Radio Review

5th AUGUST, 1922 THE PRICE 6D. NET. WIRELESS RLD AND RADIO REVIEW

Registered at the G.P.O. VOL. X. No. 19. 5th AUGUST, 1922. as a Weekly Newspaper.

The Name " BURNDEPT " GUARANTEES Cent. Per Cent. QUALITY & EFFICIENCY.

BIRMINGHAMI MANCHESTER, ISE Haw S 61, Batocia S 0 LIVERPOOL: BURNDEPT LEEDS: 10, SOUTH JOHN 4S. ST. GlONON S

-4 .7r:7 ' LON DON OFFICE & SHOWROOMS 15 Bedford Street. Strand, W.C.Z. Wireless Music, Song and The BURNDEPT ULTRA IV RECEIVER Speechinthe Home. In addition to receiving ALL BRITISH CONCERTS will also receive loudly and clearly the Hague, Paris and Berlin Concerts as well as morse code messages from allEuropean, North African, and some American commercial stations. SHORT WAVE (CONCERT) COILS. These coils have been specially designed for BROAD- CASTING and NEW AMATEUR WAVELENGTHS. They are 3in diameter and mounted on standard BURNDEPT coil plug so that they are interchangeable with BURNDEPT PATENT COILS The new coils (4 in number) replace Bumdept Coils No. 25 and 5o which am now discontinued. Price 2C- Set of Four Coils. 1/JAISTRATED CATALOGUE containing touch useful information including details of all our apparatus and complete receiving equipments for one up to four valve sets is sent Post Five for 6d. LONDON SHOWROOMS: 15, BedfordStreet,Strand, W.C.2. BURNDEPT LTD., Manufacturers of WIRELESS APPARATUS, AERIAL WORKS, BLACKHEATH, LONDON, S.E.3 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922

ELECTRICAL MEASURING INSTRUMENTS THE WESTON MODEL 280 VOLT -AMMETER Triple Range. 150/15/3 Volts. 15/1'5/015 amps. ThisPrecision InstrumentisespeciallysuitableforWireless Research Work, i.e. 3 Volt Range.Testing accumulator cells, dry batteries, measuring fall of potential across potentiometers. 15 Volt Range. -Testing8or 12 volt accumulator supplying voltage to valves. etc. 150 Volt Range.- -Testing H.T. Batteries, etc. 0.15 Amp Range (150M.A.) -Measuring H.T. current to transmitting valves,determiningresistanceofTransformers,chokes, telephones, rheostats,etc. 1.5 Amp Range.Adjusting filament currents, etc. 15 Amp Range. -Measuring output or charging current of accumulators, etc. NOT1-- -The 3 volt range may be used as a sensitive low range Milli -Ammeter. SEVEN INSTRUMENTS IN ONE CASE. PRICE £ 1 5, less 20 per cent. Leather Case15/ - Write for further particulars. WESTON ELECTRICAL INSTRUMENT CO., LTD. Audrey House, Ely Place, Holborn, E.C.1 MODEL 280 Telephone :Holborn 202g. Telegrams : Pivoted, Smith, London. MAGNAVOX THE WORLD'S 171.5\CES1

ADIO LOUD bringsit MAGNAVOX SPEAKER tellsit. No. R1293 `Broadcastingfaithfullyreproduced (14" Horn). with marvellous clarity ana' volume Sterling Telephone & Electric Co., Ltd. YOUR TELEPHONE HOUSE, 210/212, Tottenham Court Road, London, W.1 ENQUIRIES Telephone No.: 4144 Museum (7 lines). telegrams: Cucurnls, Wesdo, London.' INVITED. Works :DAGENHAM, ESSEX. BRANCHES :NEWCASTLE -ON -TYNE :9, Clavering Place. CARDIFF :8, Park Place. iii GAMAGESAUGUST 5, 1922 - THE- WIRELESS WORLD AND RADIO -REVIEW LEAD IN AMATEUR WIRELESS FIRST IN 19O8-FOREMOST TO -DAY Exceptional Offer of 'PHONES

BROWN'SDouble Head- piece49I6 Receivers, 8,,000 ohms. IMPROVED TYPE OF Ditto, 120 ohm., FILAMENT RESISTANCE The above has been produced by us to meet the present demandforacheapyet efficient Filament Resistance 4216suitable for mounting to the SULLIVAN'S Double Head-purchaser's own instruments. piece Receivers, 8,000 ohms. Itiseasily attached, and when fixed is very neat and attractivelooking. The Resistance is wound on an air core in a grooved Ebonite former. When mounting 36,6all thatisnecessaryisto Without leads. Inperfect drill a hole in the panel for condition and absolutely new. the spindle and three holes LOW FREQUENCY All sent post free. for the fixing screws. Remove the ebonite knob and screws from theresistance,insert AMPLIFIER the spindle and collar through the centre hole in the panel The single stage low frequency and attach firmly by means Amplifierhereillustratedcan ofthescrews. Replace be easily connected to any valve knobtocomplete. To or crystal receiving set, thereby indicate the " Off " position increasing the efficiency of the a mark should be made on receiver by 5o%. With the use the panel to correspond with ofthis instrument,signals are thearrowontheknob. rendered verydistinct, and These resistances are suitable many otherwise inaudible messages for one, two, or three valves. are sufficiently strengthened as to become Size zr wide by e high. readable.This Amplifierisparticularly PRICE SIB suited for the reception of telephony and music owing to the absence of noise usual with multi -valve amplifiers. The transformer used is the finest on the market, and the design and finish of the FULL VALUE whole instrument are up to our usual high standard of FOR MONEY excellence. Length r, width 6`, height 311-'. We are offering ALWAYS this fine piece of apparatus at the extraordinary low price of 42/- Post Free. "WESTON" MOVING COIL RELAYS WRITE NOW FOR OUR This well-known instrument is one of the most sensitive relays obtainable. It consists of a very delicate permanent WIRELESS magnet (" Weston "), moving coil instrument movement and is provided with a platinum circuit closer in place of CATALOGUE a pointer.The contact screws are adjustable and are so arranged that the contact closer can be set to move through Fullyillustrated,givingall an arc ranging from .11' to less than x-rooth.It is highly details and prices.indispens- recommended for all classes of work where an extremely able to the man who wants the sensitive relay is required ;the attention of wireless best apparatus at the lowest enthusiasts being especially drawn to same for the purpose prices. A copy will be gladly of experimenting in wireless recording.We are now sentPOST FREE ON offering this beautiful REQUEST. instrumentatthe low price a 5g/. Post Free. - GAMAGES, HOLBORN, LONDON,E.C. 1. A Iv THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922

All-round Engraving Nothingcomes amisstotheTaylor -Hobson Engraving Machine. Moulds for tyres or tiny seals come within its scope. Bold lettering for Name -plates, Indicators, Scale or Clock Dials-all are cut quickly and accurately. The output of the Taylor -Hobson Engraving Machine is uniform and of high quality.Its speed alone earns it a place in every efficient factory. It costs little to run.It pays for itself quickly. It is used all over the world for work on Metals, Hard Rubber, Wood and Celluloid. Write for fullest particulars immediately.

TAYLOkTAYLOV11013501i.b? 74a, Newman Street,London, W.1 Works : LEICESTER.

R.FP-3g:0 fr:V:41p0 IMPORTANT NOTICE c).34 Z D f 0 . ? ' hi it" ..a"Ng 2L.g.E.'CT ri 5, g- ". $) ,-- g ,t"4to i--°Fmncli o < Z all I'- 4 ro.p.cr 1 o A. C. Cossor, Limited, hereby give notice M 'VI. 3 that the order of Mr. Justice Russell of the P Z //1-, ' . ,2-.' = 09 g ' " V i Ef tO p ) _.-.6Oki § 1st Viarch, 1922, continually advertised by 0 0 ,t$ Q. -0-0 0 6 2 L 4 '" 0 S Pa ' 7 °- is ?-; 026' the Marconi Co., was an order ARRIVED n r" Z g a.= B-.= ts zr g c la. " --- to. EL, AT BY CONSENT. '-' Q.- n 'El !.., ch .Z.? 10 SW u.12.18 P 2 a -.. I, 'o 71 X" Z 9 .1r, M i, Being engaged at the time in the production On 2 .,14.Eri c';Om > - ri-cz,ea 17, o. 5* g. -i---.4 ,..-....- 2 of an improved and different type of valve, n. - .Q. ov . LP 7 wi f.0 A. C. Cossor, Limited, did not consider the por)a r ASACI-lt...... 0 O ... i tAA 9.e, 'Vg.1 Z patents in question of sufficient importance ea P.M in . "m" s. .. tri 0) a) to warrant the expense of litigation. 4: (54;;-.. O litc) 10.47.g a. n- 0.-.5. ,..g o g, izt,1,OiX <,17, 1 t... r....0 ni ... o n-cZ' w, 7 A. C. Cossor, Limited, respectfully leave the R g g 4 a. :s. 0 . ri public and the Trade to judge whether the r4 (-).t,ti,z' x - .2 2 v. 0 A§A a , g.. 0 constant repetition of the notification of the ,,, :-.. ..11-0-,n.,. 6, )4 co -- PIL, -..: - Z to '17) judgment referred to is necessary or expedi- 0 ..0--8. c_,, 0-op-"x C 2 ° cr. to Pr) ent in the circumstances. ci. ELV, O % a CI5-'2 51C cpa Iv' z 6-. 9,...rg 4 F.; Z-1 .1 r. F F.; < 0 .. 1',4V, n ,1 A. C. Cossor, Limited,

co ----, 5 '6**2 C. -;.`4a 0.. t, :=.rri f t . 6 1t o 1 '0 10 Cl. Aberdeen Works, z ..g ;.-) g ,.. M cr e wee o .0. -.,., Aberdeen Lane, .:1'1".1'-' .c:''' ti.,..g g II z o = Highbury Grove, N.5. AUGUST 5, 192: THE WIRELESS WORLD AND RADIO REVIEW Here is EVIDENCE of the SUPERIORITY,EFFICIENCY and the EXTRAORDINARY RANGE of

The following comment has been received from the Chief Designer of Headingley, the Manufacturers : - Arnold Road, " Thanks for copy of the very interest- Clacton -on -Sea. ing letter from your Clacton -on -Sea customer, which confirms experiments Wireless Supplies, we have been conducting. Irepeat 64, Mortimer Street, W. that in our opinion the developments in Crystal Receivers will, if anything, 26th 7aly, 1922. be even more amazing than the de- velopmen'sinWirelessTelephony Dear Sirs, itself." J. W. FOTHERGILL. As promised, I let you know that I succeeded incatching For Local Broadcasting up the WRITTLE Concert for use with headphones the last eve-over 40 MILES Crystophone isall you re- AWAY-but I had to put on quire, but there are good, a muchlargercondenser. solid reasons why it must be Willcallwhennearyour address.

A. J. PAINE. Specially designed Variable Condensers for the Crystophone will be available in 10-14 days. PRICE - 40/ - Book your Order now. WIRELESS SUPPLIES CO., 64, Mortimer Street, London,W.1 Telephone :Museum 2672. Telegrams : Adragonax, Wesdo, London." A vi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922

me am ma CC? Std bi for ERICSSON PHONES WHENyou instal your wireless set-crystalor valve I -you'll get maximum results if you fit Ericsson Phones-clarity, sensitivity, strength of signals ancribsence of " click."Specially suited to telephony. Ericsson Phones embody the accumulated experience of telephone manufacture for a generation, I Easy, to the head, light and comfortable.The magnet, never lose their strength and "shorts " are non-existent. I , Write for 'Particulars I The BRITISH L M. ERICSSON I MANUFACTURING Co., Ltd. I Head Office : 60, Lincoln's Inn:Fields, E.C.2

sIp

Telephones

MITCHELL -PHONE

HIGH FREQUENCY HEADGEAR. TRANSFORMERS To FitOrdinary R Valve Socket Overm000pairdis- tributed to the trade No. 0Range150 Metres 5/6 inthreemonths, is sufficient guaran- No. 1 11 300 6/- tee to quality.Al- No. 2 11 600 6/3 though not quite as illustration (a new No. 3 91 1200 11 6/9 mechanical im- No. 4 19 1800 19 7/6 provement being fitted) they are No. 5 11 2500 83 comfortable, highly No. 6 6000 . - 9/9 efficient,and sold No. 7 19 8000 - 12/- on a money back basis. No. 8 24000 35/- Pair. - 14,3 IMMEDIATE DELIVERY FROM STOCK, UNWOUND FORMERS 4/6 EACH. and the trade should grasp the opportunity without delay.GOOD DISCOUNTS, and the There is a good latitude on these Coils qualityissuch that you will obtain many for higher and lower ranges. REPEAT ORDERS. SHIPPING ORDERS A SPECIALITY. Fully Illustrated List Post Free - - 4d. EWLIERCETLERSICSALuds,.

MITCHELL'S H. D. BUTLER & CO., LTD. McDermott Road, Peckham, S.E.15. Bank Buildings, 222 Great Dover Street, Retail Store,188, Rye Lane, Peckam, S. E.15. Borough, S.E.I. Tel.: Hop 3029. 'PhonesNEW EROS:, i54or. .ArrousT 5,1922 THE WIRELESS WORLD AND RADIO REVIEW vii

A New Condenserfor Wireless Receivers With Clips for Grid Leak.

T Y PC THE DUBILIER TYPE 600 MICA COADENSER DURILIER MICA CONDENSER CONDENSER CO I192DL" The illustrations show two types of this new condenser for wireless receiving circuits.The condensers have the same perfect mica insulation, the same high efficiency and the same permanence of capacity as the larger Dubilier Mica Condensers WI' holt Clips for Grid Leak. used in wireless transmitters.Distortion when receiving telephony is often due to bad design of the components of the receiver-therefore use MICA CONDENSLP efficient Dubilier Condensers in your receiver DUBILIEP toobtainthebest outofyour set. CONDENSER Co (1921 PRICES: Capacity between 0'0001 and 0'001 mfd -2/6 each

- 3/- 97 0.001 0'005 THE WAY TO DUBILIERS. (inclusive)

Condensers complete with Grid Leaks - 7;'6

TRADE TERMS ON APPLICATION.

Both types of condenser (with or without clips for a grid leak) arefitted with screw terminals as well as tags for making soldered connections.

THE DUBILIER CONDENSER CO. (1921), LTD., DUCON WORKS, Goldhawk Road, Shepherd's Bush, London, W.12

Telephone-Hammersmith 1084. 1, . Hivoltcon, Phone, London. Code-Marconi International. 4,- _

viii THE WIRELESS WORLD AND RADIO REVIEW AUGUST. 5, 1922 BATTERIES FOR WIRELESS High Tension Block Accumulators Fuller "Chad" Batteries

Fuller Plate and Patent Block Cells (4 and 6 -volt sets) are eminently suitable for Wireless Work. T-WIRELESS RY ...Ilal,razpows . u=.;Es.

Block Accumulators, unlike the ordin- Designed for' use in supplying tl-e ary Plate Type. retain their energy anode (sheath) circuit of thermionic for 12-18 months on one charge. valves for receptionpurposes. Unequalled for use with Wireless Expert tests inevery case confirm Thermionic Valves. Standardised itssuperiority over theStandard sizes -1i and 3 A.H. capacity. Battery usually employed. Type No. of cells' Voltage. Capacity I Price Last much longer than ordinary Dry A I2/Z 12 24 xi A.R. 24 150 Cells, free from risks of leakage and short circuits. A 3o/Z 3o 6o xi A.H. 21000 Type No. of cellVdltageCapacityA.H.'Price A 12/K x2 24 3 A.H. 45 150 12 x approx. 5/- A 280 A 3o/K 30 60 3 A.H. 212 100 15 x approx. 7/- B 8 12 4} approx. 11/9 EBONITE-Rod, Sheet and Tube 50 15 4 approx. 16/ - FULLER'S UNITED ELECTRIC WORKS, LTD. WOODLAND WORKS, CHADWELL HEATH, ESSEX. Telegrams: " Fuller. Clsadwell Heath." Telephone :Ilford 171 (4 lines). London Telephone Area.

" SEMAPHORE" The most reliable and efficient High Tension Dry BatteriesReceivReceivinge sets Batteries for Wireless Work are

TERMINALS. - The 15volt Batteries are supplied (unless otherwise ordered/ with 2 Brass Connect- ing Strips as illustrated.Ail the STORAGE othersizes have2 Insulated Plugs.Brass Sockets are fixed to every other Cell so that Tappings can be taken at each 3 volts. BATTERIES Other sizes can be supplied and quotationsgivenon receiptof D.P. Batteries are made to fit al- enquiries. The " 81191APHORE "is TR! most any size of box. The output Battery for Wireless Work. of our Works runs to hundreds Ds Specialities :-No " Crackle." of thousands of plates yearly. Low resistance throughout long life. Trade raPPliei PUY. London Made. Terms oa catkin. Write us for particulars SEMAPHORE, Ltd., DSPECIALISTS The D. P. BATTERY CO., td. 28, John Street, Bedford Row, London, W.C.1. BAKEWELL - DERBYSHIRE Telephones . . MUSEUM, 5422 and 5423. & 11 Victoria St., London, S.W. Telegrams . . AitWtLIDITE. HOLB. LONDON. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW ix T H E CRYSTAL RECEIVING SET PRICE H.& S. Complete with H.R. Telephones, 100 ft. Aerial Wire, &c. 126/ British Valves : " R "27/-. " R.M.R. "17/6. " Ora "15/-. RUSSELL & SHAW, 38, Great James Street, Bedford Row, W.C. 1 THE WIRELESS WORLD AND RADIO REVIEW THE OFFICIAL ORGAN OF THE WIRELESS SOCIETY OF LONDON A MAGAZINE DEVOTED TO WIRELESS TELEGRAPHY AND TELEPHONY CONTENTS Radio House :The Central Wireless Telegraph Station 577 Experimental Station Design - - 581 An Amateur Station at Harringay. By A. S. Mills - - 585 Remote Control by Radio. A New Relay Recorder. By F. W. Dunmore 586 Contents continued on next page. SELF CONTAINED OR UNIT SYSTEMS Marconiphones, Marconi Scientific Units, Waveora System, Etc.

Crystal Set complete ,A t our Showrooms / 68 Regent Street, with Phone, Aerial W.1 and Insulators wegivedemonstrations £ 3 2 6. to purchasers.

Tuners, Coils, Rectifiers, Amplifiers, Valves, Loud Speakers, Microphone Amplifiers, H .T.andL.T.Batteries,andallWirelessAccessories. Special quotations for "Cechnical Colleges, Schools and dducational Institutions.

Telephones: Telegrams: Gerrard 3039. The Radio Waveora Co. Wychwood, Western 847. 168 Regent Street, London, W.1 Phone, London. a THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922

MEN IN THE WIRELESSSERVICES DESIRING RAPID ADVANCEMENT should train in spare time with the College which ensures this I " U.E.C." (Regents Park, London, N.W.1) has in Twelve Years secured hundreds of successes by Individual Postal Training for Engineering Examinations and Professional Work. State YOUR ambition in confidence. to-SECRETARY'S DEPT. (Desk W.), UNIVERSITY ENGINEERING COLLEGE, WESTGATE-ON-SEA, KENT, and expertadvice with the New prospectus. No. 8. will be sent you without obligation.

CONTENTS(Continued)

Manchester 1 K.W. Amateur Station - 592 How to Get the Best from your Set (continued).By Percy W. Harris. 593 Notes - 594 Comespon dence - 595 Wireless Club Reports - 597 The Wireless Telegraphy and Signalling Bill- 601 Questions and Answers - 603

THE WIRELESS WORLD AND RADIO REVIEW is published weeklyon Saturdays. All correspondence relating to contributions should be addressedto THE EDITOR, THE WIRELESS WORLD AND RADIO REVIEW, 12-13, HenriettaStreet, London, W.C.2. No responsibility can be taken for MSS.or photographs sent without stamps to defray cost of return postage. Editorial and Publishing Offices, 12-13, Henrietta Street, Strand,London, W.C.2. Telegraphic Address :" Radionic, Rand, London."Telephone No.: Gerrard 2807. Advertisement Managers, Bertram Day & Co., Ltd., 9 & 10,Charing Cross, S.W.1. Telephone No.: Gerrard 8063 and 8064. SUBSCRIPTION RATE S.- 28s. per annum, post free.Single Copies 6d. or post free 7d. Registered at the G.P.O. for transmission by Magazine Post to Canadact Newfoundland. HOLLOW STEEL MASTS FOR AERIALS These masts are light, strong, easily erected, and will lasta lifetime.All lengths over 15ft. are made in sections and each mast is supplied complete withbaseplate, finial, rope cleat, pulley sheave, guy clips, three steel guyropes and strainers, painted one coat ready for immediate erection.Being made of steel, no lightning conductorsare required PROMPT DELIVERY. PRICES F.O.R. FOR CASH WITH ORDER, EACH 10ft. ... 32/6 15ft. ... 42/6 20f t. ... 45/- 25ft. ... 57/6 3Oft. 84/- 4Oft. 126/ - Other Lengths supplied at equally Low 'Prices. Trade Inquiries Invited THE WIRELESS STEEL MAST & ACCESSORYCOMPANY Lombard Street West, West Bromwich Telephone No. 447 Aro:113w 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW xi THE IDEAL WIRELESS SET CAN BE BUILT UP ON THE MARCONI SCIENTIFIC UNIT SYSTEM F you invest in this series of units you need not scrap any of your gear when you wish to improve your set. Units I, 2 and 4 form a nucleus which will give you all the broadcast programmes and all telephony and telegraphy between 300 metres and 26,000 metres.

NUCLEUS SET

This nucleus consists of a Variable Condenser ;a Retroactive Tuner ;and an Amplifying Detector. If you want greater range add Unit 3, a High Frequency Amplifier. If you want greater audibility add Unit 5, a Note Magnifier. If you wish to use low resistance telephones add Unit 6, a Telephone Transformer. THE FULL SYSTEM,

FULL DETAILS AND FREE ADVICE upon the combination most suitable for your special needs willbe sent onreceipt of your enquiry by THE MARCONI SCIENTIFIC INSTRUMENTco., LTD. TELEGRAMS: THEMASINCO, WESTCENT 40 DEAN STREET, SOHO, W.1 TELEPHONE : GERRARD 7745 zii THE WIRELESSWORLD ANDRADIO REVIEW UWIST 5, 1922 Ideal Valve Accumulator. 50 Amps. By firthe best VALUE, QUALITY and EFFICIENT SERVICE value in Accumu- latorso n t h e market. Ask those Who already have. them.

volts 1.0/ A De Luxe 4 20/- 80/ - Crystal Set Carriage. of remarkable efficiency. 2volts .. x/- Capable of receiving 4 ,, . 2/ - broadcastsfrom high up to power35 miles sendingstations,also Dimensions of each special coil for receiving cell8 x 4 X 3. Paris time signals.Sup- Weight without A one valve panel suitable plied in handsome polish- Acid 51 bs.for receiving broadcasts up to edteakcabinetwith 5o miles. Soundly constructed, hinged lid and best qual- carefully tested, and supplied ity high resistance phones complete withfull instruc- Price.. 6 Brown Sterlingtions for working. 17 12 Price VI each (without valves) Phones. Multi -Magnet Type High Tension VALVES Battery. We Stock. The world renown- Mull ard 's "Ora" ed headphones giv- Wates Speciality. 15/- each. ing unsurpassed r5 volt,x r cell standard Marconi - Osram efficiency. size 9r. ix .1. R Type 120 ohms .. 48/- Price--3/6 each. WO each. 2,000 51/-

52/- 4,000 T 2 8 BYR02.\i .: Completewith best WIRELESS ENGINEERS `,'"-

quality cords. 13-14.GTQuEs ST.Kincsway LonooKIV.C.2. / .... r..... Ste Telegrans ZtWATISM WESTCEM

II MOINE II IIM MI II Don't Buy Shoddy CONDENSERS when we can offer strong, well -made Fine Tuning and Variable Condensers that are both better and cost less. We must apologise for the delay in executing orders until W. A. C. SMITH now, owing to the huge demand and the difficulty' of obtaining raw material, but having made arrangements to overcome this, we are now in a position to greatly augment our production, 236, Argyle Street, which is now running into four figures weekly. Prices :-Pine Tuning Condensers, 6/9.Variable Condensers, 7 fixed vanes (nominally .0003), 131- GLASGOW, 15 fixed vanes (nominally .0005), 16/- ;26 fixed vanes (nominally .001), 22/6. We can also supply Ebonite Knobs, Mica, and other Insulat- are Sole Scottish Agents for the ing Materials, Terminals, Switch Studs, and other Brass Parts. Agents :-LONDON-Selfridge & Co., Ltd. ;Gamages, Ltd. ; Radio Supplies, High Holborn ;R. Winter, Radioelectrico, Famous Burndept Receivers Little Titchfield Street, Oxford Circus ; Hamblin Clapp & Co., xxo, Strand ;Scientific Appliances, Ltd., Sicilian Avenue, Southampton Row ;Russell & Shaw, Ltd., Gt. James Street, Bedford Row.Peoviscas-BeresfordBros.,BullStreet, Birmingham ; ,..... Mechanical & ElectricalEngineeringCo. Bradford Street,Walsall ;G.S.Baynton, New Street, Birmingham ;E. Dyson, Baker Street, Oakes, Huddersfield ; Radio Experimental Co., Ltd., Gell Street, Sheffield ;Bates F. WIGGINS & SONS & Co., Electrical Engineer, Bury St. Edmunds ; Electrical Supply Stores, Albert Terrace, King's Cross, Halifax ;Reynolds, Telephone : Ltd.,GreyfriarGate,Nottingham ;BrantinghamBros., Holmeside, Sunderland ;E. T. Chapman, Serpentine Road, Poole, Dorset ;Tunbridge Wells Wireless Co., The Pantyles, Avenue 2248 Tunbridge Wells ;Santon, Ltd., Bridge Street, Newport, Mon. ;Barnsley Co-operative Society, Radio Section, New Largest Stock Street, Barnsley ;F. Hough, Sussex Road, Southport ;Cross Bros., Ltd., Cardiff ; Bacon & Coates, Royal Arcade, lieighley. MICAin the World. Others wanted in districts not represented, also Colonial and foreign. Genuine Traders please write for discounts. Post free if no agent in your district.Send P.O. to- FOR CONDENSERS H. E. Ashdown (Birmingham) Ltd. AND ALL PURPOSES. AldridgeRoad, PerryBarr,Birmingham. 102,103 & 104,Minories, London, E.1 THE WIRELESS WORLD AND RADIOREVIEW THE OFFICIAL ORGAN OF THE WIRELESSSOCIETY OF LONDON VOL. X.No. '9. AUGUST 5TH, 1922 WEEKLY Radio House LONDON'S MAIN WIRELESS TELEGRAPHOFFICE. N the following article it is proposed to Alongside the. transmitting. instruments are give some account of what may be termedthereceivingcircuits from therespective Ithe nerve centre of the commercial highcountries, so that it is possible for the operator speed wireless telegraph services of the Marconi who is transmitting to be checked or inter- Company. rupted at any moment by the receiving station Radio House, situatedatthe corner ofat the other end.It is of interest to consider WilsonStreetandEldonStreet,in the in detail the handling of traffic on these tables, city,is thebuildingfrom which all theseand as an example we will take the case of the servicesarenowcontrolled,andtraffic Paris circuit shown in Fig. i, and trace the withtheUnitedStates,Canada,France,operation of the instruments shown. Spain and Switzerland, and the extension of The messages to be transmitted are taken the American service to South America, thein turn from the rack shown on the right of WestIndies,andAustralasia,allpasses the table, and are punched up on the paper through the instruments locatedhere.Attape by means of the keyboardperforator. Radio House every effort has been made to Fig. 2, which illustrates the table of the Berne meet the special requirements ofspeed andcircuit, shows an operator engaged on this accuracy, andthewholeorganisationfor work.As messages are punched in Morse dealing with the trafficisas up-to-date assymbols on this paper tape, the tape is fed possible. through a Wheatstone transmitter, this instru- From the counter in the public office runsment serving to reproduce the dotsand dashes a conveyertoa circulation table equippedin the punched tape as electrical impulses of with numerous time -saving devices, and thecorrect duration, on the line which goes tothe different transmitting and receiving circuitswireless transmitting station and controls its are located round thistableinthe mainoperation. operating room.Each circuit hasits own For those who are not familiar with the special table, and Fig.ishows thetableWheatstone transmitter, it may be mentioned allotted to the service with Paris, the call -that it is practically a special form of Morse sign of the wireless station at Paris beingkey, which is mechanically driven, and capable UFP.This table is typical of the others.of high speed operation, and is controlled by At these tables, which are standard in design,means of the punched paper tapeinstead of by messagesarefirstreproducedinMorsehand.At Radio House the Wheatstone trans- characters on a perforated paper tape, by meansmitters are driven by special electric motors of keyboard perforators seen on the extremehaving a wide range of speed, and can be set right of the table.These keyboard perfora-to run exceedingly steadily at anyparticular tors are operated in the same way as a type-speed required. is writer.The paper tapeisthen fedinto Alongside the Wheatstone transmitter automatic high speed transmitters, which inplaced an ordinary hand -operated key, which the case of the French and Swiss circuits,can be used when the volumeof traffic does working. actuallyoperatethewirelesstransmittingnot justify the use of high-speed stations located at Ongar, in Essex. The galvanometer shown near the key is for .578 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 the purpose of balancing the line against the So far, reference has only been madeto the artificial line in duplex working. apparatus connected with the transmitting As is well known, a simplex telegraph circuitside.On the left of the artificial line are the is an arrangement of a key, battery and sounderinstruments which record the received wireless at each station, so that either one or the othersignals from the distant station, which, in the station can transmit. case of Fig. 1, is Paris. The wireless receiving In duplexworking,bothstationscan station for Paris is located at Brentwood, and transmit and receive at once, and repetitions,from thence to Radio House the received etc., can be asked whenever required. wireless signals are conveyed by land line. The There are two main systems of duplexreceivingapparatusatBrentwoodisvery working, known as the " bridge " and themuch of the usual type used ata C.W.

Fig. 1.TheParis Tab.'e.

" differential "methods.Thedifferentialreceiving station, but instead of receiving the system is employed at Radio House. On thesignals in telephone headgear in the ordinary left of the key, and sunk ina glass -coveredway, these signals have to be sent over the well in the table, are located the instruments,land line to Radio House and there operate comprising the artificialline, together withinductive,pulsating currentswhichare two relays-one a differential relay (which is relays. Since the average relay is highly the distinctive feature of the differential duplexsuited to telephonic reception are not suitable system), and the other a transmitting relay,for actuating relays.It is therefore necessary which is controlled either by Wheatstoneor to smooth out these pulsating currents in order hand -operated key, and passes out the signallingthat they may be able to control a relay, and current to the line. this relay in turn conveys the Morse signals AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 579 into the land line connecting Brentwood withthe usual manner by means of a sensitive Radio House.In the case of reception byelectro-magnet.Whilst spacing current flows head telephones, it is of course necessary thatthrough the coils of the electro-magnet, a con. the currents should be pulsating, in order thattinuous straight line is drawn by the syphon they may actuate the telephone diaphragms. on the tape, but when marking current is Returning again to the standard table of theflowing, the syphon isdeflected across the Paris circuit at Radio House, shown in Fig. r,tape, and remains there until the spacing the signals from Brentwood are fed to the coils current returns.The result is that a repro- of the differential relay referred to above, andduction is made of the dots and dashes sent into this in turn controls a local circuit consistingthe line by the relay, the relay being controlled of either a sounder or an undulator or Creeddirect by thewirelesssignalsreceivedat

Fig. 2.Traffic handling at the Berne Table.

apparatus.The Morse sounder is not capable Brentwood. of working at speeds of the order of 8o to Ho With the undulator it is possible to receive words a minute, and the undulator is thereforeat very high speeds, and it may be mentioned used for high speed reception, the sounderthat messages are frequently transmitted and only being used in conjunction with the hand -received duplex at speeds of about t to words operated key when there is a small volume ofa minute for hours on end.Messages received traffic, or for the purpose of breaking in duringin this Way are recorded in Morse symbols on transmission._ The apparatus is actually a typethe paper tape, which next passes to operators of syphon recorder.It is driven by a smallwho are working typewriters, each fitted with motor, and feeds paper tape past a silver ora special rest to hold the message formin a. glass syphon.The syphon iscontrolled inconvenient position for typing.The operator 580 THE WIRELESS WORLD AND RADIO REVIEW Al7GISTST 5, 1922 translates the Morse slip and types out theoffers a variety of methods for sending and message in Roman capitals on another form,receiving.The particular method to be used which is the actual message handed to theis decided by the operator, who is guided in addressee. his decision by the volume of traffic to be So far we have referred only to the un-handled at the time, and also by the wireless dulator and sounder methods of reception, conditions.In cases of rush of traffic, and but these are not the most important, sinceunder good wireless conditions, the Wheat- the principal method for dealing with trafficstone transmitter would be usedathigh is now by means of the Creed receiver andspeedfortransmitting,andtheCreed Creed printer. A description of this:apparatus receiver for receiving, duplex working being has already appeared in this journal, on pagesconducted. 475 to 48o of the issue of October 29th, 1921. In the event of any interruption owinzgto a

Fig, 3.Teletype Machines and Lamson Carriers. By means of this apparatus, the receivedfault in any of the instruments, one of the signals are made to punch paper tape in exactly other methods can be used till the fault is the same way asthe keyboard perforatorrectified. already referred to.This tape is then fed In addition to these methods, itisalso through the Creed printer, which automaticallypossible to receive by means of telephone translates the punched Morse signals, on theheadgear in the ordinary way, provision being tape into Roman capitals, and types out themade on the table for plugging in telephone message on a paper strip in Roman capitals.leads when required. and the receiving station This paper strip is gummed on themessageat Brentwood would then be requested to send form for deliveiy to the public. through the signals in the form of pulsating It will be seen, therefore, that the tablecurrents, instead of smoothed -out currents, AtrousT 5, 1922 THE WIRELESS WORLDAND RADIO REVIEW 581 to which reference has been made in the caseAll messagesarrivingatRadio House go of operating a relay. direct to a distribution table, whence they It may be of interest to trace the course ofare distributed to their correct pigeon-holes a message from the time it is handed in overon the respective tables.Lamson conveyers the counter until its arrival in the rack on the(shown in Fig. 3)are used extensivelyin right-hand side of the table shown in Fig. 1.Radio House for conveying messages from Messages handed over the counter at one ofone place to another. the Marconi branch telegraph offices are sent In addition to the principal tables, which -:to Radio House .by teletype, which, being adeal with foreign circuits, there are a number special form of printingtelegraphat theof lines for conducting the traffic of many receiving end of the telegraph line, prints thebusiness houses. message which hasbeen typedout on a Beneath the instrument room thereisa typewriterkeyboardatthetransmittingspecial repair.shop for the purpose of effecting end. Fig. 3 shows some of these instruments.repairs to any of the apparatus in use. ExperimentalStationDesign Continued from p. 511, July 22nd, 1922. These articles, which will appear in alternate issues, are intended not only tobe a complete guide tothose new to wireless, but to give explicitdetailson the constructionof allthe components of the experimenial station.Actual designs will of necessity in some instances be somewhat crude, in order that They may be made up without elaborateworkshop equipment. Practical working instructions will be given where necessary for the help ofthose unacquainted withthemoresimpleprocessesof instrumentmaking. Of course, where good workshop facilities exist, the designs may be readily modified. Economyismade anessential feature,bearingin mind always that wherelow-priced component parts can be obtained their use has been embodiedin the designs. For those who do not desire to" make their own apparatus, the descriptions will assistthem in selecting the equipment for their stations. The information contained in the first few articles under this heading is tohelp those new to wireless and whose first aim is to build a simple set capable ofreceiving broadcasted telephony andconsequently may cover ground already familiartomany readers. The succeeding instalments, however, will advance by easy stages, and in the course of theseries the construction of an elaborate station will be evolved. IX. AN AIR DIELECTRIC VARIABLE CONDENSER. IT is intended that this condenser shall be constructed without the use of a lathe, 3/EN and to permit of this certain departures from the usualpractice have been made, such as the omission of metal bushes for bearings for the main spindle and collars on the spindle which can only be obtained by

turning.The end plates (Fig. I) are made 7/32 DIA first from f in. polished ebonite sheet.These 0 N are made to size by careful filing and the edges are finished as described in previous 4 BA articles under this heading, and must be at right angles to each other and at right angles 05/3 to the faces.The dimensions given are based 0 upon the use of condenser plates of the sizes shown in Fig. 2.There are many varieties 3" of condenser plates on the market, which, TOP AND BOTTOM PLATES though very similar in outline, vary slightly Fig. 'Ebonite end plates, Thickne.ss r .Three as to radius and location of holes.If the readerof the nuts are on the rods carrying the plates is unable to obtain plates similar to these. and the other holds the steadying rod. 582 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 shown he will need to make slight modifications The dimensional drawing of the spindle in the dimensions of the end plates, which(Fig. 3) can only be worked to provided the will present no great difficulty.One of thespacing >washers are 3/32 in. thick and the fixed plates may be used asa template forplates of 20 S.W.G.If washers and plates making the holes in the correct positions.of these dimensions are not availablea simple A plate can be clamped to the face ofone ofcalculation must be made to determine the the end pieces in the vice and two of thelength of spindle that is required between the holes drilled through, takingcare not to forcetwoscrew -threads.There is no reason of the holes in the soft plate asideas the drillcourse, why the number of plates shown in the passes through into the ebonite.Placing thedrawing should be adhered to,as no exact shanks of similar size drills or well fittingcapacityisaimedat.For simplicity one brass rods through these two holes, the platemighteasilyadopt the dimensionsgivdn, will be held in position for drilling the third.putting on as many plates as space permits. A hole is also made to carry a steadying rod,The spindle is made from hard brass rod of a size exactly fitting the hole in the movable plates, which is usually 5/16 in.After being cut to length, the ends are filed clean and by means of a centre -punch, holes are punched in the ends to indicate the exactcentres. The spindle can be then spun between pin- points to observe whether there is any wobble indicating whether or not it is perfectly true. Alternatively, it can be tested by rollingon a flat surface.Truing up can be done by hammering with a wooden mallet should it be necessary.Absolute trueness is essential, and will save a great deal of trouble when assembling.The filing of the ends to a smaller diameter must be very carefully carried out in order that they may be concentric with the main portion.Opposite sides are filed down to nearly the required diameter, and the new edges which are now presented should appear exactly parallel to each other. Two other flat faces are next made at right

