avoided. be well advised to bear in mind the figuresbe of high -resistance in that case, had To obtain the best results from the setgiven above.He should remember, too,been inserted direct in the plate circuit, shown, the grid condenser C should havethat enamelled or otherwise insulated wirethecomparativelylargepotentialdif- a capacity of approximately .0003 micro -has a capacity twice or three times asferences existing there might break down farads, and the grid leak R should begreat as a similar piece of bare conductorthe weak insulation of the bobbin wind- about 2% megohms (r meghom = 1,000,000similarly situated. ings, particularly when the interior of the JULY 15, 1922 113 Ontattur Wireless receivers accumulates moisture from beingstrength of the signals received when theysubject to no unnecessary de -magnetisation. worn for a length of time.In additionare reversed, butitisbettertouse aAnother point fa-.-ouring the use of a trans- tothis,the continuous plate -circuit cur-telephone transformer,asthe secondaryformer is that neither the capacity nor the rent may be in such a direction as to tendcircuit only carries current when varia-leakage to earth of the 'phones can dis- tode -magnetise them and so to weakentions occur in the plate -circuit current-turb the tuning or potential distribution the signals. that is, during the period of actual recep-in the plate circuit when connected in its This may be avoided by comparing thetion of signals-and so the telephones aresecondary. SIGMA.

THE elimination of the lesstelephoneandtele- 35 accumulator would do44,000.0 graphequipmentof much to make home wire- watts aerialoutput, with

less sets more convenient. RADIOGRAMS a sending range of about

Numerous experimeters 180 miles at 900 metres' have endeavoured to make wave -length. Thecom- use of the usual direct or alternating cur-much happier he will be with his ownpletewirelessequipmentweighsonly rent lighting circuit.The difficulty here isapparatus away from yourover -zealous 125 lb.An air -propeller -driven generator the hum of the lightingcircuit,whichefforts.Besides, he won't send round tofor6volts and 700 volts and a 6 -volt must be eliminated oratleast broughthave you make his set work every timestorage battery supply the necessary cur- down to a reasonable degree in order notone of these minor accidents has occurred."rent.A 3 -valve amplifier is used for re- to interfere with the reception. It is stated We wonder if in No. 8 the writer meansceiving on all wave -lengths between 3co that it is now possible to operate a receiv-"make the valve howl." metres and i,000 metres. ing set and amplifier on lighting current, but so far only meagre details are avail- Wirelessconcertsare now becoming A receiver has recently been installed in able.. The interference has been prac-quiteafeatureofbazaars and similara London restaurant for the benefit of its ticallyeliminatedbybalancingresist-organisations. customers. The innovationisone that ances, grid condensers, and special grid might well be adopted inother places leaks of comparatively low resistance, tele- Taxation is never equable. The positionwhere the customers necessarily remain for phone transformer in the output circuit, some time. and a crystal detector instead of a vacuumin wireless isthat the person possessing tubedetector. a home-made crystal set with a telephony range of about fifteen miles pays the same According to Dr. Charles P. Steinmetz, is mown amount as the owner of the most elaborate engineerofthe A receiving set has now beeninstalled thechiefconsulting set with a range of zoo miles. GeneralElectric Company, U.S.A.,the in a London picture hall, andthe pro - ether is non-existent. gramme includes such items asmay be wireless broadcast. A greeting was sent to all nations from The beam oflight and the the children of Wales on the morning ofwave, he says, are merely due to changes Part of the overture and the principalJune 28 by wireless.It was arranged thatin a field of electrical force, occurring at fixed intervals.A wireless station sends items in a new musical play, which willthe message should be wirelessed before In doing so it throws out a not be seen on the stage until the autumn,dawn from LeafieldStationinOxford-out a sigrial. were broadcast on Friday last.The trans-shire.This station has a wave -length offield of force which extends to the receiving station. mission took place from Marconi House,8,750 metres, andisoneofthe most the artistes being Miss Florence Smithson,powerful in the world. who will take the principal part in this Fears are expressed in the musical world new production, and Mr. Emmett Adams, that people who can listen by wireless to The post office administration of Ger-great singers will cease to attend their the composer of the piece, which will bemany has entered into an agreement with known as "Lumber Love." concerts.The gramophone, however, has a news distributing agency for the circula-proved that the reverse of this might be tion of market prices of stocks, prices ofexpected. In an article in "Electrical Times andmaterial, and so on.Subscribers to the Lighting" on selling receiversets someservice pay 4,000 -marks per annum to the adviceisgiventotheretailerofthepost officeforinstallation and mainten- Arrangements are being made by the method he should adopt with the prospec-ance and a subscription for the news ser-Air Ministryforbroadcasting meteoro- tive customer who wishes to listen -in forvices to the press agency.Reception oflogical reports to enable the agriculturist too long a period.The recommendationsnews services which are notsubscribedto plan his work in accordance with the are as follows :" (t) Give the only pair offor is partially prevented by changing thesuitability of the weather. connected'phonestosomeoneelsetofigures, which have to be decoded by the Three kinds of messages will be sent listen; (2) disturb adjustments; (3) let thesubscribers entitled to the particular ser-out : customer try to adjust; (4) have a twisted vice.The apparatus consists of a single - I. General inference, which deals with connection in the aerial and earth leads, wireaerial and asingle -valvereceiver the whole country.This will be wire- and trip over them; (5) try other pairs ofsupplementedwherenecessarybytwo lessedtwicedailyat9.15a.m.and headphones; (6) walk rapidly away afterstagesofaudio -frequencyamplification. 8 p.m., and will be in ordinary language. adjusting.The alteration of capacity willAll apparatus is enclosed in sealed cases, 2.Codified messages giving fullde- in many cases upset the tuning; (7) tapinspection windows being provided so that tailed information as to particular areas. the valve or crystal;(8) make the valvethe condition of the tubes may be readily These will be issued three times a day, oscillate, or start the testing' buzzer;(9) ascertained. at 9 a.m., 3 p.m., and 8 p.m. earth the 'phones by touching one of their 3.Synoptic messages,alsoin code, giving full particulars received from the terminals; (to) connect a different set and Increasingadvantageofwirelessis repeat the performance." seventeen weatherstations throughout being taken by jewellerstoobtain the the country. The article continues. "The `free enter-Eiffel Tower time signals. tainment for nothing' brigade considers these as unadulterated annoyances-they An amateuratCroydoniswakened are excellent training for the ultimate cus- There has been installed on one of thepunctually at 6.3o each morning by the tomer, who will not be slow to realise howLondon -Paris aeroplanes a combined wire-first call-up at the aerodrome...... entattur Wireless 114 JULY 15, 1922

OUR INFORMATION BUREAU

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to use two pieces, and these may be fastenedtive terminal of the battery, so that when SHORT ANSWERS together with a couple of bolts, afterwards E. I. R. B. (Liverpool).-You have sent ussecurely lashing the joint, or, in place of themounting there will be no confusion.- some crystal -detector drawings but no namelashing, iron straps may be fitted and drawnL. B. P. (Birmingham). or address, simply your initials.Will youup with bolts. kindly communicate with us ? S. W. (Ripley).-There is no such apparatus Licences C. M. L. (Felsted).-Yes, but the note heardas you require actually on the market, but it SIR,-With reference to the recent state- will be of very low frequency. (268) would be quite possible to have it made.It J. S. (Kilmarnock).-(r) Ear pieces of headwould necessarily be costly and also delicatements concerning the proposed increase of telephones are connected in series so that eachand, moreover, would have to be the subjectthe "listening -in" licence fee, I think it ear piece of a 2,000 -ohm. pair is L000 -ohm.(2) of a certain amount of experiment. A valvewould be far better to allow about five A crystal set will receive telephony, music, andor valves would have to be employed together minutes' advertising at the beginning of spark signals.(3) It is best to use a lead-inwith sensitive telephone apparatus.If you wire of about the same gauge as the aerialare likely to proceed in the matter we may beeach broadcasting programme. This would wire.It need not necessarily be continuousable to provide you with suggestions as to thenot only help to defray the cost of broad- with the aerial, but the joint must be sol-lines it should be constructed upon. casting, but would enable the majority of dered. (93) Motors (Strathspey).-No, an ignition coil"listeners -in" to adjust their instruments H. Vic. (New Brighton).-Your oblong in-is useless, though it can be used for trans-before the start of the concert. ductance would be quite satisfactory if themission purposes over short distances.What corners were slightly rounded to prevent sharpis generally termed the crystal is simply a Increase in the licence fee would either bends in the wire.(rig) crystal of a certain mineral (of which there arespoil people's interest or incline them to W. IL (Hull).-The subject of your lettera number), and which possesses the propertyinstall more simple apparatus.I under- will be dealt with in an early issue. (216) of only allowing the electricity to pass thestand that the cost of the scheme is to be A. L. (Lampeter).-We thank you for yourpoint of contact between the crystal and some notes concerning electrolytic detector, and ifother conductor in one direction.You willcovered to a great extent by the purchase you will complete your set and then send infind some very informative articles on theof apparatus, therefore that which will a full description of the detector, and whethermatter in current issues. bring in the bulk of the broadcasting ex- it compares favourably with a crystal detector, we should be pleased to consider publishing it. penses will certainly not be the simple An article will appear shortly on the con- 0crystal sets, as these can be quite easily struction of telephone transformers. (217) constructed with the aid of the various M. H. R. (Chester).-An article on rewinding CORRESPONDENCE handbooks on the subject,or, as in the ordinary receivers appears in this issue. (185) writer's case, "The Amateur Mechanic."- G. W. D. (Liverpool).-(a) A crystal set will receive telephony within a range of about Mounting Coils C. H. B. (South Tottenham). fifteen miles.(b) High -resistance -'phones are SIR,-Apointoftenoverlookedby commonly used.Suitable resistances are 2,000 amateurs when winding and mounting Appreciation ohms each receiver.(ion) SIR, -I should like to take the oppor- C. W. R. (Gillingham).-Use reaction coup-slab, honeycomb or basketcoilsisthe ling from " plate circuit " to grid circuit, asnecessity of ensuring that all the wind-tunity of stating, that as one who has had shown on p. 14 of AMATEUR WIRELESS. Grid ings proceed in the same direction.Re-no previous knowledge of electricity or condenser, .0005 microfarad or .5j a r.Youversed windings in a tuner result, exceptwireless, how much success I have been will require a larger aerial inductance of about able to obtain from the instruction given 5,000 to 6,000 mics. (approx. aerial capacityunder certain conditions, in weak recep- .00i mf.), 5,000 mic. inductance for primary,tion or total. absence of signals. Unlesson pp.io andi iof the first number of or condenser in series up to .005 mf.Secondarythe direction of the winding in each coil"Amateur Wireless."I have made the set will have to be greater in value, or else in-is known at the outsetitisadifficultas described and have had wonderful re- crease capacity across it to .002 mf.Vario-matter generally to ascertain it. sults, using a telephone receiver with a meter coilisnot required with reactance The fol- coupling.Forreception,lesswires,lesslowing is a simple method, however, littleresistance of 4,000 ohms in each earpiece. capacity, less atmospherics and interferenceknown toamateurs, which never fails :-DEVON. from stations near at hand on other waveAttach the ends of the coil to the terminals Interference: A Warning lengths. Aerial coil 12 in. by 6 in. 20 S.W.G.of an ordinary flash lamp battery. d.c.c. several tappings.Primary coil 6 in. by Put SIR,-Perhaps you will allow me to say 4 in. 24 s.w.G. d.c.c. several tappings.Second-a knitting needle or iron rod through thea few words to some of the newest recruits ary coil 6 in. by 5 in. 26 or 28 S.W.G. d.c.c.coil, and arrange thisso thatitpointsto wireless with reference to the trouble several tappings. (207) approximatelynorthandsouth. Nowof the oscillating valve.I should like to B. F. J. S. (Worcester Park).-As far as wepush a compass under the end of the rod have been able to ascertain, there is no com- remind them that it is within their power pany with the name you mention. farthest from the battery, and the mag-absolutely to ruin any broadcasting that F. J. W. (Redditch).-The use of fir is gener-netism in the rod, induced by the flow ofmay be done- simply by the mai-adjust- ally advocated for wireless masts, though any current round thecoil,willcausethement of their reaction coil. straight -grained wood willserve.An im-compass needle to be vigorously deflected portant point is to use wood which is as free A small receiving set when itis in a from knots as possible.It is quite feasib eto the right or left, according to whichstate of oscillation, of course, is a small way the current is flowing in the coil.transmitter, and Ishall not be accused By simply changing over the connectionsof drawing the long bow when I say that Ask A.W." for Cassell's to the battery when necessary the coils canitisperfectly possible to hear a single be arranged so that the compass needlevalve receiver at a distance of five miles, List of Technical Books. will be deflected in one direction only forand it may very seriously interfere with each coil.When this is done the coils aretelephony at a distance of two miles. It is gratis and post free. alluni-directional,andasmallknot What happens when one is working to should be placed in the lead to the posi- (Continued on page 116.) JULY 15, 1922 115 tnateur Wes

CHARGE YOUR OWN ACCUMULATORS AND SAVE youREcEivEz) TIME AND MONEY. AVE The Stevens" Accumulat r Charging Board will do this fot OUR ,ea with perfect safety from your House Supply p ovided it is direct Current. S ecificatt n.-Polishedhardwoo NEW COMPLETE ILLUSTRATED use beard, Ammeter c.-6 amps., Switches Resistance.Lampholders and Terfinals. Starld irdsize tasillustrated), charging up 11 CATALOGUE 4 amps , acc,ading to supply volt- of Wireless Apparatus and Accessories ? If not, age.Other sizes made to order. Full huartieti:ns with send 3d. and a copy will be - Every Board. - POSTED BY RETURN Price 39/6 carriage paid. Cash, with Order to the Makers: Please4rmention " Amateur Wireless." C. H. STEVENS & CO., HAMBLING, CLAPP & Co. 8, Fenchurch Buildings. Phone 8806 Gerrard. 110, STRAND, LONDON, W.C.Z. LONDON, E.C.3.

CONDENSE it S Single Valve Tune;-, £5 103. 0015 Set of Parts 25/- Assembled 30/- 300-1,100 metres, for broadcast

'001 19/-, ,,, 24/- receiving

The "TRAFFORD" RECEIVER -0005,, 12/13, 15/ - Vernier.- ...3/- 4/6 Filament Resistance 4/6, Valve HoldersCrystal Sets £2 10s. Sintle Slide Tuner, Condenser, Super -sensitive 1/6, H.T. Batteries 3/6, 15 volts. Switch No. 1si-CrystalDetector,AerialandInsulators, Single Valve Detector Panel, 25/- Terminals for Earth, Aerial and Phones.Mounted Q5j. Studs 1/6 doz., Arms 2/. on Polished Mahogany Base ...Pricela' W.C.2I Tuner with graduated radialscale, Super. B. L. HOUSTOUN, 65, ENDELHONEL'P REGENTLONOON,4911. No. 2e-sensitive Crystal Detector, Condenser, Termi- nals for Aerial, Earth and Phones, on Ebonite Panel.Enclosed in Handsome Polished Mahogany Cabinet with Snap and Handle. Compartment for Phones. Price (including Aerial 60/ and Insulators) WE DON'T WASTE YOUR IME. VALVE PANELS, We hold good stocksof everything Wireless, and make Parts.- NMENIL 17,ZESrIZ CONDENSERS,eta it our boast that every letter has attention Phones, 1,400 ohms, WITHIN 24 HOURS. For Above Sets.- 3111t.per pair. KEEN PRICES TR 4 DE SUPPLIED Complete Lists two stamps. ELECTRICAL SUPPLY STORES, ADDlE g HARTLEY, Carver St., Old Trafford, Manchester 5, Albert Terrace,King Cross, HALIFAX.

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= -_--,- WORLD'S OUT TO -DAY , .= E= THE CONSTRUCTION OF WIRE- -WIRELESS- LESS RECEIVING APPARATUS E---- _E EXHIBITION AND -a' By PAUL D. TYERS. = -1-= = The only book which tells you HOW to MAKE ALL the PARTS of a _--E-- CONVENTION Valve or Crystal Set. E -Z- Inductances - Resistances - Condensers - GridLeaks - High -Tension = = will be held at the = nattertes-Detectors-Potentiometers-etc. :-...-- In fact, EVERYTHING you wish to make. No Lathe or expensive tools E HORTICULTURAL HALL = required.Essential to alt who wish to make their own sets. E = PRICE 1s. 6d. Net.(Post Free.) WESTMINSTER, LONDON, S.W.1. E E. EiiiiiiiitiiiiiiiiiiiiiiiiiiniiiiiiiIiiiiitnimiliiiiiiiiiiiiiiiiiiiimiiiiimminliniiiiiiiiiiiiiiiiiiiiilimininE SEPT. 30th TO OCT. 7th E OUT ON JULY 19th (SATURDAY) (SATURDAY) E = This will be the most representative Wireless Exhibi- WIRELESS VALVES SIMPLY tion ever held in Great Britain. EXPLAINED This Exhibition has the full support of the whole By JOHN SCOTT-TAGGART, F.Inst.P. of the trade. Over 50,0oo copies of John Scott-Taggart's books have been sold by us in Only BRITISH allied and kindred trades are entitled three months.There is a reason.This new book from his pen is largely an abridgement of his "Elementary Text -book on Wireless Vacuum Tubes, to make applications for stands. which has had a phenomenal success. The price of this simple book has been cut down to a highly competitive figure, and is based on the prospect of very large sales, Applications should be addressed to -- ORDER AT ONCE. THE MANAGERS, PRICE 2s. 6d. Net.Cloth, 3s.(Post Free.) BERTRAM DAY & CO., Ltd., Official Advertising Agents for THE WIRELESS WORLD, RADIO PRESS LIMITED, 9/10, CHARING CROSS, S.W.1.Gerrard 8063-4. If 35, Norfolk Street,- London, W.C.2. _54 71111111111111111111111111111mMIIIIHOIIIII111111111111111111111111111111111111111111111111111[1111111111111111111111111111-: entateur Winless 116 JULY 15, 1922

(Continued from pager4) is the strange fact that these people whoourselves.It is true that evolution on the a faint station ,is this :You are strainingmake such noisesare absolutely incap-red planet has gone forwardtoafar your ears when all 'of a sudden it is justable of hearing the telephony -you can'tgreater extent than on the earth, -and this as though somebody litad blown a loudhear telephony with an oscillating valve -gives colour to the idea that there may whistle in your ear, and itis quite im-and yet they sit there and howl peoplebe astronomers and otherscientistson possible to do any more work. down who are engaged on some seriousMars possessing instruments of a precision There is another side to this -if anybodyexperimental work. and accuracy, not to mention power, far will look at the licence granted by the There is just one hint -if you are un-greater than any we are capable of con- P.M.G. he will see that one of the condi-able to control the oscillationsof yourstructing. Even so,as we said before, tions is "that the apparatus will be ad-valve just for once let your good mannershow are they to make us understand their justed in such a manner that it will notovercome your curiosity and leave the twomessages and how are we to acquaint them cause interferencewith otherstations."experimenters in peace. -J. B. (Bradford).with the fact that we have done so ? There is also the matter of courtesy.If In the writer's opinionitisquite as one saw two people talking together,it Signals from Mars possible that our other near neighbour in would not be considered the best of good SIR, -Commenting upon the article onspace -Venus -is inhabited; but asthis mannerstoimmediately make suchainterplanetary communication that appearsplanet is in an earlier state of evolution noise that it would be impossible for any-in the issue of "Amateur Wireless" ofeven than ourselves the possibility of its body to hear himself speak.Then thereJuly r itappearstothewriterthatinhabitants ( ?) being able to communicate the initialdifficulty would be the prac-with us has apparently been ruled out. PREPAID ADVERTISEMENTS. ticalimpossibility of decoding the mes-Considering, however, that Venus is almost MonthlyCompetition,Free. -40-f aerialmast. sages.For example, mysterious signals Particularsandlist,zd.-F. Armstrong,Wireless exactly the same size as our own globe, Mast Works, Weybridge. [3 have already been noticed as apparentlyand that she is always enveloped, as the Newtonian Wireless Factory. -2,000telephonere- ceivers, single 215., cords Is. 6d.; double, with headcoming from space, but even supposingearth also is,in such a cloudy envelope band, 405.-15-15, Whitcomb Street, W.C.z.Regent that they were actual communications fromthat even her rotation period remains in 843. Newtonian Wireless Factory.-Reelinsulators, the inhabitants of Mars, how are we todoubt, it seems rather premature to assume samples, 6d. each; condenser plates, 3d. pair; crys-decipher them?Their language would be If tal cups, 4d. each; ebonite inductance sliders,rod. that the silvery planet is uninhabited. each; 3 by 72 ispiralwoundtubes,9d. each; "Greek" to us as ours to them. it were possible for us to view our own shellacinsulating varnish,rod.per bottle ,square rods, drilled, 13 in. long, 6d. each. -13-15, Whitcomb Then again, there has always been anglobe from space, or from another planet, Street, W.C.z.Regent 643. extraordinary predilection in the popularthe earth would appear to be enveloped in Newtonian Wireless Factory. -Completecrystal set for making up your own apparatus, comprising allmind in favour of Mars as being the onlyclouds in the same way as her sister planet materialsandz,000 -ohmreceiver,reducedprice, planet of the solar system that could pos-does to us. 435-6d. ; carriage,25.-1, 1g,WhitcombStreet, W.C. 2.Regent 643. sibly be inhabited by sentient beings like The sun, the great centre of the solar Sale. -Wirelessvalveset, with valve, telephones, andallaccessories. Justpurchased,roros. system,is continually throwing out into Unused. Price, O. -Wilkinson, Solicitor,28,Bed- HIGH CLASS ROTARY VARIABLE CONDENSERS. space electric currents far greater than any ford Row, W.C.r. [1s 'coos in Polished Cabinet, 4' Y 4', Ebonite Engineers° Breastdrills.-Two-speed,ball -bearing, Top and Knob, Ivorine scale, o*-r8o°, 16'6 signals which could be sent from another spirit -level, self -centering chuck;manufac- Ditto for Panel (scale extra) 10/6 planet by man-made wireless, and these turer'slist,39s.6d. Indispensable edperimenters, '0004 inCylindricalBrassCase, Lacquer finish, 195.9d. Hand -drills, chuck, balanced pinions, Ebonite Top and Knob, Ivorine scale ; a very would have the effect of "jamming" any 9s. gd.Genuine bargains. -139, London Road, Man- handsome instrument ... 16/ - signals from Mars or Venus, even suppos- chester. [2 s CrystalDetector withBall and Socketadjustment on Special this Week. -Guaranteedtuningcoils,is ebonite base ... 5/6ing we were capable of decoding them. x4 formers, mounted mahogany,25s. Detectors %VEATHERALL dc Co., 28. Woodbridge street, complete on ebonite base, 5s. 6d. -Fox and Worsf old, Clerkenwell. London, E.C. Estab. over so lea,. Theagitationofmagneticneedles 182, Albany Street, London, N.W.List stamp. [3 s Aerial Wire,16 gauge hard -drawn copper, rooft. duringthe"magneticstorms"which 3s.gd., carriage paid. -Gibson, Somercotes, Derby- occur during sunspot maxima are only the shire. [4 s MastRope,realManila,maximumstrength, REMARKABLE Offer in WIRELESS SETS.greater and more noticeable manifestations lightness, zain.thick,robft.long; price,4s.6d., We have in stock a number of MARCONI TRENCH of whatiscontinuously going onun- carriageIs.3d. -Gibson,Somercotes,Derbyshire. WIRELESS SETS, Crystal Type, 50 Watt complete Established 1849. Telephone :No. 19 Somercotes. [4 is less Headgear.Bent to any address for £10 10s. each. heeded.Indeed, there is a theory which New Voltmeters,o-6,5s. Other readings sup- Honestly worth double.Cannot he replaced at twice goes so far as to assume that the sun has plied.-Ackrill, 63, Barr Street, Birmingham. [5s our price.Secure your set berore all sold. Filament Resistances, 4s. ;radial switches, ebonite no real "heat rays"as we understand mounted, 5 -way 50., zo-way 75. ;switch arm, 25.6d. ; DAVIES,75, Dale Street. LIVERPOOL. mounted knifeswitch,S.P.,2s.3d. Post free.- them, but the "rays" or "waves" when Micklewright,Ltd.,Manufacturers,Perivale Lane, they leave the solar surface are electrical Alperton, Middlesex. [6 s Receivers. -A largestockoflow -resistancere- waves, that is, waves of electrical poten- ceivers,tootozoo ohms, each ex -Post Office and SITUATIONS VACANT Government watch pattern,forsale from3s.6d. REQUIREDby Wireless Engineers forcertainareas, tial, quite cool in themselves, but capable each, postfree.Wireless double head receivers, London and Home Counties, and in every principal town, of being turned into heat rays on passing 4,00o -ohm, London manufacture, from 35s. each, post to act as Sales Agent for the sale of Wireless Apparatus and free.Everything stocked for the amateur assemb- Receivers.Splendid Terms.Small deposit against Sample through a resisting medium. This medium ling his own apparatus. -W. H. Agar, 8, Finsbury Outfit.Enthusiastic amateur preferred.Apply in writing - is found in our atmosphere, which converts Avenue,E.C.2(nearLiverpoolStreet). 'Phone: London Wall 3305. [8s BOX A, COMMERCIAL PUBLICITY COMPANY, electric energy into heat. Watch TypeReceivers. -Limitedquantity,P.O. pattern,suitablerewindingforwireless,5s.6d. 59, NEW OXFORDST., LONDON, W,C.1. This theoryiscertainly borne out by each; perfect. -R. Heaton, z9, Ludgate Hill, E.C.4. the results of Very's researches into the (7 s 25 Sets ex -Government wireless double headgears, DELIVERY BY RETURN-heat of the moon. 120 ohms; complete with cords, perfect order, com- It paratively new, ars.9d.set, post free. -E. Martin, is well known that our satellite has' 2, Frenchem Road, Portsmouth. [9 s SPECIAL WIRELESS LINES practically no atmosphere, although some CONCERT HONEYCOMB COILS. -Waverange 300 recent observers claim to have discovered WIRELESy AMATEURS AND RETAILERS to Soo metres.Very efficient.Hand wound. PRICE per evidence of air in the valleys.The fact pair,primary and reaction -Unmounted51-,Mounted PARTS SUPPLIED FROM STOCK 11/6.Post6d. that there is no air on the moon, accord- Littfree.Condenser Plates, VS don.pairs(post3d). FRASER, SENTINEL Ho. SOUTHAMPTON ROW, LONDON VALVE LEGS -withtwo nuts and washer -lacquered,ing to M. Very's careful experiments with 21d. each.9d.per set of 4. very sensitive instrumentS, shows that the Special terms to the tradesurface temperature of the lunar rocks, Send for list, even under the full rays of the sun, does WHOLESALE ONLY Actual Makers: CHAMP, KAY &CO High-grade Cabinet Work to your own design not rise above about 3o deg. to 4o deg. F. in the best materials only Electrical Engineers, 92, Saltisford, WARWICK. Were the rays of the central luminary Prompt Delivery. Satisfaction Assured Write for Quotation TO WIRELESS EXPERIMENTERS. PATENT YOUR really heat rays, atmosphere or no atmo- ADDIE & HARTLEY INVENTIONS. sphere, the rocky surface.of our satellite They may prove very valuable.Particulars and consulta. should attain the temperature of boiling Carver Street, OA Traffer0, Manchester tions free.BROWNE & CO.,Patent Agents, 9, Warwick Court, Holborn, London, W.C.r.Est. 133o,Tel. Chancery 7547. (continued on page 118) JULY 15, 1922 117 emateur 4419.55

WE CAN SUPPLY YOUR WANTS FROM A TO E A.E.G. & Telefunken Valves,tested10/6 Sq. Brass Rod, le Xi'X 3'... 9d. Valve Holders, Screwed Legs & Nuts1/6 Enamelled Wire, for Inductances, -RADIO EXHIBITION-4 Condenser Vanes, Aluminium (accu- 23 gauge, * lb. ... 1/6 rate size and gauge), per doz. 1/0 Crystals (special selected), Bornite, Do., Large Spacers (true twooe) 6d. Carborundum, Silicon, C. Py- Do.,Small Spacers (true to .00r") 4d. rites, etc. etc. 6d. Do., Scales Ivorine, o to 1800... each 1/ - Crystal Cups, Brass, with Fixing Do., Ebonite Tops and Bottoms WIRELL vitaioN (bushed)1'3 Fusible Alloy (for fixing crystals) 6d. Inductance Tubes, leX3' ... 6d. Hellesen,36 v.H.T.Batteries, 0 22 X 4' 9d. with Plug ... 8/8 Headphones, Double, 2,000 ohms, Sliders, Ebonite, with Plunger ...9d. AdjustableBand,excellent Aerial Wire, Stranded, 7/23 too' 4/6 for speech and music ... 35/ - The event of the year for all Do., Egg Insulators (high insulation)8d. FilamentResistance panel mounting4/ - Do., Reel ,, best quality 4d. SwitchArms, laminated, with bush RADIO ENTHUSIASTS Do. Pulleys, Aluminium, with cord1/8 and spring .. 2/6 DEMONSTRATIONS CENTRAL HALL Panels, Tuners, Transformers.Postage extra. Demonstrations Daily. CONFERENCES WESTMINSTER THE og,ce t Showrooms CLUB MEETINGS. Etc. SEPTEMBER 2nd to 8th ESSEX WIRELESS CO 499, GROVE GREEN RD., Organisers:DALE REYNOLDS & Co., Ltd., 46, Cannon St., E.C.4.(Bank 3477). (Wholesale LEYTONSTONE, E.1 1; Telophone-WANSTEAD 749., (1 min. from Station, O.E.R.)

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4 v.80 ...28/2 6 v.80,, ...37/3 CRYSTAL SETS, VALVE SETS, etc. EVERY 4 v.100 30/- 6 v.100 41/6 NECESSITY & LUXURY FOR THE WIRE- SPEC IALS -2 volt 16 amp.Ebonite cases. -1 only, 3/9 post free. 2 or 3, 3/6 each, post free. 4 to 6, 3/ - LESS EXPERIMENTER. each, carriage forward. Fully Illustrated List of Wireless Goods, post free, 4d. 4 volt 24 amp. in celluloid cases, absolutely new- only 11/9 each.Postageif..

H. D. BUTLER & CO., LTD. WE CAN SUPPLY THE HIGHEST QUALITY GUARANTEED Office: BANK BUILDINGS, 222, GT. DOVER ST., S.E.1 ACCUMULATORS AT THE LOWEST POSSIBLE PRICES (Opposite Boro Tube Station). 144, Works CANON BURY, LONDON, N.1 F. YATES & SON, KLONENSINGTONEN BSS, Telephone: Hop 3029. Teleg.: "Ingenuity, 'Phone London." 'PhonePark 4276Write for lists, (One minute from Notting enclosing stamp to cover postage. Hill Gate Station). WE CAN GIVE YOU DELIVERY AT ONCE

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Single slider 4 in.Inductance, Blocking Condenser. Vernier Var. Condensers '0001capacity 10/-each

Readily adaptable Detector, Highly sensitiveCrystal. 29 f I .0003 - 12/6 Wave - lengthzoo -goo metres, Telephony x3-zomiles. '0005 16/- Mounted on Oak Panel. 11 11 - Supplied ready for Panel mounting Price (with Headphones)£4 10e,

Crystal Detectorson Ebonite Bases 6/6 No. 2.THE "ACME" Glass Enclosed 10/- Double slider3in. by sr} inr Inductance, Valve Panel,complete, less valve 45/- Blocking Condenser, Highly sensitive Crystal De- Firt?,,4 91 tector (glass enclosed), Wave -length 200-1,600 metres, Filament Resistances 4/- & 6/. Telephony 30-4o mules,Mounted on Oak Base, irt highlyfinished: Basket inductances 2/6 & 3/- Price (with Headphones) £5 15s. Resistance Panels- - 17/6 PO H.T. Batteries, 85 Volt(Mahogany Cabinet)- 65/- Inductance Switches(5 stud) - 13/6 No. 3. THE "AEROWAVE" 91 (10 stud) - 1816 ,111 Double slider Inductance, Variable Condenser Porcelain Switches 1/- Blocking Condenser,Special Galena Crystal Detector (Ball- jointed Movement), Wave -length White Earthenware Insulators - 6d. ., 500-1,650 metres, Telephony 3o -4o miles. Compact Aerial Wire,7/22 Copper per 100 ft. 5/- in Mahogany Cabinet.