25,08 -Dm, angles to those just made.This will leave four corners, or four rounded corners, according Fig. 2.Condenser Plates of the pattern usuallyto the amount of reduction in the diameter obtainable.Thickness is No. 20 S.W.G. required.These corners are filed away until the width between opposite corners is the same and the position for this is found by placingas between the two opposite faces first made. a plate with its two corner holes over the twoThe rod is by this process reduced to octagonal side holes just made, but with the third holesection and all edges must run precisely parallel. in the plate on the opposite side.The thirdMeasuringfordistancebetweenopposite hole now indicates the position for making facescan be accomplished by means of the hole for the steadying rod.Holes are also callipers or if not available, a slot can be made through the four corners at 1 in. frommade in a piece of brass sheet of the exact each edge to provide for fixing the condenserwidth and used as a gauge. The eight corners to the panel or other apparatus in which it iswhich the rod now presents must be removed mounted.The twoendpiecesmay beby filing until the width of the face thus made drilled through together, one over the other,is equal to the width of the remaining portion but if this is done great care must be takenof face.The rod now presents 16 edges, that the drill passes in exactly at right anglesand these are removed by revolving the rod to the face.Especially does this apply to theon the side of the bench whilst the file moves centre hole, which forms the bearing for theacross it.It will soon become quite round, spindle. and must be tested for fit from time to time AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 583

732"

cO tr) 4BA 4BA rritr

rr e WHIT

5D,NDLE

ID I

IIP91

Fig. 3.Method of assembling the Condenser.The arrangement of the end pieces permits of critical adjustment and correct setting for movable plates and a condenser made to these dimensions and with the plates very carefully and evenly spaced has a capacity of about '0012 mfds. 584 THE WIRELESS -WORLDAND RADIO REVIEW AUGUST 5, 1922 in the holes made in the ebonite.It shouldbe faced with zinc or lead to prevent damage be filed down until it is a very tight fit, andto the spindle.It should not project out of then by the use of emery cloth the scratchesthe vice more than is necessary, to eliminate can be removed and the fit of the spindle inthe danger of bending.The die securely its ebonite bearings made a little easier.Thefixed in its holder is forced down on the two ends are treated in this manner to the shoulder produced by the reduction in diameter distances shown in the drawing.The cuttingof the end of the spindle, and rotated in a of the threads is effected by the use of a dieclockwise direction.It is as well to turn the of the required size.The spindleishelddie back through a distance of half a revolution vertically in the vice, the jaws of which shouldafter every one or two complete revolutions in order to break off the chips that may get wedged in the die.If the reader has never attempted the cutting of small screw threads previously 'he should experiment on a piece .4- 716° -O. of scrap rod.It is not necessary to make a shoulderfor,practicalpurposes,butthe removal of the abrupt edge at the end of the rod will assist the starting of the die.The SAW CUT job could easily be carried out by the iron- monger if necessary, and a light file mark might be made on the spindle to indicate to him the distance to which the thread must be carried. On completing the spindle, the next step isto assemble the moving plates upon it. BA -7/32"DIA Two hexagon brass nuts are locked together at one end, followed by a spacing washer of about a in. in diameter, or as may be supplied with the particular style of plates purchased. A plate is then placed on the spacing washer and followed by other plates and washers alternatelyuntiltheplainportion of the spindleiscompletelycovered,when the plates are pressed together tightly.A spacing washer, followed by two lock -nuts screwed home tightly, will hold the plates securely in position after they have been arranged in Alignment. Two otherwashersarethen placed over the ends beyond the nuts, and the distance at which the ebonite end pieces are to be mounted will be indicated. When this is done the supporting rods for the ebonite pieces and fixed plates can be cut to length from brass rod of such a size as will just pass through the holes in the fixed plates.These holes are usually of a size that will just pass rod which is suitable for taking a 4BA thread, but unfortunately, as the size of the hole is not standardised, the reader may require to use larger rods, such as may need a 3BA thread.The construction of the rods is quite apparent from the drawings, and little explanation is required, four rods being necessary, one of which is merely for the purpose of steadying.Before L'I14*j proceeding to assemble the fixed plates the F . 4.Handle and Pointer. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 585 ebonite end pieces should be rubbed down The condenser is now complete except for with fine emery paper, as described in ana manipulating handle, which may be con- earlier article, and given a good matt finish.structed from a strip of 5/16 in. ebonite sheet The fixed plates can now be assembled onto the design shown in Fig. 4, which is a the rods and tightly locked home by meanssufficient guide toitsconstruction without of end nuts.The moving plates are thenfurtherexplanation, excepting perhaps that dropped into position, and the ebonite piecesit might be mentioned that the hole which pushed on.The other nuts carried by theis to carry the spindle should be made prior rods supporting the fixedplates serve forto the saw -cut.This type of handle is to be critically adjusting the ebonite pieces, so thatrecommended on account of the fact that the there is no play on the spindle, and alsohand of the operator is kept well away from facilitatethecorrectsettingof thefixed the spindle while adjusting the condenser. plates relative to the moving ones.Should In fitting the condenser to an instrument the reader require to provide a stop to preventpanel a clearance hole must be made for the the moving plates from rotating through morespindle, say of g in. diameter for a 7/32 in. than 18o degrees, this can be done by insertingspindle, as it is not intended that the panel under one of the nuts which clamp down theto which the condenser is mounted should fixed plates, a small piece of brass sheet bentserve as a further bearing.Attachment is round to engage on the end moving plate.arranged by passing four brass screws through This serves also as a short circuiting contactholes in the panel which coincide with the to connect across the fixed and moving plates,corner holes in the ebonite end pieces.Nuts and so throw the condenser out of actionare run up on these screws tight against the after it has reached the position of maximumback face of the panel, and with the aid of value.For the purpose of making contactfour other pairs of nuts the condenseris with the spindle, a small curl of wire is solderedspaced a little way from the panel to allow to its projecting bottom end and carried acrossfor the nuts projecting from the ebonite end to the supporting rod which does not passplate of the condenser. through the fixed plates. F. H. H. An Amateur Station at Harringay By A. S.MILLS. THE accompanying photographisofseries parallel switch for A.T.C., switch for my five -valve set.This set tunes fromcutting out the amplifier and aerial earthing 200 to 25,000 metres-from 200 toswitch.All connections are made beneath 2,000 by means of a loose coupler (I find thisthe table, and altogether the set has a very stillbest for the shorter wavelengths) andneat appearance. from 2,000 upwards I use honeycomb coils. Results are very good on spark, C.W. and The loose coupler can be seen in the centretelephony.Many amateurs can be heard at of the photograph with the coils on the left. quiteadistance from thephones, whilst The switches in the front of the coil holderMarconi House can be heard using no aerial are for changing over from the loose couplerwhatever. to the coils. On theextremeleftisa three -valve L.F. amplifier, and behind thisaloudspeaker mounted on a single -valve amplifier.Actuallythisisin a room below the set so that the family may get the benefit of the concerts.It is, however, soontobereplacedbya Brown H.I. r _.- f Theswitch -boardonthe , 4,.... i. rightcontains the H.T. and 7 I. L.T. batteries andvoltmeters, Mr. A. S. Mills' Amateur Station at liarringay. B 2 586 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 Remote Control by Radio. A NEW RELAY RECORDER. By F. W. DUNMORE.

The following abstract of a paper read before the American Institute of Electrical Engineers on April 19th; 1922, describes the development and method of operation of a new type of relay recorder which operates directly from the output terminals of a wireless receiver.Two types of relay are described, which are classified as Type A and Type B.Type A is designed to be operated by batteries, whilst Type B is operated from 6o cycle lio volt lighting circuits. A valuable and distinctive feature of the relay is that it is tunable to different frequencies and can be made to respond only to signals of one particular frequency.

TYPE A.-FOR USE WITH BATTERIES. and capable of maintaining its adjustments ; I.Objectof Development.Theobject (7) it must be portable. of this investigation was todevelop a relay 3.Circuit Used.In order to avoid the which should operate by received radio signals.use of a very sensitive relay designed to operate 2.Requirements.To be satisfactory as aon currents of a milliampere or less, with relay recorder the device should have thedelicate adjustments and light contacts and followingcharacteristics :(t)itmust bespring tension, advantage was taken of the of simple construction with few adjustments ;radio -audio amplifier (which has now become EXTERNALIITIIATTERY G ? 180V 1 J 1 I i AUDIO TRANSFORMER -1111-1------21. , K K Q 0.0008,al. A BFI

INPUT(TootTPUT OF AUDIO AMPUF/ER) RELAY 150011 WOO TURNS 38 SSD_ 20y 0-111111-1 0 A 0 OUTPUT

40 VOLTS BVD.C. 110V.AC. Fig. 4.Circuit diagram of Relay Recorder for use with Batteries. (2) it must be easy to adjust and capable ofa reliable radio instrument) to increase, the being put into operation quickly ; (3) it mustinput voltage to the relay circuit, thus making be selective and as free from static and suchpossible the use of a simple ordinary high - disturbances as possible ; (4) it must be capableresistance telegraph relay.The relay device of operating at a speed of at least 12 timeshas therefore been developed to operate from per second ;(5)it must respond to weakthe output circuit of any suitable amplifier in signals; (6) it must be of strong design, durable,place of the ordinary telephonereceivers. AUGUST 5, 1922 THE WIRELESS WORLDAND RADIO REVIEW 587 The only adjustment necessary is that of aneffective in causing a plate current toflow, ordinary telegraph relay. due to the fact that - 3o volts is already Fig.i shows the wiring diagram. A 'is asufficient to reduce the plate current to zero. telephone plug for connecting the relay deviceThe result will be a pulsating direct current to the amplifier output. B are phone terminalsof 10 milliamperes, maximum amplitude, in so that if desired the operator may listen to thetheplatecircuit. Thiscurrent,flowing received signal in the ordinary way. C is anthrough the plate circuit and condenser F, audio transformer of the type used in audio(Fig. I), causes an increase in the plate current amplifiers.E is a two-meghom, gridleak. at the keying frequency, which change, passing Q is a o.0006-microfarad variable condenserthrough the relay coil, will pull the relay armature over, making contact at T, which contact may control any mechanism desired.With thegridbattery voltage adjustedfor a maximum sensitivity it was found that static induction,etc.,operated therelay.When these disturbances are not as strong as the CURRENT IN AUDIO CURRENT IN B (-PASS CONDENSER RELAY COIL signal, their effect on the relay may be overcome as shown in Fig. 3.For example, the grid batteryis shown increased to - 35 volts, the critical value for maximum sensitivity being - 3o volts.The disturbances due to stray currents, etc., merely reduce the grid battery GRID VOLTAGE voltage to - 3o, which is not sufficient to cause plate current to flow.However, the signal, being of greater intensity than the stray AUDIO FREQUENCY VOLTAGE IMPRESSED ON GRID currents, reduces the voltage to - 25, which causes a plate current of five milliamperes.

Fig. 2.Tube Characteristic showing principle of operation of Relay Recorder.

or0.0003-microfaradfixedcondenser. D CURRENT IN AUDIO isa 6o -volt variable grid battery,variable EIY-PASIS CONDOGIER CURRENT IN in steps of approximately three volts. J is a ,....,RELAY COIL I6o-voltdryH.T.battery,self-contained sio within the set. K is a type UV -2o1 Radiotron. 113%.1 F and H are each a one-microfarad paper GRID VOLTAGE T is an ordinary telegraph relay 35 condenser. I I rewound with 1,200 turns of number 38 S.S.C. e5 enamel wire.A' is the output to be connected 30 to the apparatus to be controlled.L is a step-

down transformerforoperatingthetube SIGNAL AUDIO FREQUENCY filaments from the iio-volt A.C. supply when VOLTAGE IMPRESSED ON GRID such a supply is available. 4.Principle of Operation.The principle of

operation is illustrated in Fig. 2.By means VOLTAGE IMPRESSED ON GRID of the variable filament battery D, the grid BY STATIC INDUCTION. ETC. voltage is adjusted to approximately 3o volts,Fig. 3. Method of eliminatingstaticand at which value the plate current is zero, asinduction noises which are not stronger than shown at A.The incoming audio -frequency the signals. voltage impressed on the grid varies the grid potential, for example, from - 3o to - zoIt will be seen, therefore, that all disturbing volts. The 10 volts decrease from - 3oeffects, if of less intensity than the signal, do to - 20 causes an increase, for example,not affect the relay. from o toio milliamperes, while the in- 5.Method of IncreasingSensitivity and crease from - 3o to - 40 volts, is not Selectivity.During the development of this

588 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 relay it was found that the rectified audio- taneously has been selected and caused to frequency current in the plate circuit causedoperate the relay although all were of equal the relay armature to chatter rapidly and makeintensity. a poor contact with the fixed contact point By the use of two relay recorders connected through which the circuitisclosed.Thisin series across the output terminals of a single was overcome completely, however, by theradio receivingset, two messages, sent on addition of a one-microfarad condenseracrosspractically the same wavelength, but of different the relay coils.This served the purpose ofaudio frequencies, have been accurately received an audio -frequency by-path for the highlysimultaneously. inductive winding of the relay, thus greatly 6.Speed of Operation.Tests showed that decreasing the resistance of the circuit.Thewith a signal strength sufficient to produce a change of plate current due to this audio-plate current of 10 milliamperes the relay frequency caused a second change, whichcould be operated at a speed of 48 contacts occurred at the keying frequency.This latterper second, the contact being sufficient to change passes readily through the relay coilsoperate a buzzer.With three milliamperes and exerts a strong steady pull on the relayin the plate circuit a speed of 27 contactsper armature without the least chattering. second was obtained.With one milliampere It was also found that the o0006-microfarada speed of 19 per second. In each case the variable condenser (Fig. 1) across the secondary relay armature spring tension was adjusted of the input audio transformer made possiblefor the best operation. 7.Sensitivity.As stated above, this relay was designed primarily with the intention of obtaining a device which should be durable, simple in operation, and strong in construction. Sensitivityis .obtained by means of radio- audioamplification, therebyincreasingthe voltageinputtotherelaycircuitand eliminating the necessity of extreme sensitivity in the relay.Tests at 600 cycles showed that the relay circuit was fairly sensitive, as approximately 1.3 volts at the input terminals of the audio transformer in the relay circuit caused a current of five milliamperes to flow through the relay coil in the plate circuit. 8.Durability.As therelayinstrument Fig. 4.Type A Relay Recorder for use withused in this recorder is of the ordinary telegraph Batteries. type its durability is well established.The only elements requiring occasional renewal audio tuning, which increased the selectivityare the two electron tubes, the 6o -volt grid considerably. This tuning was very sharp, and battery, and the 16o -volt H.T. battery. it was found that the European stations could 9.Portability.The completerecorder, be made to operate the relay whilea high - with the exception of the filament lighting power station here in the United States wouldbattery, is contained in a cabinet 7 ins. by fail to operate it, although the high-power 13 ins. by ii ins., as shown in Fig. 4. station was coming in on the same wavelength 1o.Uses.-(1) As an ordinary receiver it and slightly stronger.This was made possiblehas advantages over reception with telephone by adjusting the heterodyne note of the Euro-receivers, for one may receive by buzzeror pean station to a frequency different from that ofsounder withallinduction and interfering the local station and then tuning the secondarynoises eliminated (if not louder than the signal). of the audio transformer to that frequency. (2) A tape or drum -type recorder may be The o0006-microfaradvariablecondenserused and a copy made without a trained radio may be replaced by a o0003-microfarad fixedoperator. condenser and the audio tuning accomplished (3) Time signals may be recorded. by adjusting the heterodyne note to theresonant (4) A call system may be worked by a time frequency.By means of this audio tuningswitch connected to close the filament circuit one ofthreestationstransnlittingsimul-for a given time at set calling intervals. 589 AUGUST 5, 1922 THE WIRELESS WORLDAND RADIO REVIEW (5) Any form of mechanism may be operated except that the plate and gridvoltages are t to -volt A.C. by an incoming signal. supplied from the 6o -cycle, (6) A receivingstation may be locatedsupply.The current for operating the tube remotely from the transmitting station and thefilaments is also obtained from this source, so that the recorder isoperated entirely inradio signals relayed by wire to the operating It is room some miles distant. dependently of any form of batteries. In conclusion it may be stated that a relay ofonly necessary, therefore, to connect to the this type should operate satisfactorily, without to -volt A.C. line and the recorderis ready to attention, on anairplane where mechanicaloperate.

po %ALVES uHf 4T T I IP AUDIO TUNING CONDENSERS 0 -000E5F EACH

RECTIFIERS RELAY 150021. 1200 TURNS. 38 5.5.C.

P W14.µF U ,"`

tif L M

TRANSFORMER

TO 110 V 60 C SUPPLY Fig. 5.Circuit diagram of Relay Recorder for use on the 110 -Volt A.G.Supply. vibration may be excessive, as the pull on the The method of operating the recorder from armature with three milliamperes, or over,the A.C. supply consists in the use of the two in the relay coil makes possible the use of areceiving tubes as rectifiers, as shown in Fig. 5 spring tension on the relay armature sufficientThe tubes Y and Z are used as half -wave to keep it from moving due to mechanicalrectifiers, one supplying the plate voltage, vibration of the relay. and the other the grid voltage.When used It would seem that the above -mentionedas rectifiers, receiving tubesshould have the feature makes this remote control relay moregrids and plates electrically connected together. serviceable than those now on the market,A special transformer M with six windings is which require delicate adjustment of springused. Two of the windings, G and .7, supply tension, contact points, and suspended vibrat- the filaments of the two rectifier tubes. A third, ing elements. I, the filaments of the recorder tubes. A fourth, U, the high voltage for the plates.The TYPE B.-FOR USE ON THE 60 -CYCLE, I IO-VOLT fifth, L, supplies the grid voltage, and the sixth, A.C. SUPPLY. E,istheto -volt primary winding.The This recorder issimilarinconstructionrectified alternating current is smoothed out andoperationtothe Type A recorder,by means of four-microfarad condensers, P 590 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 5, 1922 and R, connected across the output terminals. As the currents in the grid and plate circuits are small, smoothing out inductance was found unnecessary.It was found necessary to put 40,000 ohms as shown at 0, across the output circuit of therectifier tube supplying the voltage to the grid, as the grid is otherwise insulated from the filament of tubes K by the rectifiertube.By means of thefilament rheostats, X and W, the grid and plate voltages may be varied over any ranges desirable for the most efficient operation of the recorder.By the use of binding posts with straps, as shown in Fig. 6, the type B recorder may be operated from filament, H.T. and gridbatteriesfor supplying the filament, plate and grid voltages respectively in cases where the A.C. supply is not available. In cases where very high-speed operation Fig. 6.Type B Relay Recorder for useon the is desired, the ordinary relay may be replaced ito-volt A.C. supply. by one designed for high-speed operation. Manchester's 1 kW. AmateurStation By A MEMBER. APROPOS of the success attained bythe Society, suggested thatan effort be made Mr. W. R. Bume, of the Manchesterto get into touch with the Americanamateurs Wireless Society, in gaining the firstby means of a special transmittingplant to prizeinthe recenttransatlanticreceivingbe erected by the members. test, Mr. Y. W. P. Evans, Hon. Secretary of A formal application was madeto H.M.

Laying out the mast preparatory to erecting. ArGun. 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 591 Postmaster -General for permission to use antion by asking for a special licence to cover a input of i kW. and special aerials. periodoftwelvecalendarmonthsfrom The preliminary details were forwarded toJune 1st, 1922, and up to the time of writing London, with the application, in March, and this had not been confirmed. Whilst these various negotiations were in progress the members of the Society were busy erecting the station.Difficulty was at first experienced in the choosing of a suitable site. Altogether eight different sites were offered, all having certain advantages and a supply of A.C.orD.C., on thespot. Eventually, Mr. J. H. Brown (Vice -President), of Redbrook, Baguley, very generously offered to purchase a plot of land about one and a half acres in extent, and loan this to the Society for an indefinite period, and this site was finally chosen. A committee of four members was elected for the purpose of working out the approximate cost of the station and after allowing a suitable margin for sundry expenses, this was estimated at £120. A working committee of twelve members was then formed and invested with the authority to design a I k W. station at a minimum cost. The masts were the first consideration and these, it was decided, should be 8o ft. high, consisting of two 4o -ft. poles, 6 to 3 m. taper, surmountedby five8 -ft.socketedsteel sections.The first method of raisingthis mast was of simple design consisting of two 12 -ft.ground timbers,6ins.by 3ins., sunk to a depth of 6 ft., 6 ins. apart.Two holes were bored at a height of 4 ft. from the ground, and a similar hole through the wooden pole at the same height from the base. A bolt was then passed through these holes, the foot of the mast being raised accordingly, so that it was pivoted at a point 4 ft. from its lower extremity and 4 ft. from the ground.Stays The mast nearing the vertical position. were fixed at equal intervals along the mast and brought to a common point, being secured after consulting the various government depart- together by means of a rope strop which was ments concerned, facilities were granted byhooked in the one -ton hauling blocks, the the Post Office authorities whereby the Society other end of the blocks being secured to a would be allowed to make a special test ex-double line between two trees at a height of tending over a period of two to three days, 20 ft. from the ground.The mast was then using the 1 kW. transmission power. raised to an angle of 20 degrees by means of It was obvious that to make the attemptladders and very gradually worked up until the in midsummer would be asking for failure or strain of the whole mast could be taken by the practically so, observing that most Americanblocks, this position being with the mast at an amateurstationsreported excessiveat- angle of 40 degrees.Three ladders were mospherics and consequently wereclosing used, 20 ft., 3o ft., and 45 ft., the latter two down,asfaraslongdistance work was were now removed and each side staymanned concerned. by two members, slowly the weight was taken Not wishing to abandon the idea of a test,and a good 45 degree angle obtained.This it was decided to modify the original applica-was the most critical point, and consequently 592 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 5, 1922 the greatest strain was exercisedat this moment. steel sections, 3 ins. in diameter and raised in The wooden mast proved unequalto the taskprecisely the same manner as the three -section and after buckling slightly at about3o ft.mast. On this mast, four sets of stays were fromitsbasethe whole mastcollapsed,necessary owing to the number of sections fortunately without any casualties. used and adjustment was muchmore difficult From this moment the system employedthanwithoneoffewersections. A for raising the mast was abandoned, andafter six -wire aerial was next constructed, the working committee had reviewedthepending the authority of the P.M.G., and this situation it was decided to adopt the fallingwas erected on 6 -ft. star spreaders.The two derrick principle.Mr. Hallam constructeda end spreaders were madeup of six i-in. model mast and derrick to scale, equalto ancanes, 6 ft. long, three couples being lashed 8o -ft. mast witha 3o -ft.derrick,and together and these double lengths securedat the centre, forming a six -point star, 6 ft. indiameter. The four intermediate spreaders were made of three single canes similarlyar- ranged. The lead-in was made on the same lines, with 6 in. three-ply discs, fin. thickasspreaders. The peripheries of these were divided into six, at each point of which a slot was cut,in.wide and A group of Members of the Manchester Societyand Friends. in. deep, the centre section of three-ply working from this he demonstrated that withwas turnedouttoadepth of in., a 2 lb. weight at the top of the model mast, athusformingachannelaroundwhich pull of 6 lbs. was registered on the springbinding wire could be secured after fixing the balance for the first pull, gradually diminishingsixlead-inwiresintheslots.The total until the falling derrick balanced the mastlength of wire in the aerial is 66o ft. and in the proper, after which the mast assumed an up-feeder 618 ft. of 7/22 enamelled with 1/18core. right position quite easily.Material beingThe total cost of the work above describedwas obtained, the second mast was constructedapproximately k40. and consisted of three 27 ft. sections of 3 -in., The next item was the earth, and itwas 2 -in., andj; -in. steam piping, with a fallingdecided to dig a trench 5 ft. deep by3 ft. derrick 3o ft. long of 3- n. piping. wide between the masts, and as there iswater The stays were measured off to the exactat this depth it was considered to be a better length on two sides and made secure to stakessystem than counterpoise wires which had at driven obliquely into the ground, the backfirstbeenproposed. Four1 -in.copper set of stays being made fast to the head of theconductors were laid in the trench and acon- derrick.The blocks were then fixed to thenection taken from the centre of each to the derrick and a pull taken from a section of thetransmitting room. The area covered by the broken wooden mast, which had been previously water at a depth of 5 ft. is roughly three to four laid to rest in a 3 ft. trench, around whichwas acres,so that this may be said to constitute the a steel rope strop. earth.It is damp all the year round, thus en- Everything being in readiness, the mastsuring a constant earth resistance.The above was raised comfortably by six of the members, workwascarriedoutbyabout3o (to and lent itself readily to adjustment bymeans 4o membersat week -ends, andis really of the bottle screws in each stay.The secondvery creditable to sosmall asociety (145 mast was constructed of eleven 8 -ft. socketed members). AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 393 How to Get the Best from Your Set HINTS ON THE MAINTENANCE OF RECEIVING APPARATUS By PERCY W. HARRIS. (Author of " The Maintenance of Wireless Telegraph Apparatus.") V. THE HIGH TENSION BATTERY AND ITSnections for the desired points.These are MAINTENANCE. also useful but arenaturally more expen- WHILE many amateurs and begin- sive. Very close adjustment of the plate ners exerciseconsiderable care involtage is not often required, variation of the regard to theiraccumulators, thefilament brilliancy being all that is sufficient high-tension battery is often carelessly chosen.for fine adjustment in most cases.Personally, In this, as in practically everything else inI have given up the " wander plug " type in wireless, you get just what you pay for.Andfavour of the 15 -volt units, as the former do seeing that faults in the high tension supplynot seem to me to be worth the additional cost. are not readily recognised, trouble arising from The individual cells in a high tension battery this source is often neglected. should not be too small, as although very little The first consideration in choosing a highcurrent is taken from them the utmost steadi- tension battery is, what voltage is needed forness is required and this cannot be obtained the particular valve or valves in use ?Whilstwith very small cells.Further, the larger cells most valves are sold for given voltages, muchlast much longer and the cost of high tension depends upon the use to which the valve isbatteries per annum (the only true way of com- put, and the circuit in which it is used.Theparing values), is always lower if good cells popular hard " R " valve will work quite wellof fair size are purchased in the first place. as a detector with forty to fifty volts onthe If a high tension battery is bad, failing or plate, but sixty to eighty may often give better worn out, it gives evidence of its state by noises results.When usedasa high frequency which are frequently taken to be atmospherics. amplifier with transformer or reactance capacityTo test whether the noises are due to atmos- coupling, the same voltage can be used, butpherics or to faults in the receiver itself, dis- with resistance -capacity coupling a hundredconnect the aerial and see if they still continue. volts will not be found too high.When valvesIf they cease, they are invariably due to causes are advertised for certain voltages, no accountoutside the receiver.If they continue, they is taken of the drop in voltage in resistance -may be due to bad connections, bad valves, capacity couplings, and if such couplings arefaulty grid leak or coupling resistances, faulty used the voltage must be increased thirty tolow tension battery, faulty low or high fre- fifty per cent. to obtain the best results.Thequency transformers, or more likely than any QX valve, which works well as a detector withof these, to one or more faulty cells in the H.T. 25 to 3o volts on the plate, needs 6o to 8o ifbattery. usedinreactance -capacityortransformer To remedy the trouble, if 15 -volt units are coupled amplifyingcircuits, and loo withused, cut out each unit individually.More resistance coupling. often than not the fault will be in one unit only, High tension batteries are sold in severaland this should be discarded and a new unit forms.Very popular and useful are the 15 -voltput in place.With " wander -plug " batteries units now made by several firms.It is verytake a short length of wire and quickly tap convenient to make a wooden box to hold foureach successive pair of contacts, being careful units side by side, and to place the batteriesnot to short them for more than a moment at with their unlike poles together, so that shorta time.Usually the noises will cease when wires can be soldered on to the lugs to makeone pair of plug sockets is shorted.The bad the necessary series connections.Connectioncells thus found can be permanently shorted should be permanently made to one end ofin any convenient way, such as by two spare the series, the other connection from the setplugs connected by a length of wire. being a flexible lead, terminating in a spring High tension accumulators made up of tiny clip which can be clipped on the end of thesecondarycellsareobtainable.They are first, second, third or fourth unit. much more expensive than the dry cell type, Some makers sell high tension units withand, of course, must be periodically charged. tappings for every three volts, and plug con-High tension wet batteries of the " leclanche " 594 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 type are also on the market.The resultsBroadcasting Licences. The Postmaster -General said in the House of obtainable with both are good, and the readerCommons on July 27th :- can judge for himself whether in his particular " No licences have yet been issued to establish case the advantages outweigh the disadvantages.broadcasting stations, but I understand that the The first cost is high, but in the long run theyprincipal manufacturers of wireless apparatus in Great Britain will combine to form a company or are both probably cheaper than the dry cell companies to provide broadcasting services.Any type, although rather messy. bona filemanufacturer in this country will be ad- A fixed condenser connected across the highmitted to membership of any company so formed, tension terminals of a receiver is always anand the companies will make themselves responsible for raising the necessary capital and maintaining improvement. The value should never beefficient services.It is proposed that the receiving less than ool mfd. and is better much larger.apparatus which may be used under the licence This condenser serves the double purpose ofshall be limited to types submitted by members of preventing high frequency current passingthe broadcasting companies, and that it should conform to certain technical standards. through the battery (this always does harm) " I have been informed that the broadcasting and smoothing outslightirregularitiesincompanies, when formed, will probably desire to voltage. impose on their members the condition that British - It is usually better to use separate H.T. made apparatus only shall be sold by them, and I batteriesfor have intimated that I will assent to this condition notemagnifiers. A commonfor a period of two years.It will rest with member- H.T. battery for several valves isa fruitfulship of the companies to determine to what extent source of interaction and howling. this condition shall apply to the component parts Finally, buy your H.T. batteries from aof the apparatus. " The functions of the Post Office will be limited maker of repute and from a dealer whomto approving types of apparatus submitted by you know to keep his stocks fresh. members of the company, and inspection of individual sets will not be necessary.Provision will be made under which amateurs who construct their own receiving sets, and licensees who have already purchased imported receiving sets, will be allowed to use them. " The revenue required for providing the services Notes will be derived partly from a contribution by the manufacturers to the company on each set sold by Clifden Receiving Station Destroyed. them, and partly by a proportion of the annual Marconi's Station at Clifden, West Galway, whichlicence fee, which I shall propose to the House had been held by Irish rebels for a few days, was shall be paid to the companies financing the services. put out of action on July 25th.The ReceivingThe cost of erecting the stations and providing these house was soaked inpetrol and burned. Weservices is likely to be considerable, and I have understand its work has now been transferred toreceived no intimation from any firm that they are Ongar, Essex. willing to undertake it without guarantee or payment." New 'Berne List. Mersey Dock Music Discontinued. Le BureauInternationaldeL'UnionTele- ThePostmaster -Generalhasforbiddenthe graphique, Berne, is publishing a new list of stationssending of musical items from the Mersey Docks arranged alphabetically.Persons desiring to ob- and Harbour Board's telephone station at the tain the list, including supplements covering 1922 Dock Office.The musical items which have hitherto and 1923, should send to the Bureau Internationalbeen given at about 9 o'clock each evening have six Swiss francs. therefore been discontinued. Reservation of Wavelengths. Memorial Service to Cardiff Student. Mr. Pike Pease said in the House of Commons A memorial service was held at St. John's Church, that steps had been taken to reserve for the Empire Canton, on July 16th, for the late Mr. Eric Preen,the right to use certain wavelengths necessary for a student of the Cardiff Wireless College.Mr. long distance transmission. Preen was drowned on his first sea voyage. First Sermon by Wireless. New Companies. Dr. J. Boon, President of the Peckham Christian Union preached a sermon to his congregation on ' ',We note that the Ashley Wireless TelephoneSunday, July 30th, by means of wireless telephony Company of Liverpool, and the WrentMores from the stationof Mr. W. W. Burnham at Amalgamated Engineering and Construction Com- Blackheath. pany have just been formed. The Ashley CompanyFrench Agricultural Service. has a capital of £50,000 in £1 shares, and the Wrent For the benefit of agriculturists the Ministerial Mores Company's capital is £12,500. The objectsCouncil has decided that theEiffel Tower shall of these two new concerns are both on wirelesstransmit weather reports three times a day.Re- lines, the former dealing in telephone apparatus, ceiving sets are to be erected by the Mayors of every the latter carrying on business as electrical andlocality in order to pass on to farmers the informa- wireless engineers. tion which may be of use to them. Auousr 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 595 The sensitivity of this receiver being so great, Correspondence loop antenna reception is possible and atmospherics can almost wholly be eliminated. To the Editor of THE WIRELESS WORLD JOHN C. STOTT. AND RADIO REVIEW. SIR,-I read with interest this morning the article To the Editor of THE WIRELESS WORLD onMajorArmstrong's newsuper -regenerative AND RADIO REVIEW. receiver.I have not had the opportunity of SIR,-On June 20th, at 8 p.m., while I was testing the circuit myself yet, owing to lack of the listening -in on 750 metres, I heard telephony in necessary components, butI have a friend in English by 5 BO working to 5 CH. Can you or any Newark, N.J., to whom I am indebted for the of your readers tell me who these are ?Speech was following information re this receiver and thoughtexcellent even under very trying conditions, viz., that it might be of sufficient interest for you tojamming byspark' stations,condenser -turning publish for your readers. fiends(I heartily endorse the recent letters by The valves used should be capable of taking aM. J. G., Mr. Banks and Mr. Whiteside and others plate potential of at least 90 volts and the higheron this subject), and the hash from Leafields arc. this can be raised, the greater the volume of sound The latter is especially bad here, as, of course, I produced in the telephones.The American UV -202 am situated less than 20 miles from Leafield, but issuitable, but doubtless the M.O. Valve Co. itisparticularly annoying inall parts of the produce similar valves. country and itis quite tmnecessary for me to If an entirely new receiver is desired to be builtdescribe what unfortunately is heard from this up then the arrangement shown in the figure isstation which is" the latest production of an perhaps the most convenient up-to-date country."MightIsuggestthata CI and C, = 0.001 mfd. (or more). petition be sent to the P.M.G. (say through the The coils L, and L, may be plug-in type of theWireless Society of London), asking that trans- Burndept short wave series and are varied according mitting be done by valves instead of the present, to the wavelength to be tuned to. arc.It is, of course, appreciated that harmonics L4 and L, may be Burndept coils Nos. 1000 (L,) would still exist but it is what is rightly described and 750 (L5), and of course, do not vary withas the " hash " of the arc that is so particularly wavelength changes occasioned by L L, and 1.13 troublesome. (a variometer). I have just been listening to 2 LO sending out An outdoor aerial may, of course, be used instead a most excellent programme by members of Dalys of the loop, but if both are used together thenand the Lyric theatres, to St. Dunstan's, which was interference from otherstations on aslightlypunctuated by the hash, and if this is allowed to different wavelength may be entirely eliminated. continue when broadcasting becomes general,I The outside aerial is loosely coupled to L, by awould advise amateurs around this part of the coil about the same size as L and has a variablecountry to keep their money in their pockets. condenser of 0.001 mfd. in series for tuning.The G. COURTENAY PRICE (2 OP). coupling may vary with somewhat different sized aerials. To the Editor of THE WIRELESS WORLD The desired signal is then tuned in on the loop AND RADIO REVIEW. and the outside aerial is tuned to resonance with SIR,-A conference of Midland Wireless Clubs is the interfering signal and then the coupling between being promoted by this Club, with a view to dis- the aerial coil and L, is gradually increased untilcussing the interchange of lectures, and other the jamming signal is balanced out. matters of mutual interest.

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Diagram of the Armstrong Super -regenerative Circuit referred to above. 593 THE WIRELESS WORLD AND RADIO REVIEW AnausT 5, 1922 It is proposed that the conference shall be heldsets, would welcome some reports through your in Birmingham, as early as possible in September,columns on results obtained by other people. and all Midland clubs are invited to send delegates. Low power telephony is a subject in which we I shall therefore be very glad if secretaries of suchare all interested and it would be a great help to organisations will communicate with me at themany to know at what distance it should be possible earliest possible date. to receive the telephonic transmissions of amateurs FRANK S. ADAMS, using 10 watts or less, on a single valve. Hon. Secretary. Perhaps some of these gentlemen who hold Birmingham Experimental Wireless Club. transmission licences and who give us much pleasure by their excellent music, would kindly publish the distances they regularly work when using one, To the Editor of THE WIRELESS WORLD two, three or more valves. AND RADIO REVIEW. ROBERT G. ELLIS. SIR,-With the advent of wireless broadcasting there is, without doubt, a very great number of the public, both young and old, who desire to become more conversant with this branch of science.Also there will be a vast number of " home " installations set up ;some will be of a very simple character, Calendar of Current Events whilst others will be of more or less elaborate con-Sunday, August 6th. struction, according to the abilities of the person Transmission of Telephony from 8 to 9 p.m. on launching out to fathom the lather.There will, of 1,070 metres by PCGG, The Hague, Holland. course be many difficulties to be overcome beforeMonday, August 7th. any kind of apparatus of home construction is SOUTHEND AND DISTRICT WIRELESS CLUB. completed.For the person who does not desire Garden Fete and Public Demonstration in the to know anything more of wireless than the manipu- Rectory at Leigh -on -Sea. lationof a" fool -proof " receiving instrument, Wednesday, August 9th. much cannot be said, but for the genuine experi- Transmission of Telephony at 8 p.m. on 400 mentists, who wish to discover or know the " why metres by 2 MT, Writtle, near Chelmsford. and the wherefore," there is something to be said, Thursday, August 10th. i.e., there is help awaiting them, if they will only Transmission of Telephony from 8 to 9 p.m. on avail themselves of the opportunities which are 1,085 metres by PCGG, The Hague, Holland. open for them. ILKLEY AND DISTRICT WIRELESS SOCIETY. This help may be found in any of the Amateur 7 p.m. Regent Café.Meeting. Wireless Societies or Associations of which many STOCKTON AND DISTRICT AMATEUR WIRELESS now exist, and those which have been in existence SOCIETY. for any length of time have been affiliated to the Monthly Meeting. Wireless Society of London.Of course, no one WEST LONDON WIRELESS AND EXPERIMENTAL is under any obligation, at present, to join such an ASSOCIATION. Association, if they are going in for the reception No meeting.(Closed until August 31st.) of " Broadcasting "Just one further point, and ILFORD AND DISTRICT RADIO SOCIETY. one that cannot be too strongly emphasised :It At St. Mary's Hill, High Road, Ilford.Lecture is certainly most advisable for any person who on " Reaction," by Mr. J. F. Payne. anticipates using valve circuits or apparatus toFriday, August 11th. become acquainted both theoretically and practi- SOUTH SHIELDS Y.M.C.A. AMATEUR WIRELESS cally with them before endeavouring to search SOCIETY. the lather, for if one has not attained even the 8 p.m., at Y.M.C.A. Buildings, Fowler Street, most elementary knowledge of the functions of South Shields. Meeting. the oscillation valve, then there isa likelihoodSunday, August 13th. of causing disturbances in the lather that neither Transmission of Telephony in afternoon and themselves or others will get much enjoyment forfrom 8 to 9 p.m. on 1,085 metres by PCGG, their labours.The writer will be very pleasedThe Hague, Holland. indeed to answer any enquiries respecting theTuesday, August 15th. Association to which he is the Hon. Secretary. Transmission of Telephony at 8 p.m. on 400 HORACE W. COTTON, metres by 2 MT, Writtle, near Chelmsford. Hon. Secretary. WIRELESS SOCIETY OF EAST DORSETSHIRE. The West London Wireless and At Branksome Liberal Club, Salisbury Road, Experimental Association. Upper Parkstone. General Meeting and En- 19, Bushey Road, rolment of Members. Harlington, Middlesex. Wednesday, August 16th. 21et July, 1922. YORK WIRELESS SOCIETY. 8 p.m., at Grand Picture House Café, Clarence Street, York.Preliminary Meeting. To the Editor of THE WIRELESS WORLD Thursday, August 17th. AND RADIO REVIEW. Transmission of Telephony from 7 to 8 p.m. on SIR,-There must be a number of amateurs 1,070 metres by PCGG, The Hague, Holland. having receiving apparatus oftheir own con-Transmissions from 2 LO. struction who, not being able to get an opportunity We understand that 2 LO may transmit on of comparing their results with those of othersAugust 7th from 5 to 5.30, 6 to 6.30, on August more experienced by actual listening -in on other 9th and 10th 5 to 5.30, 6 to 6.30, 7 to 7.30. AUGUST 5. 1922 THE WIRELESS WORLD AND RADIO REVIEW 597 Wireless Club Reports NOTE.-Under this heading the Editor will be pleased to give publicationto reports of the meetings of Wireless Clubs and Societies.Such reports should be submitted without covering letter in the exact form in whichthey are to appear and as concise as possible, the Editor reserving the right to edit and curtail thereports if necessary. The Editor will be pleased to consider for publicationpapers read before Societies. An Asterisk denotes affiliation with the Wireless Society of London. Newcastle and District Amateur Wireless A meeting was held on Monday, July 17th, at Association.* Headquarters, Wireless School, Eldon Square. Hon. Secretary, Mr. Colin Bain, 51, Grainger Birmingham Experimental Wireless Club.* Street, Newcastle -on -Tyne. Hon. Secretary, Mr. Frank S. Adams, 110, Ivor On Monday, July 10th, an Ordinary Meetingwas Road, Sparkhill, Birmingham. held.After the committee had finished business At a meeting held at Digbeth Institute on Friday, in private an address was given by Mr. MasonJuly 14th, Mr. L. J. Dore lectured on " Condensers on his experiences and difficulties during the de-in Radio -Circuits."ThePresident (Mr.A.L. velopment of his present receiver (a four -valveLancaster) took the chair. circuit, using two high frequency, tuned trans- Mr. Dore commenced with the electroscope as former method of coupling).Several of his remarksa means of detecting static charges, and gave a wereseverelycriticisedby members present.description of the action of a condenser.He then The criticism, however, as usual, proved of benefit described a large number of different methods of and interest.Mr. Dixon rose and dealt at lengthconstructing condensers, which could easily be with the various methods of connecting the in-used by amateurs. Many of the ideas described dividual windings of the transformers, and with the were extremelyingenious,particularreference inter -relationship of the windings of the transformers being made to methods of obtaining fine adjustment, following in the circuit.The remarks passed by Some particulars were then given of the uses to critics were very instructive as to the effect of thewhich condensers could be put in valve circuits, reduction in transmitting wavelengths down toand the functions which they performed when 180 to 450 metres.It appeared that the tuned inserted in various positions. A discussion followed, transformer method had been giving much dis-in the course of which regenerative and retroactive appointment (so far) on the shorter waves.Trans-circuits were drawn on the blackboard, and their missions from Marconi House(2 LO), Writtlerelative advantages discussed. (2 MT), and various amateurs had all been received Mr. Dore, who is a vice-president of the Club, was so weak as to be useless (that is, when anythingunanimously accorded a vote of thanks. had been received at all). A new financial year commenced on August 1st. The majority of members seemed to be turningIntending members are advised to communicate to the variometer type of regenerative circuits. with the Hon. Secretary. Experiences with the Reinhartz tuner showed many desirable features, including very sharp tuningThe West London Wireless and Experimental with complete absence of undesirable capacity Association.* effects from the body and hands. Hon. Secretary, Horace W. Cotton, 19, Bushey Road, Harlington, Middlesex. After the minutes of the last general meeting A meeting was held on Thursday, July 20th. had been read and passed, the Chairman calledon Morse practice was given by Mr. R. T. Wright and Mr. Colin Bain to deliver his lecture upon theseveralmembersavailedthemselvesofthe relationship between wavelength and frequency. opportunity to brighten up their reading. Mr. Bain dealt with the subject in a most interesting Owing to the large number of new members now and lucid manner, chiefly in order to assist thosejoining the Association, Mr. J.F. Bruce com- members who have but recently joined the ranks of menced a series of elementary instructional chats, wireless experimenters. which dealt with inductances in various forms and Mr. Dixon, the Chairman, then lectured on themethods of construction.In turn he minutely various oscillations produced in " Spark " trans-explained the making of formers, the winding, mission, giving a very detailed account of the pro-various methods of tapping, finishing and mounting duction of wave trains, dealing first with the in-of coils, and gave some data for a very efficient duction coil, the the spark gap, and finally with theloose coupler, which from personal use and ex- oscillations between the aerial and earth.He thenperience he has found most effective and efficient. explained the systems used by some of the largeMr. Bruce was shown how his chatty lecture was commercial spark transmitting stations, and theappreciated by the round of applause which burst wave effects produced from each, illustrating eachforth when the President asked the assembly to section of his lecture with very clear diagrams. express their hearty thanks.The next " chat " of A discussion followed upon the peculiar actionthisseries will be " Single Valve Panels " and of a tapped high frequency transformer, which" Reactance Inductance."Owing toso many gave three high efficiency " peaks " at differentmembers taking their annual vacation just now wavelengths for the first tapping.Further experi-the committee desire all members and prospective ments are being carried out with this transformer,members to note that the next meeting will not be the results of which, when completed, will beheld until Thursday, August 31st next, at the explained to the members. Club Rooms, Belmont Road Schools, Chiswick, 598 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 W.4.The Secretary will be pleased to reply to allThe Dewsbury and District Wireless Society. enquiries from intending members, respecting objects Hon. Secretary, Mr.' A. Horsfall, Willow Grove, and subscriptions to the Association. Lee Street, Ravensthorpe, Dewsbury. North Middlesex Wireless Club.* On July 13th a General Meeting was held in the Hon. Secretary, Mr. E. M. Savage, " Nithsdale,"society's roomsin South Street, Dewsbury, at Eversley Park Road, N.21. 7.30 p.m., the President, Mr. S. S. Davies, presiding The 93rd meeting of the Club was held atover a good attendance of members. Shaftesbury Hall, Bowes Park, on July 12th.As The chief items under discussion were the new previously announced, a special instruction class forrules and suggestions for Morse classes ; the first beginners was held from 7.30 p.m. to 8.30 p.m.,item was speedily dealt with, and the arrangements when the chair was taken by Mr. A. G. Arthur, the for Morse classes are that a class be formed and President of the Club. meet on Thursdays at 7.30 p.m. to receive instruc Owing to pressure of business, the Hon. Secretary tion and buzzer practice.Mr. C. J. Johnson (a was unable to be present, and in consequence many member of the committee) will instruct, and it duties, such as interviewing prospective members, is hoped that a good number will take advantage of which usually fall to the Secretary, devolved on these classes. Mr. Holton.Having received from a correspondent, At the close of the business a lecture was given Mr. Vincent, in India, a very interesting booklet,by the President, his subject being " How to' Make containingtheresultsofhisresearcheson a Single Valve Receiver." atmospherics, Mr. Holton read these out to the The lecturer first enumerated and explained all audience. A veryinterestingdiscussionthenthe necessary gear, and by diagrams and practical resulted on the origin of these atmospheric dis-demonstration made it quite clear how a single turbances.Mr. Holton explained the nature ofvalve receiver could be made and work efficiently lightning, as far as is understood, and showed howat a moderate cost. a lightning arrester works.Mr. Wordham also The lecture was, most interesting and profitable contributed to the discussion, and explained how to those members who are constructing their own he had endeavoured, with considerable success, to sets.At the termination of the lecture an interest- screen his aerial from interference from high tension ing discussion followed, after which the usual vote overhead wires. of thanks was accorded the lecturer, which was During the evening four new members weresuitably acknowledged. declared elected. The Malta Radio Society. Particulars of the club may be had on application Hon. Secretary, Mr. Paolo Bonnici, Workers' to the Hon. Secretary. Union Headquarters,S.Santa Lucia,Valetta, Wakefield and District WirelessSociety.* Malta. Hon. Secretary, Mr. Ed. Swale,11, Thornes A wireless society has been formed under the Road, Wakefield. abovename. Thecommitteeconsistsof :- A meeting of the above was held at 8p.m. onPresident, Senator Zammit-Hammet ;Vice -Presi- July 21st, at the Y.M.C.A., Grove Road.Mr. H. A. dent, Mr. E.Tonna-Barthet,F.R.Met.Soc., T. Burbury (President) was in the chair.AboutM.B.S.E. ;Hon. Secretary, Mr. P. Bonnici ;Hon. 40 members were present. Treasurer, Mr. E. Xerri ;General Member, Mr. R. The minutes were read, after which Mr. Burbury,, Galea, M.B.S.E., Stud.I.E.E. jnr., ably dealt with " The Formation of a Valve The present number of members is 22, but this Receiver," in a clear and concise manner, with figure is steadily increasing. blackboard illustrations. Paddington Wireless and Scientific Society. Questions were then put and answered, on Hon. Secretary, Mr. L. Bland Flagg, 61, Burling- different difficulties that had attended members'ton Road, Bayswater. sets, the answers to queries being both interesting The above Society held their first field day on and edifying. Sunday, July 16th, at Stanmore, Herts, and, taking A hearty vote of thanks was expressed to Messrs.into account the inclement weather, a very enjoyable Burbury for their joint kindness in making the day was spent. meeting such a success. During the day the members were able to hear The Hon. Secretary will be happy to receivethrough the medium of a nine -valve H.F. amplifier, names of prospective members. to which was connected another amplifier (three - South Shields Y.M.C.A. Amateur Wirelessvalve L.F.) and a loud speaker, some excellent Society. signals and music, which were thoroughly enjoyed Hon. Secretary, Mr. J. Teasdale, 38, Readheadby a large and appreciative audience. Avenue, Westoe, South Shields. The Committee tender their thanks to the follow- The above Club has now been formed, and aing gentlemen for the loan of apparatus :Dr. single -valve receiver has been installed. Eccles, F.R.S., of Finsbury College, who kindly Intending members should communicate with thelent the nine -valve amplifier, and Mr. L. McMichall, Secretary or attend any of the meetings, which areM.Inst.R.E., of Kilburn, for the loan of the L.F. held every Friday, at 8 p.m. in the Y.M.C.A. amplifier. Buildings, Fowler Street, South Shields. To Capt. Palmer, of the Stanmore Brewery, Port Talbot Wireless Club. Stanmore, the members are very grateful for the Mr. T. E. Nicholas, 22, Beverley Street, Portuse of the park known as " The Grove," Stanmore, Talbot, Glamorganshire, would be glad to receivewhere the apparatus was installed, and which was communications from those in his district who areprotected from the elements by a spacious pavilion. desirous that a society or club shall be formed. A further field day is being arranged for August Amateurs particularlyarerequestedtowrite20th,of which an announcement will appear direct to Mr. Nicholas. in Calendar of Current Events. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 599 The Leicestershire Radio and Scientific and lecture on H.F. currents, Tesla coils, and Society. Wimshurst machines. Hon. Secretary, Mr. J. R. Crawley, 269, Mere Those desirous of joining should write to the Road, Leicester. Hon. Secretary or apply personally at Ill, Chats- The monthly meeting of the above Society wasworth Road, Clapton, Thursdays only. held on Monday, July 17th,at Headquarters, York Wireless Club. VaughanCollege.ThePresident,Mr. C. T. In connection with the formation of a Society Atkinson, was in the chair.The usual business in the York district a meeting has been arranged was transacted,togetherwithcertainspecial for August 16th, at 8 p.m., at the Grand Picture matters of great interest to all.Two new members House Cafe, Clarence Street, York, to discuss the were elected.The President then called upon organisation. Mr. J. W. Pallett to read his paper on " Continuous Mr. White, Grand Buildings, Clarence Street, Wave Transmitters."With the aid of diagrams,York, will be glad to give any information to Mr. Pallett showed a number of circuits as used interested persons, and to receive any suggestions in practical C.W. work and concluded with a selec- which may be offered. tion of slides kindly lent by the Marconi Co.,The Lowestoft and District Wireless Society. depicting various types of actual gear, including Hon. Secretary, Mr. L. W. Burcham, " Gouzea- the well-known 2L0. court," Chestnut Avenue, Oulton Broad. The paper was given in the characteristic style The above Society has not been by any means of its author and at the conclusion a hearty voteinactive.The lecturesthat have beengiven of thanks was given to Mr. Pallett, proposed byinclude " Earth Currents and their Detection," the the President, and seconded by Mr. H. E. Dyson.lecturer dealing with his work in France in a very All communications should he addressed to theinteresting and at times amusing way.Another Hon. Secretary. lecture dealing with the work in France was " Sound Ranging."This lecture, although not The Hornsey and District Wireless and Modeldealing with wireless, nevertheless proved very Engineering Society. interesting and showed how British science played Hon. Secretary, Mr. H. Davey, 134, Inderwicka great part in winning the war.Another inter- Road, Hornsey, N.S. esting evening was also spent on a discussion on A meeting of the above Society was held onshort wave reception and the efficiency of the July 18th, 1922, at 29, Felix Avenue, Weston Park, Reinartz tuner. Crouch End. It is with much regret that the Committee have The first demonstration ofthe club set wasto announce that the proposed exhibitionfor given. A good selection of Morse messages wereAugust 3rd and 4th has had to be postponed heard and taken down by advanced members,indefinitely owing tothe unsettledconditions also all members enjoyed the music, etc., from prevailing in the manufacturing wireless line. 2 MT and 2 FQ. The set is of the progressive The membership of the Society has increased type, mounted so as to be convenient for fixing toconsiderably in the last month or so but there wall or to stand on a table.The set at presentis still room for more. consists of a rectifying panel and single note Fulham and Putney Radio Society. magnifier, with positions for adding high and low Hon. Secretary, Mr. J. W. Dewhurst, 52, North frequency amplifiers.All connections are made End Road, West Kensington, W.14. in such a fashion and with different coloured The above Society has been recently formed insulated wire, that the circuits can be easilyand held a meeting at their temporary headquarters traced. on Wednesday, July 19th.Considerable business Meetings of this Society are held on Tuesdayswas done regarding starting the Society on a and Fridays, at 7.30 p.m.New members areproper basis, the officers were elected, the subscrip- cordially invited.A series of lectures for beginners tion fixed, and the meetings arranged for every has just been started. Thursday evening at 7.30 p.m.Also it has been RadioSociety. proposed to start a technical library and workshop Hackney andDistrict for the use of the members.There is an aerial Hon. Secretary, Mr. E. R. Walker, 48, Dagmar fittedtotheSociety'sheadquarters andthe Road, South Hackney, E.9. founder, Mr. Houston, has promised a valve panel A meeting of the above Society took place atand other apparatus.The standard will not be 111, Chatsworth Road, Clapton, at 8 p.m. on too high for the beginner and yet a good selection July 20th.A large number of members were of experienced amateurs have joined as members present.Nine new members were enrolled duringand the Committee willcaterforboth. An the evening.Mr. D. R. Ison opened the meetingelaborate programme is being prepared for the with Morse instruction.He then proceeded tocoming season and prospective members of both lecture on the " Three Electrode Valve " andsex are invited to write to the Hon. Secretary showed how the filament, on becoming incandescent,for particulars. discharged electrons, and how these were controlled by the grid.The subject was capably handled The Wireless Society of East Dorsetshire. and made clear even to the beginner. Hon. Secretary, Mr. E. T. Chapman, I.R.E., Numerous questions were asked and an anlinated " Abbotsford," Serpentine Road, Poole. discussion followed, showing how keenly enthusi- On Tuesday, August 15th, at Branksome Liberal astic were the members.Later on a lengthyClub, Salisbury Road, Upper Parkstone, a General discussion on accumulators took place. Meeting is to be held, and new members will be On July 27th, Mr. Valins gave a demonstration enrolled. 600 THE WIRELESS WORLD AND RADIO REVIEW AufausT 5, 1922 SheffieldandDistrictWirelessSociety.* candles.Then a weird descent was made to the Hon. Secretary, Mr. L. H. Crowther, A.M.I.E.E., " Lords dining room," a cavern 300 ft. below the 156, Meadow Head, Norton Woodseats, Shef- surface. A short single wire aerial was erected field. across the cavern 10 ft. from the floor and connected In accordance with a pre -arranged programme, to a low power transmitting and three -valve low on Sunday, July 16th, 20 members, includingfrequency receiving set. two ladies, of the society journeyed to Castleton The technical committee were quickly engrossed for the purpose of carrying out experiments within the operation of getting into communication a portable apparatus in the famous Blue Johnwith Mr. Jakeman at his house in Hope, three

A Birmingham Wireless Concert. A novel feature of the Midland Musical Festival held recently at Bournville, Birmingham, was a wireless exhibition and telephonic concert arranged for the entertainment of visitors.The instruments were operated by students of the Stirchley Continuation School, under the able supervision of Mr. A. E. Vick, the wireless instructor of the School. Special music was transmitted to the Festival by prominent Birmingham amateurs, Messrs. Baynton, Whitfield, Rogers, Beresford and Scammell. The Stirchley School is one ofthe few of its kind to hold a transmitting licence.The wireless class is held on Friday evenings.The students hope to arrange shortly a similar public exhibition and concert at the School. mines ofDerbyshire.Although the ascent ofmiles away.Success was soon attained, and tele- Mam Tor Road and crossing to the entrance to thegraphic messages freely exchanged. mine was made in heavy rain and high wind, Those who had the unique experience of listening everyone cheerfully accepted the adverse conditions, to messages to the accompaniment of the ceaseless no doubt thrilled by anticipation of the most inter-noise of unseen underground rivers will not soon esting experiments about to be carried out.Each forget it. member willingly carried his share of the gear and The results obtained fully justify further and other necessary stores, and on arrival at the entranceearly experiments in working mines which itis to the mine was provided with one or more lightedhoped will be attempted at an early date. AUGUST 5, 1922 THE WIRELESS WORLDAND RADIO REVIEW 601 Burnley Y.M.C.A. Wireless Society. The Anerley Wireless Society. We are informed by Mr. Arthur L. Critchard, The fourth general meeting was held at the General Secretary of the Y.M.C.A., 11, St. James'SOciety's headquarters, 179, Maple Road, Penge, Row, Burnley, that a society has been formedon Wednesday, July 5th. with the above title. The business of the meeting included the election Wireless Society of Hoylake, West Kirbyof officers, and Mr. Bailey and Mr. Ford were re- and District. elected Secretary and Treasurer respectively. Mr. T. C. Welding, 6, Marine Parade, Hoylake, The Society will be glad to welcome new members, Cheshire, has intimated his willingness to convenewho can obtain any information, etc., from Mr. a meeting with a view to the formation of a society in his district.He will be glad to hear fromG. D. Ford, 63, King's Hall Road, Beckenham. anyone who is likely to become a member.Com- StocktonandDistrict Amateur Wireless munications should be sent direct to the address Society. given above. Hon. Secretary, Mr. W. F. Wood, 4, Birkley Coventry Wireless Society. Square, Norton -on -Tees. Mr. H. H. Thompson (2 LY and 2 VX), 44, This Society held its usual monthly meeting in Northumberland Road, Coventry,isforming athe concert hallofthe Malleable Workmen's society, and would be glad to correspond withInstitute, Stockton, on Thursday, July 13th. amateurs in his district who would like to become The Secretary read the minutes of the previous members.Those interested should write directmeeting and discussion arose as to the best methods to Mr. Thompson. of using the time at disposal each evening, so as to Hereford and District Radio and Scientificenable each section to receive the maximum benefit. Society. It was announced that the membership had gone Hon. Secretary, Mr. G. C. Davies, Y.M.C.A., up by leaps and bounds, and a definite time -table Hereford. was decided upon, which would in a short time An inaugural meeting was held at the Y.M.C.A.,cover all grades.Morse instruction will be given Hereford, on July 31st, when the President, Mr. each evening and at times that will suit any member. J. C. Mackay, gave his opening address. The business meeting closed at nine o'clock, after It is hoped that considerable interest will bewhich the Secretary gave a short paper entitled shown by the amateurs and other wireless people" The Transmission of Electrical Energy." in the district, who will be warmly welcomed at The next monthly meeting will be held on any of the meetings.Particulars of the SocietyThursday, August 10th, and the name of the may be obtained from the Hon. Secretary. lecturer and his subject will be duly announced.

The Wireless Telegraphy and Signalling Bill. The following is the text of the Bill which amends theWireless Telegraphy Act,1904, and makes further provision with respect to the regulation of Wireless Telegraphy and Visual and Sound Signalling. BE it enacted by the King's most Excellent Majesty, by and with the advice and consent of the Lords Spiritual and Temporal, and Commons, in this present Parliament assembled, and by the authority of the same, as follows :- 1.-The Wireless Telegraphy Act, 1904 (hereinafter referred to as the principal Act), shall become a permanent Act, and any provision in any Act in force at the time of the passing of this Act which limits the period for which the principal Act is to remain in force shall cease to have effect. 2.(1) The Postmaster -General may, notwithstanding anything in the principal Act, make regulations- (a) as to the terms, conditions, and restrictions on or subject to which licences or any class of licence under the principal Act are to be granted, renewed, suspended, or withdrawn ;and (b) requiring any operators or other persons engaged in the working of wireless telegraphy to be provided with certificates, and making provision as to the manner and conditions of the issue and renewal of any such certificate, including the examinations and tests to be undergone, and the form, custody, production, cancellation, suspension, endorsement and surrender of any such certificate, whether issued before or after the passing of this Act ;and (c)for preventing interference with the working of wireless telegraphy by the generation or use of etheric waves for any purpose other than the transmission or reception of wireless messages ; and (d) for giving effect to, and securing compliance with, the provisions of any international convention signed on behalf of His Majesty, and any regulations made thereunder, so far as the same relate to wireless telegraphy ;and (e)prescribing, subject to the consent of the Treasury, the fees to be paid in respect of the grant or renewal of any licence or certificate. (2) Regulations under this section may provide that any person acting in contravention of or failing to comply with the regulations or any of them, or the terms, conditions and restrictions or any of them, on or subject to which any such licence or certificate as aforesaid has been granted, shall be liable, on summary conviction, to imprisonment for a term not exceeding three months, or to a fine not exceeding fifty pounds, and, in the case of a continuing offence, a further fine not exceeding five pounds for each day during which the offence continues. c2 T.

602 THE WIRELESS WORLD, AND RADIO REVIEW AIIGIUST 5, 1922 (3) Subsection (6) of section one of the principal Act is hereby repealed. 3.-Subsection (1) of section two of the principal Act, which makes special provisions as to licences for experimental purposes, shall cease to have effect, and licences for those purposes shall be subject to the general provisions as to licences for wireless telegraphy contained in section one of the principal Act. 4.-(1) A person shall not- (a) send or attempt to send by wireless telegraphy a message or communication of an indecent, obscene, or offensive character ;or (b) send or attempt to send by wireless telegraphy a signal of distress of a false or misleading character, or a false or misleading message as to a vessel in distress ;or (e) improperly divulge the purport of any message sent or proposed to be sent by wireless telegraphy. (2) If any person acts in contravention of this section he shall be liable on summary conviction to a fine not exceeding ten pounds, or on conviction on indictment to imprisonment for a term not exceeding twelve months. 5.-The penalty to which a person is liable on summary conviction for an offence under subsection (3) of section one of the principal Act shall be imprisonment for a term not exceeding three months, or a fine not exceeding fifty pounds, and, in the case of a continuing offence, a further fine not exceeding five pounds for each day during which the offence continues. 6.-Any provisions of the principal Act or this Act which are applicable to ships, shall apply also to aircraft, with the necessary modifications, and in particular with the following modifications :- (1) For the reference to British ships in the territorial waters abutting on the coast of the British Islands there shall be substituted a reference to British aircraft in or over the British Islands and in or over the territorial waters abutting on the coast thereof ;and (2) For the reference to British ships whilst on the high seas there shall be substituted a reference to British aircraft outside the British Islands and the territorial waters abutting on the coast thereof ;and (3) For the reference to a foreign ship in territorial waters there shall be substituted a reference to a foreign aircraft whilst in or over the British Islands or the territorial waters abutting on the coast thereof ;and (4) Subsection (5) of section one of the principal Act as amended by this Act shall not apply. 7.-(1) The provisions of the principal Act as amended by this Act shall apply to any visual or sound signalling station used or intended to be used for the purpose of communication from the British Islands with ships at sea as they apply to wireless telegraphy stations. (2) For the purposes of this section " visual or sound signalling station " includes any permanent or fixed apparatus for the purpose of visual or sound signalling, and the provisions of the principal Act and this Act shall apply to the maintenance of any visual or sound signalling station in existence at the time of the passing of this Act as they apply to the establishment of a visual or sound signalling station. Provided that nothing in the principal Act or this Act shall apply to visual or sound signalling stations or apparatus on ships or aricraft, or to any signal station established by Lloyd's under the powers conferred by the Lloyd's Signalling Stations Act, 1888, or to signalling stations and lighthouses under the control of the Board of Trade or of any General or Local Lighthouse Authority. 8.-If at any time in the opinion of a Secretary of State an emergency has arisen in which it is expedient for the public service that His Majesty's Government should have control over the transmission and reception of messages by wireless telegraphy or visual or sound signalling, and notice to that effect is published in the Gazette, it shall be lawful for the Postmaster -General during the continuance of the emergency to make such rules as appear necessary with respect to the possession, sale, purchase, construction, and use of apparatus for wireless telegraphy or visual or sound signalling, or component parts of such apparatus, and to impose penalties and forfeitures in respect of any breach of the rules, and make such further provision as appears necessary for the enforcement of the rules : Provided that- (a) rules under this section shall not provide for the imposition of a term of imprisonment exceeding six months, or a fine exceeding one hundred pounds, or, in the case of a oontinuing offence, ten pounds for each day during which the offence continues ;and (b) any rules made under this section shall be laid as soon as may be before both Houses of Parliament. 9.-The principal Act as amended by this Act shall not extend to British ships or British aircraft registered outside the British Islands, except that any such ships or aircraft shall, whilst in or over the British Islands or the territorial waters abutting on the coast thereof, be subject to the provisions of the principal Act as so amended with respect to foreign ships and aircraft in like circumstances. Provided that if after the establishment of the Irish Free State the legislature thereof makes other provision with respect to ships and aircraft registered in the Irish Free State and with respect to ships and aircraft when in or over the Irish Free State, or the territorial waters abutting on the coast thereof, the foregoing provisions of this section shall have effect as if the expression " British Islands " did not include the Irish Free State, and the principal Act as amended by this Act shall cease to apply to foreign ships and aircraft when in or over the Irish Free State or the territorial waters abutting on the coast thereof. 10.-(1) This Act may be cited as the Wireless Telegraphy and Signalling Act, 1922, and shall be construed as one with the principal Act, and the principal Act and this Act may be cited together as the Wireless Telegraphy and Signalling Acts, 1904 and 1922. (2) Any reference in this Act to the principal Act or any provision thereof shall, unless the contrary intention appears, be construed as a reference to that Act or provision as amended by this Act. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 603 Questions and Answers NOTE.-This section of the magazine is placed at the disposal of all readers who wish to receive advice and information on matters pertaining to both the technical and non -technical sides of wireless work.Readers should comply with the following rules :-(1) Each question should be numbered and written on a separate sheet on one side of the paper, and addressed " Questions and Answers," Editor, The Wireless World and Radio Review, 12/13, Henrietta Street, London, W .C.2.Queries should be clear and concise.(2) Before sending in their questions readers are advised to search recent numbers to see whether the same queries have not been dealt with before.(3) Each communication sent in to be accompanied by the " Questions and Answers " coupon to be found in the advertisement columns of the issue current at the time of forwarding the questions.(4) The name and address of the querist, which is for reference and not for publication, to appear at the top of every sheet or sheets, and unless typewritten, this should be in block capitals. Queries will be answered under the initials and town of the correspondent, or, if so desired, under a " nom de plume."(5) In view of the fact that a large proportion of the circuits and apparatus described in these answers are covered by patents, readers are advised, before making use of them, to satisfy themselves that they would not be infringing patents.(6) Where a reply through the post is required every question sent in must be accompanied by a postal order for the amount of 18., or 3s. 6d. for a maximum of four questions.(7) Four questions is the maximum which may be sent in at one time. " EARTH " (London)asks (1) Forthe 1 Kan. C capacities of condensers C.1, C.2 and C.3, and the mfds. =900,000 4rd maximum capacity of the A.T.C. in a certain set K -= specific inductive capacity ofdi -electric, described in the June issue. (2) Maximum and say 8 for mica and 1 for air. minimum wavelength of the same set. - (1) Insufficient dataisgiven for calculation, a = area in sq. ems. of overlap of foils. but suitable values would be - A.T.C.,0.0005 n = number of sheets of dielectric. mfd. ;C.1, 0.0002 mfd. ;C.2, 0.002 mfd. ;and 71. = 3.14. C.3, 0.0003 mfd.(2) Suitable for all wavelengths d = thickness of dielectric in ems. up to say, 10,000 metres with appropriate coils, We add calculations for your 0.001 mfd. condenser butinsensitivebelow 1,000 unless the A.T.C.as an example :- is used in series. 0.001 = 1/1,000.Mica = 0.002" = 1/200 ems. " E.H.C."(ArdinglyCollege)enclosesa Assume an overlap of 3 sq. ems., which is a con- diagram of set and asks(1) For windings of basket venient figure, then formula gives :- coils if suitable. (2) Capacities of C.1 and C.3.- (3)Will a home-made telephone transformerbe 1 1 8 x 3 xn efficient.(4)Would flash -lamp batteriesdo for 1,000 900,000 12.4 x 1 B.1 and B.2. Thesetshownisofvery poor type.The 48n 1,116 crystalisuselessinan L.F. circuit as shown. 1- n - = 23. The grid circuit of the valve is untuned, and the 9 x 12.4 48 reaction coil couples into the aerial circuit (see 6 4 " (Southend-on-Sea) asks (1) For Fig. 5, page 124, April 22nd issue), but with ana circuit for use withcertain apparatus. (2) aerial circuit loose coupling into the lower end of Details of plates for condenser. the closed circuit inductance.(1) Basket coils (1) See diagram page465, Fig.1,issuefor may be used, their size depending on the wavelength July 8th. Filament resistance 5 ohms., other required, which you do not state.(2) A closeddimensions as usually given.(2) Assuming 1/8" circuit condenser 0.0005 mfds., grid condenser,is the distance between the neighbouring fixed 0.0002 mfd., anode circuit condenser, 0.0005 mfd. plates, 16 fixed and 15 moving will be sufficient. Series A.T.C.if used, 0.001 mfd.(3) Yes,if, " B.C." (Seven Kings) sends a sketch of a of sound design and carefully made. (4) Yes, circuit and asks if itwillreceivetheLondon but they must be switched off when not in use. broadcasting. " J.A.B." (Bayswater) encloses diagram of Except for the leads shown short circuiting set and asks (1) If the circuit sketched is suitable the telephones, which is probably a clerical error, for telephony. (2)Ifitwouldworkwitha the circuit is correct and should give the desired frame aerial.(3) Particulars of a suitableaerial. results, but a series A.T.C. of about 0.0002 mfds. (1) O.K. if a leak is supplied for the second would be an improvement. valve.(2) Yes, but it would not be very sensitive. 40turns " E.W." (Hornsea) asks (1) If it is necessary (3) Frame 4 ft.square, wound with to have a reaction coil with a certain tuner. (2) of No. 18, spaced 1" and tapped at 3, 6 and 15 reactioncoil. turns. Particulars of how toconnectthe " RADIO 3 UC " (Nottingham) asks (1) If (3) Diagram of a one -valve set for use with a tuner. values given for four condensers are suitable, and (1) A reaction coil is not necessary, but skilfully what should be the numberoffoils,withsize, used would considerably increase the range of the in each case, using 0.002 mica.(2) The maximum set.Unskilfully used it might lead to serious re - capacity of a certain variable condenser, and dimen- radiation. (2) The coils might be 3"x 5" of sions and number of foils for a fixed condenser ofNo. 32, connected in the anode circuit and coupling the same capacity. into the end of the secondary of the loose coupler (1) and (2) We think it would be far more profit- remote from the primary.(3) See Fig. 1, p. 465, able to you to work these out for yourself, andissue for July 8th, for a simplified theoretical will therefore quote the formula. diagram of the circuit. 604 THE WIRELESS WORLDAND RADIO REVIEW AtiatisT 5, 1922 " L.R.C." (Cheshire) encloses a diagram of but very useful results, including PCGG and FL, his set and asks (1) If a variable H. F. transformercould be obtained with a set costing about £25. is more efficient than a plug-in.(2) Could he get (3) Yes, provided you have some aptitude for work 2MT telephony.(3) Is it safe to use a six -voltof this nature.(4) Many circuits are possible, accumulator on " Ora " valves.(4) Any suggested but we recommend that you look through the improvements to his circuit to receive telephony. diagrams given in these columns and pick out a (1) No, we prefer the plug-in type as a rule. three -valveor two -valve and crystalset with (2) For some reason, at present unknown, Cheshiredimensions for the parts quoted. appears a bad district for 2MT. Except for this, " J.G.N." (Tonbridge)asks(1) Why no you should get results.(3) Only with the use ofsignals are received above 600 metres when the set some series resistance.(4) Set is O.K. as it standsreceives 2MT and 600 metre spark signals quite except that a condenser is required across the well. (2) Approximate maximum and minimum primary of the L.F. inter -valve transformer. wavelengths using two methods.(3) If the method " G.W.C." (New Southgate) asks two questionsshown is a satisfactory way of adding a L.F. valve about engraving ebonite, and (3) For an inexpensiveto existing set.(4) If an " Ora " valve will work book on the construction of sets.(4) Times andin conjunction with R " valves, having 45 volts wavelength of FL Sunday telephony. on the plate and using the " Ora " as L.F. (1) and (2) This is generally done on engraving (1) Set should be O.K. but there is little to be machines, which are very expensive machine tools. heard above 600 metres until you get up to about You might be able to devise a substitute by means 2,600 metres, except air stations, which you should of a flexibly driven drill chuck guided by a suitable beabletoget.(2) (a) About1,500metres. pantograph.Fillingiseffected with a special (b) Approximately the same. PCGG should prob- white wax, resembling in composition sealing wax. ably be received with series condenser and about (3) " Radio Experimenters' Handbook," by P. R.half the coil, but difficult to predict exactly.(3) Coursey (3s.6d.) ;" How to Make CommercialYes, quite O.K.(4) Yes. Type Radio Apparatus," by M. B. Sleeper, obtain- " J.McV " (Belfast) has a two -valve resistance able from Wireless Press. capacity coupled set with reaction and asks (1) If " S.F.H." (Barnes) asks(1) Whatisthe a four -valve L.F. amplifier is added could he receive highest wavelength that can be received by a crystal Dutch Concerts.(2) How to make theset more set.(2) How many loose coupled tuners will besuitable for receiving short wavelengths.(3) If a reqiured from zerotothis wavelength.(3) Whatrange of 300/30,000 metres is possible in view of gauge of enamelled wire is needed from the primarythe coupling employed. and secondary of the coils.(4) Could more than (1) Doubtful. We should prefer more H.F., one slider be used on the primary. but in any case do not think your prospects of (1) Any wavelength could be received if suitablegood results very great.(2) Suitable transformer transmitting sets were in use, but at present there coupling for resistance capacity.(3) Yes. is no spark transmission over about 3,500 metres. " A.S." (Stockport) encloses diagram of his (2) It is impossible to make a tuner to tune down tosingle valve set and asks (1) If a two -valve L. F. zerowavelength. 100metresisa commonamplifier added to a panel would be the best three- minimum. We suggest the use of the coils youvalve combination.(2) If so, how to add amplifier mention wound with No. 22 and No. 26, and anotherwith leastdisturbance of panel connection.S.(3) pair 6" x 4" wound with No. 22, and 5" x 3"How to make a L.F. transformer for same.(4) If wound with No. 26 for short wave work.(3) No. 32 S.S.C. wire would do for making the above. Primaries with sliders, secondaries with 12 taps (1) Possible, but it would be better to add one each, the distance between the taps being approxi- valve as H.F. amplifier and one as L.F., diagram mately proportional to the number of turns of wirebecoming similar to Fig.3, page 340, issue for in the circuit at each tap.(4) More than one isJune10th.(2) Foryoursuggestionconnect unnecessary. filaments in parallel on the same supply, put " F.H." (Romford) asks (1) If H.F. plug-in transformer in place of telephones, and bring anode transformersmustbemounted onebonite. (2) circuit of each valve back to the positive of the Whether 0.001 mfd. A.T.C. is better than 0.0015 forH.T. battery.(3) Core j" x 4" of iron wires, general work. winding 1 oz. and 3 oz. of No. 44.(4) No. (1) Eboniteisabout the best material, but " P.P." (Liverpool) asks (1) If the ends of presspahn, paxoline, micanite, bakelite and various an inductance coil should be connected directly to the similar insulating materials may be used if desired.first valve of a circuit.(2) What relation should the (2) Somewhat preferable, but very little in it.. inductance of the secondary bear to the inductance of aerial circuit.(3) How is the value of the reaction " C.W." (Wimbledon Park) asks for advice related to the number of turns in the primary or second- in purchasing a receiving set on which hecan hear ary coils. the English broadcasting stations, Eiffel Tower and (1) Coupling through a secondary inductance the Hague Concerts, also (I) Minimum length foris better as it gives better selectivity. aerial.(2) Approximatecostofset. (3) If he (2) The would save money by assembling the set himself. inductance of a secondary should be such as to (4) What apparatus to obtain. tune to any required wavelength with a parallel condenser of capacity not greater than 0.0005 mfds. (1) Aerial suggested would do quite well if of (3) There is no fixed relation, the value depending sufficient height above the ground or buildings-on constants of the valve, etc.For most circuits say not less than 20'.(2) If you wish to hear alla value somewhat smaller than that of the coil the English broadcasting stationssatisfactorily with which it couples is desirable except on very the price would probably come out at nearly £100, small wavelengths, when rather more is required AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW sill eimaxam5 IN i,., IIVVllllll .1Rtitii111101111100111111 gkl''111.44"nrmrr"."-77,,7.7:61-' GREAT REDUCTIONS i rN. PRICES 074' MULLARD ACCESSORIES4-,