Best Hemp Rope (20 yard Skeins) 1/. Price(complete with Headphones,

Headphones(High resistance) 35/- Aerial, etc.)£6 6s. WE GUARANTEE THAT OUR WIRELESS INSTRUMENTS & ACCESSORIES ARE OF BEST WORKMANSHIP, MATERIAL AND MANUFACTURE (DEPT. AW), 11, QUEENE.C.4 VICTORIA ST., LONDON, HENRY J. BREWSTER & CO. (Few Doors from Mansion House) Wireless and Electrical Contractors

=11111=1111111111111. amateur Wiroles3 118 JULY IS, 1922

(Continued from page irr6) of the society at their headquarters at thedetecting and amplifying.Speech and music water under a constant and continuous in-Highgate Literary and Scientific Institution. were received from several stations, and by sulation of about I.3 days. Mr. Hogg dealt very carefully and lucidlymeans of a simple loud speaker were rendered with the construction of tuning coils and con-audible to all present.The time passed So If these rays, then, emanating from thetrastedtherelativemeritsofcylindrical,quickly that Mr. Gartland was unable to go sun,areelectrical,travellingthroughbasket and honeycomb coils for various wave-fully into the many other uses of the valve, space at an enormous speed, how can welengths.He showed how a simple one -valvebut the brief outlines which he gave were hope to pick up the comparatively smallcircuit should be connected up and then dealtsufficient to show that the applications of the in detail with the assembling of the variousthermionic valve were only just beginning to disturbances of the ether produced by thecomponents which go to make up such a set.be realised. supposedlyhighly -developedinhabitants Mr. Hogg's lecture was followed with great of Mars orthepossiblyless advancedinterest by those present. Hornsey and District Wireless dwellers on Venus? The lectures on the theory of wireless and and Model Engineering Society Be this as it may, it would appear thatthe construction of apparatus are being con-Hon. ,Sec.-MR. H. DAVY,134,Inderwick there are very many difficulties to be over-tinued, each Friday, until the middle of August. Road, Hornsey, N.8. The hon. secretary will be pleased to, receiveA MEETING was held on Jrily 4th when a set come before we can communicate with orinquiries from anyone interested and to furnishwas " rigged up " and the concert from receive messages from possible inhabitantsfull particulars of the society. Chelmsford clearly heard. of other members of the solar system. Croydon Wireless and Physical " Mr. H. J. Pugh demonstrated a 2 -valve re- Finally, this present opposition of Mars Society sistance -capacity set, the only " aerial " being is by no means the most favourable for one of the members standing on an insulated making the experiment which Signor Mar- (Affiliated with the Wireless Society of London).pedestal with one finger on the aerial terminal. Hon. Sec.-B. CI,APP, " Meath:I-10°r," Brighton Messages were quite clear and readable, coniisundertaking.On August 23rd,Road, Purley. many stations being heard. 1924, Mars will be nearer to us than forA MEETING of the Croydon Wireless and In future meetings will be held at 29, Felix many years past or to come, the distancePhysical Society was held on Saturday evening,Avenue, Western Park, Crouch End. of the planet from us on that occasionJuly 1st, at the Central Polytechnic, Croydon. Applications for membership are invited. being only about 34,000,000 miles on some Mr. A. H. Peakman, a member of the society, very kindly provided two buzzer sets for Morse Brighton Radio Society occasions, so that it' will be readily under-practice, and the members divided into two (Affiliated with the Wireless Society of London). stood how favourable an opportunity forgroups, one consisting of the more advanced Hon.Sec.-MR.D.F. - UNDERWOOD,68, interplanetary "conversations" will be theMorse readers who practised high speed work,Southdown Avenue, Brighton. opposition of the "fiery planet" in 1924. and the other of the less experienced, who wereAT a recent meeting of this Society an in- If Signor Marconi's experiments in thedesirous of improving their Morse reading.teresting discussion ensued, during the course After spending a profitable hour, the membersof which the methods of short-wave reception United States fail on the' present occasionhad an informal talk on innumerable wirelesswere considered.Various useful suggestions we must hope for bettersuccess at thesubjects, ranging from the harmonics of G.N.L. were offered by different members who were nearer approach of Marsin two years'to the date on which broadcasting would com-present and it was ultimately suggested and time. D. W. H. mence, these subjects in particularcallingdecided upon that at the next meeting all Tunbridge Wells. forth some forcible remarks.The meetingmembers who so desired should bring their terminated with a vote of thanks to Mr.short-wave sets along for trial with a view to Peakman for the loan of his instruments. comparing results. The secretary wishes to announce that there As a means of assisting the beginner as far will not be a meeting of the society in August.as possible in the construction of a set capable CLUB DOINGS The next meeting will be held on Saturday,of attaining the best possible results at the Proposed Durham City and DistrictSeptember 2nd.He will be glad to hear fromminimum cost, Mr. Magnus Volk very kindly Wireless Club any lady or gentleman who may be desirousoffered to provide the funds for the con- of joining the society. struction of a set upon these liqes which WILL all interested please write to Mr. GEo. should be used solely for the, assistance of BARNARD (Sec.pro,tens),3, Sowerby Street, North Middlesex Wireless Club members. Sacriston, Durham. (Affiliated with the Wireless Society of London.) Applieations for membership are invited. Hon. Sec.-E. M. SAVAGE, Nithsdale, Eversley Ilkeston Amateur Wireless Club Park Road, London, N.2r. APPLICATIONS for membership of the aboveTHE ninety-fourth meeting of the Club was newly -formed club are invited.Hon. Sec.(proheld on Wednesday, June 28th, at Shaftesbury FORTHCOMING EVENTS tem), Mr. It. W. EMINSON, 2, Station Road,Hall, Bowes Park.Mr. W. Gartland gave a Leeds and District Amateur Wireless Society. Ilkeston. paper entitled " The Miscellaneous Uses of theJuly 14, 8 p.m.Lecture by Mr. D. E. Petti- Thermionic Valve." grew on " Maritime Radio Communication." Birmingham Experimental Wireless Those of the members who have heard Mr. Leicestershire Radio andScientificSociety, Club Gartland on previous occasions were antici-July 17.General meeting, and lecture by Mr. (Affiliated with the Wireless Society of London).pating something interesting, but all were sur-J.W. Pallett on" Continuous -Wave Trans- Hon. Sec.-FRANE: S. ADAsis, ITO, Ivor Road,prised to hear the very good and consistentmission." ' Sparkhill, Birmingham. results obtained by Mr. Gartland on apparatus which he had just brought to the hall, and had TELEPHONY TRANSMISSIONS THE monthly " General Discussions " meetinghad very little time to adjust.Anyone who The Hague, Holland(P C G G). 1,070 was held at-Digbeth, .Institute on Friday, Junehas had the unpleasant experience of bringingmetres.July 16, 3 to 5 p.m. 3oth. a lot of instruments for a lecture, and has Writtle(2 M T). 400metres. July 18, The discussion was opened by Mr. B. A.failed to produce the results intended, will the8 p.m. Matthews. more readily understand how gratifying it is Eiffel Tower (F L). 2,600metres. Each Mr. Matthews' valve receiver was criticisedto be able to record that. Mr. Gartland's ex-afternoon (Saturdays and Sundays excepted). at length.'Several other members then men- MarconiHouse(2 L 0). July12, 5 to tioned difficulties which they had met, andperiments did not fail, but were a great success.5.2o p.m., 6 to 6.2o p.m., and 7.3o to 8.3o p.m. The chief instrument was an altered Mark IIIJuly 20, 8 to 9 p.m.Transmission tests. these were discussed.by the meeting.Severalreceiver, and by means of an ingenious barrel interesting and original ideas were describedcontact switch either one, two, or three valves by members. could be used as desired.This enabled _the ANNOUNCEMENTS The next meeting will be held at Digbethlecturer to show the valve being used for Institute on Friday, July 14th, 7.3o P.M. " Amateur Wireless and Mikados." Edited by The Tierna'rd E. Jones.Price Threepence.Published on secretary will be pleased to hear from intending Thursdays and bearing the date of Saturday imme- members. diately following.It will be sent post free to any partof the world -3 months, 4s.6c1.; 6 months, gd.;ismonths, 17s.6d. Postal Orders, Post Wireless Society of Highgate Office Orders, or Cheques should be made payable to the Proprietors, Cassell & Co. Ltd. (Affiliated with.the Wireless Society of London). General Correspondence is to be brief and written Hon. Sec.-MR. D. H. EADE, Gatra," 13A, on one side of the paper only.All sketches and drawings to be on separate sheets. Sedgemere Avenue, East Finchley,. London, Contributions are always welcome, will be promptly N.2. considered, and if used will be paid for. ON Friday, June 30th, Mr. F. L. Hogg, gave Communications should be addressed, according to theirnature,to TheEditor, The Advertisement the first of his series of lectures on " The Con- Querist's Coupon Available until Manager cr The Publisher, "Amateur Wireless, - struction of Wireless Apparatus " at a meeting Saturday, July 22, 1922 La Bat Sausage, London, JULY 15, 1922 119 Ontateur Wes

noi 1. 7twtw wow serES NI I= Ming Do You CQ .1111 get FL ?

Specially YOUR crystal or valve may be the designed best of their kind-your aerial high for as Snowdon, your tuner perfectly tuned,butunlessyour'phonesare Broadcasting O.K. you won't get maximum " sigs.' Signals come "thumping in" through ERICSSON PHONES. They're built that way:-for never - failing clarity and sensitivity.The magnets never lose their strength and "shorts" don'texist. And they're easy and comfortable to the head.1 BackofERICSSON PHONES i's the accumulatedexperienceofagenerationin. te!ephone manufacture. Write for particulars- HEADGEAR RECEIVERS THE BRITISH L.M. ERICSSON' Designed and manufactured by leading Telephone Manufac- MANUFACTURING CO., LTD. turers.Backed by many years experience.Highest efficiency, Head Office: 60, Lincoln's Ian Fielrds,W.C. concentrated magnetic field, instantaneously adjusted to the ears, comfortable in wear, either receiver detachable from head- band, protected terminals, light weight, twin series cord.

A.T.M. LOUD SPEAKING A.T.M. CRYSTAL DETECTOR RECEIVERS. SETS.Highest Grade.Maxi- Three types of Amplifying Horn. mum Efficiency.Moderate Cost. Ask your dealer for A.T.M. Broadcasting Apparatus AUTOMATIC TELEPHONE MANUFACTURING CO., LTD., Head Office & Works : London Office: Milton Road, Edge Lane, Liverpool. fo, Lincoln's Inn Fields. O MEOW EN MWMII ION III WW1. haphazard purchases till you have DON'T MAKE sent for our CATALOGUE of TELEPHONE DOUBLE HEAD SETS. Cryaittejvar WIRELESS 2,000 Ohms, 32/6 ;4,00B Ohms, 3416.In stack. RADIO, qECTRICAL & MECHANICAL SUPPLIES. INSTRUMENTS, MAKE up your own receiving sets.Our price for complete set of parts ACCESSORIES carriagie paid. coMprising wound inductance with ebonite panel SCIENTIFIC SUPPLI STORES- drilled for 20 studs, necessary studs, ebonite knobs, etc., crystal detector, terminals, wire for condecting.(No eidras to buy ;nothingto mate) 8. NEWINCT3h1 CAUSEWAY, .and. Morns. for List. fiNDON. :SEI. MATERIALS P. H. BOYS & CO., 187, Goswell London, LC.1 We stock everything for the Experimenter who wishes to build his own Set. THE " ESI-FIX " AERIAL Patent applied for FOR TOOL BARGAINS "PIX IT LIKE A CLOTHES -LINE " CALL or WRITE TO -DAY to ; A new "eneisiece" aerial compete with patented continuous insukotion, lead Before buying elsewhere compare our prices. Remember, we have the in tale, mice end socket, straining eye and aajz.st4le had. No joints no .sol- Largest Stock of Tools to select from in London. We guarantee you de, trig, no leaking, no kilter. A ha&uteweatherfiroof: Send cash ro.ri4 order satisfaction, so you can safely shop by post. Bargain List sent post Free. and Secure delivery at once.Length, 50 ft., 12/6 ;75 ft.; .7/6 ;loot., 346. Carriage paid in U.K. Agents wanted. -6, HIGH HOLBORN, GEORGE ADAMS, D.PT. kW. 255 , CHAMBERS & ELLIS,6 & 7, CRAVEN HOUSE, KIHOSWAY, LAWN, W.O..2

1R\T CID PRICES ! ! Condenser Vanes, Aluminium, accurate Size and Gauge per doz. 10d. TO THE TRADE (Special Price for Quantities) DAVIS &TIMMINS! All kinds of parts Condenser Scales, Ivorine 9d. made to order, LIMITED Ebonite Knobs. Drilled 6d. Quickdelivery. Ebonite Sliders, with Plunger .. 8d. Also Gear Cut- ting, [Gear Rob- 34a, York Road, King's Cross, N.1 Brass Rod, I Square, 12'. 5d. ;13". 6d. bing; Experi- Enamelled Wire, 24 Gauge lb. 2/2 mental Work Small Brass Terminals doz. 1/6 done atlowest Strong Spacer Washers, Large doz. 6d. prices.

Small 3 doz. for 9d. POSTAGE EXTRA.QUOTATIONS FOR QUANTITIES ACTUAL MANUFACTURERS. NO RETAIL PROFITS SCREWS AND TERMINALS . A "Nr Da CO 1V 27, LISLE STREET, LEICESTER SQUARE, W.C.2 FOR WIRELESS SETS (Opposite Daly's Gallery Door) Cmateur Wss

PETO'S POPULAR PARTS

THE "SPHINX " 111111111111111111 111111111111111111 COIL HOLDER as shown on illustration 2/9 each We can also supply with band mounting CONDENSER VALUE Complete Sets of Parts for VARIABLE INSIST ON HAVING A CONDENSER ready to assemble Nu Drilling or. Fitting required FULLER "BLOCK" TYPE '0)13 -001 005 0003 *0002 '0001 27:- - 211- 14/- 111- SI- 7/ - Cabinets : ACCUMULATOR 4/9 4/6 4/3 41- 3,9 219 IFOR YOUR WIRELESS SET ! The above are supplied with Ivorine Scale for Panel mounting or Ebonite top The only Accumulator on the market that will hold its charge from 12 4rx 41- for box mounting. to 18 months when not in use. We can substitute Ebonite Bevelled dial in place of scale for 3/6 extra. 4 -volt 40 amp, hours,£1 126. plus 1/3 carriage

'PLEASE STATE WHICH YOU REQUIRE. 6 -volt 40 £2 89, 1/6 Note :-These prices are 33% below those of the actual makers. ILLUSTRATED CATALOGUE (AIW) 6d. 24 PAGES. ALSO LIST OF TRANSMITTING STATIONS. 8,000 Sold. 20,000 still in stock. Details at All Accessories the Amateur Needs. Descriptive and Instructive Pamphlet on request from- The CITY ACCUMULATOR Co. (Dept. 14) 79 Mark Lane, E.C.3 (AT:IMO PETO SCOTT (The Condenser King), ALSO SUPPLIED BY- Selfridge & Co., Ltd.,Wireless Section ;A. W. Carnage, Ltd., 7, FEATHERSTONE BUILDINGS, HIGH HOLBORN, Wireless Dept. ;Barnsley British Co-operative Society, LONDON,W.C.I. (Turn up by No. 63.) Radio Section;IFtichfOrd and Co., 153,FleetStreet, E.C.3, ; TheSouth Wales Wireless Installation Co, Ltd., xt3,West Also at 17, Frome Road, Wood .Green. Bute Street. Cardiff.

Fr,.:gratringiVisgsi:.Q.,13,11Vai4V4I.M412-0IPOL-9i-4.P"4 t:4i-*WitgltXA% AWAPgliiVC:VMVzsMVigr-*-'gL,--;-QgIe-ViPtPK-''-e"4:s4M3g1-ViCl

- zt, XT. Wireless is attracting all- men.The Amateur- is entering the field in great numbers, and he wants to know all about it. He will require

Material,- Parts, Tools. He will also want tosell surplus material. tr-z "Amateur Wireless" is out to cater for this class of reader, who will be eager for knowledge and bargains. To meet him, use the Sale and Exchange columns, which he is sure to search. Rate 3d. per word,3s. minimum, prepaid. Latest date Saturday mornings. at

ADDR ESS. THE ADVERTISEMENT MANAGER AMATEUR WIRELESS. LA BELLE SAUVAGE, LUDGATEHILL, LONDON, E.C4.

4,if,,,Aniummaetanannomananannorianninnawnnnwannonnamaannamannanannzur,,,,,!,,,,r,-,,,,nrarantu

Printed and Published in England by CAsszta. & COMPANY, LIMITED, Ludgate Hill, London, E.C.4.Sole Agent forSouthAttica.CENTRALNews AGENCY,L114.1TgP., attkalay, July tLLva._.-- 121 PROPOSE A GOOD FEATURE & TRY TO WIN XI

"Q A P" Queries Answered Promptly

No. 7 SATURDAY, JULY 22, 1922 Price 3d

Our Chief Features This Week Page

A SIMPLE THREE -COIL TUNER 123

THE NATURE OF THE ETHER 124

A WEATHERPROOF LEAD - IN 125 A PORTABLE RECEIVER WEIGHING 28 OZ. 125 HIGH - TENSION BATTERY NOTES ... 126 ELECTRICAL BENCHWORK : Blowpipe Soldering 127 WHAT WIRELESS TERMS MEAN...... 127 Wireless Crystal of Iron STARTING WIRELESS :Finishing the Simple Receiver 128 Pyrites, magnified about Three Times. PROTECTING THE AERIAL FROM LIGHTNING 129 (See "All About Crystals" ALL ABOUT CRYSTALS 130-131 on pages 130 and 131.)

PRACTICAL WORKING WITH VALVES... 132

MARCONI PATENTS AND THE AMATEUR 132 BROADCASTING AND THE PUBLIC ,,133 Can You Radiograms ;Information Bureau ;Club Do'ngs ; Send "AJY." Forthcoming Events ;Correspondence, etc. Any Interesting Lavishly Photographs? Illustrated

A Typica: Crystal Detector emateur Wits 122 JULY 22, 1922

1 1 Head Office :10, FITZROY CO N 0 M I SQUARE, LONDON, W.1. MTCHELFONES E 1.___ IC Are not a spasmodic production to meet ESTAB. Write a sudden demand, but have been on the E LECTRI C 1896 To -day for market for over three months, and during LIMITED. I 100 Page -I GENERAL LIST this period 27,000 have been distributed or 36 Page WIRELESS LIST to thetrade, and consequently we have post Free 4d. not been able to offer them direct to the

retail buyer. 1000 per week are now available, and we announce DELIVERY FROM STOCK

You postyourorder,orcallatour premises and get them at once. Think

what this means to you-you, perhaps, who have been waiting and are stillwaiting.

S Standard resistance 4,000 ohms, dbuble headgear with double headstraps,comfortable,highlyefficient, and foolproof 35/..per pair.

Special Terms to Traders and deliveries

that will surprise you.

MITCHELLS Electrical & Wireless Ltd.,

Postal Address: McDermott Road, Peckham, LEAS.. Retail Address: 188. Rye Lane, Peckham, S.E.15. 'Phones: New Cress 1540/1541. UNIVERSAL TUNER THE "MOSQUITO" BUZZER GREAT BRITAIN'S GREATEST WIRELESS STORE New Showrooms: Teleih one : Bi anch Showrooms r 303, EUSTON ROAD, N.W.1. MUSEUM 1055 TWICKENHAM

101111 tar 'J.7.munt

TRADE MARK Cirelcp

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Porcelain CONDENSER VANES Light, +

BRASS STUDS per dos. EGG INSULATORS Clean cut. per dos. Aluminium, accur- t. high x dia, 010 Highest efficiency. ate gauge and size1,6 olo

i" 1',, 010 Large Spacers ...6d. 8d.

Complete with Nuts each.

and Washers. Small 4d. INSIST ON HAVING A

CRYSTALS rCRYSTALS

FULLER"BLOCK"TYPE

ONE DUALITY THE BEST

GALENA, BORNITE, SILICON, CARBORUNDUM, ACCUMULATOR

IFOR YOUR WIRELESS SET ! GRAPHITE, Per6d.Pkt. COPPER PYRITES,

The only Accumulator on the market that will hold its charge from 12 Etc. Etc.

to 18 months when not in use.

Prospective Purchasers areinvited tocallat our 4 -volt 40 amp, hours, 6, plus 1/3 carriage £1 12 showrooms and inspect cur varied assortment

6 -volt 40 £2 89, 1/6 ,, OF

Note :-These prices are 331% below those of the actual makers.

WIRELESS AND ELECTRICAL APPARATUS

8,000 Sold. 20,000 still in stock.

Descriptive and Instructive Pamphlet on request from- HIGHEST QUALITY. COMPETITIVE PRICES.

The CITY ACCUMULATOR Co. (Dept. 14),

79 Mark Lane, E.C.3 (AT:lautoth

ALSO SUPPLIF.D BY- GRAFTON ELECTRIC CO., Selfridge & Co., Ltd.,Wireless Section ; A.W. Gamage, Ltd., 54,GRAFTON STREET,

Wireless Dept. ;Barnsley British Co-operative Society, 153, Radio Section;Richford and Co., Fleet Street, E.C.3, TOTTENHAM COURT ROAD, LONDON, Wam The South Wales Wireless Installation Co, Ltd.,18, West

Te:ephonei Museum 241. Telegrams s 2=catri.ongon. Bute Street, Cardiff, k2.3

1.;

No. 7 July 22, 1922 A SIMPLETHREE -COIL TUNER An Instrumentof Wide Range Made from Oddments tyTIL recently I havebeen satisfiedfor the top and i ;Liin.for the bottom ofparts.On the bottom rod of the primary with a tuner consisting of A.T.I. andeach holder.In addition, the rods of oneholder I have clamped a bevel gear, and reaction coil.But with the advent of shortholder, whichisto be the centre one,on thereaction holder a pinion. The wave -lengths for telephony I have foundshould be threaded for about in.ofholders are now assembled, the centre one it necessary to use a two -circuit set fortheir length.Holes are also drilled rightbeing screwed - into the top ebonite, then maximum efficiency, and since it will bethrough the breadth of the holder aboutthe bottom ebonite .serawed on- to the bot- necessary for amateurs todiscardtheir in.aparttoaccommodate ordinarytom rod.. Then screw the: bottom .strip of single circuits Shortly,Ithink it ebonite to the baseboard and. slip will help them to get good, results in the side holders, the rods being ifIdescribe .my tuner; which is inserted in the top holes first: The made up of odd parts which I had bevel gear of the primary- engages at hand. with .a bevel on a "Meccano" rod, The base of the tuner consists of _Supported in rear by a "Meccano" an old valve panel box 7in. by strip benttwice. at :right angles. s% in, by 2 in.The ebonite panel The pinion of the reaction engages which used to form the top of this with a worm gear on a second box was too, badly damaged to be "Meccano" rod.'Ihave fitted a usedagain,andnotpossessing slow motion geai in this case for much ebonite I had to be content fine- adjustment, though a bevel with a top partly wood and. partly gear may be usedif, preferred. ebonite, both 3,?% in.thick. The The free ends of the "Meccano" wood,which -isfretwoodready rads are threaded 3 B.A. and screw planed,is4M.- in. by t3 in. by into tapped circles of ebonite for 75 in.The -two fit close together handles. and leave in. overlap all round Fig. 1.-Photograph of Complete Tuner. The only thing remaining is to fit the box.On the top are mounted terminals and: wire up.The ter- two wood pillars 3% in. by tin. by 4% in.valve sockets.Next drill three holes inminals are in three sets of two, one set at supporting a pieceof ebonite 4 -in.by the top piece of ebonite 0 in. from 'theeach end of -the ebonite base strip and one 2 in., which has a projection of tin. to-edge and g in. apart to accommodate thepair either in the middle of this strip or on wards one side of 'the base, preferably thatbrass rods, the centre hole being tappedthe top piece of ebonite.Though I have side fitted with ebonite.This allows the3 B.A.The bottom rods of the holdersput thestripof ebonite at the side of primary and reaction coils to swing wellfit in corresponding holes in a small stripthe base nearest the handles, itis prefer- away from the secondary, which is fixed. ofy4.in. ebonite 3% in. by % in., whichably placed at the other side, under the The coil holders are composed of threeis supported on brass screws % in. abovecoils,todo away with capacity effects pieces of ebonite 3 in: bytin by .2.5in. the wooden baseboard.The outer holeswhen the hand approaches the handles. which were cut from the top of a Mark III -should he drilled not quite through theFlex should be used in the wiring of the tuner (see Fig.1). These are drilled at.ebonite, the centre one being tapped rightmoving coils, the wires being separated, each end about % in. from one edge, andthrough as' above. brought through holesinthe base and are tapped 3 B.A. to accommodate pieces In order to provide means of movingsoldered to the terminals.. of brass rod, which should bet in.. longthe coils I have made use of "Meccano" The coilsused a e basketsfor,sho

Group of Basket and Slab Coils. emoleur Vretes 124 JULY 22, 1922 waves, giving better coupling than honey- The following table gives an idea of theing to some mutually understood plan or comb coils.Each is clamped between twoturns needed an the coilsp with a .00i con-code.Yet there is apparently no material pieces of wood, one piece being sufficientlydenser,on the primary and,.a .0005 on theconnection between the "transmitter" and secondary. Reactiopisobtainedthe "receiver." The only alternative to re- from a coil noein use asmprimarygarding this as'a ,case of action at a dis- or secondary, tance, which isirrational,isto acknow- ledge that the space between the lamp and MeanNo. the eye must be filled by some medium Diam.ofWave -length Gauge (metres) havingdefinitephysicalproperties and (ems)turns functions.In fact, to explain fully this and other similar problems it is necessary 6 9 18o -36o Primary 22 320-640 22 S W. G. to imagine this medium, which is known Io 6o 600-1,500 d.c.c. as the ether of space, as existing 'every- 36 180-400 Secondarywhere, permeating even the most dense 8 68 370-800 30 s.W.G. matter, as water does a sponge or a bucket Fig. 2.-Coil Holder, 12 I20 600-1,200 d.c.c. of sand. The above illustration is something more The coils are easily wound on athan an analogy; itis an actual case of former consisting of a piece of cur-wireless telegraphy, differing only in meatis, Fig. 3.-Method of Mounting Coils. tain pole about zin.in diameterthough not in underlying principle, from havingfifteenholesdrilledatthe system in commercial use at present. equal distances. round its circum- Science has certainly discovered the ex- ference.Into these holes are in-istence of the ether and determined some

long to protrude 1 in. from the side ofserted 2% -in.nails.The wire is woundof its properties, yet it is strangely elusive the coil.Small pieces of g in. eboniteround and round, basket fashion, until theowing to its immaterial nature.It cannot 3 cm. by 2 cm. are drilled with two holesrequired number of turnsiscompleted,be handled or examined, as, say, a newly, 2cm. apart, and arefitted with valvethen the coil is dipped in a bath of moltendiscovered gas: legs to plug into the sockets.These mayparaffin wax, is removed, and when the The property of the ether we are most be obtained quite, cheaply.The ebonite iswax has set the nails are taken out andinterested in is its ability to vibrate if set screwed to the wood projection and thethe coil eased off the curtain pole.Thein motion by suitable means. coil ends soldered to the pins.This isphotograph (Fig. i) shows the finished in- clear from Fig. 3. strument. F. C. Wave Motion It is worth while to get as clear a conception as possible of wave -motion.It is WCCi.ccEcccccc.ccccccccccccc.ceccccccc.c,_cccca.cccccccccc_p theessentialofwirelesstransmission, 4 eCand the clearer our ideas on the point the 4 better will be our understanding of the whole subject.With vibration or wave - 4 The Nature of the Ether motion of any sort one usually associates d.1.:11333351333a1331.',733,133-33333333(133130333333,33330333333\1C theripples on the surfaceof apond. These ripples are, however, only the sur- THE firstquestion to occurtothosecase of a man looking at a lamp. By facemanifestationoftheactual wave - whose interest has been newly awakenedsome means the source of light is creatingmotion itself.Beneath the surface, waves in./ wireless matters is, "In what manner isan impression on the retina of his eye,of alternate compression and rarefaction one station in touch with another ?" We surface of are travelling outward from the centre of may not know the technical details of the water. disturbance in the manner shown in Fig. i. tE-Centre of disttrbance* transmission of speech and written mes- A But for the disturbance of the surface we sages sent by wire, but at least there is Aulihil kjakidilii)1 g ) should be unaware of their existence.The some material connection between sender motion wesee,however,helpsusto and receiver in that case, whereas with visualise and represent what takes place wireless there appears to be none.Modern .....0.)ss.,....,) in the body of the water. science, though it cannot claim to have Before going any further we must notice fully answered this, can yet provide an ex- one important point.It is only the wave planation which gives usa very satisfac- -which isnothing more nor lessthan tory understanding of what takes place. , _.,.._ strain, or energy in tabloid form, soto Much 'of this explanation is wrapped up in speak-which moves forward.The water mathematical formulae, but a good prac- Fits. 1.-Sectional View of a Pond showing itself merely surges forwards and back tical conception may be obtained without Waves on the Surface and in the Water. again.Thisisillustrated by the effect making use of these by considering other upon a cork floating at A (see Fig. i).As similar, though more familiar, problems. L each successive wave reaches it it will both 'rise and fall, and move backwards and Analogy forwards, but it will not travel onwards This method of gaining an insight into with the wave. the less obvious workings of nature will In a similar manner 'asuccession of prove very helpful in introducing us to waves or strains in the ether will travel new ideas, but such comparisons are -only out from a centre of disturbance (a trans- for the purpose of getting a first grasp or mitter) in spheres of ever-increasing radius impression and should not be carried too without entailing any motion of the ether far.It cannot be expected that an analogy, Fig. 2.-Representation of Wave Motion. in bulk.From this train of waves the however wellitillustrates some points, energymaybeliberatedbysuitable will compare throughout with the problemand if a second person has his hand on theapparatus (a receiver) placed at any point it is intended to illustrate. light switch he may "transmit" a messagein their path and made to actuate, say, a For our first analogy let us take theto the first by turning it on and off accord -pair of telephones. In this case, of course, JULY 22, 1922 125 emntour VtrolesS there is no surface, as the ether is con-tration it was brought about by the heatingCC,COMGVENCCCCCCEIQCi:CCLVCC;CI tinuous in all directions.It is, neverthe- and conseqlient energetic and rapid motion3 ftt; less,still useful to represent a train ofof the particles of which the lamp filament3 waves by a rippling line such as is shownwas composed.For producing thein- A Receiver P in Fig. 2. finitely longer waves used in wireless a4 somewhat different method has to be em- PPI Characteristics of Waves ployed. The electrons of which all matter41 Weighing 28 oz. f, Waves differ in three important respectsis ultimately composed may be regarded as LJ -in length, in intensity or strength, andcentres of strain or knots tied in the etherc.433333333a33333333333331333333e in shape.The length is the distance, Litself.The passage of °an electric current in Figs. THIS isa portable receiving station i and 2, and the intensity is re-consists in the handing pn of some of these complete in a polished mahogany box presented by the maximum height H.Forelectrons from molecule to molecule. the present we will neglect the equally The6 in. by 6 in. by 3y in., with a wave- process is almost as rapid as the motionlength zootoi,000 important factor of shape and assume them range of metres. of the waves of which we have been speak-Although so small it is quite efficient.A to be sine waves, as are those shown ining, but itis slowed down somewhat by Fig: 2. single receiveris used in place of the the disturbance it creates in the materialusual double -headgear telephones.There Whatever their length or shape, theyof the wire or conductor.As the elec- travel at a constant speed in all directions,trons, the motion of which constitutes the so long, of course, as they move in thecurrent, are thus part and parcel of the same medium. This is an important point.ether, their progress naturally produces an The speed with which they travel is de-effect on the ether surrounding the wire, pendent solely on the ratio of the elasticityand if the currentis made to oscillate of the medium to its density.Thus in abackwards and forwards in a suitable cir- dense substance which is highly elastic dis-cuit, as in the transmitting apparatus of a turbances will travel at the same speed aswireless station, waves of strain will be in an attenuated, inelastic substance, pro-flung clear of the wires forming the aerial vided the ratio between the two propertiesof the station and set free to travel out- is the same in the two cases; but if eitherwards in the ether or space. SIGMA. density or elasticity changes independently of the other, it will entail a change in theCCCCC.CCCCQCCCC-CCCCZCCQCEiCC0Ctr speed.This fact is mentioned as it has a bearing on long-distance wireless trans- (40 mission. A Weather- The Receiver Open. 300,000,000 Metres per Second . are only three components in the set- The speed of wave -motion in ether is the "figure -of -eight " variable inductance, 3oo,oeo,000 metres a second, and isthe proof Lead-in the detect'or, and the telephone. A "block- greatest velocity known.It corresponds41333333330a33333333513Mv-,..331ing across the telephones is to a journey eight times round the earth in found unnecessary, asthe difference a second. A CORRESPONDENT writesasfol- in All ether waves in space, of lows : "As rain is likely to be led intosignal strength with and without thisis whatever intensity, length or shape, travel almost imperceptible. at this speed, but as they move outwardsthe leading -in tube by running down the wire and by capillary -attraction, I suggest The detectorcrystalcupis mounted- from the point where they are generatedthat a copper funnel be soldered in anon aflatnickelsilver spring, and the they decrease in intensity or height. invertedpositionon "pointcan be mo% ed about to touch any The number of waves which pass a fixed the downlead." This isa useful suggestion where itis spot in a second is known as the frequency,necessary for the lead-in ,to be brought and a moment's consideration will show usdown vertically, but itis a bad way of thatthisrate(measuredin waves per second)multiplied bythewave -length (measured in metres) is equal to the speed of transmission(in metres per second). But we have just seen that this speed is the same for waves of all lengths, consequently we arrive at .the important conclusion that the greater the frequency of a disturbance the shorter the length of wave generated, and vice versa. The range of wave -lengths in which it is possible to make the ether vibrate is extremely wide, varying from less than a thousandth of a millimetre on the one hand to thousands of metres on the other. Diagram of Weatherproof Lead-in. Naturally the properties of waves at dif- The Receiver Closed. ferent points on such an extensive scaleleading -in because any pull on the wind vary very considerably, and the only por-strains the tube.The better arrangementportion of the crystal without disturbing tion of the scale which is at present foundis shown in the illustration.In this thethe cup. suitable for wireless transmission is thatstrain on the wire is taken by the insulator No buzzer is included in the set, but it containing wave -lengthsof from 3oto attached to the wall, and the lead 'in is runis advisable to have one, as the detector 20,000 metres. upwards into the tube.However, this iscan be adjusted much more easily.How- only necessary for heavy wire; a light wireever, it is often found that the buzzer will Making the ether Vibrate can easily be bent round the tube. Aautomatically start the detector working. The next point to consider is how we areglass tube answers well for this purpose; it The makersoftheinstrumentare enabled to set such, an intangible substancecan be tent to any shape in a gas flame. Mitchells Electrical Wireless, Ltd.,188, as the ether vibrating.In our first illus- J.F.S. Rye Lane, London; eimateur Wireless 125 JULY 22, 1922