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SPECIAL ANNOUNCEMENT ! Our name is so well known as MANUFACTURERS of BRASS TERMINALS, STUDS, SCREWS, NUTS, WASHERS and in fact every description of TURNED AND PRESSED PARTS, that we are constantly receiving enquiries for small quantities from enthusiasts building up their own sets, and we therefore take this opportunity of stating that we do NOT supply RETAIL. Our trade is with MANUFACTURERS, SUPPLIERS AND USERS OF FAIR QUANTITIES ONLY. We do NOT supply small lots to amateurs. TRADE NOTE! Wherever possible in sending us your enquiries, kindly submit samples to quote to, stating quantities required and thus ensure rock bottom prices. The larger the quantity the keener the price ! SPEARS and COMPANY CAPSTAN REPETITION WORKS, PARK ROAD, HOCKLEY, BIRMINGHAM Telephone : 3265 Central. Telegrams" Firettes, Birmingham." AUGUST 5, 1922 THE WIRELESS WORLDAND RADIO REVIEW 605 " S.C." (Beckenham) is constructing a three - " W.C.P." (Watford) asks for help with his valve receiver, and asks (1) Dimensions of coils and set which gives very distorted speech. number of tappings for an aerial inductance tuning The arrangement of the set is quite correct and from 200 to 3,000 metres(2) Dimensions of reaction we are not clear why you are getting distortion. coil to rotate in the aerial primary. (3)Dimensions It may be due to one or two causes, namely poor of aerial inductance for tuning from 3,000 to 30,000 design of the L.F. intervalve transformer or your metres, and (4) A reaction coil, 3,000 to30,000 allowing the set to oscillate.You might try a metres. grid potentiometer to the first valve, and weaker Size of the inductance depends upon the dimen-reactance coupling. sions and design of your aerial.If of the two -wire " C.C.S." (Sheffield)asks (1) For windings type, and of the maximum dimensions laid downof a reaction coil suitable for use with a loose coupler. by the P.M.G., you should use a coil 6" in diameter, (2) For capacities of condensers.(3) Wavelength with 5" of winding of No. 28 D.C.C. wire.The range of his set.(4) Ratio between A.T.I. and winding should be tapped out on to a switch havingreaction when honeycomb coils are used. 15 to 20 studs, the long wave tappings stepping off (1) Coil might be 5i" x 4" of No.26. (2) further distances along the coil than those for short0.001 for the aerial circuit, 0.0005 for the closed wave.Such a coil will not efficiently tune to such circuit.(3) About3,500metres.(4) Thereis low wavelengths as 200 metres, and you would beno definite best ratio but, except for very short well advised to construct a special inductance forwavelengths, the reaction coil can generally be short wave reception.This may consist of 1" ofsomewhat smaller than the A.T.I. winding of No. 24 D.C.C. on a 4" former. (2) Former " DYNAMO " (Clapham Junction) asks for 3i" in diameter, having 1i" of winding of No. 34advice on the erection of an aerial. S.S.C. with about 10 tappings at increasing distances along the turns.For short wave work a sliding Your situation appears somewhat unfavourable coil should be used, closely fitting inside the aerialand you do not give us much idea as to the coil, and being of approximately equivalent in- possibilities.Fairly useful results might be obtained ductance.(3) These windings must be found byby fixing a mast in the top of the tree and running experiment, and you would do well to build upa lead from the receiving room up towards the eaves inductances of the type shown on page 328 of Juneabove it, but not too close to the wall, and from 10th issue, assembling a large number in series with thence to the mast in the tree.A better alternative, insulated paper between, and making sure that they if possible, would be to run an aerial up to the are connected up so that there is no reversal in thesame point near the eaves and thence to the house direction of winding.They should be held securely 60' away. We are afraid your range with a single in position, as any fluctuation in the distance valve set would be somewhat limited. between the coils materially alters the inductance " H.C.S." (Kirkby Stephen) asks(1) If a value.(4)Thereactioninductance may betransformer sketched will do for amplification of similarly constructed, and for the purpose of pro-telephony on 300 to 600 metres.(2) If a H.F. viding coupling between the two inductances, one transformersketched wouldbemoreefficientif coil of each should be brought out and so arranged two sections were used as primary with switch for that their relative positions may be varied. the other six.(3) Where to obtain particulars for the construction of H.F. and L.F. intervalve trans- " S.F.H." (Barnes) asks (1) What is the highest formers in order to make them in quantities. wavelength.(2) How many loose coupled tuners (1) If properly made this should give useful with primary 6" x 12" will be required to tune to results.(2) The suggested scheme would probably thehighest wavelength. (3)What gauge of wirebe satisfactory, but experimental test would be is required for the primary, and whether more than necessary to determine the best wavelength for one is required.(4) Gauge of wire for secondary each one of the sections.(3) These columns are and number of tappings. intended for the assistance of amateurs in difficulties (1) Wavelengths of 23,000 metres are at presentand not for the guidance of persons desiring to used, and the tendency may be to increase this. undertake quantity production-presumably for (2), (3) and (4) We presume you mean to connect commercial purposes. your tuners in series with one another, which is " A.R.B." (New Barking) asks (1)For a not a very satisfactory arrangement.The amount diagram of three and seven -valve circuits with details of wire depends upon the size of the aerial, and of construction.(2) If a circuit with one valve as for one wave you are advised to make use ofH.F. amplifier, one as rectifier and one as L.F. specially wound coils of the basket, slab, honey- amplifier needs transformer coupler. comb, or other well-known type.When using (1) For a three -valve circuit see Fig. 2, page 304, a receiving circuit embodying reaction, resistanceissue for June 3rd.For six -valve circuit see Fig. 1, in the aerial circuit is, within certain limits, of page 368, issue for June 17th, to which an additional little consequence, as any jamming that may beH.F. or L.F. valve can be added if desired. We produced is compensated for by tightening thehave not space to give full design details for these reaction coupling.No. 28 D.C.C. is suitable forsets, but typical values for each component have aerial circuit, and No. 32 D.C.C. for reaction coil. been frequently quoted.Details of a valve set, were given in issues 16 to 22 of Vol. 8.(2) Trans- " G.D.G.T."(Oundle)askstwoquestions former coupling is probably the best for all-round about a four -valve circuit. purposes, but needs a series of transformers to cover We prefer two H.F., one detector and one L.F.a big range. A resistance capacity coupling is valve, which should give quite good results on agood for all wavelengths above 1,000 metres, but 6 -ft. frame aerial. very poor below this figure. 606 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 " E.A.A." (West Ham) gives particulars of (1) Diagram is correct except that the reaction his set, from which he gets no results, and asks why. coil should be on the valve side of the iron -cored The set appears fairly correct and should give winding, but should have a 0.001 mfd. condenser results.It would be better, however, to connectacross it.(2) Yes.Wind full with two coils of one end of the coil to earth and one side of the No. 44, the secondary having approximately twice condenser, and one slider to the aerial and theas many turns as the primary. other slider to the other side of the condenser. " H.W.K." (Peckham) asks(1) Gauge and Try reversing the polarity of the potentiometerinsulation of three samples of wire enclosed. (2) If battery.No. 30israther thin for the A.T.I. 130 ohm telephones could be used.(3) If he would Possibly the crystal is defective.(The resistance ofget results from a 30' aerial running parallel with carborundum is far too high for you to light thea tram and electric railway system. lamp through it.) (1) No. 1 = No. 37.No. 2 = No. 37.No. 3 " T.B.R." (Newcastle) asks questions about = No. 32.(2) It should be O.K.(3) You may Marconi high speed services. have rather troublesome induction effects. A certain amount of fairly high speed work is " A.F.R. " (Boscombe) has made up a Rein- done by the transatlantic stations, with speeds up hardt tuner, described in May 13th last, and wishes to 50 to 60 words per minute ;times irregular, to know if he can add a five -valve magnifier, a circuit depending on traffic requirements and receptiondiagram of which he submits, and comprising two conditions.TheLondon -Parismedium powerH.F. valves, one detector, and'two L. F. service is nearly all high speed, varying from 70 to 130 words per minute, according to traffic requirements.The service is at all hours of the day and night, but generally slack during the night.No call letters are used, but stations are in constant communication.The wavelengths used are 3,800 metres for the English station, and 2,300 for the French. " J.B.B." (Cambridge) asks (1) Particulars of a certain loose coupler.(2) Gauge of wire to be used.(3) Under what wavelength areresistance capacity coupled H.F. amplifiers inefficient. (1) and (2) Primary 6" x 4" of No. 22, tapped at 14", 24" and 4".Reaction 4" x 6" of No. 26, with tappings at 2" and 3".(3) About 1,000 metres. " K.W." (Sidcup) asks (1) The best type of coil to use to receive' wavelengthsfrom 100 to 25,000 metres.(2) Sizes of the coils and gauges of wires. (1) and (2) To cover such a range of wave- Fig. 1. lengths it would be best to use a series of honeycomb You cannot conveniently add your amplifier to coils, with the number of turns ranging from aboutthis receiver and work with common H.T. and L.T. 40 to1,500.These coilsare generally woundbatteries, unless you care to make use of a choke with about No. 26 or 28, and can be bought fromcoil at the point of distribution of the H.T.For various dealers. circuit diagram see Fig. 1. " EXPERIMENTER " (Folkestone) asks with " HOPEFUL " (Brixton) asks (1) If a diagram regard to a diagram for a three -valve amplifier oniscorrect. (2) If any additional condensers are page 340 of June 10thissue(1) Would not a necessary and their capacity.(3) If the set would potentiometer control for the third and fourth gridsreceive the Dutch concerts. be an advantage.(2) Would the use of a 0.002 mfd. (1) and (2) Correct, except that the grid potentio- condenser across the primary of a H.F. transformer meter shown to the first valve must be omitted from improve the set.(3) For short wavelengths, wouldthis set, and a condenser of say 0.001 mfd. should results be improved by using a loose coupled tuner'be in circuit across the primary of the first inter - with reaction. valve transformer.(3) Yes. (1) For first and second grids it would be an " CONSTANT READER " (West Kensing- improvement ;not necessary for the third.(2) ton) asks certain questions about H.F. transformers. Yes, but the value is rather high.(3) This would The method of winding you suggest is not very give greater selectivity on all wavelengths. good as it involves considerable risk of breakdown " K.H." (Delhi) encloses a diagram of his set between the coils.There is no formula for calculat- and asks (1) If the circuit is correct.(2) If furthering the wave range of such transformers, as this similar H.F. and L. F .amplifier units can bedepends on the self and mutual capacity of the coils attached.(3) If the grid potentiometer X on thewhich it is impossible to predict.The wavelengths H.F. amplifier is desirable.(4) Should the blocking of the transformers you mention might come out condenser Y on the rectifier be variable or fixed. about 500 metres, 800 and 1,200 metres, but it is (1) Quite good.(2) Yes.(3) Yes, unless con-quite possible that the values may vary very denser rectificationis employed.(4) Fixed willconsiderably from this. do.About 0.001 mfds. " ZETHERDOWN "(MillHill)asks(1) " C.H.W." (Capetown) asks (1) If a circuit What stations he could receive with a crystal receiver sketchediscorrect.(2) If he could use certainusing an aerial 40/45' high and 60' long, twin wire. transformer cores for intervalve transformers, with (2) The name of the Wireless Society covering the details of winding. Mill Hill district.(3) A list of the instruments AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW NV

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WE stock complete sets and all accessories required by theamateur at reasonable prices consistent with quality. We cansupply in quantity the following goods ofour own manufacture, immediatei delivery. Tuning coils, filament resistances, Iciw frequency transformers, telephones, valve legs, valve holders, condenser vanes, slab inductances, switcharms, Dionne scales, grid condensers and leaks, etc. Our works are fitted with latest type engraving machines, andwe can engrave ebonite panels to your requirements. Send for Illustrated List, post free 3d.

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Head Office : London Showrooms : Clifton Junction,219/220 Shaftesbury Av. Nr. Manchester. W.C.2 8 Volt 80 Amp. Hour Exide Battery. uaus5, 1922 THE WIRELESS WORLD AND RADIO REVIEW 607 necessary to construct a simple and efficient crystal " C.W.A." (Wandsworth Common) wishes to set. (4) DetailsofthestationnearHendon make use of alternating current supply at 50 periods Aerodrome. 205 volts for the purpose of supplying the high (1) Ships, broadcasting and other shore tele-tension current at 400 volts required by his small phony in London, air stations and stations such aspower telephonytransmitter, and asks(1)For Eiffel.(2) Wireless Society of Highgate, High-diagram of connections.(2)Size and typeof gateLiteraryandScientificInstitute,South transformer to be used.(3) Details of chokes and Grove, Highgate.(3) Aerial,earthconnection, condensers.(4) Details as to power consumption loosecoupler withslidertuningofprimary,for the purpose of working his transmitting valve on variable condenser,perikonorsimilarcrystal, 10 watts. pair of H.R. telephones.(4) If you mean the (1) See diagram Fig. 3. (2) The transformer Marconi Company's research station, we regret should be of the closed core type, the core of which that the only information we have is that publishedmay be made either of soft iron strip or wire. on page 219, May 20th issue. That part of the core which passes through the " AMATEUR " (Shepherd's Bush) asks four windings should have a cross sectional area of not questions about a set of which he gives a diagram.less than three square ems. and 2E' long.The (1) We do not understand your circuit, as you primary should be wound with No. 22 double cotton speak of a loose coupler and show a single coil. covered wire and consist of five layers.The second- Also, your data for coupler are very vague.The ary should be wound with No. 28 D.C.0 wire up

124B

ilia

Fig. 2 circuit might possibly tune up to 1,500 metres. to a diameter of 2".The secondary would best be (2) The circuit is fairly good as shown except that a wound in 11 flat sections. A separate choke coil parallel A.T. condenser should not be used on short should be made up and connected in series with the waves. (3) Londonbroadcastingand manyprimary winding for the purpose of still further amateurs in London district, and air stations nearreducing the current taken from the mains, and London.(4) Very few additional stations wouldalso for adjusting the power factor.(3) The two come into your range unless you also introducedchoke coils shown should be wound on iron wire reaction, although all stations would be increased cores, 6" long by E' in diameter, with No. 32 S.S.C. in strength. wire, up to a diameter of 1 A piece of thin " E.R.W." (E.9) asks for circuit diagram ofinsulating paper should be placed between each receiversuitable for thereception of short wave layer.The condensers should have the values telephony, and capable of operating a loud speaker.shown and be capable of withstanding 1,000 volts, We would advise you to use three H.F. amplifiersi.e., mica insulation of not less than 0.002" should and efficient rectifier, and three note magnifiers. be used for building them up.(4) You would find The only difficulty in making up such a set is the it very convenient to connect a milliammeter with design of the H.F. transformers.These must all a maximum reading of 25 in the negative lead. be identical in value, for should one have a slightlyIf your oscillation circuit is so connected that the different optimum wavelength, it will filter out H.T. plus is above earth potential, the accumulator signals on which the other two would be capablewhich heats the filaments must be well insulated. of giving good amplification.These transformersYou will be well advised to use special rectifying should be wound on 1" ebonite rod, the primariesvalves instead of the ordinary " R " type.Alter- and secondaries being wound in the same direction, natively connect two valves in parallel on either insulated from one another by a single layer ofside of the transformer. empire cloth, and consisting of 300 turns of No. 38 "A.E.F." (Fleetwood) asks (1) What languages S.S.C.The finishing ends should be taken to the the press and weather transmissions from Bucarest, grids and plates.For circuit, see Fig. 2. Budapesth, Prague, Sarajevo and Nikolaiev are in. 608 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 (2) Where it is possible to obtain the Berne inter- aerial tuning condenser in series with the inductance, national list of wireless station -9 and regulations.and you may find it convenient also to bridge the (3) Where to obtain a diagram of the Marconi reactioncoil witha small variable condenser, multiple tuner.(4) If it could be used with a valve having a maximum value of about 0.0004 mfds. for ship stations. The diagram referred to gives the amended circuit (1) French is usually employed.(2) Bureaudiagram, and in addition, shows how youmay International de T.S.F., Berne.(3) See diagrammake up additional amplification circuits. From your sketch it is difficult to say the best method for connecting in the H.F. transformer, as we are unacquainted with the direction of winding. If the windings are in the same direction, the inner ends of primary and secondary should be taken to grid and plate, and if in opposite directions, the two ends that come out between primary and secondary winding, should be the grid and plate.

0.001/ff 33 TURNS N928 MCC. Fig. 3. 3 -FORMER

Fig. 4, whichissimplified by the omission of MI1 the switching arrangements.(4) Not suitable °Z. 0-00035µ for use in this way, as it was designed for use with a magnetic detector, which has a low resistance. I I k C> C> We should recommend dismantling,andre- i$ arranging the parts to form a modern tuner. " E.A.D." (Wooler) has a three -valve which does 3 not give very satisfactory results.He describes the components, and wishes to know the probable cause 41P of his trouble. In the circuit you submit you have connected nw small condensers in series with the grids of all valves.This should not be done.The grid condenser and leak should only be connected to the last H.F. valve, that is the one which is to rectify. It is very important that a condenser having a value of about 0.001 mfds. should be connected across --till- ill the telephone receivers as a by-pass for H.F. current that is to pass to the reaction coil.The reaction Fig. 5. coil is incorrectly connected, and should be arranged as shown in the diagram given to " J.W.B." (Northfield). We would recommend you to procure " J.W.B." (Northfield) givesparticulars of a low frequency intervalve transformer, in orderhis tuning coils and asks(1) What wavelengths that the last valve may be connected as a note they will tune.(2) For a circuit diagram of three - valve receiver suitable for the reception of telephony. (1) It is impossible to advise you as to the wavelength range of your coils as it materially depends upon the dimensions of your aerial.The approximate range on a two -wire aerialof maximum dimensions would be 200/1,700 metres.(2) For circuit, making use of the apparatus you have, see Fig. 5.

SHARE MARKET REPORT Prices as we go to press on July 31st, are :- Marconi Ordinary .. £2 5 0 Preference .. 2 1 3 Fig. 4. Inter. Marine.. 1 6 14

I Canadian .. 10 6 magnifier, as it is very difficult to make two inter - valve oscillation transformers of identical value, Radio Corporation of America :- and moreover, a low frequency amplifier will give greater amplification.For the reception of short Ordinary .. 1 0 74 wave telephony, you should, of course, connect your Preference .. 13 6 AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW xvii JUST OUT WIRELESS VALVES SIMPLY EXPLAINED By JOHN SCOTT-TAGGART, F.Inst.P. Author of " ElementaryText -bookonWirelessVacuumTubes," and " Thermionic Tubes in Radio Telegraphy and Telephony," etc.,etc.

This brand new book is the ideal one for all amateurs who do not desire to spend very much on books.It is sold at 2S. 6d. in an attractive paper cover, and also at 3s. in a well -bound cloth cover.It is only by very large quantities being sold that the remarkably low price is being justified.No book of as wide a scope has before been produced at a similar price, and prospective purchasers should remember that this new volume from Mr. Scott-Taggart's pen is not one written years ago, but represents the very latest practice and ideas. CONTENTS. Preliminary Remarks - Introduction - Fleming Valves - The Three -Electrode Valve and its Applications - Cascade Valve Amplifiers - Reaction Amplification and Self -Oscillation - Reaction Reception of Wireless Signals - Continuous Wave Receiving Circuits - Valve Transmitters - Wireless Telephone Transmitter Using Valves - Notes on Wireless Broadcast Receivers - Conclusion. 13o pages of sound practical instruction written in a simple lucid style by an expert for the beginner. Buy your copy from your wireless dealer or order direct, post free, from us. PRICE 216 NET. CLOTH31-NET. POST FREE. THE CONSTRUCTION OF WIRELESS RECEIVING APPARATUS By PAUL D. TYERS. AN IMMEDIAVE SUCCESS - THOUSANDS SOLD. The huge sales of this booin a few days are due to the fact that itcontains the information the amateur w 'Its.It explains how to make the various parts of a crystal or valve set without the us.. of a lathe or expensive tools.It is the result of years of experimental work based on sound principles, by a practical man.Buy your copy now. 116 NET, POST FREE

Our books are sold by all wireless dealers of standing or may be obtained post free by return from RADIO PRESS LTD. Publishers of Authoritative Wireless Books 34/35, NORFOLK STREET, LONDON, W.C. 2

1 A xviii THE WIRELESS WORLD AND RADIO REVIEW AusiusT 5, 1922 THE WIRELESS WORLD EXCHANGEAND MART TARIFF.Advertisements are accepted for SITUATIONS VACANT. this Section at the rate of twopence per word ELECTRADIXRADIOS with a minimum charge of two shillings.The advertiser's name and address will be charged for, Advertisers require an experienced man, capable Hundreds of Head and single letters and single figures will be countedof making spare parts, or complete wireless instru- Sets in Stock.All as words. Compound words willbe countedments. -Apply, stating salary required, TEXALO with cords.Ster- as two words. MANUFACTURING CO., South Shore, Blackpool. ling Brown Phones, Wireless Engineer who isconversantwith Marconi Standard DEPOSITS. Alladvertisements must beWireless Circuits and capable of designing Wireless 2,000 ohms, 51/ - prepaidintheformofPostalOrders,theApparatuswantedimmediately.Verygood pair ;4,000 ohms, remittance being forwarded to Messrs. Bertramprospects.-PEEL-CONNER TELEPHONE WORKS, 52/- pair ; Brown's Day & Co., Ltd., 9 & ro, Charing Cross, S.W.r. Coventry. A 120 ohm L.R. head 'phones, 40/- pair,Sullivan'sL.R. FOR SALE. ditto,with 6ft. I Buy Wireless Gear cord plug and jack. Aerial Wire, 7/22 Stranded Copper, roo ft., 22/, of every description. Head Send your particulars to : 4s.rod.; Engraved Ebonite Condenser Dials, HighRes. with bevelled edge, 2S. 8d.;Condenser Vanes, Sets, z,5oo ohms. WILKINSON, is.8d.perdoz.pairs.Allcarriagepaid. 26/-; 4,000 ohms. BIRCH, 22, Portland Street, Hereford. 80/- complete, Second-hand 8o - Lonsdale Rd., Kilburn, N.W.6 Wireless Masts. -Selected pine, painted. Sixte,11 ohm head - sets SAME ADDRESS SINGE 1900. feet, 2r base,2s.3d.,.13' by II",Is.8d. ; guaranteed, 15/-.Single L.R. Receivers, 4/8. 8' by I$", IS. 2d. ;17' by 2S. 3d. (two parts) Cords for double 'phone, new, 2/6 and 8/9. each.Easilyjoined.Fittings, orcomplete Used, 1/6.4 Way Plugs, 2/, aerials or masts.Stamp for reply.-DowNEs, Microphone Transmitters, breast plate, 12/6 ; Potteries Wireless Men 61, Arthur Street, Derby. Hand, 2/6.Insets, 9d. Get all your wireless requirements from Three -Valve Set Complete, Tuner, Condensers, Aerials. -Wire and every accessory in stock. Valves, Batteries, Telephones, Loud Speaker, etc., Condensers. -Fixed and variable in all sizes, BEW & COMPANY, t15.-SuarsoN, 233, Gipsy Road, West Norwood, Relays, G.P.O., 21/- ;Weston M.C.. £210s. London. MorseInkers,45/-.Soundersetsfor Liverpool Rd., BURSLEM. making rectifiers, 12/6 each. Postal orders dispatched same day.Telephone Variable Condensers, New. -Ebonite top and Panel SwitchFlushFitting,D.P., 8/6. Enquiries invited. Expert advice. knob,scale21platesinpolished mahogany Plugs and Jacks, 1/6 pair. 6o volt Battery. SEE OUR WINDOWS. cabinet, 14s. 6d. each. -D. LEES, 209, Selhurst 4}v. units, inpolished mahogany case, six Telephone -Central 1225. Road, South Norwood. sockets, two plugs,17/6.Finest set ever Wireless Headphones, 4,000 ohms, latest model offered. for valve or crystal set, 35s. post free.Money Receivers, all new.Marconi Trench, 5o D.C. returnedifnot satisfied.P.O. to DEPT. W, Cost £40.Complete, £5 10s. 18, De Crespigny Park, S.E.5. Amplifier Receiver, Mark II, 2 valve, with variablecondenser,2710s.Singlevalve Single Valve H.F.Panel,fittedSullivan's Panel, 85/6.3 -valve Mark £8. Enamelled Wires Transformer, Mullard's Grid Leak and Condenser, H.T. Motor Generators to r,000 volts, £15. for etc.,La15S. .0005 Mark IIIVariable Con- x kW 220 to 25 volts, £30. denser, 61.-DAwE, 14, Oakfield Road, South- EVERYTHING FOR WIRELESS. gate, N.14. Call at our Electrical Showrooms and inspect. Wireless. SparkTransmitters,Model54 A complete. LESLIE DIXON & CO.. Near Aldgate Station, Met. Ry.First Turning Fitted with high-class spark gap, auto trans- ' 4042 44 46 47 S.W.G. former and coupled aerial inductance, Dubilirr on left in Minories. 6/68/- 12/619/6 30/-lb. condenser,Helix enclosed,allebonite pan,i, splendid instruments, approximate sjze,12"L.

if by 6", fitted with sliding back panel. 1 32s. each.Carriage and packing 3s.-Can5I AERIALS H.D. Copper. BROS., Alpha Mews, Alpha Road, New Cr, - FOR SECURING YOUR AERIALS London, S.E.14. and a Thousand Purposes where Great 7/22 7/20 :: Strength and Strain is needed:: PLAIN 4/-5/-100 ft. Coils. Two -Valve Receiver Cabinet, etc., perfect dition, used two weeks, cost Li r,sacrifice , ENAMD.5/-6/6 Inspectioninvited. -Cox,42,ClaytonRo., FLEXIBLE STEEL WIRE ROPE. Silk and Cotton Covered Peckham. Aeroplane Cable made to Govt. specification to PricesonApplication. Wanted. -Mark III Tuner, state condition and specified breaking strains. price. -BARKER, Oxford Road, Worthing. qAliA i I I Terms: -CASH WITH ORDER Condensers at Condensed Prices. -Scientifically POSTAGE EXTRA. made variable condensers, capacities .003, 425. 64; MP+ 16 '001 5,34s.;.001,27s.;'0005,18s.; 00 PRICES BELOW COST. I7S.;0003,16s. ;.0002,13S. 6d.Fittedit, Breaking Price ebonised or mahogany finished cabinets, compl. t. No. Dia. Strain. per roo ft. HORROCKS &,ASPIN, with scale and pointer. We also make cabin 3/32" ro cwt. 6/- to amateurs own specifications.Trade supplied. 3 r 20 cwt. 8 - 12, SCHWABE STREET. CLARMAC Co., 13, Stonest Street. London, N.4. 51 5/32" 25 cwt. 10 - RHODES, MANCHESTER. C.M.K. In three -valve amplifier and single - 53 3/16' 45 cwt. 12/- 56 70 cwt, 16/- valvereceivingset,sparkC.W. Telephony, 8o cwt. 19/- 180-4,000metres,formingcompletestation. Good reason for selling, Cro.-" B," Hill House, 7 5/16" roo cwt. 20/- Alton, Hants. 8 r ITO cwt. 22/- 9 7/16' 140 cwt. 24/ - TELEPHONE TRANSFORMERS Telephones, 4,000 ohms, Headband and Cords, to }" 160 cwt. 26/ - for 120 w. 'phones. new, 3rs. 6d.Telephone Transformers, I2S. 6d. STRAINERS for use with above, right and left High-class job, complete with terminals. and Earth to Valve, 155.V24 Valve holders, upright, hand threads, 9d. each, or 8/6 per doz. 4s.Army type buzzers, 3s. Vernier Condensers, guaranteed by the actual manufacturers. 5 Plate, 5s., etc.-LASSMAN, 429, Barking Road, Orders of rot- and over carriage pail, other- Price 13/6 post free. East Ham. wise please add II- for postage. Delivery per return. I CondenserVanes. -Fixed andmovable,in SMITH & ELLIS Rockland Works. I best quality aluminium, 7s. 9d. per gross, rod. (Dept. 65), 11. LITTLE BRITAIN. E.C.I H. H. SPICEREagle St., Coventry per dozen post free. -A. CLARKE, 24, Albert Place, Rusholme, Manchester. Tel. No. City 8994. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW XIX THE WIRELESS WORLD EXCHANGE ANDMART THIS COMBINEDOFFER -SAVES YOU OVER 5001o..- W. J. HENDERSON, and enables you to get signals perfectly. 2, Hollywood Road, South Kensington. (Nearest Station, Earl's Court.'Bus Routes, HEATH & Co., Ltd. SULLIVAN HEADPHONES, 120 Ohms. Nos. 31, 14, 98). Instrument Works, New Eltham, S.E.9 Double 'phones, complete with cords and areprepared to undertake in their fully adjustable double headbands.Perfectly Delivery by Return. Satisfaction Guaranteed. new. Equal to expensive high resistance Amplifiers, C.Mk. IV, 3 -Valve, L.F., every one equipped works-Wireless Apparatus 'phones when usedwith Transformer guaranteed perfect, complete with telephone andParts for the trade. Quotations given below. Price (while transformer, each £6 Bs. stock lasts) ... 18/6 Plug and Jack, suitable for plugging -in tele- toBluePrints.Immediate attention. phones, transformers, etc., etc. WIRELESS 'PHONE TRANSFORMERS. 1 6. Phone-Lee Green 3o1. Wire-Polaris, London., For panel mounting ; Low Resistance Telephones, 150 ohms, double, very compact. complete with headbands, verysensitive, Speciallydesigned foruse with Low per pair, 15/-. Resistance 'phones.Strengthen and Condensers, Mk.IIIType,complete with Tubular Steel Masts with bassplate finial, rope clarifysignalstoexceptionallyhigh bevelled scale and knob, .0015, 40,-. cleat, gup clips, painted, light and durable, degree.Every one tested 1 3/6 Accumulators,unspillabletype, 12 ft., 25'- ; 25 ft. befor despatch. in wooden (2 sections), 40/-; 40 tt. Only... case,actual capacity, 16 amps., in new (3 sections), 80/-.Training Wire, 4 insulators, SEND ONLY30/-FOR THE TWO. condition, every one guaranteed, less than halyard,pulley, lead in tubs, 100 ft. 7/22 half listprice. Terms: Cask with order and Post free. copper wire, 17/8 extra. Carriage forward. 6 volts .. .. 30'- Works :5, Kramer Mews, Earl's Court. Order NOW to avoid disappointment.2 10 volts .. 50 F. HARRISON, Valve Boxes, wooden with padded interior, to LL.S. COMPTON,1 46, Brooke Road, Walthamstow, E.17. take three valves, each 2/-. 17, FERNSHAW ROAD, CHELSEA, 8.W.10 Rubber -Covered Cable, 40'36 stranded tinned copper, per yard, 41d. Valveholders, ebonite type with flange, each 1 6. TRADE ENQUIRIES. Aerial Stay Wire, steel flexible cable, 15 cwt breaking strain,sample on request,per Wireless Repetition Work for trade.-LIBERTY MU LT I E RYST 100 ft., 5/-. ENGINEERING CO., LTD., Acton Town Station, W.3. Trade Enquiries Invited. Keen Quotations Wanted for all Wireless Parts PM a " Multicryst " to your Wireless Set - Terms, Cash with order.Goods above £2 and materials, manufacturers only. Also stamp- in value, carriage paid. and increaseitsUtility, Efficiency and ingsanddiecastings.-IRVINEBROOK,LTD., Delicacy by g00% No single crystal can Brooksmouth Mills, Brighouse, Yorks. possibly give best results under all conditions. FOR SALE-continued. To Manufacturers.-Wanted quotations for all With a " Multicryst " you Radio Accessories and components from actual have a choice of three makers only.Please quote lowest trade prices and crystals, thus ensuring the Hague Receiver, Complete, including selected valve, two Vcs.,5 5s.Headgear and transformer,state when delivery can be given.-Box Es, most efficient signals under 3xs. BERTRAM DAY'S ADVERTISING OFFICES, 9 and ro, EVERY condition. To Marconi Scientific Detector panel, including Mo.valve,£3 Jos.Frenchintervalve, 19s. Charing Cross, S.W.x. fitthe"Multicryst" = oo6 Vc. cost Ern, Brown loud speaker and Advertisers Request Quotations from manu- simply unscrewexisting sensitive galvanometers,facturers for all parts used in constructionof -stal holder and replace wireless instruments, also condenser scales, knobs the" Multicryst." Post Free. otheritems,allnew.Stamp,requirements. with Demonstrated week-ends.-W., 113,St. Jamesrheostats, switches, etc.-TEXALO MANUFACTURING AGENTS WANTED EVERYWHERE cast' WITH Road, Tooting. Co., South Shore, Blackpool. TRADE DELIVERIES GUARANTEED ORDER Two -Valve Panel, two valves, two condensers, Advertiser (Business Man, who is also Wireless transformers,inductances andallaccessories,Amateur)aboutpurchaseshopBirmingham WIRELESS SUPPLIES Co. District, to set up Show Room Wireless Goods, pho,....64 Mortimer St.. London.W.I 'Grams: complete set.Never used, £8 los.Reason for Museum V672, Adragostax. Wesdo,London,' selling,landlordforbidserectionofaerial.-requiresPartnerwithWirelessorElectrical LetterstoF. WILSON,36, Boundaries Road,Knowledgeandableinvestportioncapital Balham. necessary.Box B.3, BERTRAM DAY'S ADVERTIS- Radio Fans use " Orosite "Crystal, for bestING OFFICES, 9 and to Charing Cross, S.W./. PURCHASE YOUR WIRELESS results, mounted 25 cents.-H. J. DAVIS, 200, Ridgewood Avenue, Brooklyn, N.Y. BUSINESS FOR SALE. REQUIREMENTS THROUGH Special Line, Wireless Girder Masts, Light and Strong, 3o' Ex, 35' 22S. 6d., 40' 25S, 45' 30B,, Wireless Business for Sale, London Suburb.- The Viper Re -Covering Co., Ltd. 5o'35s. Cash withorder,carriageforward.Good will and fittings, Ex,5oo per annum. Lock- 7/8, POULTRY, E.C.E. -F. ARMSTRONG, Weybridge. up shop.Best offer accepted.-Box D2, BERTRAM (x minute from Bank) Tele. : City 1897 Wireless Instrument Cages,Wainut or Mahogany,DAY'S ADVERTISING OFFICES, 9 and xo, Charing finest finish, if by 7}- by 4' (outside), 8s. 6d.Cross, S.W. x. Marconiphones, Sterling and R.F.H. Sets, etc., Second quality,7s. 6d.Any size proportion Place your orders NOW. ately. prompt delivery. Trade inquiries invited.- can be supplied. HITCHCOCK, Colchester. WANTED. Aerial Insulators.-British Made Egg Type Wanted.-Intervalve Transformer. Loud insulators 6s. per doz. post free.-Cuairr,zo StarSpeaker.Good condition,cheap. Also any Street, Edgware Road, W. broken wireless components.-Rommrs, 55, RADIOPHONE TUNERS, Tungsten Rivets. diameter of Head ir" shanksFairfield Road, Bow, E. 200-1,400ms...... 88/ - screwed g B A 3/16" long.Price carriage x6s. a gross.-BELOW. Valve Panels for above ..21/- Wireless Transmitters, Complete.These instru- SITUATIONS WANTED. 1005 Variable Condensers ..18/8 ments are very popular with wireless enthusiasts, Wireless and Electrical Engineer.-Ex Officer Above 8 make an Ideal Receiver. internal fittings include high class spark gap, x"R.N.A.S., A years technical training.Diploma Broadcast Concert Coilspair 2/ - Sterling spark coil and condenser, external HelixNine years wireless research.Any progressive and tuning aerial clips on ebonite panel, spark gapcapacity.-Box C4, BERTRAM DAY'S ADVERTISING Grid Leaks and Condensers 8/6 adjuster, all terminals, ets., and diagram of internalOFFICES, 9 ancl io, Charing Cross, S.W.i. Fixed Condensers ...... 2/6 connections.Price 17s. 6d. each, post and packing Drawings andTracings fromSketches.-C. 5 -Plate Condensers .... 6/6 2S. extra.-CADNEY BROS., Alpha Mews, AlphaSTANTON, 6, St. Leonard's Avenue, Stafford. Road, New Cross, London, S.E. 54. Young Man Skilled in Wireless, do all except 2 -Valve H.F Amplifier Panels82/ - lathe work, wants situation, wireless firm, or MISCELLANEOUS. firm taking up WIT., or will instal aerials and bet our New Bargain List. instruct in using any type receivers for anyone. Printing,-Memos, Billheads, Cards, PriceTerms, fares, and time.-WALKER, 43, Liverpool Lists,etc.,very lowprices,samples free.-Street, King's Cross, W.C.I. AMATEUR SUPPLIES, VICTORIA PRESS, 368, Knutsford Road, Warrington Young Amateur,fouryearsexperimenting, 184,COTEFORD STREET, Designs of Receiving Sets, Motors, Generators,wants situationconnected with wireless, can TOOTING, LONDON, S.W. etc., supplied.-Puciu.E, 33, Sandringhamread Morse, also driveacar.Willing to go Gardens, Ealing, London, W.5. anywhere.-KITCHEN, so, Beech Road, Epsom. X X THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 LE LIE iICMELTD PROVIDENCE PLACE, WEST END LANE, KILBURN,N.W.6 Ser.:ce1. 8.16. 28.31 ellpassWest EndLone TelephoneHAMPSTEADI261Nearest Tube Station KILBURN PARK J BAKERLOO) Complete. Concert Receiver This Set has been specially designed to give maximum amplification for use with. three Valves.The first valve acts as a high frequency amplifier, with valve holder provided for plug in high frequency transformers. The second valve is the rectifying valve, and in connection with this will be found a grid leak and grid leak condenser of special design.The third valve, which is a low frequency amplifier, is provided with a low frequency transformer, giving maximum results, and has been chosen from a number of other types of transformers after careful test.Filament resistances are provided controlling the filament voltage, and the accurate working of these and gradual increase and reduction of filament voltage is one of the features of the Set.Two variable condensers with ebonite calibrated scales are provided, the right band being across the primary of the high frequency plug in transformer, giving great selectivity in reception.The left-hand condenser is the aerial tuning condenser.The whole Set is mounted in a polished mahogany box, the finish of the panel work being superfine. All terminals are lacquered, and the general appearance of the Set is one that pronounces it to be of the finest workmanship. The Price of this 3 -Valve Instrument (without valves)... £10 10 0 COMPLETE installation including aerial insulators, high tensionbattery, accumulator, set of 3 high -frequency transformers, set of 6 tuning coils,mahogany and ebonite coil holder, leading -in tube and full instructions foranyone without previous experience to enjoy wireless music and speech .... £21 16 0 For your WIRELESS APPARATUScome to a firm of WIRELESS ENGINEERS. The Directorsof this firm have had Twelve Years' WirelessExperience. CONDENSERS (In Stock) VARIABLE in Oak Cabinet. "LESMAG" CONDENSER .001 mfd. 30/- 0005 mfd. 22/6 PANEL TYPE for mounting in sets. Well made and guaranteed. * 001 mfd. 22/6 '0003 mfd...12/6

0005 17/6 00005 .. 6/9 " LESMAC " TYPE (as illustrated). This condenser which although entirely suitable for panel mounting is provided with ebonite feet and terminals and can be used therefore without further mounting. Capacity '001 mfd. 24/- *0003 mfd.

'0005 16/6 '00005 . 8/- Fully Illustrated Catalogue, 16 pages, post free 6d. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW This is Not PETO'S First Appearance See Our Advertisements long before the Boom EVERY ARTICLE ILLUSTRATED DELIVERED FROM STOCK

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Series Parallel or Double Pole Change -Over SWITCH for TEMPO STANDS onPolished Panel Mounting. Mahogany base, 22/6. Supplied lees Terminal Board & base,19/- VALVE HOLDERS. Illustration one - Long Tuning Handles supplied if Turned from solid third actual size. COIL MOUNTS supplied to fit any size desired, same price. Ebonite, 1/9 Price 2/. coil, 2/9.Fits standard coil holders. SEND FOR OUR NEW ILLUSTRATED CATALOGUE WITH LIST OF TRANSMITTING STATIONS. POST FREE 6d. NOTE PETO'S NEW HOME PETO SCOTT (The Condenser King) Featherstone House, 64, High Holborn, W.C.1 (Also at- 17, FROME ROAD, WOOD GREEN)

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MANUFACTURERS & RETAILERS apply for Illustrated List and TRADE' TERMS. KEEN PRICES. PROMPT DELIVERY. 27.71.ORMOND ENGINEERING CO., 199, Pentonville Rd., King's Cross, N.1. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5,1922 WIRELESS YOU WANT

Large or Small Contact Studs . .. .. doz. 1 0 ACCUMULATORS Valv, Legs, complete with nut and. washer .. each 3 Hart Accumulators, 4 -volt, 24 amp. hour . each 149 GET THEM AT Postage and Packing extra .. ..each 1 3 STILL THE CHEAPEST F. YATES & Son, Ltd FIRM FOR WIRES. S.W.G. S.C.C. D.C.C. Single Silk Dbl. SilkEmd.', HAVE THE BEST. 12 1/10 1/11 4/- 5/4 1/8 14 1/11 2/- 4/- 5/4 1/9 BRAND NEW, GUARANTEED BRITISH. 16 2/- 2/1 4/2 5/6 1/10 18 2/1 2/2 4/4 5/6 1/11 6 volt 40 amp. Actual in 3/ volt separate 20 2/2 2/3 4/8 6/2 2/6 22 2/6 2/11 5/- 6/8 2/8 Glass Cells, contained in Teak Crate - 49/6 24 8/- 3/6 5/6 7/4 2/8 4volt 24 amp., Celluloid Case, 11/- Postage 1/- 26 8/7 4/1 6/8 8/2 8/2 2 16 Ebonite Free. 28 4/4 4/7 7/2 9/- 8/6 8/9 Post 30 5/- 5/6 8/- 10/- 8/10 ALL IN CELLULOID CASES. 32 6/- 7/3 9/2 18/- 4/2 34 7/- 8/8 11/6 14/- 4/4 4volt 40 aLp. 18/6 6 volt40 amp. 28/8 36 10/2 14/- 15/6 4/8 8/8 4 60 21/8 6 60 31/9 38 11/8 18/2 16/- 10/- 5/8 40 15/- 18- 18/6 22/6 6/6 4 80 28/2 6 80 87/8

42 17/3 21,/- 81/6 84/- 9/ - 4 100 30/- 6 100 41/8 At per lb. All orders of 1 lb. or over wound on reels free.For less than PACKINGFREE. 1 lb. reel 3d. extra. Wireless Set in Upright Oak Cabinet, Sloping Panel, Farther Lists on application.Trade Supplied.Postages extra One Valve, M. Two Valve, V. Three Valve, £10. Crystal Set, very superior quality, - - 80/ - Head Phones, 4,000 ohms, - - - 33/- J. B. Bower & Co., Ltd. 7/22 Aerial Wire- - - per 100 ft. 5/ - Wireless Manufacturers, Trade Supplied. All Goods Carriage Forward. 15, Kingston Road, WIMBLEDON, S.W.19 144, Church Street, Kensington, W.S. 'Phone : Wimbledon 1030. Works :Merton. 'Phone-Park 4276. One Minute from Notting Hill Gate.

A £20,000 DEAL IN WHICH EVERY ACCUMULATORS ETC. WIRELESS AMATEUR MAY PARTICIPATE ALL NEW STOCK & GUARANTEED. 4 Volt 25 Amp. Celluloid 11/3 each. "BROWN" "A" TYPE Postage5/- 4 Volt 40 Amp. - 17/6 6 Volt. 4o Amp. - 25/6 RADIO HEADPHONES 4 PI 6o /1 . 21/3 6 6o - 81/- Guaranteed new and unused. NOT re -conditioned. 4 ,,So ,, - 27/- 6 - 88/- Packing 1/6 extra Packing 21- extra. y/22 Aerial Wire 6/- per zoo ft. 8,000 Mullard Ora Valves 15/- each. 120 x5 Volt Siemens H.T. Batteries - 4/- ohms. ohms Accumulator Charging Board 87/6 Voltmeters, Watch Pattern, 0/12 Volts - - - 42/6 49/6 CASH WITH ORDER.Goods despatched per return. Maker's Makers LOWKE & SONS, Ltd., Northampton. Price Price 58/. 66/- W. H. PORTER & CO. SULLIVAN 8,000 ohms,...36/6 44, CHURCH STREET, BIRMINGHAM Why pay the full price and wait weeks for delivery when Special Quotations to the Trade for Quantities. we can supply from stock atless than trade price ? Wireless Parts & Apparatus Terms cash with order.Postage 1/- extra. Approval for 7 days. A general list is supplied but for special quantities Trade enquiries for quantities solicited. al way state particular lines and quantities. FULLER" BLOCK "TYPE AC- Variable Condensers, Grid Leaks and Condensers. CUMULATORS 4 volts, 4 amp., 32/6 Filament Resistances. The finest makes on the market. the only practical battery for wireless. Marconi Type 16 Receivers to the trade in quantities I@ £8 each. THE CITY ACCUMULATOR CO. Marconi Short Wave Tuners less Condensers in 79, MARK LANE, E.C.3. splendid condition and most suitable for converting Phone :Avenue 9x. Telegrams :' Tyche, Fen, London.' into valve sets£1 10 0 each. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW axiii North Wales Wireless College & Amateur Supplies COLWYN BAY. 'Phone 407. Most Complete Stock of all Wireless Students prepared under ideal conditions as Instruments and Accessories. Wireless and Cable Operators POSTAL AND RESIDENTIAL TUITION. PROMPT DELIVERIES. SPECIAL POSTAL COURSE FOR AMATEURS. LIST BY RETURN.lid. STAMP. PROSPECTUS POST FREE. BE UP-TO-DATE CONDENSERS. MAKE A JONSEN-RABECK LOUD SPEAKER AS ILLUSTRATED IN THE " WANT." AND '0003 Variable Air Condensers .... 12/6 '0005 9 9 9 9 99 9 15/-

'001 19 99 9.9 24/- Let Your Friends Hear. '00005 Vernier ...... 4/6 AGATE CYLINDER FOR ABOVE El 2 6 '00001 ,, ...... 4/6 TWO -VALVE DETECTOR -AMPLIFIER 2 176 High Resistance Phones ...... $2 10 0 CRYSTAL RECEIVER ... 200 Filament Resistances ...... 3/6 & 5/ - CRYSTAL DETECTOR... 50 FIXelD CAPACITY CONDENSER 1 6 Contact Studs ...... doz. 1/6 FILAMENT RESISTANCE 46 Switch Arms 2/6

Mail Order Office - Mullard Ora Valves. Parts to build your own sets. 126, FOREST ROAD, EVLINSDALSTON , LONDON, E.8 B. L HOUSTOUN, Price List Post Free on application. TRADE SUPPLIED. Regent 4911.66, ENDELL STREET, W.C.E. THE TINGEY UNIT SYSTEM THE "ESI-FIX" AERIAL has proved its Patent applied for efficiency " FIXITLIKE A CLOTHES LINE." Wrirrfor A new " one-piece " aerial with patented continuous ILLUSTRATED insulation, complete withstrainingeye,adjustable CATALOGUE suspension and terminal. No lead-in tube, or other which contains an article on insulators required. No joints, no soldering, no leakage, Wireless Made Easy and no bother.Can be thrown up anywhere, andis Complete List of all Wire- absolutely weatherproof.Maximum efficiency guaran- less Goods in Stock teed.Send cash with order and secure delivery at once. Length 50 ft., 10/- ; 75 ft., 12/6 ; 100 ft., 15/-. WriteforIllustrated Catalogue 3d. post Free Carriage paid its U.K. Agentswonted. 92, Queen Street. CHAMBERS & ELLIS W. R. H. TINGEY9 Hammersmith, London.W.B. 6 & 7 Craven House, Kingeway, London, W.C.2

SKINDERVINEN BUTTON. A Supersensitive Microphone. Known all over the world and patented SPECIAL in every civilized country. Over 60,000 sold.ENGLISH Manufacture. THIS WEEK! Make up your own Loud Speaker. Transmit your GRAMOPHONE music VAR. CONDENSERS .003 to any room in your home. The only practical Microphone for use in Detectipbone Seta. Skeleton type9/6 Price 5/- each Special Low ResistanceReceivers(for use with HEADPHONESBritish27/6 Skinderviken Buttons) 10/-each

Special Gramophone Attachments 1/- Write for 19 page BOOKLET fully illustrated and con= much useful information forallinterestedinElectrical HENRY J. BREWSTER & CO, Bound Transmission.6d. Post free. 11 QUEEN VICTORIA STREET, E.C.4 Sole Proprisiors: "Phone: City 768. MIKROLTD., 274/6, Pentonville Rd., London, N.I opp. Hine's Cross (MO.) Illy Station). PHONES (Paitria=1:17. 30/- CRYSTAL SET 40/- Special Wireless Telephones, 4,000 ohms, 30/- post free.Receiving Set on Mahogany base, double slide Tuning Inductance, Fixed Condenser, Crystal Detector, Terminals, 40/ - post free.Valveholders in Ebonite, first quality only, 1/-. I. K. STEVENS & Co. Wireless Section, 32a, Chester St., GrosvenorPlace, S.W.1 xxiv THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 ExPERFArcE A BARGAIN WIRELESS ,E85 TELEPHONE HEAD SETS Cannotreplaceunder1,285 IMMEDIATE Electric Lighting DELIVERY FROM STOCK & Power Plants DESIGN. These telephones are of the Country Houses highest grade diaphragm type and have for been specially designed for the reception Workshops, Cinemas of wireless broadcasting. CONSTRUCTION. Every part is of standardised construction and thoroughly well finished. The cases are of polished aluminium. The terminalsarefitted with insulating caps.The set is light and comfortable to the head. SENSITIVITY.These telephones are highly sensitive, being of 4000 ohms resistance.The diaphragms inevery set have been accurately adjusted for maximum sensitivity. Other diaphragm type telephones may cost more, but none are more sensitive. PRICE.Each set complete with two earpieces and flexible connections. 35,6 Carriage paid in the U.K. Do notconfusethesehighgrade telephones withthe cheapinferior AUSTIN and STANDARD 3f K.W. imitations you may be offered. CALL and 4.1. K.W., no volt, direct coupled AND SEE THEM. Let us show you LIGHTING AND POWER PLANTS, their perfect internal construction. Order at once to secure delivery. complete as above, £85 F.O.R.Suit- OTHER PRODUCTS. We also invite able for either no voltor5o volt, enquiriesfor :-Short Wave Anode country house lighting, garage, work- Reactances ;Efficient Tuning Induct- shop and cinema plants. ances ; PrecisionAirCondensers ; H.P.Transformers,andanyother AUSTIN 220 volt 20 amp. plants also components used in wireless practice. supplied.Will run on petrol, paraffin, Every articleis manufacturedat our own works under the direct supervision or gas.Special Switchboard Do extra. of the directors. Spares of every description always in stock. RADIO INSTRUMENTS Ltd Managing Director:J. Joseph, Late Manager to Mr. H. Sullivan. COMPLETE ARMY WORKSHOPS Chief Designer: W. A. Appleton, M.E.E., M.I.R.E. Late Admiralty Technical Research Officer. AND LATHES ALWAYS IN STOCK. ONLY ADDRESS- Works, Offices, Showrooms : 12a, Hyde Street, C. H. & L. 0. SMITH NEW OXFORD ST., W.C.1 75, Canal Street, NOTTINGHAM 'Phone : Regent Igo& 'Grams : Instradio, London. L. 6. E.P.S. AUGUST 5, 1922 THE WIRELESS WORLDAND RADIO REVIEW xxv At What Station does the train of Oscillations A Prize for the Bost Answer. stop?Watchthese Advertisements for Winners. Write on a separate piece of paper (one side only). Endorse " Competition " top of left hand corner of paper. Aerial Wire, 7/22's Enamelled Hard Drawn Copper, 6/- per coo ft. Tin Foil.Free from lead.Sheets, 26" by 13", 4d. each. Aerial Pulleys, 2/6 each. Valve Sockets.With nut and washer.Fine finish, set of four, 10d. Aerial Insulators, Shell type, 21 x 21", green, 1/6 each. Valve Holders.Best quality ebonite, 1/8 each. Reel type, 2- diam., white, Sid. each. Valves.a -pin vertical filament, 10/6 each. Batteries.For H.T.Make your own.Flash Lamp Batteries, VALVE PANELS.Single Valve.Mahogany case.Baize -covered 6/- doz. base,ebonitetop.Containinggrid,leak and condenser, Buzzers for Morse practice, 3/- each. telephone condenser.Filament resistance, and with terminals Condensers.Fixed.Exceptional quality.Terminal connections; to allow the addition of extra panels. A beautiful piece of from 000x to oor, 2/9 each. workmanship.Price, 29/6 each. Condenser Vanes.Not rubbish.Best Aluminium, 1/- doz. Condenser Spacing Washers.Accurate.Small, 4d. doz.;large, 8d. doz. SUPERIOR QUALITY WIRE. BRITISHMADE Condenser Screwed Rod.Brass, 12" lengths, 2 B.A., 9d. each. All wire wound free. Post extra. 4 B.A., 6d. each. S.W.G. S.C.C. D.C.C.Single SilkD. Silk Emd. Contact Studs.Studs, not rubbish, 2/- doz. 12 1/10 1/11 4/- 5/4 1/8 Copper Foil Sheets.9' x 3', 6d. each. 14 1/11 2/- 4/- 5/4 1/9 Dials, Ebonite, graduated o-x8o, 2/6 each. 16 2/- 2/1 4/2 5/6 1/10 Ebonite.Best quality. Any size, rod or sheet, 5/- per lb. 18 2/1 2/2 4/4 5/6 1/11 Filament Resistances.For panel mounting. A speciality. 41- each. 20 2/2 2/8 4/8 6/2 2/6 Inductance Tubes.if long.Specially impregnated.24", 6d. 22 2/6 2/11 5/- 6/8 2/8 . 34', 7d. ;34", 8d. ;4", 10d. ;41',1/- ;5',1/2; 6",1/6each. 24 3/- 8/6 5/6 7/4 2/8 Postage, 9d. each. 26 8/7 4/1 6/8 8/2 8/2 Inductance Slider Rod, r square in r2' lengths, 7d. each. 28 4/4 4/7 7/2 9/- 8/8 Insulating Tubing, 6d. per yard. 30 5/- 5/6 8/- 10/- 8/10 Ivorine Scales.o to x8o .Engraved (not printed), 1/2 each. 32 6/- 7/8 9/2 18/. 4/2 Ivorine Tablets.Set of 6, 9d. 34 7/- 8/3 11/6 14/- 4/4 Knobs.Ebonite.if" diam.Superior finish.Knurled, 8d. each. 38 8/8 10/2 14/- 15/6 4/8 Mica.Pure Ruby.Pieces,3" x 3" x oofthick. 6d. each. 38 UM 13/2 18/- 19/- 6/2 Paraffin Wax, 1/- p,F. lb. 40 15/- 18/- 18/6 22/6 8/6 ResistanceWires. Elsi " brand.22's (i ohm per yard), 24'S 42 17/8 21/- 31/6 84/- 9/.. (c7 ohms per yard), and 28's, enamelled (4 ohms per yard), At per lb. 2d. per yard. Switch Arms.Exceptionally strong and well made, 3 -leaf. 2/6 each. Terminals. A very neat wireless terminal.Polished, complete Carriage extra. Please remit ample postage, balance returned. with nut and washer, 2/6 doz. Orders over 42 carriage paid.Money back if not satisfied. J.L. CARTWRIGHT& CO., Manufacturing Electrical and Radio Engineers " Dept. W." 'Phone-Os*. 420g.Dept. W. 130/132,LONDON ROAD. MANCHESTER. 'Grpos-Plolorsm, Masshalor. Special Terms to the Trade, SALES AGENTS WANTED for an unlimited supply of " BROADCO Crystal Receiving Sets, price 70/- complete, i.e. Receiver, 'Phone, Aerial and Insulators. The Maximum Efficiency at a Minimum Price ENTIRELY BRITISH MADE Send for illustrated pamphlet and trade terms to: THE BROADCAST WIRELESS CO. 2, Tower Royal, Cannon Street, E.C.4 'Phone-CITY 8482. Telegrams-ADORNERS PHONE LONDON. N \ I THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 1111111111111111111 iteirrl. 11111111111111111111 TUBE, SHEET, WIRE, STRIP, I I ROD& CASTINGS IN

INSIST ON HAVING A PHOSPHOR BRONZE, I FULLER `BLOCK' TYPE I COPPER, BRASS,&c.,&c. ACCUMULATOR CHARLES CLIFFORD & SON, LTD., FOR YOUR WIRELESS SET! IThe only Accumulator on the market that will hold its charge from 12 to x8 months when not in use. BIRMINGHAM, I4 -volt 40 amp. hours, g 1126, glue 1/3 carriage 6 -volt 40 £2 89. 1/6 Note:-These prices are 331% below those of the actual makers. I HAVE IN STOCK 8,000 Sold. 20,000 still in stock. Descriptive and Instructive l',unphlet on request from- 5000 BROWN'S TheCITY ACCUMULATOR Co. (Dept. 88) PAIRS (120 (thins)A " PHONES 79, MARK LANE, E.C.3 (Tel. No. Avenue 91) NEW AND UNISSUED Also SUPPLIED BY- POST PER Selfridge & Co.. Ltd..Wireless Section ;A. W. FREE45/- GaMage, Ltd.. Wireless Dept.;Barnsley British PAIR Co-operativSociety. Radio Section :Richford CASH WITH ORDER & Co., 153, Fleet Street, E.C.3.The South Wales Wireless Installation Co.. Ltd.,18, West Bute Street, Cardiff. WILKINSON, Lonsdale Rd., Kilburn, AGENTS WANTEDINALL PARTS.I I TRADE SUPPLIED (Same address since 1900) N.W.6

30th EDITION NOW READY! The Most Interesting, Instructive and Complete CATAI,COUE of " Everything Electrical and Wireless " ever published. POST FREE 6d. A wile range of Crystal and Valve Receiving Sets is shown and in addition we list the most wonderful range of Units ant components for making own sets.

Small Condensers. Contact Studs. Knife Switches. Valve Socket Terminals, Low -Frequency Inter - .0004 and .0005 3/ - Small Size.. 2/ -per doz.S.P. I way, 1/9; 2 way,2/4 ValveTransformer. 1/8 per set of 4. Anode Resistances. Large 8/- D.P. s way, 3/9; 2 way,I1/.. Plug Connecter, Best quality, 21 7s. 8d. 30,000 & 8o,000 ohms 3/6 Aerial Insulator. Grid Condenser and Lnk, CompetitionType,re- Variable 2 -pin, 1/8 xe'.. 1/3at" - 2/8 7'6 liable quality, 21 Is. Anode Resistance. 2' Reel, 4d. Double Receiver, Telephone Transformers.20,000 CO I00,000 ohms, Blocking Condenser, 5/ -With Head -Band & Cord. Best quality, 11 2s. 6d. Aerial Wire. Grid Leak, 3;- 2,000 ohm, 35/-:4,000 7'6 per too feat. Skeleton Buzzer. ohm,37/6; 8,000 ohm.45/- Competition type, 21 Le.Filament Rheostat, 7/8.3/20 4/-7/22 Extremely sensitive, for Inductance Tubes. Condenser Parts, Fixed & 6/ Brown's Loud Speaker, Length if. 3/19 ..4/63/18 .. 8/8 Crystal Testing, 2/8. Type H.2, 2300 Moving Vanes, 2,8 doz. 7/20 . Diem. Diem. 7/8 Single Receiver, High Tension Batteries. CentreRod, 4.1", 4/8 Regulating Screw, 1/ - With Head -Band & Card. 15 v., 3/8.Variable 21" 8d.4." 1/- Laminated Switch Arms, Ebonite Knobs, 120 ohm, 24/-; Soo ohm, Type,36 Tapping 3 ..3d. .. 1/6 2/6. 3d., 1/-, and 1'6 27/13; i,000 ohm, 80/- er 3 7 31" 106.6'.. 2/ - Valve Socket, 1/9. Insulite Sliders, 1/ - 2,000 ohm, 82/8 ,':postage Extra. AIIGIIST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxvii HENDON PATENT POTENTIAL BATTERY ACCUMULATOR

25 VOLT UNITS, LEAKAGE FOR USE AS REDUCED TO GRID BATTERY. AN ABSOLUTE NO CONNECTIONS BETWEEN CELLS. MINIMUM

Designed and Manufactured with particular regard to the RequirementsofWirelessTelegraphyandTelephony by HOBDELL, WAY & CO.,LTD., 124 MINORIES, LONDON, E.1 DESCRIPTIVE MATTER ON APPLICATION

Telegraphic Address :Hobnails, Ald, London. Telephone : Avenue 3810.

cSrxer )41AkGENUINE & ORIGINAL DON'T READ THIS It you axe a millionaire

H ELLESEN DRY -412.2 B ATTERIES -,-Ms KNOWN THE WORLD OVER AS IO ,,,,Actual size BEST Price, 2/6 per dozen, p aced ;3'- brass ;small type, 9d. per doz. THE One valve detector panel complete with filament resistance valve holder, and grid leak and condenser, fitted with insulated terminals, mounted on solid ebonite base in mahogany instrument case PRICE25/ - Leading -in Tabe, ebonite, R.A.F. pattern with brass rod and fittings. .. PRICE 3 6 Aerial Real Insulators, tested to 25000 volts PRICE 4 Accumulator Charging Resistances PRICE26 - Universal Tuners.These tuners have been designed to tune in Marconi concerts, broadcasting, and Dutch Concerts, so that a baby can use them.Wavelength range, 300-1,500 metres, with0005 m.f. condenser, PRICE 7, - 4,000 ohm phones, new patent 3 -magnet type, fitted cords and tags, complete with nickel plated head CODEWORD CODEWORD bands .. . PRICE35; - " WIRIT " Size 61x 21 X 3. WIRIT ' 36 volts. Transmitting Keys,G.P.O.pattern,fitted platinum SPECIAL TRADE & WHOLESALE TERMS. contacts.. PRICE 5/ - Valve Holders, fitted in solid ebonite, fixing case drilled CODEWORD VOLTS DETAILS PRICE fitted with valve earthing clip.. PRICE 2 6 " RON " 55 SCTEW terminals 4/- Grid Leaks and Condensers, mounted on solid ebonite " WIRTO " x3 Strip 4/- PRICE 5, - " WIRIT " 36 2 wander plugs 86 Instrument Cases, solid mahogany, 9" x 6" a 21", highly " WIRIN " 6o 14/- finished, fitted ebonite panel, undrilled PRICE ALL LISTS FREE ON APPLICATION. Postage extra on all the above prices. The trade supplied. Enquiries solicited. A. H. HUNT, LTD. 614, OLD FORD RD. H.A.H. Works, Tanstall Rd., Croydon, Surrey J. LIPOWSKY, Bow, LONDON, E.3 'Phone :East 3345 xxviii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 E IHAE LT D. PROVIDENCE PLACE, WEST END LANE,

. KILBURN, N.W.6 11.. 1. A. 16..212., 31 611 pe.sW..IE6c1 Len. Telephone HAMPSTEAD 1261 Nearest Tube Station KILBURN PARK I BAKERLOO) BROWN'S HIGH RESISTANCE BROWN'S LOW TELEPHON ES RESISTANCE (With Cords) TELEPHONES 8,000 ohms. There is no tele- (With Cords) phone headgear 120 ohms. Price 55/- Per Pair in the world so Price 50/- Per Pair sensitive and so We have completed an comfortableto We shall supply to exclusive purchasewith wear as a amateurs and our friends Messrs. S. G. Brown, Ltd., " BROWN." in the trade as freely as for somethousands of deliveries permit. their re -conditioned Ex- Government Telephones. A considerable stock is at present available. The telephones we offer bear the hall markof Messrs. S. G. Brown Ltd.-purchasers should not be misled into buying ex -Government Brown diaphragms-these we are offering have Phones which are of the older type with paper Brown's factOry ALUMINUM diaphragms, and are direct from

EGG INSULATORS. 9d. each.

This switch is a double pole change over-a most useful AERIAL WIRE. piece of apparatus for panel mounting .. ..One 3/6Enamelled Copper, 7/22 Mounted in teak box with terminals .. .. Two 7/- too ft. .. .. 7/6 5 50 coil . . .ide 111.ii1111111111i1111111111111116111111111111111/11111111111111111111/1111014111111116111,161111111111111ti4, 3 in.3

_ '1... LEADING -INTUBES. SPECIAL TERMS r Ebonite with Terminalseach end. TO THE TRADE 6" long, 2/3 re long,t8/- .. 58' long 3/9 We hold enormous stocks of all these and hundreds of other lines of wireless apparatus.You are specially invited tosend your enquiries-get the benefit of our experience and if possible inspect our stock. ab POSTAGE MUST BE INCLUDED (Except EBONITE VALVE PANEL & RESISTANCE. where orders are for 82 or Inpolished Box. SWITCH ARMS. over). Price 14/ - Price 2/9 AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxis

HIGH TENSION DRY BATTERIES for WIRELESS SETS

NORMAL SIZE, No. W 7o V, 15 Volts W 71 V, 5o Volts GIANT SIZE, No. W 73, Is Volts Price5/- Price15/ - Price 6/6 SUPPLIED IN TWO SIZES FOR15,50or60VOLTS. andwithTappingsin3VoltSteps. ALL BATTERIES FITTED WITH PLUG SOCKETS AND MOVABLE TERMINALS. Complete Illustrated Price List on Application. THE EFANDEM CO., LTD., FALLINGS PARK WORKS, DRY BATTTERY MANUFACTURERS WOLVERHAMPTON

SENSATIONAL REDUCTIONS. SlabInductances,300-30,000m.Setof8,9/-.Ditt, " Oojah " make, 10/- per set.Postage, 9d. extra. Basket Inductances,300-3,000 m.Setof7,8/-.Ditt. " Oojah make, 7%- per set.Postage 6d. Basket Inductances, 150-1,300 m.Set of 5, 4/9.Post 3d. SCIENTIFIC TUNING INDUCTANCES, 150-1,300 m.Set of 5,6/-Post, 6d.The Ideal Inductance for Telephony. Designed for simple and efficient tuning for the Dutch and all Broadcasting and amateur telephony. Condenser Plates, Fixed or Moving, 1/- per doz.Post 3d. Washers for Fixed Plates, 3d. per doz.Moving, 5d. per do, Post, 2d. Threaded Rod for Spindles, etc., 5d. per foot.Post 3d. Nuts for same, 3d. per doz. 3" Semi -Circular Scales, o-ifio degrees, 8d. each.Post 2d. 11"Ebonite Knobs, with threadedcentre,6d.Post 2d. Pointers, 2d. each. Stop -pins, 1./- per doz. Bush and Loelmut,5d. Extension Handles, 4d. 'POst extra. Keystone Specially Treated Valve Legs or Sockets, 1/10 per doz.Post 3d. (complete with screws or nuts). Mark III Terminals, with nut and washer, 2/8 doz.Post 4d. RADIO CORD Vernier Condensers,3 -plate,8/-; 5 -plate,7/-.Post 9d. 7 -Strand Silicon Bronze Aerial Wire, per zoo ft., 4/-; per is. It., 5 9.Post 9d. and Fixing Connectors Best Shellac Varnish, 9d. and 1/8 per bottle.Post 68. and 9d. Copper Foil, per square foot, 6d.Post 28. forEffective Aerials Wood's Metal, 6d. per 1 oz. stick. Knife Switches on Ebonite, S.P.D.T., 1/6 ; D.P.D.T.,2/11 Post4d STOCKED BY ALL DEALERS IN Contact Studs, 1" diam., 10d. per doz; 5/x6 diam., 1/- per do,. Nuts for same, 3d. per doz Washers, 241. per doz. Post extra. RADIO MATERIAL. Filament Resistances for panel mounting, 3/9. These are only a few of the numerous items contained in our The catalogue, which will be sent free with order. EQUIPMENT & ENGINEERING Co. 2-3, NORFOLK STREET, STRAND, RADIO. ELECTRICAL & MECHANICAL SUPPLIES. LONDON, W.C.2 SCIENTIFIC SUPPLY STORES Wholesale only. 8. NEWINCTON CAUSEWAY, Telegrams : Kharparts Estrand, LONDON. LONDON, SE I. CityTelephone:io88 xxx THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 ALL BRITISH WIRELESS EXHIBITION & CONVENTION willbeheldatthe HORTICULTURAL HALL WESTMINSTER : LONDON :S.W.1 SEPT. 30THToOCT. 7TH (SATURDAY) (SATURDAY) This will be the most representative Wireless Exhibition everheldin GreatBritain THIS EXHIBITION has the full support of the trade THE CONVENTION will be held under the auspices of the WIRELESS SOCIETY OF,LONDON and all affiliated societies.

APPLICATIONS for stands will only be acceptedfrom BRITISH Alliedand Kindred Trades.

Applications should be addressed to THE ORGANISERS BERTRAM DAY & CO., LTD. WIRELESS PUBLICITY SPECIALISTS 9 and10,CharingCross,S.W.1 Gerrard8O63/4 AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxxi NOW READY The YEAR BOOK of WIRELESS Telegraphy and Telephony 1922 Demy 8vo. 1476Pages.Price 151- Nett. Postage 1 Abroad 1 /4. CONTENTS Record of the Development of Wireless Telegraphy-National and International Wireless Laws and Regu- lations-Directory of the World's Land and Ship Wireless Stations-International Allocation of Call Letters-Alphabetical List of Call Letters-Meteorological Section-International Time and Weather Signals-National Resumis of ProgresS in Wireless Telegraphy-Particulars of Wireless Telegraph Patents, 1921-Aviation Section-Tabular List of Aviation Stations-Useful Data Section-Wireless Terminology-Conventional Signs used in Wireless Diagrams-Companies Engaged in the Commercial Development of Wireless Telegraphy-Biographical Section-Literature on Wireless Telegraphy and Telephony-Directory of the World's Wireless Societies-Directory of Wireless Colleges and Schools-List of Licensed Amateur Transmitting Stations-Code Section-Special Articles on " The Earthing Resistance of Antennas," by Dr. Miessner-" The Recording of Wireless Signals," by Dr. Abraham-" The Birth and History of Long Distance Wireless Telegraphy "-" The Rectification Effect in its Reaction to the Composition and Structure of Crystals." A valuable feature of the present issue is the specially drawn map, which gives, for the first time, a simple means of finding the distance and true direction of Wireless Stations in all parts of the World,from London as the centre.

DSTEPT. W.W1243 HENRIETTA THE WIRELESS PRESS, LIMITED, .. STRANDLONDON.W.C.2

WITH GOOD APPARATUS YOU WARNING. CAN GET GOOD RESULTS MARCONI'S WIRELESS TELEGRAPH CO., LTD., v. THE " W.P. " A. C. COSSOR, LTD. Morse Practice Key Marooni's WirelessTelegraph Company, Limited, GIVE NOTICE that an ORDER was made Well Made. First-class Finish. Thoroughly Reliable in the High Court of Justice, Chancery Division, by Mr. Justice Russell on the 1st March, 1922, Price7/6 Post Free restrainingMessrs. A. C. Cossor, Ltd., from infringing the Marconi Company's Letters Patent Nos. 28413 of 1913 and 126658, except so far as THE WIRELESS PRESS, LTD. Messrs. A. C. Cossor, Ltd. manufacture for 12-13 HENRIETTA STREET. LONDON. W.C 2 H.M. Government. Messrs. A. C. Cossor, Ltd., were further ORDERED upon oath to DESTROY all articles and apparatus (other than those constructed to the order of H.M. Government) made or used by them in INFRINGEMENT of these patents, Questions and Answers and TO PAY THE MARCONI COMPANY DAMAGES AND COSTS. COUPON The M -O Valve Company, Limited, of Osram Works, Brook Green, Hammersmith, London, To accompany Questions W.6, is the only firm in this country licensed to manufacturethermionicvalvesunderthe sent induring the week patents belonging to the Marconi Company. commencing Aug. 5th, 1922. Any valve similar to those generally known as the " French type " constitutes an infringe. VOL. X, NO. 19. ment of the above patents whether manufactured in this country or imported from abroad. See Conditions on Page 603. Marconi House, Strand, London, W.C. 2. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 51922 THE ONLY WAY to prevent SURFACE LEAKAGE is to fit riZOlteit° COWL INSULATORS Patent applied for. which alone guarantee 1007. EFFICIENCY from Aerial to Instrument Rain, fog, soot and dirt are allelectrical conductors producing surface leakage which causes endless trouble, indistinct messages and often complete disorganisation. The " Crystor Cowl " Insulators are unique-madeofthebest quality Ebonite, they are absolutely essential to every aerial.Fit them NOW, and immediately youwillincreasethe efficiency of your receiver. AGENTS :-The " CrystorCowl " Insulatorswillbe used universally, and you will find them the best selling proposition in the industry. Order your stocks without delay. WIRELESS SUPPLIES CO. 64, MORTIMER ST LONDON, W.1

HorizontalWallor Window. LEAD IN Dia. of Cowl 2i". Dia. of Shank I". Vertical Roof Lengthonthe Curve 13" LEAD IN Aerial Insulator Price 10/6 post free. Dia. of Cowl 21". Length of Body 3" Dia. of Shank f". Dia. 1". Length Length Overall r x ". Overall 4". 2/6 each. Price 10/- post free. Set of four 10/ - post free. AUGUST 5, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxxiii

SIMPLICITY " K B " UNITS ECONOMY IMMEDIATE IMMEDIATF. DELIVERY EFFICIENCY SATISFACTION

By means of these units you can build up a complete one to seven valve receiving setin easy stages to suit your pocket ; while in the meantime, the units already bought are in themselves a complete receiving set, whatever their number may be.All you have to do is to place the units side by side straight across with the brass links provided. HERE THEY ARE:- UNIT No. 1. UNIT No. 2. UNIT No. 3. UNIT No. 4. CONDENSER PANEL. DETECTOR PANEL. "L.F. AMPLIFYING PANEL. H.F. AMPLIFYING PANEL No. Reqd. :Optional. No. Regd. One. No. Regd.:r, 2 or 3. No. Regd. :I, 2 or 3.