CCCCCC.: ,CCCCCACCCVECCOOT464-VCCCC4.3CCCCECCCCCCCCCECCCCC3313..3.1:13'31 CCC tr; P. or;

Frr 0HIGH-TENSION BATTERY NOTES P ci (f^ 13333a333313333:133333331333333333333,133 )333..1 11)._, -3,13333333:1:33333 -.33.--1, -*- :Y-''-, '"' --; -' '13:333- 33... 3 ', '0 ONE of themost important units of theThe other terminal and the other end ofreceive.The "depolarisingelement of a valve receiver is the high-tension bat-the resistance coil will be the connectionsdry cellis manganese peroxide, and in tery.The 3o to 6o volts most commonlyfor the voltmeter, as shown in the accom-either a crystalline or amorphous state it needed must be above suspicion or thepaning illustration.If the instrument isit much too hard for the cell to extract all reliability of the set is very questionable. putacrossacellitwillreadvolts,the associated oxygen as it requires it, its because one volt pressure applied to afunds are invested, so to speak.Ground Current Requirements circuitofi,000ohmswillcauseoneto an impalpable powder and mixed with Fortunately,theB.Battery,asourmilliampere of current to flow.Any cellfine graphite and carbon dust it performs American confreres callit,is not askedtested this way which shows one volt orits functions faultlessly. to provide much more than a milliamperemore can safely be left in the -high-tension The active element in dry cellsis a of current, and so the size of the com-battery and others weeded out and thrownpaste mixture containing flour, plaster-of- ponentsneednot begreat.Thecellsaway.Don't play about trying to repairparis, and sal -ammoniac.This is smeared must, however, be -of reliable make, butor recharge the cell.It is mere waste ofall over the inside of the zinc containing thisdoesnecessarilymeanhighintime.A cell,when once exhausted,is case. A carbon rodis supported in the price.The man who makes up his high- centre so as not to touch the paste or the tension battery by buying up a dozen or zinc case, and this rod carries the positive two pocket flash -lamp batteries because he terminal.The space left between the rod can get them for so many, or so few, pence and the paste is rammed tightly with the per dozen, is asking for trouble, especiaiey powdered peroxide mixture, leaving ifthe vendor,toconvince him of the enough room to seal off the .cell at the top freshness of his wares, lights up a small with pitch.A cell so formed gives a small bulb lamp with each one in turn to "test " fraction over 1.5 volts when new. it.One of these little lamps may easily The current drawn from a drycell require'thebest partof an ampere to should never exceed one milliampere per lightit up brilliantly, and that amount cubic in. of the black compound-that is, of current for eves so short a flash would the carbon rod and the peroxide mixture. doevengoodlittlecellsirreparable Method of Testing a High-tension Battery. For many purposes, thelifeof a dry damage. cell ends when its terminal voltage drops to one volt, but a wireless high-tension Purchase onlyfitfor dustbin.Also,don'tbattery, if the cells are not.too 'small, can In buying a new battery get one of aattempt to charge up the cell as one wouldbe used until the voltage falls to .8,or reputedmake, andseethatitisnotan accumulator. Carefultestshaveeven .7, provided that the internal resist- tampered with by theignorant.Aboveproved that the result, however promising.ance of the cell is not excessive. all, if you wish to test the voltage don'tlooking, is a failure. The wise and careful user of a high- put a low -resistance voltmeter on it, or a tension dry -cell battery insulates each cell high -resistance voltmeter either, for more Reliability fromitsneighboursoasto avoid the than an instant.If, like the writer, you The great secret of the superiority ofbattery running down by leakage, or even are fortunate enough to get hold of a lot ofsome makes ofcellsisthefinenessof worse, picking up stray noises -from the larger cells which have been rejected bygrindingwhichthepowderedcontentsfloor upon which it stands. the manufacturer for having too high an G, S. internal resistance for their intended use, you will get, at a low price, a high-tensionGDOCGCCGCW,CCCCC-leeCC-CCC,C-COCCCC-CCCCC:: battery, which, with proper care, will last for years. Blowpipe Testing Electrical Benchwork Soldering However carefulthe user,there areen'33.33131311333133131333333133333a3333 bound to be a number of cells that will .71)333333)33. )3-13330 "peter out " and lower the efficiency of the THE process of soft soldering with theknack in use, as itis no use blowing in battery, and the difficulty will come in ordinary soldering iron was dealt withgasps ;a continuous blastisnecessary. weeding these out.Nowadays one oughtin No. 4.For small parts such as areThe best way to. maintain a continuous to be abletoacquire fairly cheaply arequired for wireless apparatus the blow-blast is to breathe naturally through the sensitivemilliammeter.Choose one,ifpipe (a typical example of which is givennose and at the same time keep the cheeks possible, that has a wide range up to twoin Fig. i) is equally satisfactory. distended (see Fig. 2).By adopting this milliamperes:. Now get hold of a coil of simple dodge you will be able to keep up resistance wire measuring justshortofAdvantage of the Blowpipe a steady blast of air through the blow- r,000 ohms.Your dealer will let you have The particular advantage of a blowpipepipe.If you are working the blowpipe a reel of wire of that resistance for a few isthatit gives a fierce heat at a veryflame righttheflameisalmostsilent, pence.You can use it just as it is, on thelocalised area beyond which the solderwhereas a roaring, irregular flame is pro- reel, if both ends can be got at.It ought,does not run.You can solder spots, andduced otherwise. of course, with the milliammeter in seriesalso unsolder, resolder, or adjust soldered to measure exactlyr,000 ohms, but anparts without allowing heat to stray andA Lip Guard Necessary ohm or two more or less will not makecause trouble in other places. Unless you are more careful than I am much difference. you will often carelessly place the blow- Connect one end of the coil of wire toOperating the Blowpipe pipe after use on the bench and as care- one of the terminals of the milliammeter. The blowpipe'needs a fair amount oflessly replace it in the mouth when itis JULY 22,1922 127 , Omoivir WirdesS required.The filings,dirt,etc., whichThe jointor spot should be frequentlydealt with.Some further examples are the mouth end picks up are very distaste-touched with the solder -(not forgetting togiven which show the application of sot t- ful, and to avoid thisIplace a thickuse sufficient flux), when the solder willioldering to the building up of parts.Sup- tinplate washer near the mouth end (seesoon flow into the joint. pose, for example, you want some detector

Fig. I.-Simple Blowpipe.

If (as is likely when using a taper) soot tends to form; this must be wiped away with acloth -coveredstick soaked with flux. Smoky flames are produced when Fig. 4.-Built-up the blast is too weak; after a little ex - Finger Screw. Fig. 5.-Method of Fixing Ebonite Knob Fig. 3.-Reservoir to Arm. Blowpipe. adjustingscrews. The proper wayto Fig.i), the object being to raise that make them (although it hardly pays, so end off the bench. cheaply may they be bought) is to turn and knurl them in the lathe.A simple Spirit Lamp and Blowpipe is Best method where a lathe is not available is There are several types of blowpipe on tosolder terminal screwstopiecesof the market, but you willfind the one screwed rod or a piece cut off a screw shown in Fig.ithe best for use with a (see Fig. 4). spirit lamp or wax taper, whilst the com- A simple method of fixing the ebonite bined blowpipe and spirit lamp shown by knob to the operating lever is shown in Fig. 3 is a great improvement.If you Fig.5, a small ebonite knob is fitted on decide to have the type shown by Fig.i, to a brass screw and the latter soldered one about 9 in. long should be chosen, so to the lever. that the eyes are kept well away from the You have probably tried at some time flame. or other to solder connections to the mica - The type shown in Fig. 3 has a reser- foiltype of condenser and suffered the voir into which methylated spirit is poured. annoyance of melting the protruding ends The wick is lit and the blowpipe operated of the foil !This operation cannot satis- in the ordinary way. factorily be done with the soldering -bit Fig. 2.-Method of Using Blowpipe. ormouth blowpipe. A specialsolder Soft Soldering with the Blowpipe (Wood's metal, which melts at a lower Place the work in such a position thatperience you will soon acquire the knacktemperature than boiling water) is melted, you can conveniently blow on the spot toof regulating the supply of air. and the foil ends of the condenser, with be soldered.Then insert the blowpipe in the wire pressed into contact with them, is the mouth, and with a stick of solder inSome Examples of Soldering rapidly drawn through the solder.It will the right hand and the taper or spirit lamp So far all that you need know aboutbe found that a very neat Connection is in the left, a steady blast is maintained.soft soldering in order to do it has beenmade by this method. INGOT.

WHAT WIRELESS TERMS MEAN. -V SomeTechnical \Words Explained as Correctly as Popular Language Allows ELECTRO -MAGNETIC INDUC- effect produced upongrid connection and in front of the tuning TION. - The effect produced by aINDUCTION.-Theacoilofwire in juxtapositionto coil.It may consist of a cylinder of card- conductor being caused to cut a magneticanother coil in which a current of electricityboard wound with thick wire, or a number field.For instance, if a wire is passed acrossis made to flow, at the moment this cur-of slab coils. the pole of a magnet a current of elec-rent of electricityis started, stopped or CONDUCTOR.-The oppositetoan tricity will be induced in the wire. vaned. insulator,i.e.asubstancethat RESISTANCE. - The propertyposs- POTENTIOMETER.-A variable highpermits the free flow of an electric current essed by all substances of offering in resistance, usually of the orderof and by which it is conducted from point to a greater or less degree opposition to the200 ohms through which a current from apoint. Copper, brass and most metals are passage ofelectriccurrents.This termbattery ispassed and applied to someconductors in a greater or less degree, as must not be confused with inductance ortypes of crystals.Also used in high -fre-also are water, the human body, etc. impedence.Ironandsteeloffer morequency circuits to apply a negative poten- FILAMENT.- That part ofa valve resistance than does copper.This propertytial to the grid to stop the valve oscillating to which theaccumulator is con- is made use of when it is desired to limitwhen receiving telephony. nected, causing it to become incandescent, the current in a circuit.The effectof LOADING COIL.-A coil by means ofand in that state to discharge electrons resistance is to produce heat.It is a deter- which further inductanceisaddedfrom its surface (see Valve).It consists mining factor in arriving at the amount ofto the circuit in order to enable higherof very fine tungsten wire and is suspended electricity that will flow in a given circuitwave length to be received. It is inserted in between two supports.It is very fragile at a given voltage.Where a maximumseries with the tuning coil and may itselfand easily broken, particularly when cold. flow isdesired, the minimum resistancebe variable.When added to a valve cir-The filament must never be in contact must be secured. cuit it must always be placed below thewith any other part of the valve. entateur Wirdess 128 JULY 22.1922 CSECCCC'CCCCCeGCCCCCCCiACCCCCCCCCCCiC.CCCC(CCE'CCCCCCCCCCCCEECC.0 Ck LCCCCC C 0 er; TH e. RECEIVEER 4STARTING WIRELESS. -VII SIMPLEFINISHING (F, t.sz311 7,1 3,3, .3 333:33M333333.33 33M3a3330.1333,333333313:k3 33 3333 3333 3:333 3313:33 3 3 33 313331:3331:3 3110f', The Crystal Detector brought nearer together, thus varying theis pressed well together, and it is then THERE are a number of different formspressure between the, crystals.The crys-firmly bound round with some tough brown of detectors, perhaps the most stabletals are set in the cups with either moltenpaper which is secured with a little gum. type being the carborundum and steel -platesolder or Wood's metal.Itis usual toTo serve as a protection against damp, the combination.However, this usually re -employ apointedpieceofborniteorfinished condenser is painted with hot wax, copper pyritei resting on a flat face of agreat care being taken to cover the parts piece 'of zincite.Two terminals mountedwhere the copper foil emerges from the on the base complete the detector; con-paper.If desired, the condenser may be nection is made, of course, to the fixed cupplaced in a box, when the wires would be and the screw holding the upright. brought to two terminals mounted on a piece of ebonite on the top.' The Telephone Condenser This can be made very simply from tin Fig. 1.-Simple Detector, Connecting the Apparatus foil and paper.The actual value of'the Fig. 3 is divided into two parts.One condenser is not of very great importance, quires a potentiometer, and it is therefore partshows how the apparatus appears so that the following details need not bewhen it is connected up, and the other part a little more complicated for a beginner.adhered to very strictly. Another type consists of a very fine wire Eight pieces ofshows the standard way of indicating the tinfoil 3 in. by t% in. and nine pieces ofvarious components.Itwill be noticed (called a cat -whisker in America) whichthick writing paper 254 in. by 2% in. will bears lightly on the surface of the galena that a switch has been included between he required.Fig. 2 illustrates the methodthe telephones and the detector.It is so crystal.This combinationis perhaps aof assembling the condenser, only four little more sensitive than others, but at the arranged that either of two detectors may plates being shown for clearness.Itis same time it is rather erratic in behaviour. be used at will.This is a very convenient essential that' the insulation of the con- Reference was made to the Perikon de- method of working, as should one detector suddenly become insensitiveinthe tector in' a previous section, and this will PAPER therefore be described.Many designs of 7 middle of an important signal itis only detectors have been put on the market WIREnecessary to put the switch in the other . from time to time, each claiming some 7/07211 -- position, thereby connecting up the second detector_. As soonasthesignalhas special merit.However, the reader is ad- 'OPPER CARDBOARD.14-7-.) finished we can immediately readjust the vised to begin with the simplest form pos- COPPER FOIL A TINFOIL B sible, so that when he has gained more CONNECTOR faulty detector.The switch is also very experience he will be able to judge which, Fig. 2.-Diagram showing Construction of useful for comparing two different types type he prefers. Telephone Condenser. of detectors, since it is possible to change The detector will be better understood from 'one to the otter without disconnect- denser should be as good as possible, anding any of the apparatus. by reference to Fig.tthan by a lengthy coilpreviously description.The base may be of ebonite,therefore before the plates are assembled The tuning described 4 in. by 3 in..and % in. thick.The crystalthe paper should be well soaked in paraffinwas designed to receive wave -lengths up to cups may be drilled or turned from brasswax. Whenthetinfoilplatesareabout boo metres.However, if it is desired rod. % in. diameter, or they may be boughtassembled the four plates which project onto receive longer waves all that is neces- for a few pence.The success of the de-one side are bent on to the top piece ofsary is to insert two terminals in the posi- tector depends upon its rigidity; a weak orpaper, and the other four_are bent on totion marked x in Fig. 3.When receiving springy detector will never keep sensitivethe bottom piece of paper.The length ofon the small tuning coil these are con- for more than a few minutes, and it willthe projecting pieces should be a little overnected together with a piece of wire, but be found a source of everlasting annoy-half an inch. when it is wished to listen to longer wave ance.One crystal cup is fixed near the Two pieces ofwaxed cardboard are cutstations simply disconnect the wire and in- end of the base, as shown in Fig:z, andto the same sizeas the paper to act as asert another coil inits place.This coil the othe.r is screwed to the end of a piece of brass 2% in long, % in. wide, and a TUNWIGCo, little less than als in. thick. Nt A thick brass screw about 2 in. long is passed through a hole drilled at the other end of the base.A strong washer (A, Fig. 1) is put on the screw, together with Ci a length of stout brass tube about 0 in. Duratrolal external diameter.This is followed by the \l'HONES brass strip, which is finally secured by two Fig. 3.-Details of Connections showing Arrangement of Apparatus and Wiring Liagram. nuts.The length of the brass tube willkind of cover.Connection has yet to becan be made exactly similar, to the other, depend, of course, upon the height of themade to the plates, and this is best donebut there is no need to fix a sliding con- crystal cups.A similar but longer screwas follows :Two short lengths of coppertact since all the fine tuning can be accom- is fixed to the base with a nut B, and thewire are soldered to two small pieces ofplished with the original coil.It is only end is allowed to project through a slit incopper foil.These are placed one againstnecessary to tap the coil at varying inter- the brass arm.A nut tofitthe screweach of the bent pieces of tinfoil, beingvals, bringing the tappings to a multi -point is soldered to a small piece of thin brass,slipped between the top and bottom piecesswitch. which is then screwed to an ebonite knob.of paper and the cardboard.This should A coil of this description is usually called It will be understood that by screwing the bequiteclear from thediagram. Toa loading coil, since it loads the aerial to knob downwards thet r o cups will beensure an efficient contact the condenserthe required xvave-length.. PAUL D. TYERS. JULY 22, 1922 129 (Intakur Wireless

. ,,C.CC),CCEC.CC ZCCCCCCCC: CCCCGCCCCCCCCGCCUC..CCCCCCCCCCiC C CCCCCCCECCCCCL CCCCCCCCCCte Protecting the Aerial from Lightning -1--)331133331)''',1311131133333133313333133333$1 -13333111/33 033331313131,333355et WHEN you arrive at the momentoushalf, round off the top, and drill each pieceguard and in order entirely to cut off the decision to dabble in wireless, aboveas shown in Fig. 2. delicate apparatus from theaerial and all things do not make a start in construc- A piece of steel rod should next be ob-earth when not in use. tion or erection until you have schemed outtained 3A in. in diameter and 9 in. long. The further advantage alluded to with Cut it in half and make a nice clean pointthis method of protection is that by a suit- at one end and turn down and screw theable adjustment of the gap almost com- other end of each piece as shown in Fig. 3,plete elimination of those annoying static The arrester can now be assembled.. Fig.discharges, or X's as they are called, may 4isself-explanatory.The twopiecesbe achieved. (Fig. 2) are fixed on to the ebonite base If it is found difficult to adjust the gap, by means of o B.A. screws with a washerwhich, by the way, should be about half a 1 at the back.The two points (Fig. 3) aremillimetre, a modification can be made to slid through these 'supports and clampedthe arrester, which will render close adjust- Fig. 1.-Drilled Ebonite Baseplate. with 2 B.A. screws through the sides 'of thement more simple. supports, three washers and a thumb (ter- Instead of fixing the earth wires directly completely what you want and how youminal) nut being ,used at the screwed endon to one of the pointed rods, provide a propose to set about it.You will no doubtof each to clamp the aerial leading -in andterminal as shown in Fig. 6, and make the enlarge and extend as you go on, but it isearth leading -in wires in each case. earth leading -in connection tothis, con - well to have something basic to work on at the outset.Having thus made your decision, be very sure that you include an To AERIAL efficientmeansofprotectionagainst WEATHER -WARD k jjAr---.....LEAD-114 lightning. .17(a.vtaul With the aerial erected and the leading - in wires brought to a suitable position, it is advisable to have a protective device in- 3.11'Dts. stalled outside in order to avoid directly Fig. 2.-Holder bringing into the house the aerial leading - for Electrodes in wires with no protection. A suitable and convenient method, and one which serves a --ARRESTER dual purpose,isto fix a well -insulated 1 spark -gap type of lightning arrester into a To INSTRUMENTS suitable housing on the outside wall, and connecting the aerial through it direct to earth,thus avoiding any possibility of Fig. 5.-Method of damage. Fitting and Con- This spark -gap arrester can easily be nectionsofDe- tector. Fig. 3.-Electrode.

The method of attaching the arrester tonecting this terminal by a piece of stiff the side of the house (building, shed, etc.)wire placed under the washer to the sup- is shown in Fig.5. The method can beport post, as shown by the dotted line. varied to suit the conditions of the particu-This relieves the pointed rod of the wires lar case and the material at hand. and makes it easier to adjust.Further, if The chief point about this method of fix-it is desired a suitable screw thread can be ingis thatit is weatherproof.The ar-run up the rod, and the hole in the support rester is supported by means of suitablypost similarly tapped, giving an even finer bent -up pieces of mild steel strip arrangedadjustment. a at an inclination outwards from the wall, With regard to maintenance, paint the with roof and sides.The inclination pre-iron brackets and wooden housings, and vents rain from lodging, and, in most casesoccasionally polish up the steel points.If even touching the arrester points and thea piece of rusPess steel can be obtained, small roof and sides effectively stops sideuse it by all means; if not, well polish the and top splasking. steel rods with fine emery and oil. This arrester, of course, cannot be left Fig. 4.-Assembly Fig. 6.-Additional The connection of the aerial leading -in of Arrester. Earth Terminal. wires and the earth connection should bein circuit when transmitting, but a simple brought directly to the terminals on theswitching arrangement would overcome made as follows :Obtain a piece of ebonitepointed rods of the arrester, as shown inthis small difficulty. E. ALEXANDER. about f4,in. thick and S in. in length byFig.5, and connection made from these 3 in. wide.Clean off all the polish frompoints to the short-circuiting switch, which, THE Handbook on Wireless is acknow- both sides and edges and leave a mattof course, should be provided inside withledged to be "Wireless Telegraphy and surface.When satisfactory drill as shownthe receiver. A 20 -ampere lighting switchTelephony," one of the famous "Work" in Fig.r.Now get a piece of brass rodisverysuitable.The provisiOn ofthisseries of handbooks published at the offices switch is essential, both, as an extra safe-of this journal.The price is is. 6d. net. rin. in diameter and 3 in. long, cut it in ' emattur Wiretzss 130 131 motPiir Wass Cli',C43CCCCECAECCCUCCCECCECCCCCECCi.i.:CCC CCCCECCCCQCCCCC CCCCVCC(C4ECC CC VEC ECCCCCCCCCCCCCECC14144)CCCCGCCCCC CEA. CCCC(CCCf CCCCCC CCCi;CCECCCt CCCCCfCCC.CC4-VcC(COLCCE CCEECC (6.: CECA.V(VCCCO:CCO

tF,9) Photographic Illustrations show a Collection of the Best-known tireless CrystalsEnlarged toAboutThreeTimesNormalSize.

cee

Silicon Galena and Special Galena Bores Ca, b3, unium Copper Pyrites Badge ALL ABOUT CRYSTALS

WIRELESS signals aretransmitted same mannerasaratchet -wheelacts bornite or else zincite and tellurium.The has a metallic lustre, and is heavy. When in the form of waves created in the mechanically. latter combination is usually found to give using this crystalitisusual to have a ether which, striking the receiver aerial, Carborundum is probablythebest the better results.Zincite, or oxide of graphite contact in conjunction withit. cause small alternating currents to travel crystalforall-rounduse. Itisnot zinc,is dark red in colour; bornite is a Molybdenite is dark in appearance and is up and down it.As these currents are of affected by mechanical vibration nor by compound of copper and iron sulphides, suitable for the reception of strongsig- a very high frequency, the ordinary wire- fairly heavy electrical discharges across beingbluishgreyinappearance and nals;itis convenient for use in portable less telephone receiver cannot detect them. it, and itis very sensitive.This crystal fairlyheavy. Tellurium is alight- sets. Iron pyritesisacubicalcrystal, It is necessary, therefore, to rectify them, has to be used in conjunction with a 4 -volt colouredmetal. Theperikondetector being very metallic and heavy.It pos- or, in other words, change them into uni- battery and potentiometer, because itre- does not require a potentiometer because sesses many of the properties of carborun- directional currents, before passing them quires a small initial potential or voltage the voltage of the incoming signal is suf- dum but is not so sensitive. through the telephones.The rectified cur- to be applied across it to bring it to its ficient to bring ittoits sensitive point. The only sure way to obtain a good rents produce a movement of the telephone mostsensitivepoint. Carborundumis It has the advantage of being fairly easy crystalistosearch for sensitive points Radiocits diaphragms and thus the signals are made used with a flat steel surface, the rectifica- to adjust.Also when a crystal becomes amongst several specimens.It is wise to Permanite audible. tion taking place at the point of contact. slightlyinsensitiveitcan be scratched remember thatsensitivityisnot every- Certain kinds of crystals, such as car- This crystalismanufactured by fusing witha knife and a new surface used. thing; a good crystal should have the borundum, zincite, bornite, silicon, carbon and silicon together in an electric To obtain the best resultsitisusually qualities of being constant in action and galena, molybdenite and iron pyrites, have furnace.In practice three kinds of car- found that the crystals must make a light of not being affected by atmospheric dis- the peculiar property of being ableto borundum crystalare met with : (a)a contact with each other.This detector is turbances.Such crystals as "Radiocite" rectifysmallalternatingcurrents. We hard dark variety, having great metallic more sensitiveinaction than thecar- and "Permanite" are usually sensitised must explain how they do this. lustre which has poor rectifying proper- borundum type, but not so robust. forms of galena.They are very sensitive A crystal rectifies because it allows cur- ties;(b)a soft crystal of a pale green Silicon, galena, molybdenite and iron but not constant; a fine copper wire con- rent to flow through itin one direction colour, a colour due to the presence of pyrites, whilst being serviceable for ex- tact is used in conjunction with them. In:pr:vised Detector and does not, to any appreciable extent, copper and iron salts (this type of crystal* perimental work, do not give such satis- Thereisplentyofinstructionand allow current to flow throughitin the is a very poor rectifier) ;(e)a dark grey factory general results as either carborun- amusement to be had with a good crystal oppositedirection. Itispracticallya crystal which will be found to give the dum or the perikon detector.All these set.The range of a crystal set is about uni-directionalconductor. The ratioof bestresultsasregardssensitivity and crystalsare minerals. Siliconislight 30o miles for ordinary ship stations and currentstowinginoppositedirections stability of action. grey in colour and has not many sensitive 20 or 3o miles for high -power telephony. through a good crystal should be about The most popular crystaldetectoris points.Galena is very sensitive for long Several experts prophesy the return of the 40 :t. Itwillbe understoodthatthe without doubt the perikon detector.This ranges,butstrongsignalsdestroyits crystal and its ultimate triumph over the Enclosed Detector crystal acts electrically, very much in the isa combinationofeitherzinciteand sensitivity.Itis bluish black in colour, valve. G. H. L. N. Mercury -cup Detector

Another Double -crystal Detector Simple One -crystal Detector Carborundum-steel Detector Ferikon Detector " Drawing -pen" Detector Spring -adjusted Detector 131)33133333333313331) .7)7.7)11VM:1,1)3233333333133333) 1 111113333333333133333111133333113/133 \-31133311:170 33533133333 -)333353333,31,3133333)33333333333333333 3333355133333333351315333533333131135D emattur Wiretzss 130 131 motPiir Wass Cli',C43CCCCECAECCCUCCCECCECCCCCECCi.i.:CCC CCCCECCCCQCCCCC CCCCVCC(C4ECC CC VEC ECCCCCCCCCCCCCECC14144)CCCCGCCCCC CEA. CCCC(CCCf CCCCCC CCCi;CCECCCt CCCCCfCCC.CC4-VcC(COLCCE CCEECC (6.: CECA.V(VCCCO:CCO

tF,9) Photographic Illustrations show a Collection of the Best-known tireless CrystalsEnlarged toAboutThreeTimesNormalSize.

cee

Silicon Galena and Special Galena Bores Ca, b3, unium Copper Pyrites Badge ALL ABOUT CRYSTALS

Another Double -crystal Detector Simple One -crystal Detector Carborundum-steel Detector Ferikon Detector " Drawing -pen" Detector Spring -adjusted Detector 131)33133333333313331) .7)7.7)11VM:1,1)3233333333133333) 1 111113333333333133333111133333113/133 \-31133311:170 33533133333 -)333353333,31,3133333)33333333333333333 3333355133333333351315333533333131135D Onio to it Wireless 132 JULY 22.1922 cicti:i.C.C.viC.'ALCCEE.:CZCOLGC.CC.CCEC-CCCC(CCC,Ct:,`.C.C.CCC'CC.E.E ZC-CC.C.Cci.CCALCC CCCCCCCECCAWCioii,

HIN T S A ND PracticalWorking with Valves.IIUSEFUL NOTES ,.)1333333333333333:31133333,3:113!),33:13W#,13113333M0333333Y3--31-., Y.)-14111-')