4). 40-4,

Price. Price. Price. Price. Complete (as above) 34/- each.Complete (as above) 34/6 each.Complete (as above) 43/6 each. Complete (as above) 33/6 each Set of Parts (panel only). Set of Parts (panel only). Set of Parts (panel only) Set of Parts (Panel only). 22/6 per set. 20/- per set. 33/- per set. 18/6 per set. Mahogany Cabinet 6/- each.Mahogany Cabinet 6/- each.Mahogany Cabinet 6/- each.Mahogany Cabinet 6/- each

We also hold large stocks of complete Receiving Sets,Coilholders, Coils, Variable Condensers (Assembled and in Parts), Valve Holders, Filament Resistances, H.T. Batteries, Accumulators,AerialInsulators ;infact ALL AMATEUR REQUIREMENTS. TRADE ENQUIRIES INVITED. CATALOGUE POST FREE 4d. COME AND " LISTEN IN " AT OUR SHOWROOMS. OPEN DAILY from 9a.m. till 7 p.m. THE " K. B." RADIO EQUIPMENT COMPANY, Head Offices & Showrooms: 109, High Road, Kilburn. N.W.6. Bus Services -8, 16, a & p, pass door. 3 mins. Kilburn Park Stn. (Bakerloo Ely.) ESESS WIRELESS Telephone Headgear Receivers RECEIVERS' ALL Resistances REWOUND Special Trade Quotations 4000 Ohms O: ND UPWARDS Send Enquiries- PREMIER TELEPHONE CO., PEP 12/-S ET -- 62. OXFORD STREET, W.I. G TURNOCK 41 HIGH ST ASTON SHAM 7

xxxiv THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5, 1922 EVERYTHING FOR WIRELESS Aluminium Condenser Vanes, 31", 24d pair. Specially Spacing Washers for fixed and moving plate, 3d. and 5d. doz. designed Brass Rod, threaded 3/16th, 6d ft. Brass Rod, 1" square, 4d. ft. ;3/16th round, for 31d. ft. Broadcasting Brass Hex Nuts, 1 4id doz. ;3/16th, ld each, 9d. doz. ;1", 1/3 doz.6 BA, 4d. ;5 BA, 5d. ;3 BA, 6d. ;2 BA, 7d. doz. Brass Strip, i" x 22 gauge, 2d. ft. ;1" x 21 gauge, lid. ft. Brass Tube, 5/16th bore, 8d. ft. ;3/16th X I", 4d. ft.All sizes tube fromoutside. Brass Screws, I" and 1", 4 BA or Whitworth, 9d. doz. Washers, all sizes, 3/16th and 2 BA, 2d. doz. Condenser Spindles, 1" square threaded top and bottom, for 25 plate condenser, 8d. each. Ebonite Knobs, 7d. ; tapped 1" whit., 8d. each. Extension Handles,1/- Engraved Scales, HEADGEAR 180 degs., 1/6. Stops, i threaded, 3d. pair.Knob with pointer, 1/-. Filament Resistance with Knob and Pointer, 3/9. RECEIVERS Grid Condenser and Leak, 2/6. Telephone Con- Designed and manufactured by denser, 2/6 each. Contact Studs, Id. and 2d. each. Copper leading Telephone Manufacturers. Foil, .005, 6d piece. Backed by many years' experience. Crystal Cups, 6d. Tested Crystals, 6d. Wood's Metal, 4d. Highestefficiency, concentrated Tuning Coils, with polished mahogany ends, 1,000 metres,12/6 ;1,500 metres, 16/6 ; magneticfield,instantaneously 2000 metres, 20/-. adjusted to the ears, comfortable Ebonite Sliders, 1/3. Brass Detector with vernier in wear, either receiver detachable adjustment, 5/- each. Ebonite Valve Panels,9" x 6" x i",3/- ; from headband, protected term- 4" x 4", 1/3 ;larger, 4/- lb. inals, lightweight, twin series cord. Ebonite Rod, 4", 6d. ft. ;7/18", 1/6 ft. ;11", 3/6 ft.Sheet Ebonite, 1", 4/-lb. ;3/16 and i", 5/- lb. Ebonite Discs to 3i" diameter, 1/4 each. A.T.M. LOUD A .T .M . Crystal Mica, best ruby, 2" x 4", forcondensers, SPEAKING DetectorSets 2d. each, 1/6 doz. RECEIVERS Highest Grade. Polished Mahogany Baseboards, 9" x 7" x f', Threetypesof 4/- each. Maximum Efficiency. Polished Mahogany, Boxes for Valve Panel, amplifyinghorn. ModerateCost. 9" x 6" x 1", 7/6each.. Lead-in Tubes, Ebonite and Brass, 1/-, tube 8d. ft. Crystal Receivers on baseboard with 4,000 ohm Ask yourdealerfor telephones, £3. A.T.M. Crystal Receivers inCabinet, with variable condenser and telephones, £4. Broadcasting Apparatus Single -valvePanel,with .00075variable, £4 10s. Two -valve Amplifier, £6 10s. Automatic TelephoneManufacturing Accumulators, 4v. 20a., 15/6 ;4v. 40a., 21/- ; Co., Ltd. 6v. 40 a., 32/6. Post Free on Orders Value £2. Head Office & Works : London Office : Milton Rd., Edge Lane, 6o Lincoln's Inn Fields J.BRIDGE & SONS, Liverpool. W.C. 2 . NELSON ST. WORKS, SOUTHEND-ON-SEA and 300, LONDON RD., WESTOLIFF-ON-SEA. AUGUST5, 1922 THE WIRELESS WORLD AND RADIO REVIEW

AN ENTIRELY NEW WORK. The ABC Telegraphic CODE 6th Edition FIVE-LETTERCODE. An up-to-date Work, ccr.t..ining Five letter Artificial Code Words with atleast a TWO -letterdifference and a TERMINAL -INDEX of the words at the end of the Book Cost of Cablirg brought to a Minimum::Simple to Use. PRICE£3 3S. Od.net (U.K. and Colonies.) Inland Parcel Post116 per copy. Continental Book 'Post 2J- per copy. Publishers:- EDEN FISHER & CO., LTD., 6, 7 & 8, Clements Lane, E.C.4 And 95, 96 and 97 Fenchurch Street, London, E.C. 3.

RADIO INSULATION AS SPECIFIED AND USED BY THE BRITISH ADMIRALTY

BRITISH M -+ DE PAXOLIN BRITISH MADE

TUBES DISCS PLATES, &C. MANUFACTURED IN ALL FORMS, SIZES AND THICKNESSES BY THE MICANITE & INSULATORS Co.LTD. EMPIRE WORKS WALTHAMSTOW LONDON, E.17

TELEGRAMS -" MYTI LITE, PHONE, LONDON.' TELEPHONES,-WALTHAMSTOW738, 739

Registered -NIPHAIN- Trade Mark. A.used by H.M. War Office, Electric Supply Companies, Railway Companies, Marconi's Wireless Telegraph Company WATER - TIGHT PLUGSSIMMONDS BROS., LTD. 4.6 & 8. NEWTON STREET. HOLBORN, W C and CABLE COUPLINGS e. TO MEET HOME OFFICE REQUIREMENTS

COUPLING CONNECTING Phones: Telegrams: 2600 Gerrard. 12061 Central. "Nippon, London." SIX WAY TEE CONNECTORS Patestixi in England and Abroad. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 5;92'2 AUCKLAND'S SPECIAL OFFER ! PRICES UNMOUNTED CRYSTAL DETECTORS Coil Wave Range Price No. .00r Mid Condenser hut7 in part. 1 . 130-250 2 . 180-450 213 a 25-700 4 . 400-1,200 4i- 5 .. 500-1,600 4,6 6 600-2,500 4,6

7 . 1,000-3,000 4/8 8 . 1,200-4,500 5/- 9 1,500-5.500 66 10 . 2,006-6,500 7//6 11 .. 3,000-7,500 8i- 12 . 4,000-12,000 9/- 13 6,000-14,000 9/6 14 8,000-18,000 10 - 15 :2/6 EXACT AS ILLUSTRATED 10,000-22,000 16 15.000-30,000 151 - BRASSWORK LACQUERED POLISHED BASE, WITH CRYSTAL. ...6/6 Mounted 3/6 each extra. Mounted Coil TABLE STAND FOR COILS

IVORINE SCALES 0-180° Each 10d. TELEPHONE CONDENSER SCALES TRANSFORMERS Engraved 0-180° with Knob and Bush '6/9

Regd. Design 688454. VALVE LEGS, with Nut and Washer, 3d. each EXACT AS ILLUSTRATED. VALVE PINS, with Nut and Washer, 24d. each Unmounted (as illustration), PRICE EACH 21/ - Suitable for 120 w Phones.

Unmounted .... I5/- In Box with Terminals.. 18,6 FIXED CAPACITY CONDENSERS ------11: ---- From '0002 to '005. SWITCH ARMS --...... erffteffinwommow.s. .a - Contact. BLeafrass Bush and Nuts. Each FILAMENT RESISTANCES 2/9 Resistance wound on Erinoid Former,knobfittedwith Over 4,000 told. brass bush and pointer. Price Price each .... 3, - 2/6 each. Thousands of these resistances are now in use. Mica Dielectric G. Z. AUCKLAND & SON 395, ST. JOHN STREET, LONDON, E.C.1 Manufacturers of Radio Apparatus Factories: ISLINGTON,N. Phone-CLERKENWELL 3173. Telegranar-"ZAUCKADIO, LONDON. -

IN Printed by Sanders Phillips & Co., Ltd., Chryssell Road, London, S.W.9, for the ka: .E.W:g:11 Proprietors and Publishers, The Wireless Press, Ltd., 12-13, Henrietta Street, London, AT:211,4E. Prif4.4 W.C.2 ;Sydney, N.S.W., 97, Clarence Street ;Melbourne, 422-24, Little Collins F.1761Frra Street; New York, 326, Broadway. 12th AUGUST, 1922. THE PRICE 6D'NET. WIRELESS WORLD AND RADIO REVIEW

OL. X. No. 20. Registered at the G.P.O. 12th AUGUST, 1922. as a Weakly Newspaper.

A New Condenser for WirelessReceivers THE DUBILIER TYPE 600 MICA CONDENSER

The illustrations show two types of this new condenser for wireless receiving circuits.These condensers have the same perfect mica insulation, the same high efficiency and the same permanence of capacity as the largerDubiiier Mica Condensers used in wireless transmitters.Distortion when receiving telephony is often due to bad design of the componentsof the receiver-therefore use effiUent Dubilier Condensers in your receiver to obtain the best out of your set. With Clips for Grid Leak. WithoutClips for (rid Leak TYPE 6 MICA CONDENSER MICA CCNDENSI,P DUBILIER DUSIL-IER CONDENSES COCO:12130. CONDENSER C0119Z4Up

PRICES. Capacities from 0'0001to0'0009 mid. ,, 0'001 ,,0'005 .,inclusive Condenser' complete with Grid Leaks TRADE TERMS ON APPLICATION. Both types of condenser (with or without clips for a grid leak)are fitted with screw terminals aswell soldered connections. as tags for making

THE DUBILIER CONDENSER CO. (1921),LTD., DUCON WORKS, Goldhawk Road, Shepherd's Bush, London, W.12 Telephone-Hammersmith 1084 Telerams-Hivoltcoa, Phone. London. Code-Marconi International All American Enquiries to be addressed- DUBILIER CONDENSER CO., Inc., 217, Centre Street, New York. THE WIRELESS WORLD AND RADIO REVIEW ArrarsT 1L, 1924

CAMBRIDGE THERMO-GALVANOMETER (Duddell'sPatent

For measuring extremely small alternating currents of high frequency

Will measure20 micro -amperes,or detect2micro -amperes, and can be usedforcurrentsof anyfrequency

Further particulars on request.

The Cambride andPaul

INSTRUMENT C9 LT WORKS '- N. 45. GROSVENOR PLACE LON orh _LONDON S W "Wireless for all" Before you decide on the construction of your set. It will pay you to have particulars of- Condensite Celoron For PANELS and OTHER PARTS. 4 This material is waterproof, immune to atmospheric and climatic conditions, will not warp, has high surface and volume restivity, high di -electric strength, low specific gravity. LET US QUOTE YOU SEND PARTICULARS OF YOUR EXACT REQUIREMENTS TO THE MANUFACTURERS

DIAMOND -FIBRE HIGH ROAD WORKS SOUTVI ToTTENHAM.NIS. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW iii

Fine Instruments for Library and Drawing -Room

THE H.P.R. UNIVERSAL Patent 3 -VALVE AMPLIFIER 158455 One rectifying, one H.F., one L.F. valve, as supplied to the Air Ministry. The H.F. circuit, which is tuned over the entire range from 150 metres to 30,000 metres, is of the highest possible efficiency, six patent H.P.R. tuneable II.F. transformers being employed. These are instantly changed and tuned in a few seconds without any difficulty. No loose parts. Easily operated by anyone-absolutely no technical knowledge of any kind required. Perfectly finished within and without. Each instrument certified and guaranteed. Demonstrated with pleasure. Price £40 : 0 : 0 This instrument, combined with the H.P.R. Universal Tuner, constitutes the handsomest, most easily operated, complete, compact and efficient:t -valve receiving station obtainable at any price. May be dismantled and re -erected in five minutes. Provision is made for the addition of further amplifying units (high and low frequency) as required.

Full particulars of these and many other instruments of convenience for expert and novice alike may be had upon application Trade Supplied H.P.R. WIRELESS, LTD. Pioneer Designers and Makers of Fine Value Receiuing Instruments for Amateurs Head Office and DemonstrationRoom : CARLTON HOUSE, GT. QUEEN STREET, KINGSWAY, LONDON, W.C. 2 Tel.: REGENT 1719 iv THE WIRELESS WORLD AND RADIO REVIEW AUGUST12, 1922

$ a CC? Std bi for ERICSSON PHONES

WHEN you instal your wireless set-crystal orvalve -you'll get maximum results if you fit Ericsson Phones-clarity, sensitivity, strength of signals and absence of " click."Specially suited to telephony. Ericsson Phones embody the accumulated experience of telephone manufacture for a generation. Easy to the head, light and comfortable.The magnets never lose their strength and "shorts- are non-existent. Write for 'Particulars I The BRITISH L. M. ERICSSON I I MANUFACTURING Co., Ltd. Head Office : 60, Lincoln's Inn Fields, E.C.2 I

Telephones

MUM IM=M1 RADIO INSULATION AS SPECIFIED AND USED BY THE BRITISH ADMIRALTY

BRITISH MADE PAXOLIN BRITISH MADE

TUBES DISCS PLATES, &c. MANUFACTURED IN ALL FORMS, SIZES AND THICKNESSES BY THE MICANITE & INSULATORS CO.LTD. EMPIRE WORKS WALTHAMSTOW LONDON, E.17

TELEGRAMS-"MYTILITE,PHONE, LONDON." TELEPHONES-WALTHAMSTOW 738,739 AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW

Everything intheEtherisyourswith certaintyif youuse BIRMINGHAM. MANCHESTER 133 NEW STREET. GI, BRIDGE STREET, DEANSOATE. LIVERPOOL: 1C, SOUTH JOHN L3URNDEPT LEEDS STREET. 48, GT. GEORGE STREET.

LONDON OFFICE & SHOWROOMS 15 BedFord Street. Strand. W.C.Z. For Broadcast and Concert Reception the Burndept Ultra II This Set will receive the broadcastconcerts loudly within 150 miles radius on headphones-within 50 miles radius of Londonor other high Pt) 4000 ohms power broadcasting stations it will receive on loud speaker.Extra note Phones magnification can alwaysbe addedifdesiredforlargehalls, ,Z,S) demonstrations, etc. Complete ULTRA II Set consisting of BurndeptTuner, Ultra II- Set short wave coils, pair Brown's 120 ohm Phones, 2 Marconi Valves, 6 volt 60 amp. Accumulator, 60 volt H.T. Battery incase, Aerial 120 Ohms wire and Insulators. Phones £ 30 - 0- 0 Packed free.Prompt delivery THE ETHOPHONE No. 1 (Trade Mark) This Instrument has beenspecially designed for Price : 112 10 0 the (without Valves) receptionofBroadcast Music,Speech,etc. It can be used with satisfaction by two listeners at the same time. Receiving ri.dius 25 to 4o miles cf transmitting stations. A special arrangement is ir.c:uded which permits reception of time signals from Paris. THISSET COMPLETE AND READY FOR USE includes one good Let of High Resistance Phones. Coil cf Aerial Wi.eInsulators and complete instructIms. No:knowled&e:(f Wheless !Nuked to overate.Price £8 - 0 - 0.Packing and Postage free. SHORT WAVE (CONCERT) COILS.These coi's have been specially designed for BROADCASTING and NEW AMATEUR WAVELENGTHS. They are3" in diameter and mounted on standard BURNDEPT coilplug so that they are interchangeable with BURNDEPT PATENT COILS. The new coils (4in number) replace Burndept Coils No. 25 and 5o which are now discontinued.Price (set of 4 coils) 25/-.Wavelength range approx. 050-750 metres in conjunction with '00075 mfd. variable condenser (BLRNDEPT VERNIER). ILLUSTRATED CATALOGUE post free 6d. ;returnable with first order.This gives full details of our ABSOLUTELY COMPLETE receiving equipment for ONEup to FOUR VALVE Sets. PRICES RANGE PROM' £21. MANUFACTURERS OF WISEL' SS APPARATUS BURNDEPT LTD*, AERIAL WORKS, BLACKHEATH, LONDON, S.E.3

The Western Counties Electrical &Engineering COMPANY Telegrams-" Electron, Yeovil... Telephone -223 Yeovil Electric Lighting a Polder Engineers MIDLAND BANK CHAMBERS, YEOVIL. SOLE AGENTS fel MESSRS. BURNDEPTLTD. /or South -Midland altd South -Western Counties (exceptingthe City o/ Bristol) to whom applications for sub -agencies /or tliktarea should be adtbessed.

2 AUGUST 12, 1922 V THE WIRELESS WORLD AND RADIO REVIEW THE ONLY WAY TOPREVENT SURFACE LEAKAGE is to fit 11130..UDIT COWLINSULATORS (Patent applied for) 100% EFFICIENCYGUARANTEED Rain, fog, soot and dirt are allelectrical conductors producing surface leakage which causesendless trouble, indistinct messages and often completedisorganisation. The " Crystor Cowl " Insulators areunique-made of J. the best quality Ebonite, they areabsolutely essential to every aerial.Fit them NOW, and immediately you willincreasetheefficiencyof your receiver.

HERE IS REAL PROOF Horizontal OF THE EFFICIENCY OF Wall or Window LEAD IN

Wireless Supplies. Headingley. Arnold Road, 64, Mortimer Street, w Clacton -on -Sea. 26/11 July, 1922 Dear Sirs, As promised, Ilet you know that 1 succeeded in catching up the WRITTLE Concert last eve- over 40 MILES AWAY.Will call when near Dia. of Cowl 2i". A. J. PAINE. Dia. of Shank I". your address. Length on the Curve I 3" NEED MORE BE SAID ? Price 10/6 post free. CompleteSets from£2100

AERIAL INSULATOR Length of Body 3".Dia. If. Length Overall 4".2,6 each. WIRELESS Set offour 10/-postfree. SUPPLIES CO. VerticallRoof 64,MortimerStreet, LEAD IN LONDON, W.1 Dia. of Cowl 2i" TelephoneMuseum 2672 Dia. of Shank Length Overall 11" Price 10/- post free. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW vii ESLE IC PROVIDENCE PLACE, WEST END LANE, KILBURN,N.W.6 Bs Ser.,:ce. 1. 8.16. 28.31 all',lossWesf EndLane Telephone HAMPSTEAD1261 Nearest Tube Station: KILBURN PARKABAKERLOO)

BROWN'S iTELEPHONES GUARANTEED IN PERFECT CONDITION.These Type A (Reed type of tele )2)1) ye el:311330in erary way. They are recogniiel as the ft 283t prodyiel,are unused and guaranteed in perfect condition. BROWN'S BROWN'S HIGH RESISTANCE LOW RESISTANCE TELEPHONES TELEPHONES 8,000 ohms. 120 ohms. Price 55/- Per Pair To get the best Price 50/- Per Pair from your set use thebestphones : ILLUSTRATED CATALOGUE ILLUSTRATED CATALOGUE 16 Pages..100 Illustrations. B R OWN'S 16 Pages.100 Illustrations. Write for Catalogue (W) Write for Catalogue (W) 8d. post free. 6d. post free.

Catalogue(W)includeslistof Catalogue(W)includeslistof Complete Crystal and Valve Sets Complete Crystals and Valve Sets from 93/- post paid. from 95/- post paid. There is n1 Telephone Headgear in the World so Sensitive and so Comfortable to Wear. We hold the largest Stock in the country of Disposal Board Apparatus, tuners, receivers, amplifiers, etc.

KTEC HIGH TENSION DRY BATTERIES for WIRELESS SETS

L NORMAL SIZE, No. W 7o V, x5 Volts W yr V, 5o Volts GIANT SIZE, No. W 73, 15 Volts Price 5/- Price 15/- Price 6/6 ,SUPPLIED IN TWO SIZES FOR 15,50 or 60 VOLTS. and with Tappingsin3VoltSteps. ALL BATTERIES FITTED WITH PLUG SOCKETS AND MOVABLE TERMINALS. Complete Illustrated Price List on Application. THE EFANDEM CO., LTD., FALLINGS PARK WORKS, DRY BATTTERY MANUFACTURERS WOLVERHAMPTON iii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 BATTERIES FOR WIRELESS High Tension Block Accumulators Fuller "Chad" Batteries

FullerPlate and Patent Block Cells (4 and 6 -volt sets) are eminently suitable for Wireless Work.

4 Block Accumulators, unlike the ordin- Designed for use in supplying tFe ary Plate Type. retain their energy anode (sheath) circuit of thermionis for 12-18 months on one charge. valves for receptionpurposes. Unequalled for use with Wireless Expert tests inevery case confirm Thermionic Valves.Standardised itssuperiority overtheStandard sizes-li and 3 A.H. capacity. Battery usually employed. Last much longer than ordinary Dry No.of cellsVoltage. Capacity Price Type Cells, free from risks of leakage and short circuits. A xx/Z x2 24 11. A.H. 150 A 3o/Z 3o 6o xi A.H. B1000 Type No. of cellsVoltageCapacltyA.H. Price 8 12 I approx. C. A II/K 12 24 3 A.H. £5150 A A 3o ,K 3o 6o 3 A.H. £12100 I0 15 I approx. 7/- 8 52 41approx. 11/9 EBONITE-Rod, Sheet and Tube 13 to xs 4i approx. 16/ -

FULLER'S UNITED ELECTRIC WORKS, LTD. tprMICAl woR WOODLAND WORKS, CHADWELL HEATH, ESSEX. Telegrams:Fuller, Chadwell Heath." Telephone :Ilford 171 (4 lines), London Telephone Area. vocovagrau._

FOR YOUR AERIAL

' oo ft. 7/22 COPPER 06 WIRE, 4 REEL IN- SU LATORS, 20 yd. SKEIN ROPE CORD, MAST PULLEY,COMPLETE TRADE MARK Post free British. LEAD -IN -TUBE. Isles Henry J. Brewster & Co. The WHITECROSS 11, Queen Victoria St., London, E.C.4 COMPANY, LIMITED UNIT SYSTEM ::WARRINGTON has proved its efficiency Write for Manufacturers ofAllDescriptions of ILLUSTRATED CATALOGUE which contains an article on WIRE ROPES Wireless Made Easy and a Complete List of all Wire- less Goods in Stook AND WIRES WriteforIllustrated Catalogue 3d post free 92, Queen Street, W. R. H. TINGEY Hammersmith. London.W.8. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW WIRELESS EQUIPMENT LTD. TeL Telegrames : GERRARD RADIO ENGINEERS AND MANUFACTURERS WIREQUIP 6785. :: WESTCENNT APPARATUS AND SPARES .. . LONDO WRITE FOR OUR ILLUSTRATED LISTS OF. SETS AND COMPONENT PARTS. 3d. POST FREE Head Office :90, CHARING CROSS ROAD LONDON, W.C.2 THE WIRELESS WORLD AND RADIO REVIEW THE OFFICIAL ORGAN OF THE WIRELESS SOCIETY OF LONDON A MAGAZINE DEVOTED TO WIRELESS TELEGRAPHY AND TELEPHONY CONTENTS Wireless and Meteorology. By W. G. W. Mitchell, B.Sc., F.R.A.S., F.R.Met.S. 609 Some Experiments with a Kite Aerial.By E. S. and J. C. - - 614 An Anti -Radiation Circuit.By G. P. K. - - 615 A Four -ValveStationsuitablefor Short Wavelengths (continued).By Percy W. Harris ------616 Contents continued on next page.

RADIO TELEGRAPHY Si TELEPHONY ALL YOUR REQUIREMENTS SUPPLIED FROM STOCK. PULLEY BLOCKS, best galvanized, as illustrated, 2/8 post free, SPREADERS, finest stout ash, free from cracks,6' x I" diam., 3/. each.Carriage 6d.extra. AERIAL WIRES, best quality only supplied.Phosphor Bronze - 7/20, 18/- ; 7/22.13/6 ; 7/25,7/-.Copper -7/1o, 15/-;7/22, WC; 7/25,8/..All per Jr'coil.Longer or shorter lengths. supplied at proportionate prices.

SHELL INSULATORS. Green porcelain,size " A."21"square, weight 4 ozs. Price1/8 each.Size " B," 3"square, weight 6 ozs. Price 2/! each. EGG INSULATORS. As illustrated, size ir as'. Green porcelain.Price 86 . each.Postage extra. REEL INSULATORS. As illustrated, 1' diam., white porcelain, per dozen, 2/3, post free. I LEAD-IN INSULATORS, as illustrated, g' long, 3/. ;/2"long,3/3.Postage 4d. extra. 0)11.11.111111.11.1.0-----& 32 PAGE ILLUSTRATED CATALOGUE 7d. POST FREE. (DEPT. 1).236, HIGH HOLBORN, LONDON, W.C. 1 RADIO SUPPLIES 'Phone-Museum 6894. III Ell THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922

acquirea soundtheoreticalandpractical NOW IS THE TIME toknowledgeof THREE ELECTRODE VALVES, (as applied to C.W. Radio -telegraphy andRadio -telephony), by means of my POSTAL INSTRUCTION COURSE. PerfectlySimple 2/Lt. E.REDPATH, 71ray I Send you Particulars? 19, Niger St., BARROW-IN-FURNESS

CONTENTS(Continued) The Principles of Tuning in Wireless Telegraphy.By C. E. Field, B.Sc. 620 A Liverpool Amateur Receiving Station.By Samuel Lowey - 624 International Amateur Wireless - 627 Notes - 628 Calendar of Current Events 629 Wireless Club Reports 330 Questions and Answers 633 Share Market Report - 640

THE WIRELESS WORLD AND RADIO REVIEW is published weekly on Saturdays. All correspondence rerating to contributions should be addressed to THE EDITOR, THE WIRELESS WORLD AND RADIO REVIEW, 12-13, Henrietta Street, London, W.C.2. No responsibility can be taken for MSS. or photographs sent without stamps to defray cost of return postage. Editorial and Publishing Offices, 12-13, Henrietta Street, Strand, London, W.C.2. Telegraphic Address :" Radionic, Rand, London."Telephone No.: Gerrard 2807. Advertisement Managers, Bertram Day & -Co., Ltd., 9 & 10, Charing Cross, S.W.1. Telephone No.: Gerrard 8063 and 8064. SUBSCRIPTION RATES. - 28s. per annum, post free.Single Copies 6d. or post free 7d. Registered at the G.P.O. for transmission by Magazine Post to Canada cE Newfoundland.

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VOL. X.NO. 20. AUGUST I 2 TH, 1922. WEEKLY Wireless and Meteorology By W. G. W. MITCHELL, B.Sc., F.R.A.S., F.R.Met.S. THERE are many _classes of the com-they were not ..sufficiently comprehensive for munity to whom the weather conditionsthe more immediate needsof war.The are of the utmost importance.Theimpetus given by the war has no doubt brought aviator, the sailor, the farmer, the holiday-about a more general interest in meteorology, maker and motorist are all interested in theand the immense amount of data now dealt weather, though in very different ways.Forwith requires the use of a code for the sake of whereas some of these are chiefly interestedbrevity. in present weather conditions over a large In theorganisation of ameteorological area,othersare more naturally concernedservice three problems are involved, namely, with future weather conditions spread overthe collection, exchange and distribution of a considerable period of time (i.e., in weatherreports.The following brief outline deals forecasts).Yet again, for each of the classeswith the services undertaken in this country :- mentioned there are problems of very special (i) The collection of observations of present concern. The aviatorismore naturallyweather from a number of stations embracing interested inthe strength anddirection ofthe British Isles and the surrounding regions. the wind and thevisibility and amount ofNearly 6o stations are now included in this cloud in the atmosphere above the ground.network and report daily to the Meteorological Thisisspeciallysointhecross -channel Office at the Air Ministry.In this country flights (see Fig. 1).The farmer, on the otherreports are collected by W/T from about ten hand, naturally seeks information of futurestations, and the remaining reports are col- weather, likely rainfall and sunshine.It willlected by telegram and in certain cases by thus be apparent that any organisation which telephone.The reportingstationsareof attempts the dissemination of meteorologicaldifferent kinds :- data must be far-reaching both in regard to (a) A first -order land station or normal the area covered end the diversity of the Meteorological Observatory is one at which elements recorded and transmitted.But in continuous records or hourly readings of any case there must be included a great deal thefollowing elementsare taken :air of information which does not interest in- pressure, temperature, wind, sunshine and dividual members of the community.This rain, with eye observations at fixed hours difficulty has to some extent been overcome of the amount, form and motion of clouds, in France by the issue of a special " Agricultu- together with notes on the weather. ral meteor " at 0710 G.M.T. daily, intended (b) Second -orderstations:observations forfarmers.Forthispurpose Franceis are recorded daily at two fixed hours at divided into severalregions and a forecast least of pressure, temperature (wet and dry for the next 24 hours for each district is sent bulb), wind, cloud and weather, with daily in plain language by telephony. maxima and minima of temperature, daily During the war,the demand forearly rainfall and general remarks on the weather_ meteorological information became very acute, In some cases the duration of bright sun- and although codes for use in weather tele- shine is added. graphy had been devised as far back as 1875, (c) Third -order or auxiliary stations are 610 THE WIRELESS WORLD AND RADIO REVIEW .Aucturn 12, 1922 of the same kind as (b), but report eithe observatories in Europe.Reports from ships (i) less full or (ii) observations taken onceon the Atlantic are also received by W/T and eday only, or (iii) observations taken atare often of great value to the professional other than the recognised reporting hours.meteorologist at headquarters when making Besidesreports from these6ostations, aforecast.They areoftenindicativeof the .Meteorological Office exchanges reportsimpending changes on the western seaboard, with nearly all the principal meteorologicaland their value will be referred to later.

LONDON -CONTINENTAL AIR ROUTES. LATEST WEATHER REPORTS. ff,

[EXPLANATION i LVII13.1uf -. 6 ecLacs 1.6 MR .6 -.a

L Theatres lees eta the Isired2. Amtarral Station &Noel releeity nooks hew 4.AtemeerStetion &MeeorObserve, too ,t1/Ieethee 7 Height of lome,t nie« 8 DiStanee of ,i,obi/ilL 9 Distance of ovhilit. A...aeon-v.1,

PARIS

Fig.i.Weather chart for the guidance of pilotsattheLondonTerminal Aerodrome. The chart gives in a graphical form, information of great value to the airman.Wind, weather, cloud and visibility observations along the route are shown by means of the arrows and indicators which are frequently " set " by the meteorological staff at the Aerodrome from reports received by WIT. AUGUST 121 922 THEWIRELESS WORLD AND RADIO, REVIEW 611 The central Meteorological Office translatesThey are the basis of modern forecasting. the individual reports into a graphical formThe trained meteorologist thinks in maps. by entering the chief elements on a map. The most general thing which could be These maps, or synoptic charts, give a generalsaid about the weather is that it is constantly impression of the present weather at a certainchanging, or perhaps more precisely,itis instant of time over a very large area (comparedconstantly subject to change.Itisconse- with the area covered by individual reports). quently necessary to devise means for rapidly

Fig. 2. Croydon Aerodrome Meteorological Station. " Atmospheric" D.F. Apparatus, or " Thunder- storm Finder "-an auxiliary investigation carried out in the field of meteorology by means of wireless. 612 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 making known in a comprehensive form theIn drawing any conclusions from asingle various changes which are going on in theinference,greatcaremust beexercised. atmosphere.As we have indicated, beforeHowever, if this inference is used in conjunc- the war there was no national distribution,tion with a synoptic chart drawn up a few although some headway had been made by thehours previously (as for example those pub- publication of charts and forecasts in thelished in several of the daily newspapers), daily newspapers.Information through thesea good general idea of the changes likely to channels was of necessity several hours old.come about in any particular area can generally WIT furnishes a means of rapidly broadcastingbe estimated. A similar forecast is issued for this information. the " western seaboard " from Clifden, and The distribution now carried out by W/Tparticulars of these transmissions is given in fromtheMeteorologicalOfficecomprises the table below :- three distinct forms of report. (/3) Coded forecasts for various districts in (a) The " general inference " which is issuedthe British Isles are also issued.They are in plain language (Morse code) at 0915 andsent in code for the sake of brevity, but they 2000 G.M.T., and of which the followingwould be of greater value if they could be isa specimen :Saturday, July 29,1922. sent in plain language in a similar form to " Generalinferencefromobservationsat the French agricultural meteor. 7 p.m. (18 h.) :-A secondary depression has The districts covered are roughly as fol- developedoff South-westIreland and willlows :- probably move north-eastward, causing rain Group Ill.-Southern England (central in the west and north.Over the midland, part) :Dorset, Wiltshire, Berkshire, Hamp- southern and easterndistrictsthe weather shire. is likely to continue mainly fair with moderately Group 222.-South-east England :London, high temperature."This general inference Middlesex, Essex, Surrey, Sussex and Kent. embraces the whole of the British Isles, and Group 333.-Yorkshire, Lincolnshire, Not- its very general character is evident at once. tinghamshire.

STATIONS TRANSMITTING METEOROLOGICAL INFORMATION IN GREAT BRITAIN.

I Call Wave - Station. Sign. Latitude.1 Longitude. length. Nature and Time of Transmission (G.M.T. )

Air Ministry GFA 51°31'N. 0°07' W. 1,400C.W. Synoptic data for 0100 sent at 0200. Air Ministry GFA 51°31'N. 0°07' W. 4,100C W *Synoptic data for 0100 sent at 0600. Air Ministry GFA 51°31'N. 0°07' W. 4,100C.W. Synoptic data for0700sent at0800. Air Ministry GFA 51°31'N. 0°07' W. 4,100C.W. Synoptic data for1300sent at 1400. Air Ministry GFA 51°31' N. 0°07' W. 4,100C.W. Synoptic data for 1800 sent at1900. Air Ministry GFA 51°31' N. 0°07'W. 1,680 C.W. Aviation reports at0335, 0435, 0535, 0635, 0735, 0835, 0935, 1035, 1135, 1235, 1335, 1435, 1535, 1635. Air Ministry GFA 51°31' N. ' 0°07' W. 1,300C.W. Coded district forecasts sent at0900 (approx.), 1500 (approx. )and2000 (approx. ) Air Ministry GFA 51°31' N. 0°07' W. 4,100C.W. General inferences sent at0915and2000. Clifden MFT 53°27' N. 10° 1' W. 5,750spk. Western seaboard forecastand data (Ireland) issued at0950and2150. Croydon ..GED 51°21' N. 0°08' W. 900C.W. Radio -telephoniccommunicationwith aircraft in flight. Lympne ..GEG 51°05'N. 1°01'E. 900C.W. Radio -telephoniccommunicationwith aircraft in flight. Renfrew ..GER 55'52'N. 4°24' W. 900C.W. Radio -telephoniccommunicationwith aircraft in flight. Renfrew ..GER 55°52'N. 4°24' W. 1,300C.W. Meteor reports to Air Ministry at 0705, 1005, 1305, 1605, 1805. Lerwick ..GEL 60°09'N. 1°10' W. 900spk. Meteor report (Reykjavik) to Air Ministry at1005.

* Note.-In cases of breakdown of the main set or other delay in commencing transmission on 4,100 m. the message will be issued on1,400m., commencing 10 minutes after the routine time. AITGR/ST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW 613 Group 444.-South-east Scotland(placesmethod adopted will be givenin a future within a 5o mile radius of North Berwick).article. Group 555.-South-west England :Devon- The table on page 612 gives a complete list shire and Cornwall. of regulartransmissionsof meteorological data in Great Britain. Group 666.-North-west district :Lanca- The main problems involved in the applica- shire, Cheshire, Shropshire and Northtion of W/T to the science of meteorology Wales. have been indicated above.There are, of Group 999.-England and Southern Scotlandcourse, other matters such as the electrical, taken collectively.The forecast for thisoptical and acoustical phenomena occurring groupisappendedtothe" generalin the atmosphere which are closely allied to inference " issued at 2000 G.M.T. to the science of meteorology. Among these (y) Synoptic reports are issued in code. Theauxiliary problems, W/T has been used in informationcontainedinthesemessages,the location of thunderstorms.Fig. 2 shows when plotted on a chart, graphically describethe form of direction finding apparatus em- the distribution of barometric pressure (re- ployed at the meteorological station at Croydon. duced to sea level and to a temperature ofA frame aerial is installed in the room above 32° F. in latitude 45°), the direction and velocitythe instruments. A wavelength of 30,000 of the wind, the state of the sky and/or seametres is used, and the number of " atmos- and the character of the weather from simul-pherics " heardindifferentdirectionsin taneous observations taken atcertain fixed15 seconds is counted.During the war this meteorological stations on land snpplementedmethod wasextensively used by the D.F. by information transmitted by ships.Tostationsof the Admiralty inlocating the make full use of these transmissions, the ama-positionof thunderstorms bydetermining teur requires some knowledge of the principlesthe directionfrom whichtheradiodis- of meteorology.A brief explanation of theturbances created by a storm were received.

Litzendraht Its value in the Construction of Tuning Coils.

IT is not generally realised, I think, what a withreaction,for some authorities,while great aid to efficiency is to be found in agreeing that it can compensate for the flatness the use of Litzendraht for tuning coils.of tuning which results from high resistance It is perhaps as well to explain here that this coils, hold that reaction cannot altogether make is a form of wire made up of a large numbergood the loss of signal strength. of fineseparately insulated strands, which The only difficulty likely to be met with in has the valuable property `of very law high -using Litz is the matter of making connection frequency resistance (that is, when comparedto the ends of the coil.Soldered connections with a solid conductor of equivalent directare absolutely essential, and care must be current resistance).Such wire is extremelytaken to see that every strand is well tinned desirable in all circuits whose damping cannotand soldered into the joint.If the strands are be annulled with reaction, such as the aerialenamelled and silk -covered it may be found a circuit of a loose -coupled tuner where thelittle difficult to bare them for tinning without reaction coil is coupled to the secondary circuit,damaging them. The safest way to do it is its use giving stronger signals and sharperto carefully scrape off the silk and then burn tuning.The objection to Litz, of course, isoff the enamel by placing the wire momentarily its cost, but this is not every heavy for short-wavein a -relatively cool flame, such as a match or coils, and it is greatly to be desired for all wavescandle.Morecarefulscrapingwillthen below 60o metres.It is even arguable thatproduce a clean surface to tin. it should be used for circuits which are boosted G. P. K. 614 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 Some Experimentswith a Kite Aerial By E. S.AND J. C. THERE will be some amateurs who aremight mention that a winch constructed out thinking about field days with a portableof a large sea -fishing reel was used to wind set now that the fine weather is here.in the wire.The antenna system was com- Their thoughts may naturally turnto thepleted with an earth pin, simply a 2 -ft. brass possibilities of a kite aerial. The writers give below some details of the results of several outings spent on the Yorkshire moors with a valve set and a kite aerial. The receiver was a Mark III converted to a single valve set with a wavelength range of 16o to zo,000 metres.The accumulator and H.T. were carried in a separate box.The aerial, a kite, was constructed on the following lines, after the well-known " fin " type.The length was 6 ft. and the greatest breadth 4 ft. Two strong bamboo canes formed the sticks ; light calico was used for the covering.The complete kite weighed 14 ounces. A " tail " consisting of six dusters and handkerchiefs was used. We first tried an aerial of zo S.W.G. steel piano wire, to be on the safe side for strength and as a guide to the lifting power of the kite.In a light wind, about 10-20 m.p.h., the kite easily lifted 60o feet of this wire and remained flying very steadily. We

Kite -lifted aerial comprising 600 ft. 20 S.W.G. steel piano wire. rod driven intotheheather anda ,lead soldered on. We tried- reception on the above aerial, inefficient as it must have been, with 60o ft. of wire out. The long wave stations, Carnarvon, Rome, Lyons, etc., came in louder than on two valves with a good P.M.G. aerial.The aerial was reeled in for 30o feet for shorter waves, a small series condenser being used. Ship stations could be read with telephones on the ground.The strength of signals on the lower waves, 30o to 450, was extremely good. 2 FQ, both speech and music, was heard nicely until BVN chipped in and about burnt the telephones out !Local amateurs, 2 .QK especially, were very strong.On these short waves we found no fluctuation of wavelength from any swinging of the aerial. Kite used in successful experiments with portable Encouraged somewhat by the results obtained aerial. from the steel wire we tried one of copper, AUGUST 12, 1922 THE WIRELESS WORLDAND RADIO REVIEW 615 bare 20 S.W.G., using the same tackle astried a counterpoise earth, simply a 30o ft. before.Results with this were considerablylength of bare copper wire, i8 S.W.G., laid better of course and, sinceit was Sundayalong the top of the dry heather directly under afternoon, we tested signals on the Dutchthe aerial and connected to the earth terminal. concert.This came in comfortably strongSignals were not much stronger by this method, and with astage or so of low -frequencybut it was found that the set would oscillate amplificationwould have been readable outmuch more readily and enabled us to get of a loud speaker. down to a lower wavelength, using more aerial wire than before. Inconclusion,we would state that care shouldbetakenin handling alongkite aerial,as quite large static charges are collected. We could easily draw small sparks by touching the aerial terminal with the finger. If a very small variable condenser, air dielectric, is used in series with theaerial,the ac- Mark III Receiver converted to single valve set with 16o to 20,000cumulatedchargeof metres range. staticintheaerial periodically" jumps " Of course we hadthe usualinterestedthe plates and a continuous ticking is heard passers-by who wanted to listen to " wirelessin the telephones. music," and there was some competition for Our height above sea level was about 95o the spare headphones. feet, that isto say, for the bottom of the As a comparison with the earth pin we aerial ;the direction of wind was W.N.W. An Anti -Radiation Circuit THOSE amateurs who use the well- known " tuned plate circuit " method of H.F. amplification have it in their power to adopt an extremely simple device to prevent radiation from their sets when oscillating.The device, though not new, is by no means so widely known as it deserves to be. It consists in reacting into the tuned plate circuit instead of the aerialcircuit, and it results (in the case of a well -arranged set, i.e., one in which the various circuits are well separated) in complete freedom from radiation when the set is oscillating for the reception of C.W. or searching for carrier -waves.(Itis surely unnecessary to explain that no set should ever be allowed to oscillate when receiving telephony ?) react intothe aerial circuit, and secondly, The arrangement of a typical circuit em-that since the damping of the aerial circuit ploying this device is shown in the figure. can no longer be reduced with reaction it must Two points which should be noted are, firstly, be kept as low as possible by using low -resistance that the reaction coil only needs about half thewire and the very best of insulation throughout.. number of turns which would be required to G. P. K. 616 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 A Four -Valve Station Suitable for Short Wavelengths (continued).

By PERCY W. HARRIS.

3.-THE TWO -VALVE L.F. AMPLIFIER (con- In the first place, this note -magnifier unit tinued from page509). is designed to work off the same accumulator THE third unit of the four -valve setas the previously described H.F. and detector is a two -valve low frequency amplifier,unit, and a separate H.T. battery need not fitted with a switch so that one or twobe used.It will be noticed that there are stages of note magnification can be used atH.T. terminals on each of the two units.

Fig. I.Photograph of the two -valve amplifier.

will.The general appearance of theunitWhen both units are used together the H.T. can be gathered from the photograph, Fig. I.battery should be connected to the terminals The constructionindetailisshownin on the note -magnifying unit, those on the the drawings.The circuit is of conventionalH.F. and detectorunitbeingleftdiscon- design, but there are one or two details whichnected. require special mention. The secondpointistheprovisionof AUGUST 12, 1922 THE WIRELESS WORLDAND RADIO REVIEW 617 terminals for grid cells or potentiometer. Adescribed by which the telephones could be study of the valve as an amplifier shows that,connected to the plate of any particular valve with most valves, much better results areof a multi -valve set, the valves not in use being obtained if the grid is maintained at a constantswitchedoff.In the case of the writer's negativepotential.This negativepotentialinstrument the method was not entirely appli- can be obtained either with a potentiometercable as it stood, as it was desired to use but connected to two or three dry cells or by placingone filament rheostat, for the reason that both one or two cells in the circuit of the grid.Thevalves perform the same function and can be first arrangement yields a finer adjustment, controlled together.When only one filament but has the disadvantage that the cells arerheostat is used for two or more valves, switch- continually running down through the windinging off one of them will mean a sudden increase of the potentiometer.Grid cells in circuitin brilliancy of the remaining valve or valves, can be varied only in steps of ii volts, but which is undesirable.The switching method will last for a long period as the current taken was therefore modified so that besides changing

Fig. 2.The lay -out of the panel. from them is extremely small.In the instru-the telephones from one plate to another, ment described, terminals are provided forwhen the first valve only is used, the plate grid cells, and the writer usually connectscircuit of the last valve is broken.So long two or three cells in series between the terminals as both valves are in their sockets both filaments marked.If desired, theterminals can bewill be alight, even if one is not in use.When shorted, whereupon the grid is maintained atone valve alone is used for a considerable approximately zero potential, but distinctlyperiod the second can be removed from its better resultsareobtainedwithcellsin socket and the filament resistance readjusted. circuit. Of course, if two separate filament resistances The switch to change from one valve to twoare used, the switch can be made to break the is of the telephone switchboard type.Thefilament circuit of the second valve instead of method of switching was suggested to thethe plate circuit.The writer did not consider author by thearticleinthe Mayi4th,the advantage so gained to be worth the cost 1921 issue of The Wireless World, p.i18.of a further filament rheostat, but others may In thearticlereferredto, a method wasthink differently.The modification necessary B 2 618 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 12, 1922 to arrange this will be understood on studyingtake a file and carefully file away the ebonite the circuit diagram, Fig. 4. until the limits of the marking are reached. Two fixed condensers are used, one acrossIt is not easy to do this, but on the other hand the high tension terminals (am mfd.) and oneit is not so difficult as it sounds. across the telephone terminals (ix ooz mfd.). Theintervalvetransformersshouldbe This last is not very important in practice.chosen carefully, and the dealer from whom All connections are soldered and the con- they are purchased should be asked what type densers are secured by the method describedof valve they best suit.Certain transformers in the last article. work best with certain valves.The army As first made up, the set was found tointervalve transformers,for example, work be oscillating at a frequency above audibility,very well with V24's.Beware of cheap inter - the amplification suffering considerably.Thisvalve transformers of unknown make.They was at once remedied by connecting togethermay burn out with strong signals and prove the primaries of the transformers in the way very expensive in the long run.

0 o0

OP o's ^005

Fig. 3.Wiring of the instrument. shown.At the same time the two cores were The transformers are best secured to the connected together, and to the positive polepanel by drilling holesright through the of the H.T. battery.By making these twoebonite of a size sufficient to allow clearance modifications all trouble from self oscillationfor a 6 BA screw with cheese head.The ceased and the magnification was all that couldupper part of the hole should then be recessed be expected. with a drill of the size of the cheese head for In view of the fact that full constructionaljust sufficient depth to allow the cheese head details were given in the previousarticle, tofitflush when in place.To mark the little need be said here regarding the actualposition of the holes place the transformer in fitting of parts and the connecting up.Theposition and pencil through the openings in most difficult matter is cutting an oblong holethe frame. When the holes have been drilled to take the telephone switch.To do this,and the screws pushed through, the transformer mark out on the panel the shape and size ofcan be fitted over them and secured with nuts the hole and then drill a number of round holesas shown. ntil the middle of the square falls out.Then Whatever transformers are used, see that AUGUST 12, 1922 THE WIRELESS WORLDAND RADIO REVIEW 619 the I.P., 0.P., I.S. and O.S. terminals aretaken across the instrument.All tuning con- connected as shown. densers will then be in front of the set. Other constructional details will be evident It is always advisable to use a telephone trans- from the Figures1, 2, and 3.If desired,former, and this is best fitted in a separate clipsfor V.24 valves can be fittedinsteadbox which can be connected either to the outof four -pinsockets, asthe V.24isa veryput terminals of the two -valve H.F. and good L.F. amplifying valve with most trans-detector unit, or to the output terminals of formers. the note -magnifier unit.In this way, with only one telephone transformer, the set can be used with two, three or four valves and with a minimum of switching. When listening to telephony it will rarely be necessary to use all four valves, except when a loud speaker is used. It will be found very convenient to make a special box for the H.T. battery.The writer encloses five 15 -volt units in a box just big enough to take them, the lugs being soldered together so as to give a total voltage of 75. The lid of the box is fitted with an ebonite strip with five large terminals, for negative Fig. 4.The Circuit diagram. 30 v., 45 v., 6o V. and 75 V. (positive). NOTES ON THE COMPLETE STATION. Connections from the aerial and earth to The writer ventures to think that any readerthe set are made with silk -covered electric who jfollows the instructions given in theselighting flex, the bared ends of the two wires articles will be well satisfied with the stationbeing joined and soldered to tags.Leads to sobuilt.Atfirsttherewillbealittlethe L.T. and H.T. batteries are made of the difficulty in tuning to signals, but after a littlesame flex, the positive wire being knotted at practicethedifficultywilldisappear.Ineach end so as to avoid confusion.The fact most cases excellent results will be obtainedthat the wires are twisted together is no dis- on " stand-bi," with the condenser in parallel,advantage whatever in the case of the L.T. and probably the majority of work will bebattery, and in the H.T. leads it is a distinct done in this fashion.For the highest selectivityadvantage, as the capacity effect adds to the the " tune " adjustment is advisable, althoughvalue of the condenser shunted across the itis rather more difficult to operate. H.T. battery !Twisted electric lighting flex Readers who have a complete set of plug-inis also used for the connection between the coils will be able to use the reactance -capacitytwo units, and from the telephone terminals method up to about 7,000 or 8,000 metres,to the telephone transformer. with a o000i mfd. condenser.Very little Finally the whole set is placed within an loss of efficiency will be found on long wave-oak bureau from whichthepigeon -holes lengths with a larger condenser, so that muchand other impedimenta have been removed. higher figures can easily be reached.With Interchangable coils, H.T. battery, separate the resistance unit the longest waves can beheterodynes, spare telephones and the like receivedquiteefficiently,and with muchare placed in the drawers below, so that the greatereaseof tuning.For longwaves, whole station is self-contained. however, the writer prefers his three -valve Note.-In the last article the H.T. negative set described in the issues of April 1st and 8th, of the H.F. and detector unit was shown con- using the new tuner in place of the convertednected to the L.T. positive.It should be " MarkIII.," and with oneof thenoteconnected to the L.T. negative if it is desired magnifiers added if four valves are required.to use one accumulator for both units.The There is little to choose between the two inchange is very simply made without disturbing regard to signal strength, the preference beingother connections.There will be no difference largely due to the convenience of handling. in signal strength or efficiency. If itis found inconvenient to handle the So far thirty-four of the telephony trans- reactance -tuning condenser behind the secondmitters listed in The Wireless World and Radio unit, it can be stood in front and flexible leadsReview for July 1st have been heard on this set. 620 THE WIRELESS WORLD AND: 'RADIO REVIEW AUGUST 12, 1922 The Principles of Tuning in Wireless Telegraphy By C. E. FIELD, B.Sc. wHEN an amateurfirsttakes upalternating current, and, Ohm's Law holds wirelesstelegraphy, hefinds thatgood for an alternating current circuit just thesuccessful working of an in-as for a direct current circuit. stallationdepends uponcertainelectrical There aretwo other propertiesbesides circuits being " in tune " with one another,resistance which every electric circuit possesses and one of his most important pieces of ap-in a greater or less degree. These are inductance paratus is a " tuning coil."He is, however,and capacity, and it is these properties which frequently at a loss to know exactly whatare of the greatest importance incircuits is meant by two circuits being " in tune,"connected with wireless telegraphy, and will and if he endeavours to find out from a text-now be discussed. book he will probably be confronted with INDUCTANCE. pages of mathematics which are of very little Any conductor carrying an electric current assistance. is surrounded by " lines of magnetic force," Electrical tuning, however, which is the basisthe number of which depends upon the value of satisfactorywireless transmission or re-of the current flowing.If the value of the ception, can be simply explained with thecurrent changes, therefore, the number of aidofanalogiesdrawn from mechanicallines of magnetic force changes, the lines either experiments, once the working of an electricgrowing outwards in concentric circles from circuit is thoroughly understood. the centre of the conductor or shrinking Considerfirstan ordinary steam engine.into the conductor, which is cut by the lines Steam from theboiler exerts pressure onof force as they do so.Now, whenever lines a piston and produces mechanical movement.of magnetic force and a conductor cut or e The greater the steam pressure, the fasteranother, a voltage is set up in the conduct( r will the piston travel, or in other words,proportional to the number of lines of force the greater will be the amount of movementcut per second. in a given time.Also, for a given speed, the Hence the changing magnetic field caused pressure required depends upon the resistanceby a changing current produces a voltage in that is offered to the motion of the piston. the conductor carrying the current, and this In an electrical circuit, electrical pressure,voltage acts in such a direction as to tend to or voltage,issupplied from some source,maintain the currentatitsformer value. and produces a movement of electricity,i.e., i.e., a back voltage is set up by an increasing an electrical current.The greater the elec-current, and a forward voltage by a decreasing tricalpressure, the greateristhe currentcurrent. it produces, and for a given current to flow, The inductance of a circuit is a measure the pressure required depends upon the re-of the voltage set up by a given rate of change sistance of the circuit.This result is knownof current.If a rate of change of current as Ohm's Law, and is concisely expressedof r ampere per second causes r volt to act by the equation V= IR, an expression probablyin the circuit, the inductance of the circuit familiar to all readers. is i henry. If 2 volts are set up, the inductance Referring again to the steam engine, weis 2 henries, whereas if a rate of change of know that if pressure is applied alternately2 amperes per second were required to produce to each side of the piston it will causethe volt, the inductance would behenry, and latter to travel backwards and forwards, theso on. speed of the piston being greatest in the centre Inductance is thus a property of a circuit of its stroke.In other words, an alternatingwhich opposes any change in the value of the steam pressure produces an alternating move- currentflowing. An alternating current, ment. therefore,whichiscontinuallychanging, Similarly, in an electric circuit, an alternatingencountersconsiderableoppositioninan orrapidlyreversingvoltage produces aninductive circuit. 621 AUGUST 12, 1922 THE WIRELESS WORLDAND RADIO REVIEW To obtain a mechanical property comparablea condenser is always trying tocharge the with inductance, we must find that which tendsvalue of the current. to prevent any alteration in the rate at which A comparison may be made between a a body moves.Inertia, or momentum, doescondenser and a steel spring.If, say, a steel this, and so a moving body with a large moment rule is gripped at one end in a vice, and the of inertia, such as a heavy pendulum, orfree end isbent backwards and forwards, flywheel, may be compared with an inductivethe greater the deflection of the rule the greater circuit carrying current. A flywheel can onlyis the pressure required to bend it any further, be brought up to speed, or brought to aand if the pressure is kept constant, the slower standstill gradually, and a very great alternatingdoes the movement become. The more force would be required to cause it to oscillateflexible the rule, the greater is the movement rapidly backwards and forwards through athat can be produced in a given time by a given pressure. small arc. Thus the flexibility of the rule may be CAPACITY. compared with the capacity of the condenser. A condenser, which is the apparatus em-THE EFFECT OF DIFFERENT FREQUENCIES. We must now see what is the effect produced ployed to give a circuit a large amount ofby altering the rapidity, or frequency, with capacity, consistsessentially of a layer of insulating material such as mica or air, sand-which an alternating pressure is applied to a circuit containing inductance or capacity. wiched between two metal plates. If the pressure (or torque) applied to a When a voltage is applied to one of the plates, alternated, a current flows into the condenser,and fills,heavy flywheelisveryrapidly quantity ofthe flywheel will never have time to " get or " charges," it with a certain going " in either direction, and so very little electricity. As the charge increases, the electri-movement will take place.Similarly, if a cal pressure on the plate rises, in opposition high frequency) to the impressed voltage, until the two pressuresvery rapidly alternating (or will flowvoltage be applied to an inductive circuit, are equal, when no more current very little current will flow. into the condenser. The capacity of a condenser Thus the resistance effect due to an induc- is a measure of the current required to producetive circuit depends upon the frequency of a difference of pressure betweenthe plates of If this is brought aboutthecurrent,orvoltage, aswellas upon r volt in i second. the value of the inductance.It can be shown by a current of r ampere the capacity of thethat if a voltage of frequency f cycles per condenser is r farad. If 2 amperes are required,second is applied to a circuit of inductance L the capacity is 2 farads, and so on. henries, the resistance offered to the current When a condenser is put in a closed alternating current circuit, the pressure on one plateis given by 2 irfL " apparent ohms," so that relative to that on the other is alternativelyfor an inductive circuit, neglecting any resis- raised or lowered, so that when one platetance, we can write Ohm's Law thus :- is gaining a charge of electricity, the other is V = C x 27rfL. losing a similar charge. A current therefore If a rapidly alternating pressure is applied flows first into one plate and out of the other,to the rule held inthe vice,there will be and then in the reverse direction, so that anno time for the rule ever to bedeflected far alternating current appears to go through thein either direction, and so it will never offer condenser. much resistance to movement, which will The greater the capacity of a condenser,consequently be very rapid. the greater is the current that flows into it Similarly, a high frequency voltagewill when a definite voltage is applied, so that insend a large current " through " a condenser, an alternating current circuit the amountofor in other words, a condenseroffers little current going " through " a condenser dependsopposition to high frequency currents. upon its capacity, i.e., the greater thecapacity Hence the resistance effect of a condenser of a condenser, the less the opposition it offersvaries inversely as the frequency, and also as to an alternating current. the capacity, and it can be shown that Ohm's When a condenser is being charged, theLaw for a condenser is 1 back voltage across the plates increases, and V = x sC so the current flowing becomes lessand less, and finally stops. Thus, unlike an inductance,where C is the capacity in farads. 622 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 12, 1922 Now we have seen that whereas an inductancethe spring were very flexible, it would vibrate always tries to prevent a current from changing,much less rapidly - than if the reverse were a condenser always tries to make a currentthe case. change.The resistance effects of the two The action of the condenser discharge in at any instant, therefore, work in oppositethe electric circuit is exactly similar.When directions,sothatinacircuitcontainingthe spark passes across the air gap, avery both inductance and capacity, the resistancerapidly alternating current passes round the effect of the two combined is the differencecircuit,oscillating backwards and forwards, between their individual effects. and gradually dying away. The greater the In such a circuit, therefore, inductance or capacity in the circuit, the lower V = / x (27rfL - is the frequency of this current. 27rfC)' The rapidly alternating dischargeacross the term in brackets being known as thethe spark gap sends out " wireless waves," reactance of the circuit, to distinguish it fromthe length of which depends upon the frequency theordinaryresistance,whichis beingof the discharge (not to be confused with the neglected in the cases under consideration. frequency with which the sparks pass across Let us now consider the circuits used inthe gap, this being determined by the rapidity connection with wireless telegraphy. VARIABLE Thesimplest, but fundamentalwireless CONDENSER transmitting circuit consists of a condenser and an inductance coil joined in series, the two being shunted by a spark gap, the ends of which are connected to a high tension supply, such as an inductioncoil.(SeeFig.i.) When the electrical pressure isapplied to the circuit, a current flows and charges the Fig. 2.Receiving Circuit with Variable Con- condenser.The pressure across the spark denser and Auxiliary Tuning Coil. gap will always be the same as that across the condenser, and so, as the latter becomeswith which the primary current of the induction charged, itis increased until it becomes too coil is interrupted, if the high voltage is supplied - great for the electric strength of the air inby that means).The length of the wave in the gap.When this occurs, the condensercentimetres is given by dividing the frequency discharges across the gap by means of a spark.into the velocity of light, the latter being This action could be imitated by bending30,000 million centimetres per second. the rule in the vice, and letting it fly back. For example, a wavelength of 300 metres is As there was some inductance in the electric produced by a circuit having a natural frequency of i,000,000 cycles per second. TUNS% COL The wavelength can therefore be adjusted by altering either the capacity or the inductance of the transmitting circuit. As it is much more cpnvenient, the inductance is usually altered (by increasing or de- creasingthesize of that portion of the L inductancecoilincludedinthecircuit), Fig. 1.Simple Transmitting Circuit with Fixedand it is this variable inductance that is known Capacity and Variable Inductance. as a " tuning coil." This " tuningcoil " may constitute the circuit, however, to make the comparisonwhole of the inductance in the circuit as in complete we must add some inertia to theFig. 1, or it may be an additional coil, as shown mechanical " circuit," which could be donein Fig. 2, which represents a simple receiving by fixing a lump of lead on to the free endcircuit. of the rule.When this was allowed to spring A receiving circuit is exactly similar to the back, it would continue vibrating for sometransmittingcircuitdescribed,exceptthat time at a definite frequency, known as thethe place of the spark gap is taken by a detecting natural frequency of the system. apparatus, show in Fig. 2, by a pair of tele- If the lump of lead were very heavy, andphones and a crystal detector, and the only 623 AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW

1 electrical supply to the circuitis the high whichreally meansthata frequency disturbance coming from the trans-f -27r CL mitting station. circuit naturally discharges in such a way that Suppose that waves coming at a frequency in over- of t,000,000 per second strike the receivinga minimum amount of work is done circuit, a voltage and consequent current ofcoming reactance.Thus in each circuit, the the same frequency will be set up in the circuit. 1_ value is the same, and so the value Now we have seen that the reactance of s:CL thiscircuit isgivenby theexpression of L x C must be the same in both. When 1 27rfL this state of affairs has been brought about, an-fe the two circuits are said to be " in tune,' If we want the current flowing in the circuitor " tuned to the samefrequency." to be a maximum (which we do, for the amount Next time,then,that you ".tune up " of energy caught by the circuit is exceedinglyyour wirelessset, remember that you are small) the reactance must be assmall assimply alteringthe value L x C in your possible, and obviously this occurs when circuit until it is the same as the corresponding value in another circuit, possibly hundreds fL - 1 of miles away, and you are using exactlythe 27rfC same principles as when youregulate a clock 2.77-fL - 1 by altering the length of its pendulum. 27rfC. In this article, no mention has been made 1 of aerials, only the most fundamental circuits being considered.An aerial circuit is exactly 27r X 27r X CL. similar to those described, except that the 1 aerial wire acts as one plate in the condenser, 27r VOL and the earth acts as the other, the air between being the insulating material. Hence, if the inductance or capacity in the It is, of course, quite impossible to deal at isadjustedto suchavaluethat circuit allfully either with wireless circuits or with 1 electrical vibrations in an article of this length, f =-- 2r v'CL but it is hoped that some may be encouraged to look a little deeper, and gain aclearer therewill be no reactance in the circuit,conception of the true nature of any electrical and the high -frequency voltage will only havephenomena they may encounter in working the negligible resistance of the wires to over-wireless or other apparatus. come. In the receiving circuit, therefore, just as in the transmitting circuit, a " tuning coil "Wireless Exhibition & Convention is employed, and is adjusted until the reactance WIRELESS Societies are coming into in the circuit is a minimum, which is indicated being all over the country.Those by a maximum noise in the telephones. A which have firmly established them- " tuning condenser "isfrequently used asselves have in most cases affiliated with the well as a " tuning coil," although itis notWireless Society of London. At the Con- generally given that name. vention which is to be held from September It may at first sight appear as if there were3oth to October 7th of this year members no need to have any inductance or capacityof affiliatedsocietieswill have an excellent in a receiving circuit, since some trouble isopportunity of meeting with the members expended in making them neutralise oneof other societies. another. Great benefit may be derived from the A circuit containing only resistance, however,Exhibition by those amateurs and experi- would be like a piece of thick copper wirementers who are not yet associated with any held in a vice, there being nothing tending society.The socialelement of theclubs to make an oscillatory movement take place.assembled, coupled with an atmosphere of It can be shown mathematically that the scientific gregariousness, should be an impetus natural frequency of the transmitting circuitto all who are interested in wireless matters (or of any circuit) is also given by the expression toencourageunity. 624 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 A Liverpool AmateurReceiving Station By SAMUEL LOWEY.

THE writer received his post-war permitconsecutive tappings gave about thesame about the middle of October,1919, percentage change in inductance value. and at once commenced experimerts. In the box, shown in Fig. 3 with one end The aerialinstalled was an indoor oneand front removed, may be seen one pair of consisting of four 28 -ft. lengthsat greatestcoils mounted in position, the lower or A.T.I. height of 27 ft. above ground, and, with thecoil being attached to a loose board which exception of a period when, owingto earthingslides in the bottom of the box, while the in damp weather, four12 ft. lengths weresecondary coilis attached to the underside temporarily installed, has been inuse sinceof the box top. that time.Its capacity is over half a milli- microfarad, the single down lead being 3/20 cab tyre sheathed cable. After trying numerous types of inductance coils, including an elaborateone wound on 21 pegs in a board, missing three pegs each time as shown in Fig. 1, giving a coil of extremely low self capacity, the opinionwas formed that the merits of single layer coils, especially for the longer waves, had been overrated. Fig. 2.The former with slots cut. The bottomof the box has transverse grooves cut to accommodate any wood borings, etc., that might prevent the free movement of the sliding board. A thin board is screwed at right angles to the moving board, and carries the switches for the A.T.I. (Fig. 4), the connections to arms of switches being by two flexible cords to a reversing switch mounted on top of box. Only four wires enter the box; two for A.T.I. Fig. 1. and two for secondary, all other connections Showing method of windinga coil. being external. The secondary switches are on top of the box, Finally, dry wood formers were turned andbeing identical with the A.T.I. switches just grooved, as shown in Fig. 2, the largest pair described. being rather over 3 ins. diameter and wound with ioo turns of 36 S.W.G. in each slot 151/ to give an inductance value of a tenth ofa henry. Tappings were left out at grooves5, 7 and 1o, and on trial these were found to give excellent results, the best adjustment ofcoup- ling being obtained by sliding the end ofone coil on to the end of another, whena definite zero of coupling could be reached, or coupling in the reverse sense obtained if required. The next pair of coils was wound using identical formers, about 48 turnsperslot being used, the arrangement being such that Fig. 3.The box in which coils are mounted. 625 AUGUST 12, 1922 THE WIRELESS WORLDAND RADIO REVIEW Coil 5 (Fig. 4)is on a smaller grooved TheintervalveL.F.transformersare former(13slots), with tappings at groovesmounted in a box fixed at back of tuner. to and13. The number of turns on such transformers Coil 4 :Single layer, range to about 1,800may apparently be varied between widelimits metres, witho0005microfarad capacity, andwithout much difference in results. has four tappings. The first transformer made had a primary of6,000turns, secondary30,000turns of No. 42 enamelled.

0.005 Later transformers had 8,000 and 24,000 turns of No. 40 silk covered, io,000 No.36 °

silk covered to30,000turns of No. 42 enamelled. The number of secondary turns, above 20,000, did not seem to matter much, but a good primary (about io,000 turns) having an O 0.1 HENRY inductance of about 8 henries seemed an advantage. The transformer windings were on old LOADING COIL 0.2 HENRY wirebobbins,andinconstructingthese, the writer soon gave up the common method

O Fig. 4.Showing tappings.

Coil 3 :Loose coupler pattern, four tappings, 200 to 80o metres, while coil 2 is a basket coil with three tappings from 60o to r,too metres. When all switch arms are on the first contact, connection is made to four terminals enabling any special coils to be used.The secondary coils are exactly similar to the A.T.I. coils. In the photograph (Fig.5)the aerial tuning condenser is on the left of the primary switches, and the secondary condenser is on the right; the latter being fitted with a brass flat spring connectedto moving vanes of condenser, thedistance from thefixedvanesbeing variable by a screwed brass plug with long ebonite handle. This makes an excellent vernier, having a Fig.5. View of the complete set. maximum capacity of abouto000015mfd. The valve panel is mounted on the top ofof joining a heavier wire to start and finish the box, and the method of construction isof winding wire and found it more reliable indicated in Fig. 6. to bring out the fine wires themselves,soldering The resistance wire for filament rheostatsthem carefully to unscrewed part of brass is wound in a shallow screw thread cut in awood screws in flanges of the bobbins, the 5/16in. diameter fibre rod. windings always being connected as shown The connecting wires are through holesin Fig. 7, it being quite easy to solder connecting bored in solid ebonite, all connections beingwires after the transformers were completed. soldered. After boring and turning the bobbins to The valve sockets are 1 in. Whitworth brasssize, they were boiled for some hours in screws drilled 1 in. to take valve pins. paraffin wax ;this process always elongates 626 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 12, 1922 the bobbin, and if wound first and boiled aftercompleted at Easter, 1920 a space is usually left. ;in June, 1921, a variable H.F. transformerwas added (extreme Itwas found advantageous when usingleft of photo). three L.F. transformers toreverse the direction The coils were wound in shallow when starting to wind the secondary of grooves in onecylindrical formers similar to that shownin Fig. 2.The advantage of this type oftrans- former isthat whileitgives a reasonably tight coupling (about 75per cent.), the capacity between windings is low. The transformer for wavelengths4,000 to 23,000 metres is about 3 ins. diameter, while for the smaller wavelengths it is Liins. Both were wound with No.42 silk -covered copper, the direction of winding being such that at one end the plate and grid wirescame

Fig. 6. Valve panel mounting.

(the middle) transformer ;it seemed to stop low frequency coupling between transformers. The telephone transformer hasio,000 turns of No. 36 (silk) for primary andi,000 turns Fig. 7. of No. 28 (silk) for the secondary.It is used with single 6o ohm " Brown A " telephonesout clockwise and counter -clockwiserespec- connected in parallel. tively. The loud speaker is a " Brown A " telephone The control of both is made byan 8 -way fitted with phonograph trumpet.Instead of4 -pole switch.The circuit diagram is given the standard 6o ohm winding2 X 700 turns,in Fig. 8. it In these days Morse is getting is wound with 2 X 400 turns of No. 36neglected generally, and therange has to be silk covered. expressed in terms of music. The apparatus as described up tonow was 2 MT came in very wellon three valves

8 <

SERIES - PARALLEL SWITCH FOR ATC

SOP 7 ""

Fig. 8Circuit diagram. AUGUST 12, 1922 THE WIRELESS WORLDAND RADIO REVIEW 627 on 70o metres, but since the change to 400has now given quite a number of demonstra- metres it is not received so well. tions with great success. 2 LO is quite good on three valves, and On the last occasion it was in competition FL music is quite clear all over the house onwith a steam organ on a roundabout at a recent five valves, while the Marconi installation forgarden fete, and won easily, the telephony the Mersey Docks and Harbour Board beats (includingan amateur transmission)being the lot. quite loud, and every word audible in the next PCGG is audible four feet away, using three room with door shut. valves. A Johnsen-Rahbek loud speakeris No apology is offered for the presence of sometimes used instead of a " Brown," beingcrystal detector on the set ;the writer con- nearly as good. siders it to be far more efficient and reliable It has a slate drum-not agate.The setthan any method of valve rectification.

International Amateur Wireless THE hat which is seen here being worn In the July issue of Q.S.T. Mr. Warner by Mr. K. B. Warner, of the Americanacknowledges receipt of thehat, and has Radio Relay League, has ahistory. posedforthe photographer.Inreferring Itwill be remembered that a photographto the tests,Mr. Warner acknowledges the of the hat appeared in our issue of April 29th,success of the British amateurs, and says : whenitwas announced that the hat had" Radio history was written, of course, with justbeen despatchedto Mr. Warner bythose tests, and although the British amateurs Mr. W. W. Burnham, who had taken onwere equally as successful as Mr. Godley, a bet of a " new spring hat " in connectionthe bet of the new spring hat stillstood. with the Transatlantic Amateur Tests. Mr. Burnham promptly cabled " congratulations. Cable size of hat," and the result is the special" lid " of our photograph. After describing the decoration and inscription on the hat, Mr. Warner says :- " We must express our great admiration for the beautiful way in which Mr. Burn- ham ' came through.'We thank you, sir, and sendcordialgreetingstotheBritish amateurs you typify.While the hat is hardly one which we would feelsafe in wearing to church on Sunday morning, itis nevertheless our intent to wear it on official A.R R.L. occasions. Itfitsperfectly ;thank you- our normal headsizehaving been given you in spite of the temporary swelling that existedimmediatelyafterthesuccessof the test," and he closes with the hint, " Now who wants to bet us something about a cut- away coat ? " The hat is of light grey felt and bears on one side the Stars and Stripes, and on the other the Union Jack united by wireless flashes encircling the crown. In front can be seen the inscription of dedication.Unfortunately, the photograph does not give a true estimate of the artistic appearance of the hat as the effect of colour is lacking. 628 THE WIRELESS WORLD AND RADIO REVIEW AnausT 12, 1922 Notes Extension in India. The broad principle followed is that receiving Madras Wireless Station is to be converted intoapparatus may be freely used after formal registra- a high-speed automatic plant for working inlandtion, while sending apparatus can only be installed and to Rangoon.It is reported that the Rangoonby private individuals on the authorisation of the section will replace the present land lines andUnder -Secretary of State acting on the advice of a cables from Calcutta to Rangoon for traffic betweenmixed committee of officials and experts.Sending India and Burma. According toLloyd'sListinstallations will be divided into five classes -- the present apparatus for communicating withprivatestations,stationsforfinancialnews, ships is to be replaced by a small station to be erected scientific stations, mobile stations (e.g.,of ships), near St. Thomas's Mount.This will render theand amateurs' installations.There will be a limit working with ships easier than hitherto, and at theof wavelength. same time free the big station in Madras for inland work. Honour for Senatore Marconi. The Department of Public Works now have the SenatoreMarconi,G.C.V.O.,LL.D.,D.Sc., work in hand of extending the present station andwas elected a Vice -President of the Royal Society also the erection of the new station at St. Thomas'sof Arts on July 28th. Mount.The bulk of the new apparatus and plant has already arrived, and it is hoped that the stationsSuccessful Demonstration. will be completed and ready for work before the An open-air demonstration at the small hamlet beginning of next year. of Bolton Villas proved highly successful on July 17th.The whole of the inhabitants listened to a P.M.G. on Reception in Cinemas. programme of music and conversation carried out A firm of picture theatre proprietors who hadby a concert party assembled at Heaton.Recep- installed apparatus for providing audiences withtion was particularly loud. broadcasted music have received the following letter from the Postmaster -General :- Report of Research Board Sub -Committee. " With reference to your letter of 11th inst. and telegram of the 24th inst., I am directed to A report has just been issued of the Radio Re- inform you that, pending the receipt of the pro-search Board Sub -Committee which was appointed posals of the representatives of the wirelesson October 4th, 1921, to investigate the subject manufacturing companies concerning wirelessof telephony development,Witnesses were heard broadcasting stations, the Postmaster -Generalfrom the Navy, Army and R.A.F.,- the Marconi is unable to issue permits for the use of wirelessCompany and the Radio Communication Company. receiving apparatus for public entertainmentsThe report (Cmd 1,707) is signed by Admiral Sir in cinemas, etc., or to say under what preciseHenry B. Jackson, Professors C.L. Fortescue conditions such permits will be issued.As atand G. W. 0. Howe, and Major A. G. Lee. presentproposed,however,permitsofthisCall Sign 2 FU Misused. kind will cover reception only from broadcasting stationsinthiscountry.ThePostmaster - 2 FU complains that his call sign is being used General hopes to be in a position to make furtherbyanothertransmitter.The useofanother announcement later." man's officially recognised sign is likely to lead to serious trouble. Motorists' Concert. On July 29th a concert was transmitted by theAir Route Call Sign Amendments. JoWett Light Car Social Club, Bradford, for the Notification is made by the Air Ministry as benefit of its members and allother motoristsfollows :- who cared to accept an open invitation.Demonstra- 1. With effect from August 1st, 1922, the W/T tions were given at 3.30 p.m. and 6.30 p.m., eachcall signs of Haren, Air Port of Brussels (BAV); lasting about an hour and a -half.In the eveningBrussels, Royal Meteorological Institute (HS) ; a speech was transmitted by the Lord Mayor ofand Ostend (OPV) have been altered as follows :- Bradford for the special benefit of the assemblage. Haren (Air Port of Brussels) - OPVH Mr. Bever, a member of the Club, has recently Brussels (Royal Meteorological Insti- experimented with an adaptation of a relay and tute) - - - - - OPO stentorphone set.His efforts were so successful Ostend ------OPVO that it was decided to make use of high power 2. The following changes in transmissions from telephony amplification as a means of entertain- Brussels (OPO) have been effected :- ment with a view to fostering camaraderie among (a) The meteorological reports transmitted on motorists by inviting them to a demonstration. 1,400 metres at 0715 and 1325 G.M.T. have been discontinued. Regulations in France. (b) The report hitherto transmitted on 1,400 According to the Timm the departmental com- metres at 1815 is now transmitted on 1,680 mittee appointed by the French Under -Secretary metres at 1824 G.M.T. of the Post Office to inquire into the regulation of Other routine transmissions remain unaltered. wireless installationshave drawn their report. 3. The tables in Section II (Belgium), paragraphs It is expected that rules based on their recommenda-4 and 5, of Notice to Airmen No. 43 of 1922 are tions will shortly be issued. amended accordingly. AuGusx 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW 629 Death of Dr. Graham Bell. Calendar of Current Events Dr. Alexander Graham Bell passed away on the night of August lst-2nd. Sunday, August 13th. We deeply regret to learn of the passing of Transmission of Telephony from 2.30 to 5 p.m. a pioneer among scientists whose lifework has and from 8 to 9 p.m. on 1,085 metres by PCGG made vast revolutions in the daily conduct of The Hague, Holland. industry and every form of business.His re- Monday, August 14th. search work in connection with the telephone WIRELESS SOCIETY OF HULL AND DISTRICT. has had results which are beyond estimation. 7.30p.m.-AtSignalCorpsHeadquarters, He was born at Edinburgh on March 3rd, 1847, Park Street, Hull.Lecture on " Accumulators, educated at the High School and the Edinburgh their Use and Abuse," by Mr. J. Nicholson. University. went to America and became pro- Tuesday, August 15th. fessor of vocal physiology at Boston University, Transmission of Telephony at 8 p.m. on 400 metres where he made his first telephone apparatus in by 2MT, Writtle near Chelmsford. WIRELESS SOCIETY OF EAST DORSETSHIRE. At Branksome Liberal Club, Salisbury Road, Upper Parkstone.General meeting and enrolment of members. Wednesday, August 16th. YORKSHIRE WIRELESS SOCIETY. 8 p.m.-Grand Picture House Café, Clarence Street, York.Preliminary meeting. Thursday, August 17th. Transmission of Telephony at 8 to 9 p.m. on 1085 metres by PCGG, The Hague, Holland. Sunday, August 20th. Transmission of Telephony from 2.30 to 5 p.m. and from 8 to 9 p.m. on 1085 metres by PCGG The Hague, Holland. PADDINGTON WIRELESS AND SCIENTIFIC SOCIETY. Field Day. Tuesday, August 22nd. Transmission of Telephony at 8 p.m. on 400 metres by 2MT, Writtle, near Chelmsford. Thursday, August 24th. Transmission of Telephony at 8 to 9 p.m. on 1085 metres by PCGG, The Hague, Holland. ILFORD AND DISTRICT RADIO SOCIETY. At St. Mary's Hall, High Road, Ilford.Lecture on" ShortWaveReception-withspecial reference to Damped Waves," by Mr. E. E. Hale. Books Received ELEMENTS OF RADIO TELEPHONY. By William C. Ballard, Jr., M.E. (London : McGraw-Hill Publishing Co., Ltd.1922.71" x 5f"). RADIO FOR AMATEURS. By A. HyattVerrill. (London William Heinemann. 1922. 71" x 51"). 1875. He transmitted speech over a long distance for the first time in August, 1876. The experiments were conducted in Canada Sir William Noble's Future Work. and the Dominion Telegraph Co.'s wires were It is understood that Sir William Noble, who used, a transmitting apparatus being installed has been elected to the Board of the General atParis, Ontario, and a receiver placedat Electric Company, will in future devote his attention Brantford, eight miles away. A few months chiefly to the wireless and telephone side of that later conversation was possible both ways, and company's development. the present-day telephone was born. Hotel Wireless. Dr. Graham Bell held the Albert Medal of the The " New Metropole," Northumberland Avenue, Royal Society of Arts since 1902, the Hughes London, claims to be the first London hotel to be Medal of the Royal Society since 1918, and equipped with a wireless telephone receiver.The several honorary degrees.He was a freeman of apparatus was installed by the engineer of the Edinburgh, the freedom being conferred in 1920. Gordon Hotels, Ltd., Mr. W. J. Crampton, M.I.E.E. 630 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12. 1922