THE grid leak and condenser can, withan accumulator ofatleast mooactual The reactance -capacity method has been advantage, be shielded with metal foil,ampere -hour capacity should be used forfound to be very good, and is somewhat which should be connected to the positivea discharge rate -of 5 amperes. cheaper and easier inconstruction; the terminal of the plate battery.This tends Care should be taken that all connectionsAvindings are simple, and the question of to prevent the grid of the rectifying valveare soldered, as a bad contact is often thecoupling is easily controlled.The wind- from being affected by the necessary move-cause of noises in the 'phones. ings generally consist of slab, pancake or, ments of the hand when making adjust Dustbetween,the plates of the variablebetter still, duolateral coils.Above 2,000 ments. condensersisanother fruitfulsource ofmetres the simplest, and, probably the best, Sliding Contacts noise, but fortunately the remedy is obviousmethod is resistance capacity, although it A fixed. condenser, having a value ofand simple. has the disadvantages that a higher voltage from one-third to one microfarad, should A great many experimenters,inanplate battery is required and the amplifica- be connected between theslider of theendeavour to obtain a large range with ation is not so great. giveninductance,useacomparatively potentiometer and the negative end of the A Triple -purpose Amplifier battery.This will act as a by-pass forlarge condenser in parallel.This is very radio-frequencym currents which otherwisebadpractice,asaparallelcondenser The writer is now building an amplifier might have to pass through one-half ashouldneverexceed .0005microfaradin which advantage can, and will, be taken potentiometer having a resistance of per-capacity, and is even betterifsmaller,of all three methods.It is a simple matter haps four or five hundred ohms.Greatsay .0003 microfarads.A very suitableto arrange if four -point plugs are used to care should be taken to see that the slidingarrangementistouse aseries -parallelaccommodate the transformers, etc.The contacts are good, otherwise noise mayswitch, wired in such a way that when innecessary grid leaks and condensers can result.It is surprising how many people,series with the aerial the effective capacityeither be mounted on the panel with suit- including many skilled electricians, thereis the maximum, and when in parallel theableswitching arrangementsor,asan are who take great pains to keep all oilmaximum capacityisa much smalleralternative, a separate fixed condenser and and grease away from moving contacts, leak can be p-rovided for each coil and This is totally wrong, as a sliding contact mounted on the same -plug.The latter if kept covered with a film of oil cannot method is perhaps the best, as the con- oxidise;' such a contact is also self-clean- densers and grid leaks can be adjusted to ing, due to the abrasive action of the very suit requirements of the Coil in question. fine dust Which forms (when absorbed in The writer hopes that the set he is at present constructing will be more satisfactory than the previous experiment, which Nigh -.tension Battery had fourradio -frequencytappedtrans- The plate -circuit battery generally con- Arrangement of Series -parallel Switch formers giving a range of 300 to 15,000 sists of a group of from thirty to sixty dryatnoupt.This result is obtained by havingmetres. He also hopes that these few notes -cells. Itisfairlysatisfactory provideda fixed condenser in series with the mov-will be of assistancetoearnest experi- care is taken not to short-circuit the cells, ablecondenser. The wiringforthismenters with more patience than money, or to attempt to discharge at a high rate.arrangement is as shown in the illustration.and who prefer to make mistakes and If the discharge becomes heavy the battery The reference letters in this figure areapparatus rather than buy finished appara- becomes more or less polarised, with theas follows :A, inductance; B, fixed con-tus and settle down into a round of "listen- resultthatnotonlydoesthebatterydenser, say .0005 mfd.; c,' moving con-ing in." A. F. C. electromotive force fall, but considerabledenser, say .0015 mfd.; switch to right noiseisheard due tointermittentdis-when in series. charge.Dry cells are cheap to renew, A smallswitchcanconveniently be MARCONI PATENTS and after about six months-if used, say,placed in circuit to short-circuit the fixed AND THE AMATEUR an hour a day-are generally ready forcondenser (B)if a maximum capacity in renewal.The writer always suspects theparallel is wanted.A further advantage THE Marconi Company officially an- plate -circuit battery when noises occur inof this arrangement is that the minimum nounce that, far from wishing to take the 'phones, and experience 'has provedcapacity of the condenser is reduced. advantage of their patent rights to hamper that many noises are due to this cause. and discourage amateurs, they desire to The battery should always be shunted withTransferring Power assist, rather than hinder, them in follow- a condenser of not less than one micro - It is very difficult to decide which is theing the hobby.They state that they have farad capacity. nest arrangement to adopt for transferringno intention of taking any action against the power from one valve to the next whenamateurs who construct for their own use Filament Battery dealingwithradio -frequencycurrents.wireless apparatus embodying any of the A source of trouble often quite unsus-Three common methods of doing so are :patents owned by the Marconi Company, pectedisthefilamentbattery. Some(i) Radio -frequency transformers;(2) 're-provided that such apparatus is not offered accumulators, if discharged at any value'actance capacity; (3) resistance capacity. for sale and is used only for amateur pur- approaching the rated safe discharge rate, In the first case the power is probably poses.In this particular connection "con- tend to give off gas, and it is often noticedtransferred to the next valve by a com-struction" is intended to signify the actual that when this gas is rising noise results.bination of transformer effect and reactancemanufacture, wholly or in part, of a wire- On returning several cells to the manufac-capacity, and whilst very suitable for allless set, and not the mere connecting up of turers for this reason, the makers statedwave -lengths is more applicable to thosepurchasedinstruments. Ontheother that had they known the cells were forof from zoo to 2,000 metres, as above thishand, the company intend to protect their wireless work they would have made them thetransformersbecomecomparativelyrights when unauthorised use is made of in such a way as to overcome this troublecostly owing to the cost of the wire neces-their patents in the manufacture of appara- to a large extent.They recommended' thatsary for winding. tus for sale publicly or privately. JULY 22, 1922 133 Qmateur Wireless IXCCCCCiA'CCCCE:CCE:( r Swansea Education Committee recently CAZCCCCE:CCCCCCCCIACCCCCCCA passed a supplementary estimate for L5o r 4 ce for the purchase of apparatus to enable a 4 C start to be made in teaching the principles 4) Broadcasting C Radiograms and practice of wireless telegraphy and . c T1.7;2)113.7) -331'313.3)13'3331Atelephony at the Technical College. 4and the Publice 4 C ARRANGEMENTS have been made for The more progressive newspapers in the._):11333133.1.33313.133n.333333311, theAmericanwirelessstationatStatesarealready broadcastingspecial Arlingtontocollectparticularsofthetalkstoreaders, market reports,stock THE newspapers tell us that the Post weather conditions every morning from aquotations and sporting news, in addition master -General and the committee of number of American stations and wirelessto complete musical programmes. broadcasting firms are on the pointof them to the Eiffel Tower.They will then reaching an agreement, and that in this -IN OM be broadcast from the Eiffel Tower half agreement two factsstand out promin- an hour after noon. TheSouthAfricanGovernmenthasently-theGovernmentwillsharethe approved of the establishment of broad-licencefees with the broadcasting com- casting wireless telephone services.As inpanies, and will, in due course, introduce Aninternationalorganisationofthethis country the circulation of advertisinglegislation with a view of ensuring that_ world's wireless operators has been formed.matter and commercial traffic is, however,only British -made apparatus shall be used The federation is to have its headquartersnot permitted. in the transmitting and receiving of the in London. broadcast messages.At the time of writ- In the House of Commons on Wednes-ing this agreethent is not a fact accom- The Middlesbrough Chief Constable hasday last Mr. Pike Pease said the condi-plished, and we should like all concerned been authorised to obtain an estimate oftions for the issue of wireless broadcastingtolook closely and anxiously intothe the cost of purchasing a transmitting andlicences had not yet beensettled. Hematter before a hard-and-fast agreement on receiving set and to submit the same to thehoped to make a statement on the subjectthese lines is cemented. next meeting of the Watch Committee of soon. We have long seen the very great diffi- the Middlesbrough Town Council. culty the broadcasting firms must be in. - A wireless theatre has been establishedThe public calls upon them to provide MN MN MI in Southport.Sixty 'phoneS have been in-amusement, and if the public calls the tune No officialinformationisforthcomingstalled, and patrons will be able to hearthe public must also pay.There can be as to whether either Glasgow or Edinburghconcerts from London, The Hague, Eiffelno two ways about that.The difficulty will be the selected spot for a broadcastingTower, and many other stations, generalhas been in finding a just way. of making station.There are rumours that each. citynews, weather reports, lectures, etc.:Therethe public pay.In the United States the is to be permitted one! isonecentral. receivinginstrumenttopublic has paid in one way only, that is, which thesixty 'phones are connected.by purchasing the goods the broadcasting The theatre will be open daily from tofirms manufacture and sell, and a very Broadcasting is already well establisheda.m.toto p.m., the charge for admis-good way, too.In this country the broad- in Ganada. sion being one shilling. casting firms have hesitated to start amusing the wireless public until they could be sure of their return, and that is the very A system is now being perfected on the Receivers are to be installed in everycore of the difficulty, but to allow a con- Continent by which finger prints can bevillage of any size throughout France. Onference of broadcasting firms to settle it in wirelessed. the receipt of the official weather forecastsecretconclavewiththePostmaster - from the Eiffel Tower it will be communi-General was not ideal.The public in- cated to the inhabitants by the ringing ofterestwasnotsufficientlyrepresented. The synopticweatherreportsandthe parish church bell according to a pre-The Postmaster -General represented, first genesralinferenceshithertoissueddailyarranged code. on 1,400 metres C.W. at 6 a.m., 8 a.m., and foremost, the official interest-the in- UM II terestofa' great public department in 2 p.m., 7 p.m., and also at 9.15 a.m., and A wirelesstelephonehealthbulletinwhose hands are the exclusive rights of 8p.m.(allhours are Greenwich meanservice has been inaugurated by the United time),infuture will be transmitted onStates Public Health Service.A message 4,100 metres C. NV.The synoptic rep6rt atof advice on how the average man and 2 a.m. will continue on 1,400 metres.The ELECTRADIX RADIOS 8.30 a.m. report will cease.In cases ofwoman may ensure continued good healthBROWN MARCONI H.R. 'Phones, breakdown or other delay, should trans-is broadcast twice a week. 2,000 ohms .. .. 51 s. mission on 4,100 metres not have begun Other makes. 2,000 ohms 33s. within ten minutes of the scheduled time, FORTHCOMING EVENTS 1,500 ohms .. 26s. the message will immediately be issued on Derby WirelessClub. July20,7.30 p.m.SULLIVAN'S L.R. Head Phones 20s. At " The Court," Alvaston, Derby.Lecture 1,400 metres. on " Detecting Devices," by Mr. E. V. R. Single L.R. Receivers, 4s. 6d.Used Cords, Is. 6d. n Martin. AERIALS.All Accessories in stock. Nottingham and District Radio Experimental Wireless ist6, --be used as a means ofAssociation.July 27.'Meeting. RECEIVING SETS. Marconi Trench, 50 D.C., 'aringing schools lying in outside districts Derby Wireless Club. July27,7.30 p.m. 60s.Complete with Transmitter, ES 10s. .nto touch with university life.HithertoAt " The Court," Alvaston, Derby. Lecture2 -VALVE AMPLIFIERS, £7 10s. here has been some difficulty -in inducingon " Practical Construction of a Single Valve,H.T. BATTERY, 60 volts, in polished mahogany Receiver Set," by Mr. A. T. Lee. box, 6 sockets, 2 plugs, 15s. 6d. )rofessors, lecturers and others to ge) out TELEPHONY TRANSMISSIONS o them. EiffelTower (F L). 2,600metres. Each EVERYTHING FOR WIRELESS afternoon (Saturdays and Sundays excepted). Marconi House (2 L 0).July 20, 8 to 9 p.m. Tons of electrical goods in stock.Call and inspect Authorities are of the opinion that theTransmission tests. our stock, first turning on the left down the Minories. .wireless business as itis now developing The Hague,Holland(P C G G). i,o7o metres. July 23, 3to 5 p.m. LESLIE DIXON & CO., is going to be greater than the gramophone Writtle(2 M T). 400metres. July25, industry. 8 p.m. 9, COLONIAL AVENUE, MINORIES. E.1 emateur Ws 134 JULY 22;1922 telegraphy and telephony in this country. If, for the sake of explanation, we saybowed shoulders, may, and probably will, The broadcasting firms represented them-the dielectric's electrons are vibrating tencause the closing down of their stations. selves.There was needed an equal repre-units and the light wave is vibrating at The country has nothing to gain scien- sentatipn 9f the public interest, a few goodten also, on impact the two would canceltificallybythousandsof"condenser men of affairs who could have put the caseand the light waves would not pass. wanglers" mak ng. the ether hideous with 'for the people who will have to do the I think this is sufficient to show that itthe' howling of their valves; it has every- paying.If the suggested agreement goesis not the ether that is responsible for thething to lose by suppressing the top-attie through, not only will the broadcasters belight not passing, but the electrons in theman. Which of these two distinct sections given a close monopoly, but, in addition,porcelain.-A. P. (Southsea). willsupplyourcountry withwireless they will be drawing a fee from every SIR,-G. B.'s letter in your issue of theoperators in the event of another war ? member of the public who owns a receiving8thinst.raises some interesting points. Certainly not the arm-cha.;r enthusiasts. set.The present nominal licence fee willI -J. F. G. C. think itis hardly safe to deduce any 0N.W.".".."."1\1,../\JO have to be considerably increased-per-theory from the behaviour of an electric haps multiplied by four-and that in itselfbell enclosed within a porcelain or other is not fair in view of the fact that thenon -conducting receiver. CLUB DOINGS broadcasters are shutting out foreign com- In the last paragraph but one G.B. Proposed Central London Wireless petition, as a result of which their profitsrefers to the waves of light from the sun Society from the sales of apparatus and parts must,as not travelling all around the earth'sHon. Sec.-(pro tent.).-11entAcs E. Holm, in due course, assume enormous dimen-surface, while "the electro-magnetic waves,15, Rydon Crescent, London, B.C.r. sions.We strongly dislike the idea of aas is well known, follow the earth's sur-APPJ,ICATIONS for membership are invited. monopoly.Every true Englishman does,faCe." Isthislaststatementunques-Proposed Clapham Park and District but if, in the special circumstances, itistionably established, or may it not be that Amateur Wireless Club agreed that a monopoly isdesirable inthe waves travel in straight lines through CORRESPONDENCE is invited by Mr. J. C. Elvy, this instance, let that be enough.Don'tthe earth to the several receiving stations ?A.M.I.E.B., M.I.E.S.It is proposed that the seek to make the public pay at both ends club should include Streatham, Balham and Ishall be very much interested to knowTooting. of its hobby-more for its licence, and in-other reader's views.-E. W. W. (Coven- evitably more for its apparatus. try). The Mid West Herts Wireless Club Thousands of amateurs are not interested Hon. Sec.-MR. J. R. FRANcis, " Ivy Cottage," in broadcasting.They are more or less [We are obliged by great pressure onRedbourn, Herts. serious experimenters to whom broadcast-our space to hold over many other lettersTae Secretary invites correspondence from all inanswerto G. B. assuch hasverylittleattraction. Furthercorre-willing to assist in the holding of meetings in ing spondence on the subject is not invited.-St. Albans, Harpenden, Hemel Hempstead Theirs will be a very real hardship when and Berkhamsted. they have to pay for something they doED.]. not want and will not have.Sooner or Testing 'Phones Radio Rendezvous later the whole question of the licence and SIR,-Regarding theshortarticleon709, The Broadway, Manor Park, E.12. Many amateurs fail AMATEURS in thedistrictsof East Ham, fee must be raised. testing 'phones, there is a much simplerManor Park, Ilford, Wanstead, Forest Gate completely tofind any reason why thetest which I have always found to giveand Barking are invited to become members State should take a fee and do absolutelytrustworthy results, which is as follows : of the above club.Club rooms are open every nothing for it. Place one end of one 'phone lead in thenight until so p.m., Sundays excepted. mouth, hold the other by the insulation,Birmingham Experimental Wireless ared touch the blade of a pocket knife with Club the bare end.Ifthe'phones are in a(Affiliated with the Wireless Society of London). CORRESPONDENCE sensitiveconditionadistinctclickis o Hon. Sec.-PRANK S. ADAMS, no, Ivor Road, heard each time the contactis made.-Sparkhill, Birmingham. Can any Reader Explain ? W. B. A coNFERrNes of Midland Wireless Clubs is being promoted by this Club, with a view to Sut,-There are two points your corre- " Listening.in " To Be Dearer discussing the interchange of lecturers,and other spondent should fully appreciate-firstly, SIR,-Under the above heading one ofmatters of mutual interest. that light waves are electro-magnetic inthe daily papers published a statement of It is proposed that the conference shall be held in Birmingham, as early as possible in nature, differing only in linear dimensionswhich the following is an extract : September.All Midland Clubs are invited from the disturbances which are created "Thecostofthebroadcastingpro-to send delegates, and the secretary will be byoscillatingelectriccurrents,etc.;gramme, estimated at 220,000 a year forglad if secretaries of the wireless organizations secondly, that it is of vital importance thateach of the eight stations, has surprisedwill communicate at the earliest possible date. thedielectric(inthiscaseporcelain)those anxious to listen -in, and many have Stoke-on.Trent Wireless and should be completely taken into accountwritten suggesting that the price of the Experimental Society arid studied thoroughly, because itis theGovernment'slistening -inlicence,now(Affiliated with the Wireless Society of London). "refractive index" of the dielectric whichfixed at Dos. 6d., should be increased, andHon. Sec.-F. T. JoNES, 36o, Cobridge Road, decides whether the waves are capable ofthesum chargedover and abovethe HANLEY. passing or not.G. B. is aware that wire-original figure placed to a common fund,AT a meeting of the above society on Thursday, July 6th, some buzzer practice for the benefit less waves, also X-rays, are capable ofout of which the programme could be pro-of the new members was followed by a lecture passing, but fails to see why light wavesvided.Itis understood that a proposalon " A Short Wave Tuner," by Mr. A. H. cannot if they use ether as their medium. on these lines has been placed before theWilson. Post Office authorities, and it is probable (Continued on page 136' that a considerable increase in the licence Can You Propose fee will be authorised." a New Feature for To the hundreds of wireless enthusiasts with money to spare for expensive valve "Amateur Wireless" .setsthethreatenedincreasewill make For the Best Suggestion on a littleornodifference. Tothereal postcard received by Wednes- amateurs, however, who have built up day, August 2,a Prize of £1 their sets step by step, using home-made will be awarded. apparatus and inventive genius, the addi- uerist's Coupon Available until tionalburdenaddedtotheiralready Saturday, July 29, 1922 JULY 22,1922 135 emateurWireless iniffiliniantlillmilmiliiiiiiiiiiiiiiiiiiiiiiimmumniminiinimmiiiiiminiminninillinita: = HELLO C.9 ?ARE YOU RECEIVINC THIS CALL? E.= OUT TO -DAY _ A. E.G. & Telefunken Valves,tested 1016 Sq. Brass Rod, re xexr ... 9d. = Valve Holders, Screwed Legs& Nuts 1/6 ' Enamelled Wire, for Inductances, Condenser Vanes, Aluminium (accu- 23 gauge,ij lb. ... 1/6 rate size and gauge), per doz.1,'6 Crystals (special selected), Bornite, THE CONSTRUCTION OF WIRE- Do., Large Spacers (true to 'ace) 8d. Carborundum, Silicon, C. Py- Do., Small Spacers (true to .00r") 4d. rites, Galina, etc., etc. ... 6d. Do , Scales Ivorine, o to 180.... each 1/ - Crystal Cups, Brass, . with Fixing I LESS RECEIVING APPARATUS Da, Ebonite Tops and Bottoms Screw 6d. Fusible Alloy (for fixing crystals) 6d. = By PAUL D. TYERS. =-- (bushed) 1'3 Hellesen,35 v.H.T. Batteries, E= E Inductance Tubes, r2' x 3' 8d. with Plug ... 13,6 = I ... 9d. = The only book which tells you HOW to MAKE ALL the PARTS of a = 12° X 4' .. Headphones, Double, 2,000 ohms, E Valve or Crystal Set. E re x5'...1/ - Adjustable Headgear,ex- = Sliders, Ebonite, with Plunger ... 9d. cellent for speech and music 35/- = Inductances - Resistances - Condensers -Grid Leaks - High - Tension = Aerial Wire, Stranded, 7/25 too' ... 4'8 4.coo ohms ditto...... 37/6 = Batteries-Detectors-Potentiometers-etc. Do., Egg Insulators (high insulation) Filament Resistance panel mounting 4: - E= In fact, EVERYTHING you wish to make.No Lathe or expensive ools = Do., Reel best quality 4d Switch Arms, laminated, with bush = required.Essential to all who wish to make their own sets. E Do. Pulleys, Aluminium, with cord 1,6 and spring ... .. 2,B = Panels, Tuners, Transformers.Postage extra. Demonstrations Daily. PRICE 1 s. 6d. Net.(Post Free.) =- own.. .. = THE ESSEX F_ = WIRELESSCO.. 499, GROVE GREEN RD., (Wholesale & /Id,, LEYTONSTONE. E.11. :=-Hiniiiiiiiimiiiiiiiinumilmillimilitimilimilitimiliniiiiiiilminifilimillitiliiiiiiitimmilliiii= Telephone-WANSTEAD749., (1 min. from Station, G.E.R.) OUT ON JULY 19th = WIRELESS VALVES SIMPLY EXPLAINED BARLAW RADIOPHONES EFFICIENT AND RELIABLE By JOHN SCOTT-TAGGART, F.Inst.P. 1 i. Over 3o,000 copies 01 John Scott-Taggart's books have been sold by us in Complete Receiving Sets from £4 1 three months.There is a reason.7 his new bo,k front his pen is largely an abridgement of his "Elementary Text -book on Wireless Vacuum Tubes," F., which has had a phenomenal success.The price of this simple book has been cut i. down to a highly competitive figure and is based on the prospect of very large sales, Suppliers also of Apparatus ofallthe ORDER AT ONCE. iI. Well-known Makes, Spare Parts, Acces- aPRICE 2s. 6d. Net.Cloth, 3s.(Post Free.) i i E.- i sories and EVERYTHING for Wireless. i Eillinumminiiiiiiimmilinimmiliiitimilimmiiiiiiiiiiritimiiiimumminimilmiiiiiiimilininia i .E-- .---_ RADIO PRESS LIMITED, = 1 THE BARLAW ENGINEERING CO., LTD.,I i 47, VICTORIA STREET, S.W.I. i --7 35, Norfolk Street, London, W.C.2. '---L"-- Telephone:Victoria 69;9. Telegrams :Engtbaiac, VIC, L011,1011. i .141,..49....411.11w10..1.4wd...... v.. v.0.0.1.40.*wMili...... 1....4

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and gauge. Doz., 10d.;ti doz4/6 H.R. Headphones,4,000 ohms, complete with cords. Post6d.Free Ebonite Knobs, Drilled ... 6d. (Sold elsewhere at 87/6) Ebonite Sliders, with plunger Enamel Wire, H.C., No. 24 gauge lb.2/2 My Price 301- Complete

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When writing please mention this publication Small 3 dozenfor9d. Cheap Crystal Sets a Contact Studs,X 1 dozen .8d. Comprising single slide induct- a ance coil, wound 24 enamel wire, X 1 crystal detector, condenser, ter - LESLIE McMICHAEL LTD., Ebonite Valve Socket, four legs ...1:3 initials, ready to connect 'phones

Inductance Tubes (shellac varnished) wound and aerial.All on solid bsse. Providence Place, West End Lane, Kilburn, N.W.6. 24 enamel wire ... 4,6 Square Brass Rod, 13' x 6d. 15/-201-25/ - Terminals (4 B.A.).Doz., 1/6;3 doz.,4/. Made in my own factory. Postage extra Bus Services 1,8, 16, 28, 31, all pass West End Lane.

Telephone :HAMPSTEAD /261. 1VI. RAY ®ND Nearest Tube Station ;KILBURN PARK (Bakerloo). 27, LISLE STREET, LEICESTER SQUARE, W.C.2

(Opposite Da'y's Gallery Dom) molcur Wes 136 JULY 22, 1922

......

OUR INFORMATION BUREAU

Expert Replies to Readers' Questions.Hundreds of Replies are sent by Post.

TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES

Write distinctly, give all necessary details and keep to the point.Ask one Question at a time-never more o than two.Send a Stamped and Addressed Envelope.Send the Coupon cut from page 134. o e

Valve Panel for Mark III Receiver not be such that self -oscillation of the setWalthamstow Amateur Radio Club Q.-I wish to make a valve panel for use inoccurs, as this distorts received speech, etc., Hon.Sec.-R. COOK, tiverstone Road, Wal- conjunction with a Mark III receiver, andand may cause considerable interference tothamstow, E.17. should be glad of advice. - E.U.C.C. (r5) adjacent receiving stations.Self -oscillation isAT a meeting of the above club held at the A.-The usual type of valve panel is wellnecessary for reception ofcontinuous -waveY.M.C.A., on Wednesday,Julyr 2th,Mr. adapted for this purpose, and may be con-signals, unless a piece of apparatus known asButler gave a very interesting and instructive structed in accordance with detailed instruc-aseparateheterodyneisemployed.Thelecture, accompanied by diagrams on the black- tions given in Chapter IX of the new hand-proposed arrangement should prove very use-board, on " How to Construct a Crystal Set." book, " Wireless Telegraphy and Telephony "ful, though for radio -phone reception fromNext week he is taking for the subject of his (Cassell & Co., Ltd., price is. 6d.).The usualstations within a radius of, say, 5o to 7o mileslecture " A One -valve Set." terminals as fitted will be required as follows :the Mark III. set, plus one valve functioning The club are giving a Public Demonstration (f) Valve terminals on Mark III. set to beas a low -frequency amplifier, should certainlyat the Y.M.C.A. on Tuedsay, July 25th, when connected to aerial and earth terminals ofbe triedas an alternative arrangement.-they hope to initiate a proportion of the public valve panel, that is to say, to the grid (via CAPACITY. of Walthamstow into the mysteries and plea- condenser and leak) and filament of valve, sures of 'Wireless. which may always be regarded as the " input " All applications for membership should be circuit.(2) Telephones will require to be re- addressed to the Hon. Sec. moved from Mark III. set and connected to CLUB DOINGS(Continued from page134) telephone terminals of panel. (3)L.T. and The lecturer, after outlining points which if H.T. batteries are to be connected to respec-neglected would greatly reduce the efficiency The hackney and District Radio tive terminals on the panel.(4) Reactanceof any tuner, dealt with the construction of a Society terminals on panel will require to be short-short-wave tuner on which telephony fromHon. Sec.-MR.E. R. WALKER, 48, Dagmar circuited by means of a piece of stout copperlocal amateur stations, and the wireless con-Road, South Hackney, E.9. wire, unless of course a reactance coil is madecert sent out from. the Marconi station in Essex,THE above society held meetings open to the and suitably coupled to the secondary circuitcould be received. public at air, Chatsworth Road, Clapton, on of the Mark III. tuner., Though not strictly A home-made tuner of the variometer typethe evenings of July 6th and 7th. necessary for reception of spark or telephony,constructed by the lecturer, other tuners, and The lecture given at the opening by Mr. E. a reactance coil affords a means of obtaininga large number of tuning coils were exhibitedR.Walker, was on" FirstPrinciplesin great magnification, but the coupling shouldand handed round for examination. (Continued on page 138.) I Get Your TOOLS from Us We specialise in Electricians' Requirements.Write orcall. The Chancery Lane Tube Station gives all London access to us, and is only one minute away, We can supply YOU with ALL just across the road to Chancery Lane and a few doors down brings you to COMPONENT PARTS POND TOOL Co for your wireless setstraight from stock If you wish to save money, send forour 67,69,70,t HANCERY LANE, W.C.2. Complete List SPECIAL LINES IN -- TRADE SUPPLIED Wire 'Gauges,0 to 26,S.W.G.,219; Hand Vices,4in.,solid steel,2/-; Hand Drill.taking all drills, 0 to ass in.,7/6; Combination Pliers.6,or 8in.,2/-; Aerial Wire, 7122 bare copper stranded in 100 ft. banks 5/6 hank Metal -cutting Sawsfrom 1/-;Vices,for clamping on Table, etc, 2/! to9/6; Ring Pattern Insulator, 2 in. by 1 in.,in. hbolt). ..6d.pe each. Measuring Slide Rules,3 in.,2/-; Blowlamps from 29;all poet free. in. sq. Section Brass Rod for Sliders, cut in 13 in. *length's, we have a large stock ofDrills. Metal Files, Taps and Dies, Bolts and and dtillrd each end ready for fixing ... 13d. each. Nuts, Wood Screws, Solder Irons, etc.All goods sent on approval against Inductance slider, complete with plunger cash, money returned if not satisfied. Cardboard Cylinder, 12 in. by 4 in. diameter 1014.elaccilt1* e No. 24 enamelled wire, H.C. true to gauge 2/8 per lb. Large or small Condenser Plates (Aluminium)... 1/4 doz. Writ fir our List 6d., refundable on first order Large Spacer Washers for condensers, cut true to 1,000 of an Small sparer washers Ditto ...6d. doz. SCIENTIFIC APPLIANCES Ivonne Scales . . . . 1./. each. HENRY J. DALE. W. HOLLINS. Condenser Box in Polished Oak or 'Mahogany, 3; in. by If in. by 2 in. 5/- each. 11 g 29, Sicilian Avenue, Southampton Row, London, W.C.I. '0003 mf. Condenser complete-assembled in polished mahogany or oak boxes . 17j6 each. 1 Top of Kingsway. In Centre of London. Corner of Bloomsbury Square. All necessary parts for above condenser-no drilling or fitting required, but unassembled lb- each. Ditto, but without box 11 - each. ELECTRICIANS.OPTICIANS. MECHANICIANS. Ditto, but without ebonite top, and box suitable for panel ACTUAL MANUFACTURERS at our Works, East Street, W.C., thus saving all intermediate profits, mounting each. Crystal detector, mounted t n Ebonite, complete with Crystal 51- each. The Score for all Electrical and Scientific Material Large or Small Contact Studs 11- doz. Valve Legs, complete with nut and washer ...... 3d. each. WIRELESS & RADIO MATERIALS, VALVES. 'PHONES. PARTS and FITTINGS Call and see us. View our Show Instrument Wire at Rock -bottom Prices Windows. Send for List post free 2d. Immense Stock constantly adding to, and. Making ;Specially 'or theAmateurto Build up a Set Completeand Perfect. Splendid Value in J. B. BOWER & CO., Ltdfbit EBONITE. BATTERIES. ATRIALS. Secord-hand Appliances WIRELESS MANUFACTURERS, INSULATED WIRES.CRYSTALS. ENGRAVED DISCS. MICA. HANDLES, Every Branch of Optical 15, Kingston Road, WIMBLEDON, S.W.19. SWITCHES. TERMINALS. STUDS. and Applied Science 'Phone: WIMBLEDON 1030. Works: MERTON. Scientific Appliances, 11 & 29, Sicilian Avenue, London, W.C.1. JULY 22, 1922 137 emateur Wiseizs.! ;THE PETOPHONE CRYSTAL SET £3 15s. Od. COMPLETE WITH 4,000 OHM HEADPHONES Comprises Double Slide Tuning Coil, 8 in. X 4 in., Crystal Detector, Condenser, High- class Sensitive 4,000 ohm Headphones.Set Mounted on Polished Mahogany Board. Carriage paid 75/-. Delivery in 48 hours. Satisfaction or money returned BUILD THIS VALVE PANEL

Price Price 1519 15/9 Set Set of of Parts Parts

Full Set of Parts contain Ebonite Panel, drilled and lapped, Grid Leak (Sphinx Tubular Type, guaranteed 12 months), Grid Condenser, Telephone Condenser, Systo flex, Wire, All Terminals, Set of Engraved Ebonite Tablets, Valve Sockets. Blue Print.15/9, Post 9d. We can supply a Polished Cabineeto fit at 3/6 extra - Get our Catalogue A.6d. Stamp brings it to your door.

WE HAVE SETS OF PARTS FOR ALL OTHER TYPES OF RECEIVERS & TUNERS Don't forget our NEW address PETO SCOTT (The Condenser King), ofaNew FEATHERSTONE HOUSE, 64 HIGH HOLBORN, LONDON, W.C. I EXCLUSIVE I Also at 17, FROME ROAD, WOOD GREEN. I FEATURES I Wireless I of No. 1 7_-_-- L. HOME CONSTRUC- E ROADCASTINGE; T1ON MADE EASY II Magazine and GENERAL RECEPTION --z- [THE MAN BEHIND E _= forAmateurs E - THE VOICE I Photographs of London == = _ E stations and their opera- I Hereisa64 -pageWireless tors (monthly feature) =- SingleValve Set Monthly Magazine which does ITHE fulljusticetoa wonderful E THE COMPLETE INSTRUMENT. Highest = BROADCASTER subject.Here are splendidly E.- quality throughout.Supplied with Set of Tuning Coils. -a- I BUREAU illustrated and f a scin a ting -= less Valve Phones andBatteries. Expert Advice Free articles by eminent authorities, F-- 170-2,500 metres = = = I AERIAL HINTS written in plain simple language' 7 0 0 E to enable the amateur to dip WIRELESS into wireless to his heart's con- I SOCIETIES OF tent. The BROADCASTER LE- - THE WIRELESS INSTRUMENT CO. ---== GREAT BRITAIN isthefirstEnglish Monthly --g. 328, CITY ROAD, E.C. I" HOW I DID IT:" Wireless Magazine for Amateurs. By A NOVICE To keep abreast of the times ,..-Tilliiiniiiimpliniininiitoitintinniffiliiiiiimitiintiiintintitinimilliiiiiiiiiitiliniiiimininumiri you MUST read and many other "THE BROADCASTER." Large Stock of Head - splendid features CONDENSERS phones 4000 ohms) ==.0015 Set of Parts 25/-, Assembled 30/- DON'T MISS THE £2 1 0 0 .001 19/-, 24/- EXCLUSIVE INTERVIEW WITH Filament Resistance 4/6, Valve 12/6, 15/- .0005 Holders1 /6, H.T. Batteries 3/6,15 v. GODFREY ISAACS Vernier .. 4/6 Switch Studs 1/6 don., Arms 2/-. ON BROADCASTING B. L. HOUSTOUN,85, END6Mulnhatrr4fr, wC.2. WE DON'T WASTE YOUR TIME. We hold good stocksof everything Wireless, and make Broadcaster it our boast that every letter has attention THE RADIOPHONE MONTHLY FOR LISTENERS - IN WITHIN 24 HOURS. Complete Lists two stamps. Dne Shilling ELECTRICAL SUPPLY STORES, 5, Albert Terrace, King Cross, HALIFAX. Ontattur Wire65 138 JULY 22,1922

CLus DOINGS(continued from page/A Receivers. -AlargestockoflonA.resistancere- Wireless Telegraphy,"Mr. Walker explained ceivers,ionto200 ohms, each ex -Post Office and Government watch pattern,forsale,3s.6d.and WIRELESS RECEIVING APPARATUS how the aerial became charged so that it pro- 6d.each, postfree'. Wireless double head reduced waves.After this the second lecturer, ceivers,4,00o -ohm,Londonmanpfacture,37s.6d.' of every description Mr. D. R. Ison, gave an explicit explanation each,postfree. Everythingstockedforthe amateur assemblinghisown apparatus. Ebohite Send lid. stamp for prices and particulars to of reception of the waves, with the aid of a panels, cut, engraved anddrilled to order. Marconi 31a tuner.On both evenings various Mahogany and teak cases. -W. H. Agar, 2,. Fins- H. BOWYER, la, Railey Mews, items oftelephony werereceived.Any bury Avenue, Eldon Street (near Liverpool Street). Leverton Street, Kentish Town,N.W.5. persons wishing to join the society should [7 s apply on Thursday evenings at the above address, or write to the Hon. Sec. WIIiCELIESS Cardboard Cylinders, r 2in by 3 in., 8d.; tz in. by 41n., 9d.; 12 in. by 6 in., 101d. Enamelled Wire, ca g., 3- per b. Aerial Wire/at, copper, 5/8 r o q H. PREPAID ADVERTISEMENTS. Insulators, 4 d.each. CrystalDetectors,5/13each. CrystalCups,401.each. q Sq. Brass Rod, i; in. Drilled, 8d. each. 13. in .Former Stays, Old. each. BAMBOO POLES for AERIALS MonthlyCompetition,Free. -to -ft.aerialmast. Ivorine Scales, 0-220, 1 - each.Ebonite Knobs, 8d. each.Contact AND BAMBOO OFEVERY DESCRIPTION Particularsandlist,2d. -F. Armstrong,Wireless Studs, wi! h Nws, 1,2 and 11 dozen. Spacer Washers, bid. and Std. doz. FROM TWIGS TO YACHT MASTS Mast Works, Weybridge. r Condenser Plates, Mum.. 2'9 doz: 3d. pair. Sliders andPlungers,101d. telephonere- 12 x 4 Cylinder, Shellac Varnished and wound with ay g. En. Wire. 6/-. Newtonian Wireless Factory.-2,coo Valve Legs, 2.9 ,'oz. Variable Condensers, .0003 Asseinoted in Box,18 9. Large Stocks Alwayson Hand ceivers, single 21 s., cords Is. 6d.; double, with head 4,000 0.11 it.Telephones, 37 6 pair. 1 -Valve Receiver, £6 103. 2 -Valve band, 4os.-13.13, Whitcomb Street, W.C.2.Regent Receiver, £8 10s. Complete Crystal Sets, from £4 7s, 8d. 643. W. BIRD &SONS, 33, Fulham PalaceRd.,Hammersmith,W.6 A. E. DAVIES&CO. (Importers) Newtonian Wireless Factory. -Reel insulators, TRADE SyPPLIED. 1641 Lever Street, City Road, London, E,C 1 samples, 6d. each; condenser plates, 3d. pair; crys- TelephoneH.1121t11 0738. POSTAGE EXTRA tal cups, 4d. each; ebonite inductance sliders,rod. each;3 by 12 spiralwoundtubes,9d.each; shellacinsulating varnish,tod.per bottle ;square ASTOUNDING BARGAIN rods, drilled, 13 in. long, od. each. -13-13, Whitcomb DELIVERY BY RETURN Street, W.C.2.Regent 643. SULLIVANIN Newtonian Wireless Factory. -Completecrystal set for making up your own apparatus, comprising all HEADPHONES SPECIAL WIRELESS LINES materialsandz,000 -ohmreceiver,reducedprice, 43s.6d. ; carriage,25.-13-15,WhitcombStreet, CONCERT HONEYCOMB COILS. -Waverange 30o W.C.2.Regent 643. NEW! to 50o metres. Very efficient.Hand wound. PRICE per Bargains. -7 -strand wire, 75.6d.tooft. Alimited quantityof 120 ohms Sulli- pair,primary andreaction -Unmounted51-,Mounted aerial 1116.Post6d.. Marconi " Q " valves,nos. each.Sullivan's 'phones, van Headphones, double, complete So ohms us. 6d., 120 ohms 215.6d., and 23s.pair. with Cords and Adjustable Head- o-300, case,cost VALVE LEGS -withtwo nuts and -washer-lacquered, Nlilli-amp.and voltmeter leather bands.Potectty new, offered at 21d.each.9d.per set of 4. 47,6os.secures -Service Sales,8,Great Southsea Street, Southsea, Hants. [I s PER 20/- PAIR " Premier " Timing Coils.Tune tor,000 metres, CASH WITH ORDER Send for list.Special terms to the trace andwith .005mfds. to4,000. Complete,well mounted, its., carriage paid. -Johnson's, 18o, Complete SATISFACTION or money ref urnzd Actual Makers:CHAMP, KAY St CO., Bohemia Road, Hastings. [2 s ElectricalEngineers, 92, Saltisford, WARWICK. Parcels of Assorted Brass Rods,ros.each,carriage paid.Contents, 2ft. each 1in., A in., f,in., F. HARRISON, A in.,fin.., A in., A in.,nin.and A in.round 46, Brooke Rd., Walthamstow, E.17 and iin.square.Aluminium condenser vanes,is. doz.Spacer washers, large 6d. doz., small 3d. doz. INSTRUMENT WIRESFROM STOCK Valve legs with nuts and washers, 9d. for 4.Taper plugs and sockets,2d.set. Immediate delivery. - TO WIRELESS EXPERIMENTERS. PATENT YOUR S.W.G.S.C.C. s s.c. D.S.C. EN . Sydney S.Bird, 34, Queen Anne's Grove, Bush Hill 47 110/- 120/- 41/- \ Park, Enfield. 13 INVENTIONS. Tuning Inductanoesiguaranteed, 4in.by 4in. They may prove very valuable.Particulars and consulta- 46 97/- 107/- 26/- by 14in.,doubleslide,polishedends,215.,post tions free.BROWNE & CO.,Patent Agents, 9, Warwick Court, 45 64/- 80/- 20/- Holborn, London, W.C.I. free. -ErnestBatley,Tlrongsbridge,nr.Hudders- Est. 1840.Tel. Chancery 7547- 44 50/- 66/- 16/- field. [4 s Masts. -Sendforprices. -StephensandCarter, 43 40/- 52/- 13/- Ltd., Paddington Green, London. s HICH CLASS ROTARY VARIABLE CONDENSERS. 42 31/- 33/- 9/- Aerial Wire,16 gauge hard -drawn copper, tooft. 'coos in Polished Cabinet, 4' X 4" Y4', Ebonite 41 30/- 32/- 8/- 3s.gd.,carriage paid. -Gibson, Somercotes, Derby- Top and Knob, Ivorine scale, o' -18o *, 16 6 40 14/- 17/- 18/- 22/- 6/6 shire. [6 s Ditto for Panel (scale extra) ... ..10/6 MastRope,'realManila,maximumstrength, .0004 inCylindricalBrassCase, Lacquer finish, 39 12/6 15/- 17/- 21/3 6/- lightness, in.thick,toSft.long; price,4s.6d., Ebonite Top and Knob, Ivorine scale ; a very 38 11/- 13/- 16/- 19/- 5/3 carriageis.3d. -Gibson,Somercotes, .Derbyshire. handsome instrument ... 16/- 14/6 17/3 Established 18.49.Telephone :No. 19 Somercotes.[4 s Crystal Detector withBall and Socketadjustment on 37 10/- 12/- 4/11 Aerial Insulators,white, 2 in. by rin. reel pattern, ebonite base, ... 5/6 36 8/6 10/- 13/9 15/- 4/8 1.s. 3d.doz.,carriagepaid.r.Gibso,n,Somercotes, WEATHERALL & Co., 28. Woodbridge Street, 35 7/9' 9/3 12/9 14/- 4/6 [6 s Derbyshire. Clerkensvell, London, E.G. Estab. over 20 years. 34 6/10 8/- 11/3 13/9 4/4 33 6/2 7/6 10/6 13/- 4/3 CASSELL'S 32 5/10 7/2 9/1 12/10 4/2 COLLOY WIRELESS INSTALLATIONS 31 5/6 6/10 8/9 11/6 4/- FREE Demonstration in London 30 5/- 5/4 7/? 9/10 3/10 in your home if TIME 29 4/9 5/- 7/6 9/6 3/8 area. Let our expert call and advise you. We install free TABLES 28 4/3 4/6 7/2 9/ - 3/6 and give working instruction. Provinces, stamp for list. 27 4/2 7/- 3/5 / Oter4hl 5 oniliptica8 i6on All component parts stocked at lowest prices AERIALS, 100 ft., 6/. Monthly FINE7/82 SUPPLIES.1 41, Aingtords.IATad, 4, CLONM ELL ROAD, S. TOTTENHAM 2s. net. A. E.DAVIS, Brrixton 30th Edition Universal Electric Supply BROWNSTREET 7ilephorie LINE MDR 1:1101 MR SET Sr 6.14,11N1Shla 3109 CITY 1892 =Now READY MANCHLVTER We have striven to make tliis List P.O.Bo, No 519, theMostInteresting,Instruc,..vo and complete Catalogue of- " EVERYTHING ELECTRICAL o qui a e 2427 30 33 36 AND WIRELESS" ever published, and we have suc-

ceeded. A wide range of complete Crystal and Valve Receiving Sets is shown, andin addition we listthe most wonderful range of Units and Com- ponents for those desiring to make their own sets. POST FREE Cd. JULY 22,1922 139 entakurWirdess

IsIIIIIIII tom - W IIel NI III - W CQ Std bi Specially for ERICSSON PHONES designed WHEN you instal your wireless set for -crystal or valve-you'll get Broadcasting maximum resultsifyoufitEricsson Phones-clarity, sensitivity, strength of signals and absence of "'click." Specially suited to telephony: EricssonPhonesembodytheaccumulated experienceoftelephone manufacture for a generation. Easy to the head. light and comfortable.The magnets never lose their strength and "shorts arenon-existent. Write for Particulars TheBRITISH L.M.ERICSSON MANUFACTURING Co., Ltd. HEADGEAR RECEIVERS Head Office : Designed and manufactured by leading Telephone Manufac- 6o, Lincoln's Inn Fields, E.G. 2 turers.Backed by many years experience.Highest efficiency, concentrated magnetic field, instantaneously adjusted to the ears, comfortable in wear, either receiver detachable from head- band, protected terminals, light weight, twin series cord.

A.T.M. LOUD SPEAKING A.T.M. CRYSTAL DETECTOR RECEIVERS. SETS.Highest Grade.Maxi. Three types of Amplifying Horn. mum Efficiency.Moderate Cost. Ask your dealer for A.T.M. Broadcasting Apparatus AUTOMATIC TELEPHONE MANUFACTURING CO., LTD., Head Office & Works: London Office: Milton Road, Edge Lane, Liverpool. 6o, Lincoln's Inn Fields. I818111EN1181118111118 VI' Mr MI' ME

haphazard. purchase& till yatr have, DON'T MAKE sent for our CATALOGUE of FOR TOOL BARGAINS WIRELESS CALL or WRITE TO -DAY to t RADIO. ELECTRICAL & MECHANICAL 51IPPLIES:' INSTRUMENTS, Before buying elsewhere compare our prices. Remember, we have the Largest Stock 01 Tools to select from in London. We guarantee you ACCESSORIES satisfaction, so you can safely shop by post. Bargain List sent post Free. SCIENTIFIC SUPPLY STORES 8, NI EWINCT"N CAUSEWAY, and .. 255-6, HIGH DOT. slw, HOLBORN, LONDON. S:f. MATERIALS GEORGE ADAMS, W.G.I.W.C We atJekeverything for the Experimenter who wishes to buildhis own Set.

TELEPHONE DOUBLE HEAD SETS. SuitableCrystal offor Valves THE 66ESI-FIX" AERIAL, Patent applied for. 2,000 Ohms, 3216 ;4,000 Ohms, 34/6.In stock. "FIX IT LIKE A CLOTHES -LINE!" A new " one-ftiece" aerial with 'talented continuous insulation; complete with MAKE up your ownreceiving sets.Our price for eompleie set of parts straining eye, adjustable susfiensfon and terminal.Ng. lead in tube or other. £1 18. carriage paid, comprising wound inductance with ebonite panel insulators revs:red.No joints, no soldering, no leaking, no bother.Can dr drilled for 20 studs, necessary studs, elionite knobs, etc.,crystal detector, thrown up anywhere, and is absolutely weatherAroof: Maximum efficiency terminals, wire for connecting.(No extras to buy ;nothingtomake.) guaranteed.Send cash with order and secure delivery at once.Length,. Slam, for List. 301.; 75/7., 22'6; tooft., Carriage paid in U.K.Agents wanted. P. H. BOYS & CO., 187, Goswell Rd., London, E.C.1 CHAMBERS & ELLIS, 6 & 7, CRAVEN HOUSE, KINCSWAY, LONDON, W.C.2

FOR YOUR AERIAL' DAVIS & TIMMINS! 100 ft. 7/22 COPPER WIRE LIMITED 4 REEL INSULATORS 20 yard Skein ROPE CORD 34a, York Road, King's Cross, N.1 1 MAST PULLEY ::LEAD - IN TUBE COMPLETE SCREWIAND TERMINALS Post Free 1 016 British Isles HENRY J. BREWSTER & CO. FOR WIRELESS SETS 11, Queen Victoria Street, a London, E,C.4, ac Ontateur Wireless 140 JULY 22.1922 LISTEN -IN" ON THE STERLING No. 1 CRYSTAL WIT RECEIVING SET The Sterling No. I Crystal Receiver has been specially designed for use incon- nection with the Wireless Telephony Broadcasting Scheme and is suitable for Immediate a range of about 25 miles. The set comprises: 1. TUNER.-This consists of an inductance which can be varied Delivery by means of tappings taken to stud switches.Two of these are fitted, one for coarse and the other for fine adjustment. A separate ccil is provided which can be plugged into a fitting at the back of the instrument (as illustrated) for reception of time signals, etc., from Eiffel Tower. 2. DETECTOR.-This isof the crystal type, requiring no battery, and is designed to give universal adjustment over all parts of the crystal. The, apparatus is mounted on ebonite panel and fitted in polished walnut case. The -equipment includes one pair of No. RI258 DOUBLE HEAD TELEPHONES wound to a total resistance of 2,000 ohms the pair. Sterling Telephone and Electric TELEPHONE HOUSE, Co., Ltd., 210/212, Tottenham Court Road, London, W.1. Telephone No.: 4144 Museum (7 lines).Telegrams:Cueutais, Wesdo, London.' Works :DAGENHAM, ESSEX. BRANCHES : NEWCASTLE -ON -TYNE: 9, Clavar:ng Plac PRICE 17 12 6 CARDIFF :8, Park Lane.

'WM= WWI= - 110111M 11110W mem maw Emma RoostII =sow =OM * .531** 0 tHt. c H' The

I JUNIOR SET. PRICE iOs Od - COMPLETEY. 4 15s OCR I(t.Pnirlerc vv;th5;t\sie ear rClephOtn. WIRELESSR ECEIVING SET 11-6 5er COn5.i5r5 A tborooshly efficient I ofa Tuning Co'il of ample and dependable set si3e Crystal Dete,cror, A .4Lialtx /4,,,,i topAiriL ar a price ro suitall 6 ///.... - .Ti #j ti,t Condenser,a ser of NOP pockers. I Head Telephones,Ter- All broadcastins of 01111 l_t mi nals, ere. All parrs NEWS, CONCERTS, Iready wired s. connected LECTURES,erc can sup: Aerial Wire and bedisrinclly heard 1 1insplaror5 ready for No batterl es or accumulators erection. PRATT & C2 Noirrirkin8 exrra4 0 0 0 4- 23,QUEEN ANNE'S GATE

4-c,rid,yoc_,.r prckr 4-WeSMINSTER,T LONDON,S + PRpt,116TtlEuvERM 5

TELEPHONE: VICTORIA 3326 .tea mom UMW mom mon mow UMW MIMI MOM OMNI

Printed and Published in England by CAS5ELL & COMPANY, LIMITED, Ludgate Hill; London, Sole Agent for South Africa, CENTRAL NEWY AGENCY, LIMITED. Saturday. July 22, 1922. tA4 BROADCASTING : SOME NEW FACTS (p. 152)

No. 8 SATURDAY, JULY 29, 1922 Price 3d NOTE OUR CONTENTS Page Page " Atmospherics " ...... 143How to Make an Amateur's Transformer 147 A Home-made ClockworkInterrupter 144You Heard it on the Crystal ? ... 148 Receiving C.W. Signals on a Crystal Set A Plea for the Cheap and Simple Crystal Receiver Telephony Tips...... 145Simple Aerial Erection ...... 149 St. Pancras Cadets' 1 ',-Kilowatt Set 145The Beginner's Page ... 150 and 151 Using Crystal Parts with Valve Receiver 146 Some Elementary Facts Concerning Electricity

High-tension Battery Connections ... 146 Broadcasting and the Public 152 Radiograms ;InformaCon Bureau ;Club Doings ; Forthcoming Events;Correspondence, etc.

We Sendus Answer anIdea Your and Questions Try to without WIN any

Delay Operating a Crystal Receiver (See page 151) entateur Wireless 142 JULY 29, 1922

1 EC ONOMI et-MITCHELFONES'*) Are not a spasmodic production to meet a sudden demand, but have been on the market for over three months, and during this period 27,000 have been distributed to thetrade, and consequently we have not been able to offer them direct to the

retail buyer. 1000 per week are now available, and ue announce

CRYSTALDETECTORS. IT S A FACT DELIVERY FROM STOCK - - that thereIs 15 years

practical Wireless exper- ilS4,-IIN ience behind every Youpostyourorder,orcallatour premises and get them at once.Think ECONOMIC

product, and that what this means to you-you, perhaps, who is why the results have been waiting and are stillwaiting. are so exceptional.

ASK ANY RADIO Standard resistance 4,000 ohms, double headgear with AUTHORITY ! double heads: raps,comfortable,highlyefficient, and foolproof Write To -day for 35 - 35/...per pair.

Page WIRELESS List Post Free Special Terms to Traders and deliveries 4d.

240 Illus- that will surprise you. trations. 1 COIL HOLDERS. IC LIMIT, MITCHELLS Electrical & Wireless Ltd., Head Office:10, FITZROY Telephone: PostalAddress: McDermott Road, Peckham, S.E.15. SQUARE, LONDON, W.1 MUSEUM 1055 Retail Address:188.Rye Lane, Peckham, S.E.15.

New Showrooms: Branch Showrooms: c 'Phones: New Cross 1540/1541. ltltoNDoN0A 303, EUSTON ROAD, N.W.1 TWICKENHAM GREAT BRITAIN'S GREATEST WIRELESSSTORE

THE WIRELESS CRYSTAL OF TO -DAY AND THE FUTURE ,, TRADE r ele0 mAnx "HERTZITE Iffit111011151'--ssaa SIMPLE TO USE. NO BATTERY REQUIRED Price 2/6 post free Mounted in our Patent Detector, 5/9, post free AERIAL INSULATORS We can give the best Wholesale Terms for all Crystals BEST QUALITY KNOBS Reel4d.Type Drilled and Tapped. 2.B.A. BRITISH VALVES :-" R " 27/-, " R.M.R." 20/-, " ORA" 15/ - Excellent6d.Finish The " R & S " Complete Receiving Set, with H.T. Telephones, Aerial Wire, etc., PRICE 126/ - RUSSELL - SHAW 38, Great James Street, Bedford Row, W.C.1 IVORINE SCALES DEWAR" MULTIPLE SWITCHES Engraved 0-180° Useful for Mtny Purposes SCIENTIFIC APPLIANCES 9d. 4 -Way3/6s.Way4/6 HENRY J. DALE. W. ROLLINS. CRYSTALS CRYSTALS 11i29, Sicilian Avenue, Southampton Row, London, W.C.I. COMPLETE WITH CUPS COMPLETE WITH CUPS Top of Kingsu ay. In Centre of London. Corner of Bloomsbury Sanare. ONE QUALITY THE BEST OPTICIANS.MECHANICIANS. GALENA,BORNITE, SILICON, CARBORUNDUM, ELECTRICIANS. GRAPHITE, ETC. COPPER, PYRITES, ETC. ACTUAL MANUFACTURERS at our Works, East fittest, W.C., thus saving all intermediate profits. The Store for all Electrical and Scientific Material NIRELESS & RADIO MATERIALS, VALVES. 'PHONES. PARTS and FITTINGS Call and see us. View ourShow Windows. Send for List post free 2d. SLE C Tne Immense Stock constantly adding to, and Making; Speciallyfor theAmateur to eat.%tik Build up a SetCompleteand Perfect. Splendid Value in 54, Grafton Street EBONITE. BATTERIES. AERIALS. Second-hand Appliances TOTTENHAM COURT ROAD 'WA INSULATED WIRES.CRYSTALS. LONDON,W.1 ENGRAVED DISCS. MICA. HANDLES. Every Branch of Optical TELEPHONE: MUSEUM 24I SWITCHES. TERMINALS. STUDS. andAppliedSc ienc e TELEGRkeS:GRAFETRIC, EUSROAD,LONDON

Scientific Appliances, 11 & 29, Sicilian Avenue, London, W.C.1. IIIIIIIIII111111111'i1111111111111111111111111111111111111II1II11111111I111111Ii 4-5

and Elect ries No. 8 July 29, 1922 "ATMOSPHERICS" ATMOSPHERICS are the bane of theof them.They usually get worse at night- Many ideas' have been proposed and ul wireless operator, be he professionaltime.These "X storms" are manifest astried with the object of obtaining a receiv- or amateur.Their cause is well known,a continual irregular crackling, groaninging circuit whiCh will respond to a definite but their elimination is another matter. and hissinginthe telephonereceivers.required frequency without responding to The upper airisnearly always elec-Sometimes the disturbances are so bad thatthese aperiodic, or untuned, kicks.Such trically charged with respect to the earth.receptionofdistantsignalsisrendered"X stoppers," as they are 'often termed, Even at a height of only 5o ft. above theimpossible and radio communicationis areasarule complicated and usually ground there may be a potential'of hun-suspended until the ether is again quiet.weaken the required -signals .aswell as ilfeds,or even thousands; of volts withIn hot climates, as in India or Africa; thetheatmospherics. The tiirnihationof respect to the ground.At greater heightsatmospherics are much worse than in thisatmosPheric interfereace is still one of the this potential or electrical pressure will becountry.The disturbances are worst atgreatest problems that ,faces the wireless greater still.Clouds may be charged toreceiving stations with large aerials. experimenter. millions of volts, and when these highly - Strongatmosphericsarelouderthan electrified clouds come close to others ofnormal signals, and will throw most of theCharging Up of Aerials a different potential a tremendous sparkusual types of crystal detector out of ad- It has already been mentioned that the may leap acrossthe intervening space.justment.The carborundum detectorisair quite a short- distance above ground Or, as is well known, a spark may leapthe only crystal detector that will With-may be highly electrified.This was very from a cloud to some terrestrial body; thisstand atmospherics. A valve receiver doeswell demonstrated in an experiment the happens in a thunderstorm. not suffer in this way, but the crashes andwriter was making some time ago with a Now these discharges not only makefrying noisesareamplified to an unbear-kite aerial.A large kite was sent up on light,whichisseenbytheeye,andable extent. the end of a length of stout string and was sound waves, detected by the ear,, but they made to carry up with it some thin copper also set up electro-magnetic waves in theAtanospher'cs Cannot be Tuned Out wire, the lower end of which was retained ether which are extremely powerful but The worst part about atmosphericsis on the ground.The lower end of the wire of short duration and not directly detect-that they cannot be tuned out in the ordi-escaped fora few . seconds, however, so able by the senses.The effect is heard innary way like signals from a spark stationthat the whole was entirely insulated from a wireless receiver anywhere within many-they are heard on all wave -lengths.An the ground.When a grab was made at miles of the discharge as a loud crash inatmospheric electrical discharge is like anthe dangling end of the wire a small the telephones each time a flash of light-explosion in the ether which kicks anyspark passed to the hand and a shock was ning occurs.These disturbing sounds arewireless receiver within range into violentfelt..This charging up of the wire was by no means only heard during a thunder-momentary electrical oscillation regardlessnoticeable when the kite was only 4o ft. storm; they are very frequently heard whenof the frequency to which the receiver ishigh. The weather was fine and there the weather is perfectly fine in the neigh-tuned. was no thunder about.(Several investi- bourhOod of the receivingstation,and gators haVe been killed when making this when there is hardly 'a cloud in the sky. experiment.) Largeaerialsfrequently In such cases the sounds may be due Results of Competitions charge up in a similar -manner.In hot either " toadistant thunderstorm orto countries, where theeffectisvery pro- smallerlocaldischarges between small Announced in Nos. 1 to 5 of " A.W." nounced, care has to be taken that the clouds or portions of the upper atmosphere operator does not get shocks from this at different potentials. Competition No.1.-AnOriginal -source. Short, low,or badly insulated Article. aerials do not, show this'effect -so markedly, :WINNER :-Mr.Herbert H. Dyer, theyarenot immune fromit Marconi's "X's" 22, Leopold Street, though These disturbances were noticed by Mar- Derby. entirely. Duringafallofsnow an coni in his earliest experiments on wireless amateur's aerial will often charge up suffi- telegraphy and he called them "X's," as Competition No. 2.-Novel and Use- ciently to give small sparks if the aerial they were then more or less of an obscure ful Items. switchisleft open about a millimetre. nature.British amateurs usually refer to An announcement with regard to this A strong wind with fine- drizzle will also them as "atmospherics" or "strays," while will appear in next week's issue. -rapidly charge up anaerial. Recently theAmericanshavechristenedthem Competition No. 3.-IdealBroad- .the writer was 'surprised to see a: torrent "static." cast Programme. of sparks rushing across the -plates of a Atmospherics are always present to a WINNER :-Mr.B.Robertshaw, variable condenser in series with a 3o -ft. certain extent, but they vary greatly in 63,Market Street, -aerial.A high wind was blowing at the Thornton, time, accompanied by light rain. different -parts of the world,- and also with Bradford. the time of year.In the British Isles we E. H. R. In each case the prize is a well-nal: wireless - [in a concluding instalment the author are chiefly troubled with them in the sum= receiver. The successful efforts will be pub- mer, when we frequently -get -"-X storms"; lisherlin due cot.r3e. will offer practical suggestions towards the in -the winter, however, we hear very lhtle elimination esf "atmospherics."-EDI Amateur Wireless 144 JULY 29,1922

A Home-made Clockwork Interrupter .1 Receiving C.W. Signals on a Crystal Set ir

ITisfrequentlystatedthata simplethe escapement so that the wheels rotatewith the teeth of the wheel T.A piece of crystalreceivingsetwillenablethefreely.If the spring is now wound up andflexible wire is connected to the clock - listener only to pick up spark stations andthe mechanism allowed to run it will goframe and another to the tongue; one of telephony, and that valves will have to beat a tremendous speed and be run downthese wiresisconnected to one 9f the installed beforecontinuous -wave (C.W.)ina few seconds;a governing device'phone leads and the other to one of the signalscanbesatisfactorilyreceived.must, therefore, be added, and this can'detector terminalsas shown in, Fig. 1. This is true to a certain extent, but theeasily be done by soldering, or otherwiseThe condenser C,having a capacity of following remarks will show how somefixing, a small vane cut out of thin sheetabout.or micro -farad,is shunted across of the louder C.W. stations can be re-brasstothemostrapidlyrevolvingthe tikker and telephones, asit greatly ceived by means of a very simple addition.spindle as shown in Fig. 2.Owing to theimproves the signals.Some little adjust- frictionoftheairwiththisvane thement of the speed of the tikker and the C.W. Signals mechanism will not be ableto"race,"pressureof the contact tongue may be The reason why C.W. signals cannot beand will run nicelyfor a considerablenecessary before good results are obtained. heard on ordinary crystal circuits, such astime.The actual size of the vane for bestWhen a C.W. stationistuned in(by have been described in "Amateur Wire-working will depend on the nature of themeansofthevariableinductanceL, less," is that when the key at the trans-clockwork and will have to be determinedFig.t),the detector carefully adjusted mitting stationispressed down a con-in individual cases by trial ; the larger theand the tikker set in motion, the signals tinuousrectifiedcurrent passes throughvane the slower the mechanism will run.are heard as an intermittent musical note the head telephones of the receiver, notIn the writer's own tikker the vane isor a hissing note, usually the latter. an interrupted one as in the case of sparkonly in. across and in. wide, but it and telephony, with theresultthat nois sufficient to ensure a steady run of aboutOther Methods soundisheard except perhaps afainttwenty minutes.The only other thing As a matter of fact, Poulsen did not use

570verv2//95) vane

.-LFI L .0.fmfd

Fig. 4.- Metal /*nit Tongue Fig. 2 Fig. 3 Fig. 1.-Circuit Diagram Figs. 2 and 3.-Front and Side Elevations of Interrupter. Fig. 5.-Poulsen System of of Interrupter. C.W. Reception.

click when the key is depressed or raised.that remains to be done is to fix a lighta crystal detector at all in his receiver. If, however; we insert between, 'the crystaltongue which has to 'make contact withThe tikker is put in place of the detector detector and the 'phones an interruptingthe cogS Of the fastest Wheel in the train.as shown in Fig. 5.This arrangement is device capable of making and breaking The method of mounting isshowrL in extremely reliable,but,inthewriter's the circuit at a high rate; say 50o times aFig. 3.A is an ebonite strip, sufficientlyexperience,isnot quitesosensitiveas second, then any continuous currentinthick to be rigid, through which a- holewhen a crystal detector is included.How- the 'phoneswillbe broken up intoahas been made at each end.By meansever, as crystal detectors are very liable musical note which is clearly audible. ofabolt and fly -nut one end oftheto go out of adjustment the writer would ebonite strip is fixed to a point C in therecommend the method shown by Fig. 5. The "Tikker" frame, and that at the other end will come Where a crystal detector is to be used, Such an arrangement is shown diagram-near the wheel T, a hole being made at Ceither a good piece of zincite touched by matically inFig.r. Inthisfigure Tto accommodate the bolt.The tongue Ba sharp piece of bornite or copper pyrites, isa rapidly rotating cog -wheel againstis cut to the shape shown in Fig. 4 out ofor a piece of galena touched by a small which a light metal tongue rests lightly.springy sheet brass about the thickness ofspiral of 40 -gauge copper wire; will be the The use of such an interrupter is the in-drawing -paper.An ordinary pair of scis-most suitable. Crystals,likecarborun- vention of the Danish inventor Poulsen,sors will cut the brass quite easily, anddum, which require a battery and potenti- who used it for reception of signals fromthe hole shown in the wide end may beometer, cannot be used satisfactorilyin the famous arc -transmitting system whichpushed through by any sharp tool.Theconjunction with a tikker.Much depends -bears his name.Poulsen called the in-tongue is fastened to the upper end of theon getting good specimens of crystal. terrupter a "tikker," and this is the nameebonite strip A by means of a nut and A gramophone can be used as a tikker by which the device is still known. bolt through thehole which has beenby connecting one wire to the works and The cog -wheel T may conveniently bemade there, and thethinpartof theallowing the other to rub lightly against the fastest -moving wheel in the mechanismtongue is given a twist through a rightthe edge of the revolving turntable. ,of a clock.It will be necessary to removeangle so as to bring the free end square E. H. R., JULY 29.1922 145 matcur WirelesS IIK"..1"WaW"...eMea","WWen'armS.MWMa..11%%1Wearvedlien"MalloWNW=WwWea. TELEPHONY TIPS

THESE notes are primarily addressedof distortion.In addition to getting thetensionfor telephony, and tofindthis tothoseamateurs whosevalvere-telephony atitsbest, we have the satis-proportion make the following test :Get ceivers employ reaction (either magneticfaction of knowing that we are not inter-the set into an oscillating condition, then, or capacity) to boost up the incoming sig-fering with our neighbours. loosen reaction until oscillations just cease. nals.If carefully followed the best results This point can be found by tapping the will be ensured. Other Adjustments aerialterminal while reactionisbeing There are other factors which make forloosened.Note the position of inductance Oscillating Receivers the correct reception of telephony. Theand reactance(or reaction condenserif The receptionofwirelessspeech andfilament and high-tension current must bethis is used) when the oscillations cease. music calls for very careful adjustment ifadjusted to their best values, and it willNow tighten the reaction and noticeif one is not to be a nuisance to any wirelessbe necessary to experiment a little withoscillations commence exactly at the spot neighbours, for it must be. remembered thatthe filament resistance until the best pointwhere they stopped.If thisis the case valve receivers of the. reaction type are inis found, always remembering to keep thethe proportion of high tension to low ten- themSelves transmitters of small power.valve filament asdullaspossible con-sion is correct, and the set is in its most The waves radiated from the receivingsistent with good signals. Thereisasensitiveconditionforreceivingtele- aerial, although very weak, are capable ofcorrect proportion of high tension to low (Continued on next page) travelling several miles, and consequently willaffectallvalvereceiversinthat radius.Valve receivers only act as transmitters when the set is "oscillating "-that is, when the reactance coilisso tightlySt. PancrasCadets'V2 Kilowatt Set coupled to the inductance that the valve generatesoscillationswhich arepassed into the aerial.-When the setis in this condition itis impossible to receive telephony atits best, although itis as well to let the set oscillate while searching for the carrier wave of the station transmitting telephony. The best way to find out if the setis oscillating is to tighten the coupling between reactance and inductance coils, at the same time tapping the aerial terminal with .the finger.If the set is oscillating a loud click will be heard in the telephones each time the terminal is tapped. If ' capacity reactionisused,rotate the reaction condenser until clicks are heard in the telephones when the aerial terminal is tapped. The Carrier Wave Having got- our receiver into an oscillating condition, we willtuneinsome telephony and make the necessary adjustments which will give us the speech and music at their best.By means of the aerial tuning condenser and inductance tapping switch, search for the carrier wave, whichI T isquite a common thing nowadaystrol the heavy current in the low-tension will come in with a loud howl. Now1 for cadet corps and scout organisationscircuit a magnetic switch is used, operated rotate the condenser until the howl diesto possess a wireless outfit; few, however,by means of an ordinary Morse key by the out, and it will be found that a still fur-can claim to be so completely equipped astelegraphist. ther rotation of the condenser will bringthe No.tAircraft Construction Wing of The "instructor seen in the photograph the howl in again.The dead spot between25, Camden Road, London, N.W.t, which isLieut.A. W. Hulbert,' late R.A.F., the two howls is the correct position.Ifis allied to the t9th London Cadet Organ-whose articles on the practical construction telephonyisgoing on' itwill be veryisation. of wireless apparatus appear frequently in distorted and indistinct because our set is The installation consists of aI;,/kilo-"Amateur Wireless." oscillating. To correctthis,loosen thewatt Marconi transmitting set as used on It is understood that an assistant wire- coupling between inductance and react-ships, and a number of receiving sets ofless instructoris wanted who would be ance until the set 'just stops oscillating,various types, including a trench receiverwilling to give one evening a week to the then finally tune the station by means ofand a three -valve set specially designedwork.The whole thing is quite volun- theaerial tuning condenser.The tele-for use on aircraft. tary, but the applicant,ifaccepted,is phony will now be very distinct, and if Mounted on the wall are the high, andgrantedanhonorarycommission. It theforegoinginstructionshavebeenlow-tension switchboards and the A.T.I. ofmight be mentioned that, only ex-R.A.F.' properly carried out, there will be no tracethe Marconi transmitter.In order to con-or R.E. officers are eligible. Cntatzur Wirdes5 145 JULY 20, 1922 phony.If, however, there is an overlapgreater capacity than .0005 micro -farads,oscillating you cannot be receiving pure of the points where oscillations cease andit will be found an advantage to connecttelephony, and, furthermore, you are in where they commence-that is,if they doasmallthree -platevariablecondenserall probability causing serious interference not cease and commence at exactly theacross the. aerial and. earth 'terminals of,.to everybody for several miles round.As same spot-itisnecessary toadjust thethe set.This small condenser permits ofsoon as you have picked up the dead spot high-tension supply until the two pointsmuch sharper tuning than is possible withbetween the two howls of the carrier wave coincide. the larger capacity alone. get off the oscillation point and enjoy the Iftheaerial tuning condenser has a Always bear in mind that if your set istransmission which you have tuned in.

::. :,' Using Crystal Parts with Valve ReceiverI

IT will, no doubt, be of interest to readerssary to drill a hole large enough to takethe addition of a pair of honeycomb or who have been working with crystal setsthe short, stout spindle which supports thesimilar coils as shown diagrammatically in to know how they can utilise the old partsebonite knob, the, latter being temporarilyFig. 4.Instructions upon the winding of withavalve. Furthermore,, thecOm-,removed Whilst_ mounting the regulator.honeycomb coils appearedin No. 2 of ponent parts of an old crystal receiver can,The terminalS should then be inserted into very often be picked up for quite a lowtwelve holes round the edges of the panel, figure, and such parts are well worth buy-after which the connections between the ing by those who are desirous of, con,-various pieces of apparatus, etc., should structing a valvesetat moderate cost.be made as shown by the dotted lines in The necessary alterations are quite simple.,Figs i. and practically the only part of the crystal These connections should, of course, be set to discard,' at any' rate *for the time'made with insulated wire or bate copper being,isthe crystal detectoritself,thiswirepassedthroughinsulatingtubing piece of apparatus beingreplaced by theknown as "Systoflex" sleeving, which can thermionic valve.All the remaining partsbe purchased for a few pence per foot. can be utilised on the valve panel. The first point to receive consideration is the valve panel.This need not he very large, and can best be made up from a piece of ebonite sheet measuring to in. by -.4- 8 in. by --firin. thick, or in the absence of Fig. 2.-Valve Fig. 4.-Method of Using ebonite a piece of well -dried hard wood Holder. Honeycomb Coils. could be used, but it is absolutely essential to ensure that the wood is quite free from "Amateur Wireless."These coils can, if moisture, otherwise losses due to leakage desired, be used equally well without the will occur.This panel should be marked loading coil, as will be found froM experiment.The insertion of a small variable condenser across the reaction coil, although not essential, will be found con- -,iderably to facilitate tuning.D. F. U,

RgACTArt Fig. 3.-Diagram showing Connections for Crystal Parts. HIGH-TENSION BAT- TERY CONNECTIONS Fig. 1.-Diagram of "Valve Panel. This latter method ispreferable, and is that usually adopted by manufacturers in THE reproduced sketch shows a simple out and drilled as shown in Fig.rto takethe trade.The,connections to the points method of connecting small batteries the necessary terminals, etc. marked RG, F F in Fig.. t .on the valve oftheflash -lamptypetogether. The The following accessorieswill bere-holder shOuld be made, by neatly soldered quired :a grid leak with condenser L, valvejoints.In order to. complete the panel it holderA, filamentregulatorofaboutshould he mounted upon a shallow box 6 ohms resistance, one dozen brasster-just sufficiently deep to contain the dif- minals, and a few small screws,allof ferent parts mounted underneath it. which can be procured for a few shillings The crystal receiver parts can now be Simple Method of Connecting Flash -lamp from any manufacturer of wireless appara-utilised as shown in Fig. 3, with the addi- Batteries. tus. The type ofvalve holder recom-tion, of course, of a suitable thermionic mended isthat shown in Fig.2, as, byvalve, a 4 -volt accumulator, and a high-sketch is self-explanatory, and it will be drilling a hole sufficiently large to take thetension battery of from 40 to 6o volts.Theseen that a paper clip of the sliding type portion marked A,thiscan bereadilylatter can consist of a number of ordinaryis used. mounted and screwed down to the panelpocket lamp batteriesconnected upin from the back. Similarly,the filamentseries. A Handbook specially written for the regulator and grid leak with condenser Assuming that a loose -coupled tuningamateurconstructor :"WirelessTele- are mounted on the back by means ofcoilis not available, but only a simplegraphy and Telephony," by E. Redpath, small screws.In the case of the filamentloading coil having no secondary, this canpriceis.6d.net.Cassell & Co., Ltd., regulator, however7 it will first be neces-readily be adopted for use on the panel byLa Belle Sauvage, London, E.C.4. JULY 29, 1922 147 Ontattur Winless

HowtoMakeanAmateur's Transformer

TR A.NS FORMERconstruction offers made necessary by cutting the iron and This 2 in. must be solidly packed iron little difficulty to one who is preparedbuilding it up in segments.Perhaps thesheets,soif the rings are each .orin. to approach the task with determination todiagram Fig. iwill make this clearer. thick you must have too of them for a use skill and patience.The writer gives In this figure the ring A is continuous,height oft in. from his own experience details which, ifand once we have set up a magnetic field The closer the rings lie together the less followed carefully, cannot but eventuate successfully. In the first place itwill be advisable, however, to go over a little of the theory in order that the practice may be the more intelligently followed. If two coils of wire are lying one on the top of the other, eye to eye so to speak, but having no metallic connection between them, then a varying current circulating in one of them will cause a varying magnetic field to be set up in its neighbourhood. This varying magnetic fieldwill link up with the other coil and set up in it another varying current. Lines of Force The voltage driving these currents in the second coil will vary with the number of lines of magnetic force causing it and Fig 2.-Photograph of Complete Transformer and Parts Used for its Construction. the rate at which they vary in a unit of time.Thus to,000,000 lines of force. wouldin it the lines of force have little tempta-wire will be needed to -wind on the correct need to link up with one coil of wire intiontoleave the iron.In B, which isnumber of turns.Pinch the rings up to- one second in order to produce one volt,built up of strips, the lines of force havegether in a vice, and bind them together or, conversely, one line of force would linkto leap the gaps in their race.In orderwith dry cotton tape, while still pinched up up with to,000,000 turns of wire in oneto reduce the difficulty of the lines of forcetight, until all the iron is covered.The second to produce the same voltage. getting back thestripsarelaid likeB danger point in this construction is the sharp If the path provided for the lines ofandcalternately-thatis,thebuttingedge at the top and bottom of the pack forceisof iron the number of lines ofgap comes at a different point each timeof ring stampings, which may cut through force would be increased enormously, evenand is overlaid each side by a flat plate.the tape and the cotton coverings of the using the same magnetising current.InThis construction allows the coils of wirewire and spoil all the work.If a piece the case we are considering we use flatbeing wound by machinery. of tough but not toostiff paper iscut circular rings of softiron,so that the In order to avoid troublesome calcula-into two ringsslightly larger than the whole path of the lines of force may betions for allowance of the magnetic leak-stampings and placed on the top and bot- provided and the lines of force not haveage at these joints a jointless ring has beentom of the piles it will form a protection to leave their comfortable quarters duringadopted here, and the photograph (Fig. 2)for the tape. any part of their course. shows a transformer so made.The iron If any were to get out into the air duringringsanddouble -cotton -coveredcopperPrimary any part of their circuit their mutual re-wire are also shown (Fig. 2). For the primary, or that circuit which is connected with the mains 2 lb. No. 20 a' double -cotton -coveredwirewillbere- quired, and 88o turns of it must be wound on to the ring if the transformer isin- tended for a 22o -volt circuit. Take the coil of wire as purchased, and make the round coil into a very flat oval A a by squeezing in from Opposite sides, and Fig. 1.-Different Types of Core. Fig. 3.-Core Taped for Winding. then tie it round the middle with an odd hit of tape to keep the flattened coil to- pulsion would at once assert itself, and we The thin flat rings of iron are aboutgether.This willthus form a shuttle should have difficulty in getting them back 8in.over-all diameter and about 2in.which can be passed through the taped up again' intotheir"straight and narrowwide, with a hole in the centre 4 in. inring of iron stampings.With a needle way."Therefore,in order to avoid andiameter. Youwillwantenoughtoand thread sew the commencing end of otherwise inevitable and continuous loss,assemble and build up 2 sq.in. of crossthe wire on to the tape to make it secure, we take more pains in winding our wire-sectional area-that is,ifthe rings areleaving a piece long enough for subse- that is, we thread it through the closed 2in. wide as suggested you will want aquent connections. A piece of thin rubber iron ring rather than wind it on a bobbinpile 1.in. high.If the rings are not a in.tubing should be slipped on this free end and then build up the iron into it.Thiswide they must be piled up higher so astofurtherprotect thecottoncovering. is usually done in big commercial trans-to make the 2 sq. in. of cross section-thatNow proceed to thread the formed shuttle formers, where the "air gap," which isis,if they are onlyrin. wide they mustof wire, through and through in the same the part .of the path in the open air,is be piled up 2 in. high Fig. 3). manner that the tape was wound. nulling- Omoteitr WirekSS 143 JULY 29.1922 up each turn tight as made until the no tefore winding the -secondary, however,riskof damaging thecoveringofthe turns are all on.Count after each layer,tape up the primary with dry cotton tapewire. and make a note on a slip of paper so that asyoudidtheironringsbeforethe the number of turns can be checked.You primary was wound on.For the secondarySmaller Sizes may, if you so desire, check the efficiency 21lb.of No. 14s.W.G.double -cotton - A smaller transformer might bepre- of the work in the following manner : covered copper wire will be required. Oneferred, and if so itis only a matter of volt, or a very little less, will be obtainedvarying the proportions.Thus ifitis: Testing for each four turns of wire wound overdesired to cut down the iron totsq. in.: With a 220 -volt lamp in series with thethe primary.No. 14 wire will carry toof cross section twice as many turns of winding you may turn on the current, asamperes at 2,000 amperes per square inch,wire on the primary will be necessary, or the lamp will protect the circuit.If thethe same rating as the primary, and if youeight turns pervolt. It would not be lamp glows anything like as brightly asdesire 40 volts on the secondary 170 turnsadvisable to carry this reduction pro rata it would without the transformer primaryof wire will be necessary.This figure ismuch lower than sq.in., but -to this in circuit with it, there is something wrongadopted as a convenient one. limit the rule will answer. with the winding; probably some turns It may perhaps be an advantage to It is advisable to protect the transformer are short-circuited.It will be necessarybring out a tapping at the eighty-fifth turnwhen finished, and it -may either be treated to find out what the troubleis,if anyand so have two circuits available, eachwith insulating varnish and taped over exists, and remedy it before the secondarygiving 20 volts, or it might be even moreand again varnished, or it may be placed is put on. handy to have a range of voltages to selectin a box and the box filled up solid by Supposing, however, that the lamp, iffrom, in which case it is only a matter ofpouring in molten resin. it glows at all, is a very dull red.If nocounting the number of turns of wire put In assembling the iron stampings any indication is given by the lamp, put oneon and bring out tappings where desired. burrs left by the die might be removed turn of insulated wire through the eye of This is a transformer capable of carry-from the edges, and even the stampings the transformer and connect the ends ofing half a kilowatt, and would do admir-themselves might be prevented from mak- this one turn by a piece of .25 -ampereably for any purpose needing that amounting electrical short circuits by varnishing, fuse wire or the fuse wire generally usedof energy.Also it would not be wastefulthough this latter precaution is very rarely in the lamp circuit.If this flashes youron any smaller amount.The sizes arenecessary,especiallyifthe ironisleft Work is so far successful, and the secondarygiven so as easily -to perrnif of threadingdirty on the faces, as the dirt will pre- winding can be proceeded with. the wire through the centre without muchvent eddy currents. GAMMA. rs-....---.-.------...6%-....w..e....------..-----..---.newme....r.e....r.-....-....e.w...... eir e You HeardIt On the Crystal ? ar.m.r.-...m,wwiew.,....r."Nerawmm.w.v.w....w...... woweimew.w.w.vm....w.w.w...~...... ml:. " V OU heard it on the crystal ? "On erectedinthe garden:The lead-inis crystals,onezincite-bornite,theother I many occasions has this remark been20 ft.long.The tuning .inductance con-carborundum.The advantage of having addressed to me by fellow wireless enthu-sists of three single -layer coils giving antwo detectorsisthat with the aid of a siasts, devotees of the valve, whilecom-approximate wave -length of 4,500 metres.small switch comparison of sensitivity can paring notes on the receptionofsomeTuning is effected with a four -point switchbe made one with the other. particulartransmission: -Al- The 'phones are of the S. G. though a keen admirer of the Brown type, each earpiece being thermionic valve and its uses in of 4,00o ohms resistance with a application to wireless,I must small blocking condenser con- confess to an ardent enthusiasm nected across them. for crystals,' based upon the ex- The " whole apparatus is cellent results' Obtained with a mounted on a varnished wooden crystal set since erection 'two base, and is very compact.The and a half years ago. earth leadistaken toa con- Theproposedbroadcasting venient water -tap.Situated in scheme has rekindled an active a populous district in N. Lon- interest in crystaT receivers, and don, I am surrounded by houses, asitisprobablethatmany and my aerial is below the level would-be "listeners -in" are of them all.I mention this fact sceptical as to the results likely in Order that readers can make to be obtained with suchsets a comparison of their surround- because of thecomparative ings with mine. cheapness, these notesarein- As the reception of wireless tendedprimarily toestablish telephony is the primary aim of their confidencein' crystalre- most newcomers I will first Men- ceivers by a des'cription of my tionthetelephonystationsI set and what it has done. have received.Croydon aero- As the aerial is an important Operating a Simple Crystal Receiver. drome provides a constant pro- considerationIwilldescribe gramme in controlling the Lon- that first.I ani using a single don -Parisairway,thespeech wire 5oft.long, anditisfastened toto bring in or cut out the coils as required,being very clear and.strong.Reception of the window frame of an attic 40 ft. high,with a slider on one coil and also a vari-2M T (Writtle) is good, with a slight de- sloping down to the mast 18 ft. in heightable condenser.I have worked with twocrease of signal strength since the wave- JULY 29, 1922 149 mateur Winless length was shortened. The Marconi Houseat night from ship stations at iso miles;(G F A) is received loudly, the system used station, A. 0, is the " star "-telephony trans-but as the ship to shore traffic, .and vicebeinginterrupted continuous -wave, and mitter, speech being of extreme clarity andversa, is usually very heavy, with conse-,thereforereceivableoncrystal. The the strength surprising. On a recent even-quent jamming,itisonly occasionallyweather reports issued from thisstation ing a musical programme was sent outthat, circumstances are favourable for re-are very interesting and useful, especially from Marconi House station 2L 0 in con-ceptionofthenaturallyweaksignalsso when one isconsidering an outdoor nection with a fête in progress at Caxtonemanating from ships many miles away. week -end. Hall, and to those who "listened -in"itCommercial Stations A Few Hints must have aroused the keen hope that the Paris (F L) is the regular "big noise" There are one or two hints in connection day when broadcaststationscommenceof the few high -power spark stations nowwith the use of crystal sets which, although operations is not far distant. working, signals always being very loudoftenquoted, can never be emphasised Amateur Telephony - and clear.Poldhu (M P D) is nicely read-too often.The crystals themselves should Amateur telephony stations come in wellable, and on occasions when I have burnedreceive the maximum of carein being on short wave -lengths, but not very strong,the midnight oil the C Q press at one a.m.protected from dust,dirt, and anything and I have had much gratification in hear-B.S.T.hasalwaysbeencopiedwithlikely to impair their efficiency, and if an ing several good transmissions from zON,crystal reception.-I have never yet found.especially good crystal comes along put a Walthamstow. it- necessary to switch over to my valvegreat value on it.Keep all connections When thelateSir Ernest Shackleton set. S A J,theSwedishstationwhichclean and tight, and if the setisto be sailed in the "Quest" several months agotransmits press messages, can always beself-made take the greatest care with its a telephony test was carried out betweenread,ascanthetimesignalsfromconstruction, and remember patience is a a station at Chelmsford and the ship whileNauen (P 0 Z).The Air Ministry stationvirtue. C. G. on itspassage down the Thames. My receptionofthespeech was excellent, even the sound from the noisy sirens of shipping in the river, caught by the transmitter, being heard to add to the pleasure of listening to the famous explorer's fare- Simple AerialErection well message.At various times during tests music and speech have been heard, reception being very good. ERECTING theaerial _isa bugbearagainst the eaves of the house by means of with most amateurs, but the followingthe hooks and line.A guy rope taken Morse method of erection will prove of interestfrom near the top of the mast to a point on Morse signals will not interest the be-to those who wish to do the work with athe wall of the house, to counteract the ginner at first perhaps to a great extent,minimum of trouble and expense. pull of the aerial wire, completed the job. but I feel sure that itwill be a natural The only aerial masts that were at theThe mast, as finally erected, is shown in sequence of events to ,learn the code andwriter's disposal was one of bamboo 25 ft.the sketch. copy the messages. long and a Disposals Board mast of 16 ft. It may be added that the writer had no The North Foreland station comes inin three sections. assistance whatever in the erection of the well, as does Niton, Harwich, Sheerness, The bamboo was erected at the end ofmast, andit would appear thatif any Ostend, Scheveningen, Boulogne, Lethe garden with little or no trouble, and,amateur does not desireto gotothe Havre, and Dunkirk, to mention but a fewin passing, it may be said that, up to atrouble of fixing a mast on the top o'f his of the English and Continental stations.height of about 25 ft., a bamboo has been house, the method just described is a very On an evening months ago (and on manyfound to be ideal for wireless purposes ongoodsubstitute. The windowsillon evenings since) I heard clear signals from account of its strength and extremely light which the mast restsis14ft.from the a station whose call was F F S.Referenceweight. to the call book was necessary, as I was When considering the house end of the iNSULAran unfamiliar with it, and was considerablyaerial, however, a less easy problem was surprised to find that the station was S.encountered.It was not desired to go to Maries de la Mer, situated in the South ofthe, trouble and expense of erecting a mast France ontheMediterranean. A fewon the chimney or roof of the house, and evenings later I heard ToUlon (F U T) inwhen viewing the site it was thought that the same locality, transmitting a naviga-instead of erectingit on the top of the tionwarning. Thiscouldbecalledhouse it might be an easier job to fix the "freak" reception, but itis the conimonmast to the side of the building and so experience of most amateurs to receiVe atobviatethenecessityofobtainingthe night distant stations that are quitein-assistance of the local builder. audible during the daytime. The room in which the wireless gear Ships was housed was on the upper floor of a Ship stations come in by dozens, sometwo -floored house; the eaves of the roof when in the neighbourhood of the manywere about 1 ft.above the top of the docks between Southend and the Towerwindow and projected z ft. Bridge providing signals with a density Upon these facts being noted the mast sufficient to please any loud signal enthu-was assembled upstairs.Next two large Simple Aerial Erection. siast.I have attempted on several occa-screw:in hooks were fixed into the top and sions to log the ship stations received onbottom -of one side of the outside of theground, making the top of the mast 3o ft. crystal with the view torecording thewindow frame and a supply of stout linehigh, which isa useful height for all greatest distance from which signals haveobtained from the local store. ordinary purposes.Apart from the cost been received, but unless one hears the The mast was then erected in an uprightofthemastitselftheexpensewas shipactually open communication withposition outside the window, with its footnegligible. the shore station, giving her name, posi-resting on the inside corner of the window- As regards the actual aerial, which is tion,etc.,itpresents muchdifficulty.sill farthest from the direction of the pull6o ft. long, this consists of a single wire Good signals, however, have been receivedof the aerial, and was lashed up tight (Continued on page 152)

mnasumemonmagsa -maglaiztAk 14; motenr \Virelks5 150 151 (Inv:deur Wtretts.5 THE BEGINNER'S PAGE SOME ELEMENTARY FACTSCONCERNING ELECTRICITY

IN the following articles the elementary smaller the pipe the greater the opposition other effects of an electric current flowing Inductive Effects principles of wireless telegraphy and to the flow of water. in a wire should be considered.One of In addition to the magnetic effect pro- telephony will be explained in as simple How these three main electrical terms the most common, the heating of the wire duced by a current in a coiled wire, there are combined in a very simple and very by the passage of the current, is made use is the inductive effect of the sudden pro- useful equation will be explained later; at of commercially in electric heaters, electric duction or withdrawal of a magnetic field the present time itis only necessary to irons, and electric lamps. from the neighbourhood of a second coil think of them in the way described above. It is obvious that the smaller the wire of wire, which is shown in Fig. 4. In order clearly to understand the most the greater the heating effects; therefore, A is a coil of wire connected to a battery Fig. 1.-Magnetic Field Around Current. simple theory of electricityitshould be cablescarryinglargecurrents must be B and having a switch C in the circuit to Side View of Variometer. carrying Conductor. *made proportionallylargeindiameter, switch the current on or off.By the side front View of Variometer. whereas in the case of an electric light of the coil A a second coil D is placed language as possible, no reference being 1, I. bulb the filament is fine, so that it will be connectedtoasensitive. galvanometer, made to technical formula, which is both made white hot or incandescent with as which is an instrument for indicating the andunnecessarytoanyone confusing z .r little current as possible. presence of a small electric current. taking up wireless as a pastime pure and On pressing the switchC,itwillbe simple. Magnetic Effects noticed that the needle of the galvano- Electricity and Magnetism The other effect of a current flowing meter will be deflected, while on switch- The uses to which electricity is put are Fig. 2.-Magnetic Field AroundCoiled Wire :along; a wire is the magnetic effect, and ing offthe current the needle will be Carrying Current. ,thisisofvitalimportanceinwireless deflected in the opposite direction in spite being continually demonstratedallday work, for without itwireless telegraphy long.The telephone, the tram, and the of the fact that there is no electrical con- electric light are such common examples , would be impossible. nection between the two coils A and D. rwill show diagram- that few even trouble to "wonder why." A glance at Fig. This is known as the inductive effect of maticallythe magneticfieldaround a the current, and by varying the proportion In order to make the theory of electricity single conductor along which a current of and magnetism as simple as possible, the of turns of wire on the coils A and D the High frequency Transformer. electricityisflowing. The dotted lines voltage of the induced current may be reader is asked to accept for a fact that are intendedtorepresentthe magnetic Simple Crystal Receiver. electricity is something which flows along made much higher than thebatteryB. a metal conductor such as a telephone field around the wire. This property of the induction coil is made Fig. 3.-Increased Effect by Use of Iron Core. Nov, the magnetic field produced by a use of in medical and spark coils and wire, much the same as water flows along current flowing along a single wire will a pipe.By means of a tap the flow of transformers, and also in oscillation trans- taken for granted thatelectricityexists formers used in wireless work. water may be stopped ;in the same way C the switch in the electrical circuit controls everywhere,in everything, butatrest. When certaineffectsareproducedit "D.C." and "A.C." the flow of electrical current. It has been mentioned that a battery, Itis generally known that in order to simply means that a certain amount of electricity isin motion.That isto say, accumulator ordynamoisapieceof forceacertainquantityof anyliquid apparatus for setting in motion a current through a pipe a certain pressure isre- a dynamo does not make electricity,it simply creates a pressure which causes a of electricity, generally supposed to flow quired ;the smaller the bore of the pipe in a certaindirectionlikethe flow of the more resistance is offered to the flow current to flow from one point to another. Justinthe same way, a battery or water in a pipe, the voltage or pressure of liquid andvice versa.In a similar being at its maximum at one terminal of fashion, a wire of small diameter will offer accumulator is very much like a tank full of water with the tap turned off.The the battery and zero at the other.This is resistance to the electrical current, and a water is in the tank, but at rest.If the known as direct current or "D.C." greater 'pressure or voltage will be required The other system, known as alternating Underneath View of Crystal Receiver. than if the same volume of current were tap is turned on the water will at once begin to flow ;in a similar manner, if the current or "A.C.," is so called because the passing through a thicker wire.Also the terminals of the accumulator are joined Fig. 4.-Diagram showing Induction Effects. current is continually changing its direc- pressure or voltage at the end of a long tion or sign, being alternately positive or thin wire will not be as great or capable to a small lamp with a piece of wire a not be strong or intense enough to produce of producing the same effects as the pres- currentwill immediately flow from the any appreciable effects, but if the wire is sure at the terminals of the generator. accumulator, causing the lamp to light. coiled up, as shown in. Fig. 2, the mag- Simple Valve Receiver. Certaintermsareusedinelectrical If a large pipe is connected to the tank *.teticfield will be very considerably in- work to express the properties and effects a large quantity of water will flow from creased. ofelectricity,themost common being the tank in a short time, and in a similar A still greater effect is produced when volts, amperes and ohms. way if a thick wire is connected to ,the the wire is wound upon an iron core, and Thepressureorvoltage,whichis accumulator a large current will flow with Fig.3 in the preceding column shows Fig. 5.-Diagrammatic Illustration of Single- equivalent to the head of water in the verylittlelossof pressure,technically diagrammatically the essentialdetails of phase Alternating Current. known as voltage drop.If a thin wire is an electro-magnet. previous examples, is measured in "volts," used, however, the quantity of electricity negative every half wave, as shown dia- while the current, which may be likened flowing in a given time will be less, and One particularly useful feature of the grammatically in Fig. 5.As the whole of totheflowofwateringallons,is electro-magnetisthefactthat the iron wireless engineering depends on alternat- the pressure or voltage available to do core is only magnetised when a current is measured in "amperes." work will also be smaller. ing currents it will be necessary for the The resistance which the wire or metal ,:lowing round the coils; as soon as the reader to remember a few of the diftrences conductor offers to the flow of current may Heating Effects current is interrupted the iron ceases to be between "D.C." and "A.C." A. W. H. Underside View of Valve Panel. be compared to the friction of a pipe; the Having grasped these simple facts, the a magnet. (To be continued) LooseCoupler. motenr \Virelks5 150 151 (Inv:deur Wtretts.5 THE BEGINNER'S PAGE SOME ELEMENTARY FACTSCONCERNING ELECTRICITY

IN the following articles the elementary smaller the pipe the greater the opposition other effects of an electric current flowing Inductive Effects principles of wireless telegraphy and to the flow of water. in a wire should be considered.One of In addition to the magnetic effect pro- telephony will be explained in as simple How these three main electrical terms the most common, the heating of the wire duced by a current in a coiled wire, there are combined in a very simple and very by the passage of the current, is made use is the inductive effect of the sudden pro- useful equation will be explained later; at of commercially in electric heaters, electric duction or withdrawal of a magnetic field the present time itis only necessary to irons, and electric lamps. from the neighbourhood of a second coil think of them in the way described above. It is obvious that the smaller the wire of wire, which is shown in Fig. 4. In order clearly to understand the most the greater the heating effects; therefore, A is a coil of wire connected to a battery Fig. 1.-Magnetic Field Around Current. simple theory of electricityitshould be cablescarryinglargecurrents must be B and having a switch C in the circuit to Side View of Variometer. carrying Conductor. *made proportionallylargeindiameter, switch the current on or off.By the side front View of Variometer. whereas in the case of an electric light of the coil A a second coil D is placed language as possible, no reference being 1, I. bulb the filament is fine, so that it will be connectedtoasensitive. galvanometer, made to technical formula, which is both made white hot or incandescent with as which is an instrument for indicating the andunnecessarytoanyone confusing z .r little current as possible. presence of a small electric current. taking up wireless as a pastime pure and On pressing the switchC,itwillbe simple. Magnetic Effects noticed that the needle of the galvano- Electricity and Magnetism The other effect of a current flowing meter will be deflected, while on switch- The uses to which electricity is put are Fig. 2.-Magnetic Field AroundCoiled Wire :along; a wire is the magnetic effect, and ing offthe current the needle will be Carrying Current. ,thisisofvitalimportanceinwireless deflected in the opposite direction in spite being continually demonstratedallday work, for without itwireless telegraphy long.The telephone, the tram, and the of the fact that there is no electrical con- electric light are such common examples , would be impossible. nection between the two coils A and D. rwill show diagram- that few even trouble to "wonder why." A glance at Fig. This is known as the inductive effect of maticallythe magneticfieldaround a the current, and by varying the proportion In order to make the theory of electricity single conductor along which a current of and magnetism as simple as possible, the of turns of wire on the coils A and D the High frequency Transformer. electricityisflowing. The dotted lines voltage of the induced current may be reader is asked to accept for a fact that are intendedtorepresentthe magnetic Simple Crystal Receiver. electricity is something which flows along made much higher than thebatteryB. a metal conductor such as a telephone field around the wire. This property of the induction coil is made Fig. 3.-Increased Effect by Use of Iron Core. Nov, the magnetic field produced by a use of in medical and spark coils and wire, much the same as water flows along current flowing along a single wire will a pipe.By means of a tap the flow of transformers, and also in oscillation trans- taken for granted thatelectricityexists formers used in wireless work. water may be stopped ;in the same way C the switch in the electrical circuit controls everywhere,in everything, butatrest. When certaineffectsareproducedit "D.C." and "A.C." the flow of electrical current. It has been mentioned that a battery, Itis generally known that in order to simply means that a certain amount of electricity isin motion.That isto say, accumulator ordynamoisapieceof forceacertainquantityof anyliquid apparatus for setting in motion a current through a pipe a certain pressure isre- a dynamo does not make electricity,it simply creates a pressure which causes a of electricity, generally supposed to flow quired ;the smaller the bore of the pipe in a certaindirectionlikethe flow of the more resistance is offered to the flow current to flow from one point to another. Justinthe same way, a battery or water in a pipe, the voltage or pressure of liquid andvice versa.In a similar being at its maximum at one terminal of fashion, a wire of small diameter will offer accumulator is very much like a tank full of water with the tap turned off.The the battery and zero at the other.This is resistance to the electrical current, and a water is in the tank, but at rest.If the known as direct current or "D.C." greater 'pressure or voltage will be required The other system, known as alternating Underneath View of Crystal Receiver. than if the same volume of current were tap is turned on the water will at once begin to flow ;in a similar manner, if the current or "A.C.," is so called because the passing through a thicker wire.Also the terminals of the accumulator are joined Fig. 4.-Diagram showing Induction Effects. current is continually changing its direc- pressure or voltage at the end of a long tion or sign, being alternately positive or thin wire will not be as great or capable to a small lamp with a piece of wire a not be strong or intense enough to produce of producing the same effects as the pres- currentwill immediately flow from the any appreciable effects, but if the wire is sure at the terminals of the generator. accumulator, causing the lamp to light. coiled up, as shown in. Fig. 2, the mag- Simple Valve Receiver. Certaintermsareusedinelectrical If a large pipe is connected to the tank *.teticfield will be very considerably in- work to express the properties and effects a large quantity of water will flow from creased. ofelectricity,themost common being the tank in a short time, and in a similar A still greater effect is produced when volts, amperes and ohms. way if a thick wire is connected to ,the the wire is wound upon an iron core, and Thepressureorvoltage,whichis accumulator a large current will flow with Fig.3 in the preceding column shows Fig. 5.-Diagrammatic Illustration of Single- equivalent to the head of water in the verylittlelossof pressure,technically diagrammatically the essentialdetails of phase Alternating Current. known as voltage drop.If a thin wire is an electro-magnet. previous examples, is measured in "volts," used, however, the quantity of electricity negative every half wave, as shown dia- while the current, which may be likened flowing in a given time will be less, and One particularly useful feature of the grammatically in Fig. 5.As the whole of totheflowofwateringallons,is electro-magnetisthefactthat the iron wireless engineering depends on alternat- the pressure or voltage available to do core is only magnetised when a current is measured in "amperes." work will also be smaller. ing currents it will be necessary for the The resistance which the wire or metal ,:lowing round the coils; as soon as the reader to remember a few of the diftrences conductor offers to the flow of current may Heating Effects current is interrupted the iron ceases to be between "D.C." and "A.C." A. W. H. Underside View of Valve Panel. be compared to the friction of a pipe; the Having grasped these simple facts, the a magnet. (To be continued) LooseCoupler. \Mr II Otnatettr Witelizss 152 . JULY 29, 1922 r .11%.1%1%11%%%%%11%.1%.60%.61.61.11'" The wireless telephone will make the life of the lighthouse keeper less lonesome and certainly more cheerful.Some light- housekeepers,forinstance,remainat Broadcasting Radiograms their posts for three years at a stretch, and 11111%1WLWM Wa W.1111.6 Isome of them remain without mails for ten months. and the Public

THE organisation of commercial wireless telegraphy in Austria has been It is reported that a receiving apparatus OUR article under the above title in last entrusted to the Marconi Company of Lon-many hundreds of times more -sensitive week's issue has aroused much com- don.This decision has met with consider-than existing receivers has been inventedment, and as a result of its publication we able opposition from the supporters of theby Armstrong,theAmericanof"feedare able this week to give our readers German Telefunken Company.An Aus-back" fame. some information. trian Marconi Company isto be formed Quite unofficially, but with itsregistered office in Vienna, and from a source upon which we feel we can half the capital is to be subscribed by the Recentexperimentshave Shownthatrely, we learn that licence fees are not to London Marconi Company. The Austrianwireless can be used quite effectively inbe raised, but will remain attos.as at Government will subscribe 30 per cent.mines,transmission being effected frompresent.We are told that the ten broad- The concession gives the Marconi Com-one mine to another at a depth of 35o ft. casting stations, which will be distributed overthecountry,willcost pany the exclusive right ofallwireless atleast services between Austria and other coun- Z250,000 per annum to install and- main- tries for a minimum period of thirty years. The South African Marconi Company istain.Our authority is very certain that projected with a capital of half a million, thisapparently enormouscostwillbe four -fifths of which is to be subscribed inreached, and points out that thePost- An interestingfeatureoftherecentLondon and the remainder in the Union. master -General has emphasised the neces- politicalcampaignofDame Margaret sity of the broadcast programmes being on Lloyd George, G.B.E. (for the Coalition), a high level and of every item being an through thesouth-westerncounties was A novel featureof motor -carrecord - original production-in other words, not the seriesof demonstrations of wirelessbreaking by Mr. F. S. Edge at Brooklandsa "gramophone" item.This quarter of telephony and telegraphy given by Mr.was the installation of a wireless set in thea million pounds has to come from some- D. T. Chapman, of Abbotsford, Poole, Dor-car.The idea was to keep in touch withwhere.It obviously cannot be found by set.The first and most interesting wasthe ground staff during the whole attemptthe broadcasting companies unless in turn given at the large meeting held in Cliftonat making records.An upright aerial, ofthey can get the money from the public, Zoological. Gardens, Bristol, -on July 10,course, was out of the question, and there-andthearrangement proposedisthat when a special concert was transmittedfore a trailing flexible wire was used, theforeign apparatus shall be banned, thus from the Eiffel Tower, Paris, by kind per-"earth" being the chassis of the car. giving British manufacturers a monopoly mission of General Julien. Dame- Mar- in their own country.The present inten- garet Lloyd George was an interested tion is to charge the manufacturers a sum listener -in. Further demonstrations were A firm of wireless instrument makersof money on each receiver sold, this extra given on following daysat "Cambre,"near Holborn (London) frequently enter-payment being regarded by the broadcast- Pennsylvania, Exeter, by kind permissiontains 4arge street crowds to selections ofing firms as a toll which the buyer will pay of J. W. Reed, Esq., and record signalsmusic wirelessed from Paris. in return for what in a sense will be an and music were received owing tothe absolutely unlimited broadcasting service. unscreened aerial which was at a height Although, as we have said, the British 450 ft.above sea level.Demonstrations The makers of receiving apparatus aremanufacturers will have a monopoly in were also given in the Gyllyndune Gar-at present inundated with orders, and theirtheir own country, our authority has taken dens, Falmouth, where many people heardmanufacturing resources are most severelygreat pains to assure us that nothing what- wireless for the first time.A 4 -valve re-taxed. Much difficultyis being experi-ever in the nature of a "ramp" will be ceiver was used. enced in purchasing small parts, crystals,permitted, and that the toll derived from etc. the public will be limited to the comparatively small sums which will be added to There has been installed on one of the the prices of the sets sold. London -Paris aeroplanes a combined wire- Owing to the lack of funds there was a less telephone and telegraph equipment ofgreat probability that the Dutch concerts Wireless manufacturers believe that, as 35 watts antenna output, with a sendingwould be discontinued. The "Daily Mail,"a result of the fillip to their trade Which I range of about 18o miles at goo metres'however, realising their value to wirelesssuch an arrangement will bring about, the wave -length. The completewirelessenthusiasts, has generously provided fundsMinistry of Labour will be able to transfer equipment weighs only 125lb.An air -to ensure their continuance and also de-a large number of unemployed from idle- propeller -driven generator for 6 volts andvelopment on much wider lines. nessto remunerative work, and thatif 7oo volts and a 6 -volt storage battery supply The first concert of the new series will bethey can go ahead on these lines-and, the necessary current. A 3 -valve amplifieron -July 27 between 7 and 8 p.m. (summernaturally, not until they can see profitable is used for receiving on all wave -lengthstime).It will be sent out on a 1,050 -metresbusiness in front of them are they pre- between 300 metres and 1,000 metres. wave -length and a power of 800 watts. pared to go ahead-the Postmaster -General On August 3 the Dutch service will bewill receive such a large amount of money broadcastata powerof1,50o- watts,in the form of licence fees that he will be "Listeners -in" in Germany are requiredgiving a range of 2,000 miles.The call,able to restore the penny poSt and effect to make a yearly deposit of 4,000 marks inP C G G, will at first be given in Morse,other economies !That isa very opti- order to become subscribers to the Germanthen it will be repeated alphabetically withmistic view.Let us hope itis a correct Government's broadcasting scheme. Anthe announcement, "TheDaily Mail 'one! additional' fee is payable to any one of awireless concert is about 'to begin." We put a pointed question to our in- number of wireless Press agencies which formant : What about amateur sets made at the subscriber may select.All Press mes- In The Grafton Electric Company' advertisement in home? The definite answer was given sages are coded in such a manner as to be last week's issue, some prices were accidentally omitted. that, thereisno intention whatever of The Brass Studs are respectively,xi-,1/3 and 1,6 per unreadable by unauthorised persons. dozen, complete with nuts and washers. doing anything to restrict their use or to -wwwwwwwwwwwwww

JULY 29, 1922 153 0 tun iv r WirriesS make their owners pay towards the upkeep SIR,-Bricfly G. B.'s difficulty, under the SIMPLE AERIAL ERECTICN (continued from page of the broadcasting stations.Whereas theheading of "Can Any Reader Explain ?" 149) purchaser of a new set tvill be subscribingin No.5,is that since light waves and of7/22strandedcopper,eachstrand asmallamounttothatupkeep,thewireless waves differ in some of their pro-enamelled.This Wireisveryefficient, amateur who makes his own apparatus atperties it seems unlikely that they can- both especiallyforthereceptionofshort home will avoid any share of the broad-be vibrations of the same medium, differ-waves. Ithasbeenfoundfromex- periencethat for reception a single wire is casting expense. ing merely in their frequency or wave- "How many broadcasting firms are con-length.If we decide that this differencepractically as good as a twin aerial, and, cernedinthearrangement ?"was our issufficiently fundamental to render theas the use. of spreaders is dispensed with, next question.The answer was not abso-explanation offered by the present theory itdoes not place half the strain on the lutely definite, but was to the effect thatunacceptable, we shall have to postulatemasts. the broadcasting firms-two or threeineithertheexistenceofasecondand In order to allow for contraction and number-wouldactinthenatureof slightly modified medium or that one of theexpansion of the aerial, the end of the clearing houses to which members of thephenomena is as material emission (the oldhalyardonthegardenmast was not trade would subscribe.These broadcast-corpuscular theory oflight).We mustfirmly fixed, but was joined to a weight ingfirmswouldinstall,maintain andbear in mind what a stupendous differencesufficiently- heavy to keep the aerial wire manage the proposed stations, and wouldthere is betWeen the wave -lengths of visibletaut. This allows for any variation in be supported financially by the whole oflight and of wireless waves.The formerthe length of the wire and guy ropes and the trade. must be measured in millionths of an inchprevents undue strain on the mast in wet And as we closed our conversation ourand the latter in hundreds of feet.Com- or cold weather and slackness of the wire informant gave us this parting shot :Thepared with this the range of audible soundduring dry or hot periods. E. E. H. manufacturers are out to do their utmostwave -lengths is very limited, as they vary for the amateur public, to help them in -from a few inches only up to 300 or 400 every possible way, not to hinder them, ft. The range of visible light waves is certainly not to "bleed" them; they be-equally small in comparison.Yet in both FORTHCOMING EVENTS lieve that only by mutual co-operation cancases there are marked differences inthe Nottingham and District Radio Experimental success attend the very expensive experi-properties of the waves within even those Association.July 27.Meeting. Derby Wireless Club.July 27, 7.30 p.m.At ment of initiating a broadcasting servicelimited ranges. " The Court," Alvaston, Derby. Lecture by Mr. in this country. We may compare G. B.'s- opaque bell - A.1'. Lee :" Practical Construction of Single - jar to a receiving aerial tuned to the wave- valve Receiver Set." lengths of visible light, for it is composed Liverpool Wireless Society.July 27.Meet- ing. of molecules of matter in extremely rapid, Hackney and District Radio Club.July 27, but perfectly definitely timed oscillation. 8 p.m.At I i 1, Chatsworth Road; E.3.Meet- CORRESPONDENCE Consequently ether rays having the sameing. frequency are absorbed, whereas those of WestLondonWirelessandExperimental un- Association.July 27.Lecture by Mr. F.E. differentfrequencypassthrough Studt :" Three -circuit Variometer Tuner." Can any Reader Explain? affected.Turning to the bending of wire- StR.,-Your reader states that the electro- TELEPHONY TRANSMISSIONS less waves round the surface of the earth. EiffelTower (F L). 2,600metres. Each magnetic waves are well known to travelThere are several factor's contributing to afternoon (Saturdays and Sundays excepted). the earth's surface, but do they ?To mythis, two of which are based directly on The Hague, Holland (P C G G). 1,15o metres. mind we have the Hertzian-wave theorythe great length of the waves.If we meetJuly 27, 7 to 8 p.m. Writtle(2 M T). 400metres. August of to -day simply because it became populara drum -and -fife band playing in a main 8 p.m. when Marconi took up the theory androad and suddenly turn down a side street made his announcement to the world inthe fifes become much more subdued, in ' 1896.-Tesla's theoryisthat we do notcomparison, than the drums.This is be- CLUB DOINGS depend on etheric space waves for trans-cause the high -frequency waves emittedbyIlkley and District Wireless Society mission of electro-magnetic waves, but bythe former do not "bend" so readily as doHon.Sec.-E. STANLEY DoBsoN," Lorne induced earth currents.He also. pointsthe longer ones, which is true of all waveHouse," Richmond. Place, Ilkley. out that the real Hertzian waves are spentmotion. Even visiblelight bends veryA MEETING was held at the Regent Cafe, afteP they have travelled from The senderslightly.But the enormously greater wire-Cowpasture Road, at 7.30 p.m. on Wednesday, a short distance only.I may say that I July 5th, when Mr. H. G. Evans, B.Sc., gave a less waves turn corners as readily as dolecture on " Radio -Telegraphy and Telephony." believe that we depend on induced earthsound waves.The second factor is thatThe lecturer dealt briefly with the properties transmission. Teslaalsoprovesthatthe rarefied upper atmosphere refracts andof the thermionic valve, and its application Hertzian lvaves have very little to do withreflectsethereal waves back towards theto simple wireless circuits.The lecture was the results Obtained to -day, even at a smallearth.The conductivity of the earth's sur-illustrated with lantern slides. After the lecture, Carnarvon, Leafield, etc., distance. If two grounded circuitsareface also plays an important part in thiswere tuned in on a very fine set which the observed from day to day theeffectismatter.-G. W. S. (London). lecturer had brought with him.Unfortunately found to increase greatly with the damp- the telephony which was expected, did not ness of the earth. Ithink that thereis come through, on account of a slight misunder- conductorofelectro-magnetic standing as regards the time. no better The Hon. Sec. will be pleased to hear from waves than the earth itself.Why should ANNOUNCEMENTS anyone interested, and will furnish particulars theelectro-magnetic .wavesfollowthe of membership together with the objects of the earth's surface when by ordinary etheric " Amateur Wireless andElectrics." Edited by society on application. Bernard E. Jones.Price Threepence.Published on disturbancetheycan propagateinallThursdays and bearing the date of Saturday imme- directions unimpeded? -Recently we have diately following.It will be sent post tree to any Durham City and District Wireless, tartof the world -3 months,4s.6c1.;6 months, Club heard of the "Roger's antenna" (burying gd.;32 months,175.6d.Postal Orders, Post Office Orders, or Cheques should be made payable Hon. Sec.-Ma. GEo. BARNARD, 3, Sowerty the aerial in the ground for a short dis-to the Proprietors, Cassell & Co. Ltd. Street, Sacriston, Durham. tance),also 'oftreesactingasaerials, General Correspondence is to be brief and written en one side of the paper only.All sketches andTug above club held their first meeting on signals received onsetssimply with adrawings to be on separate sheets. July rith.The attendance and enthusiastic honeycomb coil stuck in position instead Contributions are always welcome, will be promptly spirit quite exceeded all expectations. considered, and if used will be paid ter. Before proceeding to business, Mr. Barnar of an aerial connection, etc.All this, in Communications should be addressed, according tomade a few explanatory remarks, and al my opinion, proves the Tesla theory.- theirnature,to The Editor, The Advertisement Manager or The Publisher, "Amateur Wireless,"outlined the objects and aims of a wireless club, H. P. (Stockton-on-Tees). La Belle Sausage, London, E.C.4. (Continued in second column of next page) IOW eInn to 11. Wirdes3 154 JULY 29. 1922 OUR. INFORMATION BUREAU Expert Replies to Readers' Questions.Hundreds of Replies are sent by Post. TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES Write . distinctly, give all necessary details and keep to the point.Ask one Question at a time-never more s than two.Send a Stamped and Addressed Envelope. Send the Coupon cut from this page.

' Erection ofAerialfor Wireless Receivingproper and to each other just before theyexplained by Mr. Littley in a brief address, Station reach the lead-in tube at the instrument room.that in music several particular notes did not Q.-Will you kindly advise with regard toThe total length of wire employed will 'thencome out well, and it was curious to note that erection of aerial upon the roof without usingbe 86 ft. in the horizontal component of 'thethese were always the same.An advantage poles,if possible ?Conditions as shown inaerial and (say) 54 ft. in the down -lead, whichof.indoor aerials, he pointed out, was the almost diagram herewith.-L. M. (76) just makes up the regulation 54o ft.The tele-total, absence of atmospherics and the smaller A.-Querist'sdiagram(notreproduced)phone wires Mentioned, unless fairly close andliability to jamming. shows very clearly the conditions to which henearly parallel to the aerial,will not,itis The gathering was held under the auspices mustconform.Butfortheunfortunatethought, have any noticeable effect.Queristof the West Bromwich Engineering Society. presence of the centre chimney -stack it wouldmay possibly overhear telephone conversation, no doubt have been possible to erect a fairlybut that will be about all.-CAPACITY. Barnsley Amateur Wireless useful aerial, though, of course, the actual Association height above the roof would at most be but 8 ft.As the matter stands the writer regrets he Hon. Sec.-MR. G. W. WthcLuswoRTn, 53, cannot see how the use of poles of some descrip-CLUB- DOINGS (Continued from page 553) King. Edward Gardens. tion is to be avoided, and suggests that twoA very interesting and lively discussion then'A GENERAL meeting of the above club was held light poles be obtained, say about 55 to 20took place which ended in the club beingon Tuesday, July I1th, in the Guild Room of ft. in length, and tapering from about 31 in. toformed. the Co-operative Education Department, Mar- 21 in.These should be well secured to the It was decided to hold the meetings everyket Street. outer sides of the two outer chimney -stacks,other Friday at 7 p.m.A committee was then The question of permanent headquarters was and should each be fitted with light galvanisedelected to hold office for three months, afterdiscussed, and suggestions from the members iron pulley block and " endless 'rope orwhich time another election will take place.present were considered, with the result that halyard, say 1 in.in diameter, the poles orIt was decided not to elect the President, Vice -the Association is very hopeful that at a very masts to occupy a vertical position and to havePresident and Chairman, until a few weeksearly date some of the proposals brought for- an iron cleat fastened near the bottom of each,had elapsed. ward will materialise, and that the work of the to which the halyard may be secured.The The next meeting will be held in the Hall ofAssociation will commence in earnest. aerial itself should consist of two wires (No.the Rose and Crown Hotel at 7 p.m. on Friday, The annual subscriptions werefixedas 56 S.W.G. phosphor -bronze, silicon -bronze orJuly 21st, when a lecture will be given by,follow :- hard -brand copper) spaced upon light ash orMr. G. Barnard on " The Electro-magnetic Adult members, sos., Age a to 21, 7s. 6d., strong bamboo spreaders each 4ft.long.Theory and its Application to Wireless Tele-Junior Members, 5s. Insertonesmall" reeltype 'insulatorgraphy." Theexistingcommitteewasre-elected between each wire and the spreader at each Applications for membership are invited. en bloc with additions".The question of Presi- end, and a larger size " reel'or " saddle " dent, Vice -Presidents, etc., was discussed, and insulator between the bridle rope of each West Bromwich finally left in the hands of the committee: spreader and the halyard, to which same isAT present West Bromwich does not boast aApplications for membership should be made attached.The down -lead may also consist ofwireless society, but a lecture and demonstra-to the Hon. Sec. two wires soldered to the wires of the aerialtion of telephony in the local Technical School (Continued on page 558) on the 7th inst. attracted a good audience, not a few of whom were ladies. Mr. Howard Littley was responsible for Can You Propose the arrangements, and a Burndept 3 -valve loud -speaker set was temporarily fixed up in a New Feature for the physics laboratory, the aerial being slung

between two beams, and the earth taken to a "Amateur Wireless" water tap. For the Best Suggestion on a Telephony and music came in splendidly* postcard received by Wednes- from Mr. Littley's home, whence it was transmitted by Mrs. Littley, and the demonstration day, August 2, a Prize of £1 proved an interesting example of what can be - - will be awarded. done with an indoor aerial, for the physics Querist's Coupon Available until laboratory is in the heart of the school.It was Saturday, August 5, 1922 22=111 We have the "GOODS" to meet and satisfy the Boom ! TRADE ONLY Send for List A/23, containing full particulars and illustrations of our wide range of complete Receiv- ing Sets, Units and Components. INDISPENSABLE TO THE TRADE -11 3-az ard5Goldston4 PENDLETON.. ..=ILMANCIIISTER JULY 29,1922 155 mattur Wireless

WE DO NOT ADVERTISE CHEAP CATCH LINES !!! A E.G & Telefunken Valves,tested10/6 Sq. Brass Rod, x2' x I" x ... 6d. Valve Holders, Screwed Legs & Nuts1/6 Enamelled Wire, for Inductances, Condenser Vanes. Aluminium flat 23 gauge, # lb. ... 1/6 (accurate size and gauge), Crystals (special selected), Bornite, per doz.1/ - Carborundum, Silicon, C. Py- Do., Large Spacers (true twoor')- 5d. rites, Galina, etc., etc. ... 6d. Do., Small Spacers (true to .00x") 3d. Crystal Cups, Brass, with Fixing Do, Scales Ivorine, o to 180°... each 1/ - Do., Ebonite Tops & Bottoms Fusible Alloy (for fixing crystals) 6d. (bushed) 1' - Hellesen,35 v.H.T. Batteries, Inductance Tubes, :2' X 3' 6d. with Plug ... 8/6 Headphones, Double, 2,000 ohms, Adjustable Headgear,ex- Sliders, Ebonite, with Plunger ...6d. cellent for speech and music 35/- Aerial Wile, Stranded, 7/25 roo' 4,000 ohms ditto...... 37/6 Do., Egg Insulators (high insulation)8d. Filament Resistance panel mounting 4: -

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I GODFREY Wireless ISAACS on I Broadcasting Magazine PHOTOGRAPHS Exibe of London stations forAmateurs and their operators BATTERIES (monthly feature) It was bound to be a success ! BROADCASTER Wireless Amateurs all over the I BUREAU country had been impatiently FOR Your questions waiting for an English Monthly answered by an Wireless Mggazinewhich,in Expet plain simple language,would WIRELESS unfold the wonders of Wireless. AERIAL HINTS Asa result,thousands, with We specialise in the manufacture of bat- :Are you satisfied No.- Ito gtiide them, are now teriesforfilament currentsupply to Valves, and high-tensionbatteriesfor I with your Aerial ?I revellinginthisnew and application, of Anode Potential.We can fascinating hobby, and in many supply these batteries in glass, ebonite, I WIRELESS casesconstructing SOCIETIES their own orcelluloidcontainersto any desired sets.You too, with the aid of voltage. NEWS " THE BROADCASTER," can RADIO IN THE _ learn the delights of listening -in. Exide batteries can be relied upon for 1 HOME But .. .the demand forNo. Wireless Work, and retain their charge How to enjoy it is enormous. To avoid -dis- over very long periods. appointment.getyourcopy to -day.. Prices and Particulars upon 6 v. 80 amphour application. Exide Battery

,,Thbyribp ELECTRICAL STORAGE BrOadcaster COMPANY LIMITED. THERADIOPHONE MONTHLY FOR LISTENERS IN Head Office : London Showrooms: One Shilling CLIFTON JUNCTION, 219/229, SHAFTESBURY MANCHESTER. AVENUE, W.C.2. mattur Wireless 155 JULY 29, 1922

\-N GC COMPLETE SET OF PARTSTOBUILD E -7WIRELESS Combined Crystal and Valve Receiver SPECIALISTS, 4 in. by 3 in. Prepared Cardboard Former.. .. 6d. tlb. No. 20 D.C.C. Copper Wire ..9d. 2 oz. No. 26 Copper Wire - 3 in. ofin. Brass Rod fitted with Ebonite Handle.. .. 9d. Velvet 4 -leaf Laminated Switch Arm ...... 21d 7 Studs, each fitted with a Nuts _ 10d. WIRELESS The Most Suitable Valve Panel to use with above. 15 0 3 Valve £8 10 0 111 VALVE PANELS:1 Valve £1 2 ,, £5 5 0 4 £14 14 0 All highly finished and of neat appearance. WRITE for our Illustrated Catalogue which gives a full range I I of:all panels and accessories, post; free 3d. Showrooms and Offices : CallLetters: COMPLETE a=r`" 110, STRAND. 211,1 K 2 K Z. SET 15/9 PARTS Post 9d. REVOLUTION IN PRICES For the convenience of those Amateurs who prefer to make up their own Variable Condensers we are offering complete sets of parts, ready to assemble, no drilling or fitting required, at hitherto unheard of prices, in the following Capacities : '0015 *001 *0075 '0005 '0003 '0002 Contains Velvet Filament Rheostat ready 111.1UC.Sphinx Tubular Grid Leak, 2 Meg., 21/- 17/6 151- 10/- 8/- 7/ - Grid Leak Condenser,Insulating Sleeving, Wire andall Terminals;blueprint. The above are for panel mounting and, at the price, are absolutely the Polished Mahogany Cabinets to fit (extra) 3/6. best Condenser value on the market.With Engraved Ivorine Scale 1/3 extra.Mounted in Mahogany polished Cases, 41 x 41 x 3 i", with ebon- BUILD YOUR OWN CONDENSER. ite top and knob, scale and pointer, '0003,12/6;0005,113]..Vernier Set of Parts Complete. Condensers, unmounted, 3 plates,4/-;5 plates,4/9. '001 '0005 '0003 .0002 '0001 How can we Sell so Cheaply ? Answer-Mass Production 21/- 14/- 11/- 8/- 7/ - Buy from the makers and save middlemen's profits.Post Paid on £ I Supplied with Knob Pointer and Scale for Panel Mounting.If required fur Box iy Orders and upwards Mounting Send rj- extra. Send 6d. for our ENLARGED ILLUSTRATED CATALOGUE"A "withlist A. J. FALLON & CO., The Condenser People, of stations. Crammed full of the latest and best. 230a, HERMITAGE ROAD, LONDON, N.4. PET() SCOTT The Condenser King, FEATHERSTONE HOUSE, 64, HIGH HOLBORN, LONDON, W.C.1.

JUST OUT ! ACCUMULATORS WIRELESS VALVES SIMPLY EXPLAINED By John Scott -Taggart, F.Inst.P. Get them at lEgChief Technical Adviser to "Popular Wzreless." Over 50,000 copies of John Scott-Taggart's books have been sold by us in three months.There is a reason.This F. YATES & SON, Ltd. new book from his pen islargely an abridgment ofhis " Elementary Text - book on Wireless Vacuum Tubes " Brand New GUARANTEED BRITISH which has had a phenomenal success.The price of this in Celluloid 4 simple book has been cut down to a highly competitive figure Volt 40 Amp.18/6 6Volt40 Amp.26/3 and is based on the prospect of very large sales. 4. Volt to Amp.2116 fi Volf 6o Amp.31/9 Order at Once 4 Volt fin Amp.28/2 6 Volt Bo Amp.37/3 $ Voltzoo Amp.33/. 6 Voltzoo Amp.41/6 Price 2s. 6d. Net. Cloth 3s. Post Free THREE SPECIAL LINES 6 Volt 4oACTUALAmp. hrs. (So ig) in three separateGLASS CELLScon- 1:11 THE CONSTRUCTION OF tained in polished Teak crate sealed tops at49/6. 4 Volt 24 Amp. in celluloid cases at 11/- each, postage, 1;-. WIRELESS RECEIVING APPARATUS 2 Volt 16 Amp. in Ebonite cases at3/9each, post free. By PaulD.Tyers SPECIAL PRICES TO TRADE ON APPLICATION The well.known coat, qOutor to "Amateur IVireless." An Immediate Success. Hundreds Sold inaFew Days WIRELESS SET IN OAK CABINET ti The only book which tells you HOW to MAKE ALL the Sloping Panel PARTS of a Valve or Crystal Set. a Valve set£5 0 0,2 Valve set£7 0 0,3 Valve ,..et £10 0 O. Inductances - Resistances - Condensers - Grid Leaks- Crystal Set, very superior quality, 30/-. High -Tension Batteries - Detectors - Potentiometers, etc. Special line of phones 4,000 ohms, 331- per set. In fact, EVERYTHING you wish to make.No lathe or 7122 Aerial Wire5/-per 102 ft. expensive tools required.Essential to all who wish to make SPECIAL PRICES TO TRADE their own sets. ALL GOODS CARRIAGE FORWARD. Price is.6d. Net. Post Free ti Phone: Park 4276. 4 144, Church Street, Kensington, London, W.8. RADIO PRESS LIMITED Publishers of Authoritative Wireless Books One Minute from, Notting Hill Gate Station, Central London Railway and District Railway. - 35,NORFOLK STREET, LONDON, W.C.2 .5, JULY 29, 1922 157 mateur Winless' Radio Telegraphya Telephony WE CAN SUPPLY ALL YOUR REQUIREMENTS FROM STOCK

BUZZERS, idealfor testing purposes and Morse practice, in INSULATING SLEEVING, in any colour, I ram. bore, per yd. nickel plate or brass finish, adjustable high note 5/- each. - length, 6d.Per doz, yds., 5/6. INDUCTANCE TUBES, specially prepared COPPER FOIL, per sheet 18" x 4" x 003", 9d. and impregnated ready for winding, in 12" lengths only, 6k" diem., 1/-.4" diam., MICA best selected ruby, in sheets 3"x 2"x 002", thick per doz.. 10d.,3" diam. 8d.Postage extra. 3/-. SHELLAC best orange flake, per ounce, 9d. REEL INSULATORS, white porcelain, 2" diam., 5/- doz,6c1. each. SPECIAL SOLDER, acid free, needs no flux and requires only a mod- VALVE HOLDERS, as illustrated, in solid erately hot iron.Specially made ebonite, each 1/9, 2/- and 2/3. for wiring up where space is limited VALVE LEGS, per set of four with nuts and and heat must be reduced toa washers, 1/-. minimum. Per foot, 4d., per lb., 8/-. CONTACT STUDS size of head I" x 2/. per doz.Complete SWITCH ARMS, as illustrated, radius with nuts and washers. li" complete with two nuts, spring VARIOME T ER washer, etc. Well lacquered and FORMERS, made of strongly made, each, 4/-, hard wood, complete EBONITE SHEET AND TUBE, all withgroovedball, sizes and thicknesses, best quality only supplied, 7/6 per 16. outer formerand winding former, 10/-. CHATTERTON'S COMPOUND per 4 oz. stick, 2/-, 2 oz., 1/2 H.T. BATTERIES, as 1 oz., 8d. illustrated, 36 v, with KNIFE SWITCHES mounted on porcelain base, carrying capacity tappings at every 6 v. 25 amps.S. P. D. T 3/-, D. P. D. T., 6/-, Supplied com p I ete with two plugs, 37/6. TELEPHONE RECEIVERS, resistance 4,000 ohms per pair, Postage 1/-. thoroughly recommended for all round work.Price 35/-. GRID LEAK AND CONDENSER, standard valve 3 megohm FILAMENT RESISTANCES, circular pattern for mounting in and 0005 mfds., 41- each. panel, wire element wound on ebonite core, 6/-. RADIO SUPPLIES (DV), 236 High Holborn, LONDON, W.C.1

yi TELEPHONE DOUBLE HEAD SETS Suable f orValve P.C.99Use a Rover No, 3 to receive the Daily Mail 2,000 Ohms, 3216 ;4,000 Ohms, 34/6.In stock. Broadcast Station. Price £10 including tuner and coils I )11 MARE up your own receiving sets.Our price for complete set of parts In conjunction with the above use an 1E Equipment 1.Price 21s. £1 Is. carriage paid, comprising wound inductance with ebonite panel drilled for20studs, necessary studs, ebonite knobs, etc.,crystal detector, Choose 'phones. batteries, valves, etc., from my FREE LISTS. terminals, wire for connecting.(No extrasto buy; nothingtomake.) Stamp for List. G. D. HINKS, Wireless Dept., HARDINGTON, YEOVIL. Also see P. H. BOYS & CO., 187, Goswell Rd., London, E.C.1 previous issues

WHY WAS SOL ANNOYED (SOLENOID) P A Prize for the Best Answer. Watch these Advertisements for Winners. Aerial Wire, 7/22's Enamelled Hard Drawn, Copper, 8/ - Insulating Tubing, 6d. per yard. Valve Holders.Best quality ebonite, 1/6 each. per too ft. Ivorineenc Scales.a to 18c8. Engraved (not printed), 1/2 Valves.4 pin vertical filament, 10/6 each. Aerial Pulleys, 2.6 each. SUPERIOR QUALITY WIRE. BritishMade. Aerial Insulators, Shell type,21 in. X 21 in., green, 1/6 each.ivorine Tablets.Set of 6, 9d. All wile wound free. Post extra. Reel type, 2 in. diam., white, Sid. each. Knobs. Ebonite. IIin.diameter. Superiorfinish. Make your own.Flasn Lamp Knurled, 8d. each. Batteries.For H.T. Single Batteries. 5/- doz. Mica.Pure Ruby.Pieces, 3 in. x3 in. X.002in. thick,S.W.G.S.C.C. D.C.C. D. SilkEnamelled Buzzers for Morse practice, 31- each. 6d. each. Silk Condenses.Fixed. Exceptional quality.Terminal Paraffin Wax, 1,'- per lb. . connections ; from 'Goo' to 'oat, 2/9 each. Resistance Wires. " Elsi" brand. 22'S (1ohm per 12 1/to ilir Is1:1 rubbish. Best Aluminium, 4/- 514 Condenser Vanes. yard), 24's (1'7 ohms per yard), and 28's, enamelled 14 1/11 2/- 514 119 doz. Small, 4d. (4 ohms per yard), 2d. per yard. 116 /- 2/I 412 5/6 1/10 Condenser Spacing Washers. Accurate. 18 2/r 212 5/6 doz. ;large, 8d. uoz. Sw ?ph Arms. Exceptionally strong and well made, 2/6 414 20 212 213 418 6/2 1/6 12 in, lengths,2B.A., Condenser Screwed Rod.Brrss, A very neat wireless terminal. Polished, 22 216 2111 51- 6/8 218 9d. each.4 RA., 6d. each. complete with nut and washer, 2/6 dozen. 24 3- 3/ 5/6 714 218 Contact Studs.Studs, not rubbish, 2/. doz. 26 3/7 4126 6/8 8/2 312 Tin Foil. Free from lead. Sheets, 26 in. by 13 in., 4d. each. `g. Copper Foil Sheets.9 in. X 3 in., 6d.each 28 414 4/7 7/2 91 - 3/6 Any size, rod or sheet, 5/- per lb. Valve Sockets.With but and washer.Fine finish, set Ebonite.Best quality. of four, 10d. 30 516 to/. 3/10 Filament Resistances. For panel mounting. A speciality. 32 6/- 7/3 61T2 131- 4/2. 41- each. VALVE PANELS. Single valve.Mahogany case. Baize - 34 71- 8/3 11/6 141- 414 Inductance Tubes. 12in. long.Specially impregnated. covered base, ebonite top. Containing grid, leak 36 818 xcla 15/6 4/8 2i its., 6d. ,3 in., 7d. ;3} in., 8d. ;4 in., 10d. ; 4i in., and condenser, telephone condenser. Filament 38 /3 1312 16/- 1- 5/3 1/-; 5 in., 112; 6 in., 1,8 each.Postage 9d. each. resistance, and with terminals to allow the addi- 40 Isl- 18/- 1816 229/16 6/6 Inductance Slider Rad, in.square in12in. lengths, tion of extra panels.A beautiful piece of work- 42 .7/3 2t/- 31/6 341' 91- 7d. each. manship.Price, 2916 each. Carriage extra.Please remit ample postage, balance returned.Orders over La carriage paid.Money back if not satisfied. c'Petr:t0t. 1 J. L. CARTWRIGHT & Co., and ManufacturingRadio Engineers; ElectricalDept. A, 130/132, London Road, Manchester. fGrameam, Special Terms to the Trade. Manchester." moteur Wire.655 158 JULY 29,1922

CLUB DOINGS (continued from page 154) Broadcasting receiving sets, £3 ^s.Ileadphogle 4,000 ohms,36s. ;tested;posteree-Austin,143. South Shields Y.M.C.A. Amateur For SECURING Your AERIALS Farringdon Road, London. [3 S and a Thousand Purposes where Great " Newtonian" Wireless Factory. -Complete crystal Wireless Society Strength and Strainisneeded. setsfor making up your own, also comprising all Hon. TEASDAI,E, 38,Readhead materials and 2,000 -ohms receiver, reduced price 42. Sec.--jAs. -Below. Avenue, Westoe. FLEXIBLE STEEL WIRE ROPE " Newtonian"WirelessFactory. -Furtherreduc- The above club has now been formed, and tions in the price of wireless parts -reel insulators, Aeroplane Cable made to Govt.specificationto 5d. each; crystal cups, 4d. each; ebonite inductance a single valve receiver has been installed. specified breaking strains. sliders with buffers, 5d. ;shellac varnish, Sd. ; square Intending members shouldcommunicate rods drilled, 5d. -Below. with the secretary or attend any of the meet- " Newtonian " Wireless Factory. -All parts straight from the factory at competitive prices.The trade ings which are held every Friday at S p.m., supplied. --13-15, Whitcomb Street, W.C.Regent 643. inthe Y.M.C.A.Buildings,Fowler Street, PRICES BELOWCosr. Filament Resistances,best quality, 5s. ;crystal de- South Shields. BreakingPrice freakingPrice tectors, 4s.6d; crystal cups with knurled adjusting No. Dia. strain, per coo ft. No. li'a strain. per loo ft. screws,od. ;terminals,is.6d.andas.6d.doz. ; 1 3'32' 10 cwt. 13/- 6 1/4' 80 cwt.18/- tuningcoils, range 2,o0o metres, two sliders,205. 3 1;8" 2) cwt. 8/- 7 5/16' 100 cwt.20/- sliders,with spring and plunger, gd. ;I -in.square 51 5/32' 25cwt.10/- 8 8/8' 120 cwt. 22/- brass,drilledandlacquered,7d.ft.; condenser 53 3/16' 45 cwt.121- 9 7/16'140 cwt.24/- knobs, 6d.Carriage paid over tos.Satisfaction or 5 7/32'70 ctrl16i- 10 1/2'160 cwt. 26/ - moneyback. -Arthur, 53, EtherleyRoad,Nous. 3516 Wireless Parts 3516 Trade supplied. [5 s Strainersfor use with above, right and Tuning Inductances, guaranteed, 4 in. by 14 in. by Make Your Own Crystal Set left hand threads,9d.eaeli, or 8/6 per dozen. 14in., doubleslide, polished ends, 215, post free. Orders of 10,r- and seer carriage paid, otherwise please -Ernest Batley, Thongsbridge, nr,Huddersfield. Complete Set of 105 Parts, comprising the following, add 11- for postage. [7 s ready for assembling: WirelessHeadphones, 2,000 ohms, 27s. 6d. complete. Money returnedifnotsatisfied. -Direct Wireless Wound Coil --Polished Box -Ebonite Panel SMITH & ELLIS, Supplies, 49, Heaton Road, Peckham, London, S.E. Drilled,etc. - Condenser (Dept. 66), 11,LITTLE BRITAIN, E.C.1. [8 s Parts -Terminals- Crystal Tel. No. City 8904. Detector -Aerial -Diagram, \NMI HIGH CLASS ROTARY VARIABLE CONDENSERS. 3516 'coos inPolished Cabinet, 4' X4"><4., Ebonite etc.Can be assembled by Top and Knob, Ivorine scale, o° -/8o*, 166 WIRELESS AMATEURS AND RETAILERS Ditto for Panel (scale extra) ... ..10/6 the Ordinary Amateur. Expert Advice '0004 inCylindricalBrassCase, Lacquer finish, Given Free. PARTS SUPPLIED FROM STOCK Ebonite Top and Knob, Ivorine scale ; a very List free.Condenser Plates, 1/6 doz.pairs(post3d.). handsome instrument ... 16' - Price of Valve Sets on Application FRASER, SENTINEL Ho. SOUTHAMPTON ROW, LONDON Crystal Detector withBall and Socketadjustment on ebonite base 5/6 SPARE PART PRICES WEATHERALL & Co., 28. Woodbridge Street, Resistance Switches ...5,3 Washers( pscer large, doz. 5d,TO WIRELESS EXPERIMENTERS. PATENT YOUR CIerkenvrell, London, E.C. Estali. over vo pears. Condenser Vanesdoz.9d. small 2td. INVENTIONS. Condenser Scales ...8d. Terminals (large) 218 They may prove very valuable.Particulars and consulta- Ebatf te Knobs ... .. 5d. (small) 1/9 tions free.BROWNE & CO,Patent Agents, g, Warwick Court, WIRELESS APPARATUS ... each1/3 Holborn, London, W.C.I.Est. 1840.Tel. Chancery 7547. Ebonite, Plungers 8d. Valve Holders CompleteCrystal Sets on Polished Oak TRADE SUPPLIED with H.R. 'Phones, Aerial Wire, Insu- lators, etc., £4.Carriage 'Said 1-.K. STRAND ELECTRICAL SUPPLIES RECEIVERS A large stock of low -resistance receivers, 100 to 200 ohms, H.BOWYER, la, Railey Mews, eaeli ex -Post Office and Government watch pattern, for 210,Strand, London, W.C.2 sale, 8s. &I. and 5s. 6d. each, post free.Ebonite panels cut, Leverton Street, Kentish Town,N.W.5. engraved and drilled to order.Mahogany and teak cases. Details of Single Valve Panel:- £ s.d. MAKERS' PRICES. Ebonite panel, S by 6, drilled and engraved 4 6 EBONITE Ten terminals with nuts and washers 2 0 Sheet: 0 in. Is.,in. 6s.6d., Iin. los. sq. ft. Any Mahogany case, hand polished for above.. .. 60 SizeCut. Porcelain Reel Insulators,9d. each. JUST TRY US! Valve legs with nuts and washers, set .. .. 1 0 2 in. diameter 7/22 enamelled aerial wire 7s. 6d. 100 ft. Telephone blocking condenser ...... 3 '6 10s.'150 ft.highgrade. Velvet filament resistances Aluminium Condenser Vanes, fixed and Grid leak and condenser ...... 46 3s. 9d. each. Condenser dials 4s. 9d. each. Laminated moving, 1 d. each ; Idoz. 9d.; 6 doz. Filament resistance .. .. -...... 40 switch arms 2e. each. Valve holders is. 9d. each. Mullard valve ...... 150 All above goods in stock. NO WAITING ! ! ! 4/3; 12 doz. 8/-. Variable condenser, .0095 with scale and pointer.. 176 ENCLOSE POSTAGE - BALANCE RETURNED IN FULL. Large Spacer Washers, 5d, doz. ;6 doz. 2/4. High-tension batteries, 30 v. with tapping and HOUGHTON'S WIRELESS & ELECTRICAL plugs, Siemen's manufacture...... 100 SUPPLIES, High St., Blackwood, Mon. Small Spacer Washers, 3 doz. 9d.; 12 doz. Accumulator, 4 v. 40 amp., Fuller block.. ..1 126 INSPECTION INVITED. 2/8. Double headphones, 4,000 ohms, London manufac- Terminals, 4 B.A. with nut and washer, ture...... 1 176 Insulating sleeving and connecting wire.. 1 6 HEADCEARS! HEADCEARS! 2d. each ;1/6 doz. Aerial wire, 7/22 silicon bronze, 100 ft .. 76 Contact Studs, with nut and washer, i" x i",Reel insulators, six ...... 20 LOOK ! GOVERNMENT SURPLUS 9d. doz. Leading -in tube...... 1 0 Ebonite Knob, drilled, 6d. Leading -in wire, C.T.S., per yd. .. 9 25 Sets Sullivan 120 ohms at/ Ebonite Slider, with Plunger, 6d. A complete station ready for assembling for ..£7 16 6 25 Sets Sullivan 120 ohms atlli I fif 6 Set. Aerial Wire, 7/22barecopperstranded, Carriage extra. Any item sold separately. All Complete with Cords.All in good order. 9d. Postage on all Headgears.Stamp reply. 100 foot hank, 4/-. W. H. ACAR, Telephone & Telegraph Engineer, Ring Patt. Insulators, 2"x r -g" hole, 4d. E.MARTIN, 2, FRENSHEM ROAD, PORTSMOUTH. each,. 3/- doz. 2, Finsbury Avenue, E.C.2. Crystal Detectors, on ebonite, with crystal, Tel. London Wall 3305. Established 10 years. 4/- and 5/- each. Condenser Rods, set of 4 with nuts, 8d., ENAMELLED WIRES PREPAID ADVERTISEMENTS. 10d. and 1/- set. 40 42 41 46 47 S.W.G, Valve Legs, with nuts and washers, 2d. " Premier" Tuning Coils. -Tunetot,000 metres, 13/6 8/-12/6 19/630/- lb. andwith .sotmfds.to4,000. Complete,well AERIALS, -11.D. COPPER .. 7/22 7'20 each ;1/8 doz. PLAIN .. 4/- 6/.100 ft. mounked. iss.,. carriage paid. -Johnson's, ,8o, ENAMELLED 15/- 6/6 ,.. Ebonite Valve Holders, 4 legs and nuts, 1/4Bohemia Road, Hastings. [2 s Terms: -Cash with Order.Postage extra. Special Leading -in Wire, heavily rubber - Springs.=1 gross box, assorted, 2s. ;samples, 3d. HORROCKS & ASPIN, 12, Schwabe St., Rhodes, Manchester covered, yard, 5d. -Cotton,so,Derby Range, Heaton Moor, Stock- port. ' 12 Crystal Cup, with screw, 2d. each : 1 /6 doz. Southwark has its ear to the keyhole of the world. Hexagon Nuts,perdoz.,2 B.A., 3d. ;-The Southwark WirelessTelephonyAssociation, headquarters,King'shall,LondonRoad,S.E. DELIVERY BY RETURN 4 B.A., 2.d. Meeting and listening -in,firstand third Sundays. Subscription, 6d. month. Members wanted. SPECIAL WIRELESS LINES Brown's Headphones, new, ex -Gov. stock,August 6th, open competition -prizes, gold and silver 8,000 ohms, 40/- medals -home-made crystalset,transmittingfrom CONCERT HONEYCOMB COILS. -Wave range 300 Sullivan's Headphones, new, ex -Gov. stock,one end of hall to other.August zoth, single -valve to 5o. metres.Very efficient.Hand wonnd. PRICE per competition. -Apply Secretary,W.Helps. 'Phone pair,primary and reaction -Unmounted C.., Mounted 8,000 ohms, 35/-. Ilop 756. s (Limited Stock -early application desirable.) Wireless Parts made to order.Aluminium vanes, 11/6.Post 6d. 75.bd.and, Ss 6d.per gross.Trade supplied;VALVE LEGS -with two nuts and washer -lacquered, New 4,000 ohm Double Headphones, veryalso general engineering. -7, Kingsway, Coventry. 2 id. each.9d. per set or4. best quality, limited supply, 30/-.. [4 5 Twelve -inch Spark Coil, new platinum points con- Postage extra.All orders executed in rotation, but denser,base. Firstoffer,£3. Bargain. Look, Send for list.Special terms to the trade I endeavour to supply by return. amateurs, radio equipment freesellingour goods, M. RAYMOND, 27 Lisle St., Leicester Sq., W.C.2 stamp particulars. -;liaison Passant. 1;8. Earl Street,Actual Makers: CHAMP, KAY & CO 'Phone Gerrard 4637. (Opposite Daly's gallery door.)Longsight, Manchester [6 s ElectricalEngineers,92, Saltisford, WARWICK. JULY 2), 1922 159 emateur WtreLess

" THE WHISPER- PHONE93 WONDERFUL NEW SENSITIVE MICROPHONE Detects whisper (1 conversation front a distance. Strongly magnifies Wireless Signals and Telephony.More sensitive than a Crystal Detector.For constructing Detectaphone, Specially Deaf -phone, Loudspeaking Telephone.Magnifies the tick- ing of a watch. PRICE ONLY, post free. designed All illustrated leaflets sent with6/9 Instrument. Send stamped Actual dilm. 21m. line black enamelled. aft.Bestenvelope for leaflets only.-CHARLES ADOLPH, TAYLFORTH for braidedcord attached. and CO., Works, 12, Leverington St., Clerkenwell, E.C.1. Broadcasting I11111111111111111111III III III 111111111111IIlUI111111111111111111t11111111111111111111111111111111111111111111111111111111111111- DO YOU READ PRACTICAL BOOKS ? = = See Cassell's ListofTechnical,Practical and Money -saving -:--, .:=.- Books. A p.c. will ensure your receiving it. =- E.- =- = -fE CASSELL & Co., La Belle Sauvage, LONDON, E.C.4.fi :-.711iiiiiiiiiiiiiiiiiiiiiiiiiiiiiimimmuniminimininiiiiiiiniiiiiiiiiiiiiiiiiiiiiiiiiiimunniiiiiiiiiiiiiii HEADGEAR RECEIVERS Designed and manufactured by leading Telephone Manufac- OUR PRICE FOR THIS OUTFIT turers.Backed by many years experience.Highest efficiency, Carriage concentrated magnetic field, instantaneously adjusted to the £7 15 0 Paid ears, comfortable in wear, either receiver detachable from head- READ THE. SPECIFICATION OF THe WONDERFUL band, protected terminals, light weight, twin series cord. F. & B. SINGLE VALVE SET A.T.M. LOUD SPEAKING A.T.M. CRYSTAL DETECTOR Well finished wood base, upon which is mounted Inductance Coil RECEIVERS. SETS.Highest ,Grade.Maxi- and Slider, Valve Base, Mullard Valve, Filament Resistance. Three types of Amplifying Horn. mum EfficiencyModerate Cost. EVERYTHING Grid Condenser and Leak, with all necessary, terminals and connectionsmade, and insulation to all back connections. INCLUDED. 6 volt 20 ampere Accumulator for the low tension and 60 volt Ask your dealer for high tension Battery. 100feetor8120'sAerialCablewithnecessaryinsulators, leadingin tube and earthing clip. A. T.M. Broadcasting Apparatus NO Pair of Double Head Receivers, 4,000 ohms totalresistance, EXTRAS included.We also supply a very reliable crystal set, every- AUTOMATIC TELEPHONE MANUFACTURING CO., LTD., thing included, £4 160. Head Of/ice &' Works London Office TO Milton Road, Edge Lane, Liverpool. 6o, Lincoln's Inn Fields. ORDERSIEXECUTEDIN ROTATION: SEND AT ONCE TO SAVE DELAY BUY. FOX & BRATBY, Ltd., 34, Duke Street, St. James' + Mail Order Department, PICCADILLY, S.W. 1 haphazard purchases till you have DON'T MAKE sent for our CATALOGUE of WIRELESS THE 66ESI-FIX " AERIAL Patent applied for RADIO.ELECTR ICAL & MECHANICAL SUPPLIES. "FIX IT LIKE A CLOTHES -LINE" INSTRUMENTS, A new " one -Piece" aerial with patented continuous insulation, ample& with staining eye, adjustable suspension and terminal.No lead-in tube, or other SCIENTIFIC SUPPLY STORES ACCESSORIES insulators required. No joints, no soldering, no leaking, no bother. Can be thrown up anywhere, and is absolutely weatherproof Maximum efficiency 8, NEWINGTON CAUSEWAY, and . Send cash with order and secure delivery at once. Length, so ft., PM:YE guaranteed. LONDON, SE I. MATERIALS ro/-; 951t.,r2/6; looIL, 1.5i-. Carriage paid On U.K.Agents wanted. We stock everything for the Experimenterwho wishes to build his own Set. CHAMBERS & ELLIS,6 & 7, CRAVEN HOUSE, KINCSWAY, LONDON, W.C.2 COLLOY WIRELESS INSTALLATIONS FREE Demonstrationin your home ifin London FOR TOOL BARGAINS area.Let our expert call and advise you. We install free CALL or WRITE TO -DAY to ; Before buying elsewhere compare our prices. Remember, we have the and give working instruction. Provinces, stamp for list. Largest Stock of Tools to select from in London. We guarantee you All component parts stocked at lowest prices satisfaction, so you can safely shop by post. Bargain List sent post Free. DPT.AllY, HIw.cGH HOLBORN, 4,CLONM ELL ROAD, S. TOTTENHAM GEORGE ADAMS, teon,255-fl, W.C.I.

WIRELESS Prompt Deliveales ELECTRICAL SUPPLY STORES, WIRELESS TELEPHONY 5,ALBERT TERRACE, KING CROSS, HEADPHONES (Double) best French H. R. 35/- 1011411 HALIFAX. British Make 4,C00 ohms - - - 27/6 Lists two stamps. SERVICE SPECIAL CRYSTAL DETECTOR THIS WEEK Vertical column. A real precision instrument, Crystal readily replaced6, 6 CONDENSERS LargeStock of Head- VARIABLE phones (4,000ohms) CONDENSERS AERIAL WIRE .0015 Set of Parts 25/-, Assembled 30/- £2 10 0 '0003 7/22 Copper 51- 100ft. .001 19/-, 24/- Filament Resistance 4/6, Valve Skeleton Type .0005 12/6, 15/ -Holdersi /6, H.T. Batteries 3/6, 15 v. Vernier.. 4/6Switch Studs 1/8 dos., Arms 9/6 HENRY J. BREWSTER & CO., 85, Endell Stondon, W 'PHONE. EACH 11,OUEEN VICTORIAST., LONDON, E.C.4 B. L. HOUSTOUN232, Putney .feedBr dge "t REGENT 4911. 'Phone ;CITY 768. Ornateur Wits 160 JULY 29,1922

We can supply YOU with A LL expERFArc2 COMPONENT PARTSWireless Telephone for your wireless setstraight from stock If you wish to savemoney, send forour HEAD SETS Complete List TRADE SUPPLIED IMMEDIATE DELIVERY FROM STOCK Aerial Wire, 7/22 bare copper stranded in 100 ft. hanks 516 per hank These telephones are of the highest grade diaphragm Ring Pattern Insulator, 2 iu. by 1 in., t in. hole .. 6d. each. DESIGN. in. sq. Section Brass Rod for Sliders, cut in 13 in. lengths, type and have been specially designed for the reception and drilled each end ready for fixing 81. each. of wireless broadcasting. Inductance slider complete with plunger 1/. each. Every part is of standardised construc- Cardboard Cylinder, 12 in. by 4 in. diameter ... 102. each. CONSTRUCTION. No. 24 enamelled wire, Fla true to gauge 2/S per lb. tion and thoroughly well finished.The Large or small Condenser Plates (Aluminium) lid doz. cases are of polished aluminium.The terminals are fitted with insulating Large Spacer Washers for condensers, cut true to 1,000 of an caps.The set is light and comfortable to the head. Small spacer waslicrs .... fid. doz. These telephones are highly sensitive, being of Ivorine Scales... 1/- each. SENSITIVITY, 4,000 ohms resistance. Condenser Box in Polished Oak or*Mahogatty, 3! in. by 3! in. The diaphragms in by 2 in. every set have been accurately adjusted for maximum sensitivity.Other

'0003 mf. Condenser complete-assembled in polished mahog- diaphiagm type telephones may cost more but none are more sensitive, auk or oak boxes ...... 1716 etch. All necessary parts for above condenser-no drilling or fitting Eachsetcomplete withtwoearpiecesandflexib!e required, but unassembled 151- each. ('RICE. Ditto, but without box . . ill each. CARRIAGE PA ID but without ebonite 'top, and boxDitto,.ox suitable. for panel 35/6 IN THE U.K. mounting .. 101- each. Crystal detector, mounted n Ebonite, complete with Crystal:51- each. Do not confuse these high grade telephones with the cheap inferior Large or Small Contact Studs ... 1/. doz. imitations you may be offered. CALL AND SEE THEM.Let us Valve Legs, complete with nut and washer ... Id. each. show you their perfect internal construction. Instrument Wire at Rock -bottom Prices ORDER AT ONCE TO SECURE DELIVERY J. B. BOWER & CO., Ltd., RADIO INSTRUMENTS LTD., WIRELESS MANUFACTURERS, Managing Director, ONLY ADDRESS. Chief Designer. J. JOSEPH. M.I.E.E. Works, Offices, Showrooms: W. A. APPLETON, M.B.E., M.I.E.E., 15, Kingston Road, WIMBLEDON, S.W.19. Late Manager to 12a, Hyde Street. late Admiralty Techni- Mr. H. W. Sullivan NEW OXFORD STREET. 'Phone: WIMBLEDON 1030. Works: MERTON. W.C.I. cal Research Officer. Telephone:Regent 1908. Telegrams:Instradio.London. [E. P.S. 3A

DAVIS & TIMMINSI LIMITED 111111111111111111 111111111111111111 34a, York Road, King's Cross, N.1

SCREWS AND TERMINALS FOR WIRELESS SETS INSIST ON HAVING A FULLER"BLOCK"TYPE ACCUMULATOR Are You Ready for the FOR YOUR WIRELESS SET ! The only Accumulator on the market that will hold its charge from 12 "Daily Mail" Wireless Concerts? to 18 months when not in use. By installing our special receiving apparatus 4 -volt 40 amp. hours,£1 126, plus 1/3 carriage

in your own home, you can enjoy concerts 6 -volt 40 £2 89,,, 1 /6 conducted from The Hague. Note :-These prices are 33% below those of the actual makers. One to Four Valve Sets, complete from - £9 8,000 Sold. 20,000 still in stock. Component parts supplied to order.Write now Descriptive and Instructive Pamphlet on request from- forfull particulars and prices to :- The CITY ACCUMULATOR Co. (Dept. 14) 79 Mark Lane, E.C.3 (Attuttl) FREDERICK E. FRENCH ALSO SUPPLIED BYE Late Wireless C.P.O., R.N. SOlfrialge &Co., Ltd.,Wireless Section ;A. W. Carnage, Ltd., Wireless Dept. ;Barnsley British Co-operative Society, Radio Section;Richford and Co.,i53,Fleet Street,E.C.3. ; 276, Farnham Road, SLOUGH; BUCKS. The South Wales Wireless Installation Co. Ltd., 18,West Telephone Slough 240 Ellen. 90. Bute Staeet, Cardiff.

Printed and Published in Eneland by CASSELL & COMPANY, LIMITED, Ludgate Hill, London, E.C.4.Sole Agent for South Africa, Carrara Naas AGENCY, LIMITED. Saturday. July 29,toss.