Stoke-on-Trent Wireless and Experimental Folkestone and District Wireless Society.* Society.* Hon.Secretary,Mr.H.AlecS.Gothard, Hon. Secretary, Mr. F. T. Jones, 360, CobridgeA.M.I.R.E., 8, Longford Terrace, Folkestone. Road, Hanley, Stoke-on-Trent. A General Meeting of the above Society was At a meeting of the Stoke-on-Trent Wireless andheldat Cave's Café on Wednesday, July bth, Experimental Society on Thursday, July 27th, itat 7.30 p.m., Mr. A. H. Ullyett in the chair. was unanimously decided to change their head- The meeting proved very successful, and the quarters to the new Y.M.C.A. building in Marshfollowing were elected to serve until July, 1923 :- Street, Hanley.Since the Wireless Exhibition, President :His Worship the Mayor, Mr. R. C. held under the auspices of the Society a few months Wood.Past President :Mr. T. Hesketh, M.I.E.E., ago, the membership has nearly trebled, and itA.M.I.Mech.E., M.A.I.E.E.Vice -President : Capt. has been felt for a long time that their presentSt. John Butler, R.C.S.tVice -Chairman :Mr. headquarters werefarfromsatisfactory.The A. G.Mills.tCommittee :Messrs.L.Curtis,t Y.M.C.A. have kindly offered the Society the useA. G. Cox, A. Cumberbirch and T. C. Gilbert. of their lecture room for meetings and experiments, Hon. Treasurer :Mr. R. W. Piper. tHon. Secre- and the offer has been accepted.A meeting willtary :Mr. H. AlecS.Gothard, A.F.Aer.Inst., heldinthenew headquartersat7.30p.m., August 3rd. After the programme for the forthcoming year It was also decided to send a delegate to the con- had been discussed, the meeting adjourned at ference of the Midland Wireless Societies, to be 9.45 p.m. held about the end of August, in order to arrange On Wednesday, July 26th, a very successful the interchange of lecturers. demonstration inradio -telephony was given by Mr. W. J. Forster (Member) read a paper onMr. C. G. F. Pritchett, who had made special " Electrical Measuring Instruments." After first elucidating some of the more common transmit on that evening for the benefit of the electrical terms, the lecturer explained the working Society.Mr. Pritchett took great pains in explain. principles and construction of various types ofing the methods of working the circuits employed. ammeters, voltmeters,wattmetersandenergy A hearty vote of thanks was given to both Messrs. meters, as used in modern power -station practicePritchett and Bligh, the first for his successful and by consumers.He clearly pointed out theefforts in obtaining the transmission, the latter for difference between pressure measuring instruments,his kindness in transmitting. and some actual instruments were available, the The activities of the Society are at present insides of which the members were able to inspectcarried on in a private room at Cave's Café, Sand - for themselves, and note the difference. gate Road, Folkestone, where meetings are held In the subsequent discussion, the importance at 7.30 p.m. every Wednesday. ofelectrical measuring instruments inwireless Mr. Cox has very kindly consented to give work was emphasised, and how that without themquarter hour buzzerpractice every week before we should not know what the exact conditions werethe meeting.Members who desire to take advan- in our circuits, especially for transmitting stations, tage of this opportunity of practising their Morse and progress would hardly have made such rapidare requested to be at the club -room at 7.15 p.m. strides without their use.It was also remarked Full particulars as to membership, etc., can be that Mr. Forster had not touched upon galvano-obtained on application to the Hon. Secretary. meters, and the hope was expressed that he would t Denotes re-election. give a lecture on what was perhaps the most North Middlesex Wireless Club.* widely used measuring instrument among wireless Hon. Secretary, Mr. E. M. Savage, " Nithsdale," amateurs. Eversley Park Road, Winchmore Hill, N.21. A vote of thanks, carried unanimously, brought The 96th meeting of the Club was held on Wednes- the meeting to a close. day, July, 26th in Shaftesbury Hall, Bowes Park. The chair was taken at 8.30 p.m. by Mr. G. Evans, Sunderland andDistrict Amateur Radiowho introduced Mr. F. H. Haynes, who had kindly Society.* consented to lecture on the " Johnson-Rahbek Hon. Secretary, Mr. H. Burnley, 8, Briery Vale,Loud Speaker." Ashbrook, Sunderland. Mr. Haynes had brought to the hall the instru- The above Society is being reformed, and hasment which formed the subject of his lecture, changed its headquarters and name.The newand this was on view during the evening.He name is " Sunderland Y.M.C.A. Radio Society."described the action of the instrument, and illus- All communications should be addressed to thetrated his remarks by diagrams drawn on the Hon. Secretary at the above address. blackboard.He also explained the construction, AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW 631 more particularly with regard to the agate cylinder of tapping the inductances by connecting between which forms an essential part of the instrument,two condensers in series across the inductance. and drew the attention of the audience to theHe demonstrated how different capacity condensers importance of obtaining even electrical contactaffected the position of the tapping and observed between the agate cylinder and the steel spindlethat he had obtained very satisfactory results on which it is fixed. on wavelengths as high as 25,000 metres. The instrument was then setinoperation, After further explanation of the large capacity and a demonstration givenofitscapabilities.grid condenser and the low resistance grid leak The principle on which it works, which has alreadyto prevent howling, the method.of using the meter been described in The Wireless World and Radioas a separate heterodyne was put forward. Review, is most interesting, quite apart from its The members were then informed of the case of possible commercial application, and it was evidenta local amateur who was using a valve receiving set from the questions put to Mr. Haynes at the closewithout the P.M.G. licence.Owing to his instru- of his lecture that several members had alreadyment howling incessantly he was located from the decided to experiment in the same direction. Berwick and Stockton-on-Tees direction finding When the Chairman called for a vote of thanksstations, illustrating the remarkable amount of to Mr. Haynes, which was heartily respondeddamage which a badly handled valve set could do. to, he mentioned that Mr. Haynes had appliedNewport andDistrict Radio Association. for membership to the Club, an announcement Hon. Secretary, Mr. Edward R. Brown, M.S.A., which gave great satisfaction to all present, andA.T.P.I., 92, Corporation Road, Newport. another talk from him at an early date will be On Thursday evening, July 13th, the above welcomed by members. Association held their second enrolment meeting Particulars of the Club may be had on applica- at the Boys' Municipal Secondary School, Newport. tion to the Hon. Secretary. Before a large and enthusiastic audience Capt. C. H. Bailey (Vice -President) gave an address, in Newcastle and District Amateur Wireless which he expressed the opinion that America was Association.* at the present ten years in advance of England as Hon. Secretary, Mr. Colin Bain, 51, Graingerfar as wireless was concerned, but that if British Street, Newcastle -on -Tyne. amateurs were given better facilities for experi- A General Meeting of the above Associationmenting they would beat the Americans in three was held at headquarters on Monday, July 24th. months.The lecturer also gave some very inter- Dr. Smallwood was present for the first timeesting reminiscences of a visit to New York. since the last general meeting, and gave thanks to An excellent demonstration was given on a the assembly for his election as President of thesplendidly equipped set, and a detailed explanation Association.The President then called on Mr. of same was given to the members. Dixon, the Chairman, to read out certain alterations A large number of new members were enrolled to the existing rules. The amendments thenand a pleasing announcement made that a large proposed, seconded and carried, were :-(1) Thathall in the centre of the town had been obtained all candidates must be over 21 years of age and tofor headquarters. fulfil the conditions as stated in the P.M.G. licence. A buzzer class is to be held throughout the (2) All applicants to send in cards with applicationswinter months, and an immediate start is to be and proposal forms to the committee, stating made towards a library collection. name and address, at least one week before the A well -attended meeting of the above Association next committee meeting.(3) No visitor to bewas held on Thursday, July 27th, at Headquarters, admitted more than three times per year eitherMemorial Institute, Queens Hill, Newport. by one member or more than one member. Mr. E. Ogden, of Cardiff, gave a lecture on Copies of the amended rifles will be supplied to " Points to Beginners," and Mr. J. H. M. Wakefield all members.It was then proposed and seconded presided.The lecturer advised all amateurs to that Mr. M. C. Jones should be appointed Assistantget into the theory of wireless, which was an ele- Secretary. mentary essential.He indicated the various books Mr. Dixon then gave his lecture upon wavelengths and journals the amateur should read. and wavemeters in general. After dealing with the Commencing with the aerial, the lecturer pro- advantages obtained by using a wavemeter, Mr. ceeded to take each part of a simple set, illustrating Dixon went on to describe the Park wavemeter.with diagrams their functions, faults and remedies. He explained in detail the method of using this and in a simple order of sequence eventually worked instrument to tune the receiving set preparatoryup to a complicated valve set. toreceiving another transmittingstation.He The lecture was closely followed by the members, then went on to describe the honeycomb inductanceswho atthe end bombarded Mr. Ogden with contained in the meter which he stated were questions.Enthusiasm ran very high, and the effective to 8,000 metres, dealing at the same timespeaker was invited to give a further address in withthecombinationspossiblewithparallelthe near future, he being promised a warmer fixed condensers. time at questions. With the aid of diagrams, Mr. Dixon explained On the motion of Mr. W. B. Edwards, seconded in a most interesting manner the method of cali-by Mr. H. W. Winslow, Mr. Ogden was heartily brating external inductances by cutting out thethanked.Replying to the vote the lecturer con- internal inductances, and of calibrating condensersgratulated the Association upon the rapid strides by comparison with the standard condenser con- made. tained in the wavemeter. The membership now stands at 135. He then went on to deal with the static potentio- Intending members in Monmouthshire should meter method, describing with diagrams the methodcommunicate with the Secretary. 632 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 12, 1922 The Ealing Wireless and Scientific Association.Signals in Hull would be pleased to send out on Hon. Secretary, Mr. Wm. Frank Clark,52, their own set one evening per week calibration sig- Uxbridge Road, Ealing, W.5. nals on fixed wavelengths for the benefit of the The third meeting of the above Society havingmembers of the Society if so desired.This was been held at the Vestry Hall, Ranelagh Road,accepted with thanks, and the Hon. Secretary Ealing, W5., the Association may now be con- was instructed to go into the matter with the wireless sidered safely launched upon a career of great officer and report at the next committee meeting, usefulness in the immediate locality. when arrangements could be completed and an It has been decided, in view of the fact that soannouncement made to all members. many of the members are beginners in the new The concluding part of the evening was devoted science, to commence with a series of elementaryto questions and answers, which proved very useful, lectures, in which branch of the club's work Mr.a large number of members availing themselves A. Snell is contributing a very valuable part afterof the opportunity of becoming enlightened upon some twenty years of wireless telegraphy inall some difficulty or another that was causing them its branches. trouble.Fourteen new members were elected, At the meeting held on July 22nd, 1922, Mr. Snell bringing the present membership to over 70. gave, in an informative and eloquent manner, Mr. J. Nicholson will lecture on Monday, August an outline of the electron theory of matter, and 14th, on " Accumulators :Their Use and Abuse," explained how very important this subject is inwhen it is hoped there will be a large attendance the theory of wireless. to hear this important subject. A cordial welcome is extended to all who care Meetings of the Society are now held on the to accept membership with the Society, and thosesecond Monday and the fourth Friday in each who contemplate joining are urged to take advan-month at 7.30 p.m., at the Signal Corps Head- tage of these first series of lectures. quarters in Park Street.

As soon as circumstances permit, an aerial will Willesden Wireless Society. be erected and practical work and demonstrations Hon. Secretary, Mr. G. D. Wyatt, 70, Craven undertaken. Park, Willesden, N.W.10. The Wireless Society of Hull and District. This Society has now recommenced operations, Hon. Secretary, Mr. H. Nightscales, 16, Portobelloand a meeting was held on July 4th to decide Street, Hull. upon the future programme.Mr. F. A. Tuck There was a large attendance of members on the announced his resignation from the position of occasion of the second annual meeting of thisHon. Secretary on account of pressure of business, Society, which was held at the Signal Corps Head- and Mr. G. D. Wyatt was elected in his place. quarters, Park Street, on July 10th. The Society has now decided as to its future policy. Mr. G. H. Strong (President) occupied, the chair,The social side is to be developed. A larger room and was supported by Capt. W. E. Dennis, R.C.S.,is to be obtained, and a good receiving set installed. and Mr. Hy. Strong(Acting Vice -Presidents).Wireless dances, socials, and demonstrations are The Secretary's report showed that much progress to be organised during the winter, and a successful had been made, many interesting and instructiveseason is expected. Now that the society isin lectures and demonstrations having been heldfull swing itis hoped that hearty co-operation duringtheyear.The membership hadbeen by all members will assist to make the season a increased to over 50.The report concluded withcompletesuccess. Newmembersarebeing a vote of thanks to Capt. Dennis for his kindness in especially catered for.The society invites lady placing the room at the disposal of the Societymembers who are interested in radio to join the for its meetings.The Hon. Treasurer's statementmembership. Newheadquarters,whichitis showed a balance in hand of £17 155. 10d.This, hoped will be occupied in a few weeks, will have together with the Secretary's report, was consideredevery facility for carrying out the programme, very satisfactory, and both reports were adopted. the accommodation beingsufficientforabout Mr. G. H. Strong was re-elected President, together200 persons.It is announced that T. Illingworth, with Capt. W. E. Dennis, R.C.S., and Mr. Hy.Esq., J.P., has consented to become President. Strong as Acting Vice -Presidents.Mr. W. Night - Otley and District Wireless Society. scales was re-elected Hon. Secretary and Treasurer Hon. Secretary, Mr. N. Weston, 24, Guycroft, with Mr. C. B. Snowden as Assistant Hon. Secretary. Otley, Yorks. A ballot for the four positions on the Committee There was a gathering at Queen's Hall, Otley, resulted in the following being elected : -Messrs. on July 27th. W. J. Featherstone, Major F. Holman, C. B. Snow- It was proposed and carried that the Club be den and J.Nicholson.Messrs. T. Forster andcalled " Otley and District Wireless Society. T.H. Straker were appointed Hon. Auditors. The following honorary ,officers were elected :- Other business included the adoption of the bye- Mr. A. Woodhead, Chairman ;Mr. N. Weston, laws of the newly formed library which had been Secretary ;Mr. Preston, Treasurer. framed by the Committee.Mr. Hy. Strong was Mr. N. Weston gave a lecture on " Spark Tele- appointed Hon. Librarian, and for the presentgraphy' that was wellreceived.Mr.Jones, the library will be held at the office of Messrs.A.M.I.E.E., kindly lenta four -valveset,and G. H. Strong & Son, Prudential Buildings, Kingconsidering that the aerie! was only 20 ft. high, Edward Street, by kind permission.The offices and one end on a lamp -post and the other on a are open from 9.30 to 5 p.m. ; Saturdays, 9.30 toladder,resultsweresatisfactory.Upwards-of 1 p.m.It is hoped to add further volumes shortly 30 members were enrolled.Ladies are 'especially to the library, which is free to all members. asked to come forward .there are still a number uring the evening, Capt. Dennis mentionedof vacancies open to complete membership to full that the wireless sectionof the Northumbrianstringth. AUGUST 12, .1922 THE WIRELESS WORLD AND RADIO REVIEW 633 Questions and Answers NOTE.-This section of the magazine is placed at the disposal of all readers who wish to receive advice and information on matters pertaining to both the technical and non -technical sides of wireless work.Readers should comply with the following rules :-(1) Each question should be numbered and written on a separate sheet on one side of the paper, and addressed "Questions and Answers," Editor, THE WIRELESS WORLD AND RADIO REVIEW, 12/13, Henrietta Street, London, W.C.2.Queries should be clear and concise. (2) Before sending in their questions readers are advised to search recent numbers to see whether the same queries have not been dealt with before.(3) Each communication sent in to be accompanied by the " Questions and Answers " coupon to be found in the advertisement columns of the issue current at the time of forwarding the questions.(4) The name and address of the querist, which is for reference and not for publication, to appear at the top of every sheet or sheets, and unless typewritten, this should be in block capitals.Queries will be answered under theinitials and town of the correspondent, or, if so desired, under a " nom de plume."(5) In view of the fact that a large proportion of the circuits and apparatus described in these answers are covered by patents, readers are advised before making use of them, to satisfy themselves that they would not be infringing patents.(6) Where a reply through the post is required every question sent in must be accompanied by a postal order for the amount of 18., or 3s. 6d. for a maximum of four questions.(7) Four questions is the maximum which may be sent in at one time. " SPARKS " (Birmingham) asks(1)For " A.L." (Torquay) asks ifitis possible to a diagram of a two -valve circuit.(2) Could he get receive the Hague concerts and telephony at Torquay PCGG with a two -wire aerial 30 ft. high.(3) Could with a certain three -valve set. he make a reaction coil.(4) What would the induc- Some results might be obtained, but we should tance of a basket coil be wound with 44 turns of No. 30 not expect them to be very good at such a distance. S.C.C. wire. You might find one or two additional stages of (1) See diagram Fig. 1. (2) Doubtful, but possi-H.F. useful, but reception at thisdistancewill ble. (3) Yes; a reaction coil is made in exactlyin no case he easy. the same way as any other coil.(4) The dimensions given for the coil do not appear to be self -consistent. " J .B.B .M " (Bothwell)sendsdiagramof Assuming the number of turns is correct as stated,his circuit and asks(1) For criticism.(2) For the inductance would be approximately 300 mhys.dimensions of A.T.I. and reactance coils for use with 0.0004 variable condenser ;what broadcasting stations he could receive with an aerial 36' high and 60' long.(4) How much wire netting is it n me -vary to bury at a depth of 3' to form a suitable earth. (1) Circuit is quite O.K.(2) A.T.I. about 80 turns with a mean diameter of 2".Reaction coil 50 turns, also with a mean diameter of 2". N.B.-- On short waves, such as the Broadcasting Band, only approximate windings can be given, as variations in aerial capacity, etc., lead to considerable variations in tuning.(3) The range on broadcasting stations would be approximately 75 miles. (4) Two or three square yards would probably be sufficient. " F.P.J .B. " (Ealing) asks (1) To what wavelength will a certain set tune.(2) If the set would receive 2 MT, FL on 180 and 2 LO. Should PCGG be heard at all, and what broadcasting stations. (1) About 3.500 metres.(2) 2 MT, FL and 2 LO, yes.180 metres and 2 LO doubtful, and Fig.1. probably only the London broadcasting station. " LEARNER " (Walsall) asks(1) The size " J .D. " (S.E .18)asks(1)Which of four and number of plates and the size of spacing washersmethods of connecting up a valve panel isbest. for a 0.0015 condenser and for a 0.0004 mfd.(2) Is (2) Details of certain condenser plates.(3) Details a Mullard "Ora" valve suitable for a single valve of stopping condenser.(4) Exact size of foils and set. (3) Isenamelledaerialwire moreefficient number required for a certain condenser. than bare copper.(4) If 1,000 ohms high or low (1) We prefer 3 and 4 to1 and 2.3 and 4 resistances. about equally good. (2)For 0.0003 mfds. one (1) Plates should be 4" diameter, with1 m/mpair of foils overlapping i" x f".For 0.001 mfds. between the fixed and moving plate.For 0.0015 fourfoils overlapping i" x /". (3)Five foils. mfd. condenser there should be 26 fixed and 25 (4) Overlap should be 1" x i", using ten foils. moving plates.For 00004 mfd. condenser seven (It is impossible to give more than quite a rough fixed and six moving plates.(2) Quite good, butestimate, as the specific inductive capacity of the not better than various others.(3) Very littlemica may vary between wide limits, and the thick- better.(4) Too high for efficient low resistanceness of the sheets will vary from the dimensions and too low for efficient high resistance. given. ) c2 634 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 12, 1922 " CONTACT STUD " (Rotherham)asks might be 1" internal diameter with 60 turns of with regard to the Reinartz Tuner (1) For a diagram wire.For longer wavelengths increase up to of circuit adapted for three valves.(2) Could the8" outside diameter by 1" internal, two of which, broadcast signals be heard with this circuit and thein series, will tune to 3,000 metres.(4) Generally loud speaker at a distance of about 80 miles.(3) Is somewhat smaller considering that the A.T.I. is the length of a receiving aerial still restricted to 100 ft. itself very small. (4) Will the Reinartz Tuner tune to any wavelength " E.B. ' (Charlwood) has a two -valve receiving by means of external coils. set with capacity reaction, but is unable to receive (1) We have no information on a modification on a wavelength below 1,000 metres and asks how set of this set in this way, but think the scheme out- may be altered so that he can receive 300/400 metre lined in the diagram (Fig. 2) should be satisfactory. wavelengths. (2) We doubt if sufficient strength for a loud speaker As you give us practically no information about would be obtained atthisdistance.(3) Weyour set we are unable to say what improvements believe that the restrictions are still enforced, butmight be effected, except that increased efficiency the requirements of the P.M.G. are not finallyat 400 metres could be obtained by usnig a H.F. decided as yet.(4) Yes, up to reasonably high transformer in place of resistance capacity coupling. values of wavelengths. We should not recommendA similar effect can be obtained by retaining grid this circuit for very long wavelengths above, say, condenser and leak, but using a tuned H.F. circuit 5,000 metres. in place of the anode resistance. V ir CY O CY

-116111-

Fig. 2.

" R.C." (Brussels) asks (1) For winding data " E.J.K." (Portsmouth) sends a sketch of his for constructing a coil on a phonograph disc. (2) set with which he is having trouble, and asks (1) If Would such a coil do for the reactance.(3) Ifthe aerial is too small.(2) If the inductance value 400 ohm telephones be used with an L. F. transformer. isright.(3) Should he be able toreceive 2MT (4) A formula forcalculatingtheresistanceof and PCGG.(4) For list of stations transmitting copper wire. telephony, with times, etc. (1) A single coil of this nature would not be (1) No.(2) Rather big,but probably O.K. very efficient.If you use a 12" record and wind it (3) Difficultwithonlyonevalve.(4) 2MT with No. 32, you would get to about 4,000 metres. 8 to 8.30 B.S.M. on Tuesdays (400 m.) ; PCGG Put taps in at every half -inch.(2) A similar coil, 7 to 8 p.m. Thursdays and Sundays (1,070 m.). of about 8" in diameter, wound with the sameOther telephony is of an experimental nature at wire,would hesuitableforreaction.(3) No irregular times. transformer is necessary.(4) " H.W.C." (Luton) describeshiscrystalset 4L2 S and asks (1) What condensers he will require with R = L - Length. theircapacities.(2) Whatresistance w-d telephones would bemostsuitable.(3) What isthemost d =Diam. 'in ems. suitableafire for connecting.(4) The maximum S =Specificresist- and minimum ranges of set. anceof copper. (1) Condensers for each circuit might be 0.0005 =2.4 x 10-6. mfds. variable.(2) About 4,000 ohms.(3) About " L.C.E." (Sleaford) asks if No. 38 wire isNo. 20, or flexible cable with about the same thick enough for basket coils.(2) Wiring data for capacity. (4) Maximum about9,000metres. a set of basket coils.(3) What weight of wire isThere are, however, no spark stations working required.(4) If the reaction coil should be largerabove 3,500 metres.Minimum wavelength un- or smaller than the A.T.I. certain-probably about 600 metres.(The coils (1) Yes, as a rule.(2) For 250 metres the coil are much bigger than necessary.) AuousT 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW xiii MAGNAVOX THE WORLD'S FINEST

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Glasgow Depot : 15, Woodside Terrace. Newcastle Depot :17. Sandhill. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW 535 " A.S.H." (Stoneyhurst) asks (1) Dimensions " H.McG." (Lincoln) sends a sketch of his for certain windings.(2) Where a certain condenser crystal set which gives no signals and asks (1) Why. shouldbeused.(3) If atelephonetransformer (2) The wavelength range of coil.(3) The wave- is necessary with 4,000 ohm telephones. length range of set.(4) How could hebest add (1) Coil A, 12" x 6" of No. 26 ;reaction coil, a valve to the set. 6" x 4", of No. 26.Coil B, 12" x 6" of No. 30. (1) We cannot say without test.Everything (2) This condenser could be used for the anodeappears O.K.(2) You do not give us enough circuit.0.001 mfd. would do for the aerial circuit. information to enable us to say.(3) It should (3) No. receive ship sets up to 100 miles.(4) Rearrange " W.M.R." (Croydon) asks (1) If a circuitas in Fig. 2, page 369, issue farJune 17th. will give satisfactory results on telephony.(2) Maxi- " 0.J.L." (Euston Road) asks how to add a mum capacities of various condensers.(3) Informa- valve to his set of which he encloses a diagram. tion regarding his batteries.(4) Which of two tele- It is difficult to advise you with any certainty phones would give best results. without a knowledge of the internal connections (1) No.The circuitisverypoor.See theof your set, but the addition of an L.F. valve. various valve and crystal circuits given in theseas in the diagram (Fig. 3), would probably be columns recently.(2) A might be 0.001 mfd.,satisfactory. B 0.005 mfd., and D 0.002 mfd.(3) L.T. batteries 6 volts, not less than 20 ampere hours.H.T. 50 volts, flashlamp size, or preferably somewhat larger cells.(4) The higher resistance telephones should be the better.No transformer is necessary. " W.J.W." (Gosport)asks(1) Ifpancal.e coils are suitable for telephony.(2) What wavelengths could be obtained with certain arrangements of such coils. (1) Certainly.(2) You do not give us enough information to enable us to say, as you do not stet ,3 the diameter of your coils.If the mean diameter of each coil was about 2", the maximum wavelength would probably be 5,000 metres, but 0.005 mfd. is too great a capacity to use for tuning. " K.L.E.D." (East Sheen).-(1) A upto 3,000 metres.B up to 5,000 metres.(2) 0.005 mfd. would befairlysuitable. (3) Reactance should be coupled inside secondary, say 12" x 3i" Fig. 3. of No. 36.(4) Impossible to say at all accurately. Probably round about 600 metres. " S.J.W." (Keynsham).-(1) You are correct " V.B." (London) asks(1) If a two -valve in assuming that the resistance of the winding of a circuitsketchediscorrect.(2) For criticismof telephone, or similar instrument, is of no actual use,-tuning inductance as sketched and maximum wave- but serves as an indication of the number of turns length of same.(3) If he should get signals with a which the winding contains.The windings of H.R. certain aerial of which he gives particulars.(4) The telephones are of copper, generally of about No. 47 cause of buzzing which he gets, and how to tell when the or 48.Resistance wire is quite useless for the pur. setis oscillating. pose.Inter -valve transformers are generally wound (1) Correct, but a parallel A.T.C. is not wanted with somewhat coarser wire, say about No. 44, which at short waves ;also second arrangement sketched accounts for the considerably greater size.(2) is of little utility.(2) Arrangement poor, as it Finer wires are presumably in closed circuits and in allows too much coupling between the A.T.I. aerial circuits owing to the fact that these closedand reaction.Maximum wavelength about 1,500 circuits have in general much less additional re- metres.(3) Aerial very poor, but should give some sistance than the aerial circuit.Resistance of the results.Why not run it out from the bathroom wire itself in the closed circuit may therefore be window up to the top of the tree ?(4) This sounds greater without making the diameter excessive.like a bad connection in the grid circuit, but we The main object of resistance in a circuit is not so cannot say withouttest.Oscillation may be much the direct loss of conductivity for H.F.detected by howls or muffled and broken up speech currents as the damping, and consequentflat and spark reception, or by clicks when the aerial tuning which it causes. circuit is touched. " AUTO " (Enfield)asks(1) In what cases " F.K." (Wimbledon) asks(1) If a crystal can receivers of 120 ohms, 2,000, 4,000 and 8,000 circuit sketchediscorrect for telegraphy.(2) If ohms be used in wireless telegraphy and telephony. a valve circuit sketched is correct for thecapacity (2) What is the advantage of using slab inductances. for the variable condenser.(3) If copper aerial (1) 120 ohms with a transformer can be used forwire is better than phosphor bronze or silicon bronze. any purpose, and are specially useful in the valve(4) If a 30' pump well would make a good earth. circuits with high voltage valves.H.R. telephones (1) No.See Fig. 2, page 405, issue for June 24th. are good for all purposes. The higher the resis- (2) This circuit might be used, but is very poor. tance the more sensitive, but the lessrobust. See many diagrams in these columns for a better (2) Slab coils are less efficient, but more compact one.(3) No, itis not so strong mechanically. than solenoid or basket. (4) Yes, if it has water in it. 636 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922

" BRIAR " (London) asks (1) If a three -valve E.C.L." (Newark -on -Trent) asks (1) Why circuit is capable of receiving the Dutch concerts.is FL telephony received best with no reaction. (2) (2) For a list of the necessary apparatus to make Which is the better reaction, capacity or magnetic. it. (3) Would an amplifier, designed as per sketch (1) See Fig.1, page 435, July 1st issue.(2) enclosed, work.(4) If ebonite for the formers of The necessary materialconsistsof :-One coilbasket coils is of any special advantage. holder, to carry three valves ;set of slab, or honey- (1) This is a peculiarity of your set.Possibly comb coils ;H.F. transformer ; two valve sockets ;the sense of your reaction coupling is reversed, or threevariablecondensers,0.0005mfd. ; one you have some accidental reaction in the circuit condenser, 0.002 mfd. ;one grid leak ;one L.F. besides that due to the reaction coil.(2) There is inter -valve transformer ;one filament resistance ; little to choose, but magnetic reaction is somewhat one L.T. battery ;one H.T. battery ;one pairmore stable and controllable.(3) We think the telephones. principle involved is quite sound, in fact it ap- "R.W.H." (W.C.2) asks(1) For a circuitproximates fairly closely to that of some commercial embodying H. F. amplifier and crystal as detector. semi-aperio,dic amplifiers.(4) No. (2) A circuit embodying crystal detector and valve asL.F.amplifier.(3) A circuitgiving H.F. amplification with crystal detArtor and note magnifier. (1) The use of a valve as H.F. amplifier followed by crystal rectifier can be thoroughly recommended for short wave reception.Suitable circuit is given in Fig.4. (2)See Fig.5. (3) See Fig.6. All of these circuits are admirably suited for your purposes.

Fig. 5. " L.C.V." (Southsea) sends a diagram of his set and asks (1) How to add a reaction coil. (2) Size of coils and gauge of wire to tune to 4,000 metres with a 0.0005 mfd. condenser. (1) Connect the reaction coil in the plate circuit of the third valve, but it is not at all necessary if you use capacity reactance, as your diagram shows.(2) The coil may be 8" x 6" of No. 24. STUCKPHAST " (Rochdale) asks the reason Fig. 4. for certain noises in his telephones when he touches the aerial terminal. GUNGA " (Edinburgh) encloses a diagram We cannot suggest the reason for this behaviour, of his set and asks (1) What should be the capacity although possibly your A.T.I. may have a bad of the variable condenser.(2) The capacity of theconnection in it.Try rearranging the leads to the two fixed condensers.(3) Resistance of the gridvalve as these may be run too closely together. leak.(4) Wavelength range of the set. Try also reversing the connections to the reaction (1) 0.0005 mfds., but a series A.T.C. is much coil. better for short wave work.(2) Grid condenser, 0.0002 mfds., and blocking condenser, 0.001 mfds. (3) About 2 megohms.(4) Telephony up to 50 miles, telegraphy from ships up to 100 miles, high power stations further. " W.B." (Sunderland).-(1) Coils should have 80 turns of No. 28.(2) Wind coils 1" wide of No. 28, sixteen layers with taps at every alternate layer. (3)Difficult to give an average range for a single valve set.Probably 200 miles on ships, Continental high -power stations and telephony within 50 miles. "RADIO MANIAC "(Wimbledon).-(1) 5,000 metres with condenser, 4,500 without it. (2) Yes, provided that the wavelength of the closed circuit is also brought up.(3) Yes, if the dielectric between the platesis not more than Fig. 6. 1/4,000" thick, preferably mica.(4) See Fig. 1, page 90, April 15th issue, and others. " W.H.L." (London).-The circuit submitted W.E.C." (Putney) asks if a circuit givenshould give quite good results, but we should have to D .F .T ." (Lincoln), in the issue of June 10th, preferred one stage of high frequency amplification, can be used with a set of " Oojah " coils. and 0.002 mfd. is too high for grid condenser for Yes, quite satisfactorily. short waves. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW RV

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E.P.S. 7. xvi THE WIRELESS WORLD AND RADIO REVIEW AucarsT 12, 1922 THE " BROWN " MICROPHONE AMPLIFIER This Amplifier magnifies signals, or music, without distortion, and isofconsiderable interest to amateurs and scientific investigators.The Magnification is much greater than thatobtained from two valves,and thecurrent consumptionisabout 5o mifiiamps.In construction, this instrument is simple, and it is much more robust than other sensitive relays of this class.This instrument satisfies the urgent demand for a reliable, inexpensive amplifier, which the most inexperienced amateur can use, and which the most experienced requires.It is much cheaper, ultimately, than a multi -valve amplifier, and the operator is relieved from many of the varied causes of breakdown.It includes a transformer suitable for low resistance telephones or loud speakers. The price of the " Brown " Microphone Amplifier is 26 for low resistance (120 ohms) input and 18 2s. 6d. for high resistance (2,000 ohms) input. THE " BROWN " LOUD SPEAKER With an Amplifier signals or telephony may be so magnified as to cause discomfort to wearers of headphones, yet not be loud enough to be audible at any appreciable distance from the head.Every wireless experimenter sometimes wishes to let his friends hear, which would involve theuse of several pairs of telephones simultaneously with consequent loss of signal strength, as wellas considerable expense.The " Brown " Loud Speaker was designed to meet this need efficiently and economically, and is used in all up-to-datereceiving stations.The sound is intensified by means of a horn. The " Brown " Loud Speaker (120 ohms), Standard Pattern with Upright Funnel 0

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P.L. 3 a x a 27/32' 211- 3" CELLULOID 3s. Od. Ls. 2 2 2 x./x6' ed. et I I 5/3e. EBONITE 6s. Od. 5s.Sd. a x 2 P P . GLASS Is.Id. 5s. Od. E 5 2 5 no ltx}'4r. il: 6 GLASS 6s.9d. A.P. y a II as 6s.3d. I ' 61' EBONITE 8s. Od. Is.9d. THESE CELLS CAN BE SUPPLIED MADE UP IN BATTERIES OF ANY REQUIRED VOLTAGE. ,PRICES FOR SUCH BATTERIES WILL BE QUOTED ON APPLICATION. SPECIAL HART ACCUMULATOR CO., LTD. STRATFORD, LONDON, E.15 BRANCHES : BELFAST ...41, CHICHESTER STREET GLASGOW ...my, WELLINGTON STREET BIRMINGHAM .. CORPORATION STREET LONDON .. 36, VICTORIA STREET, S.W.x BRISTOL 37, VICTORIA STREET MANCHESTER 4, VICTORIA BRIDGE YORK -6, BRIDGE STREET AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW 637 " ROGNON " (Rochester) asks (1) If it ishappens when you connect up and attempt to necessary for a fixed condenser to be connected across obtain signals, it is difficult to suggest the cause the telephone terminals of a Reinartz tuner.(2) Theof your trouble.The condenser of the " billi " quantity of wire and length of former for Reitnartztype is suitable for use with the set, and should be tuner. (3) Is an " Ora " valve suitable. (4) How kept for a small value.The direction of winding to increase the wavelength of his set. of the variometer is important, and should be (1) No, in this circuit itis essential that nosuch that when the inner winding coincides with telephone condenser should be used.Compare the outer, the two windings are in opposite direc- the article in the issue of May 13th issue.This tions.Reaction effects are obtained in this set information is given on pages 382 and 383.The by the closeness in the two variometer coils marked length of former may be about 5".(3) Yes. in your diagram, B and C.These must be in the (4) This set is not suitable for very long waves,right direction one with regard to the other, and but the wavelength can be increased somewhat you might try reversing the leads which pass from by increasing the number of turns on the coils. one of the variometers ;that is, in the diagram given on page 284, change over the leads that pass " S.A.B." (Gloucester)encloses a diagramto terminal P and one of the telephone terminals ; of his set and asks (1) For criticism.(2) Shouldotherwise everything would appear to he in order, we advise alterations to the circuit given in page 438, and should function correctly.If you care to send July 1st issue.(3) Which is better for low wave-us the instrument we shall be pleased to criticise lengths for telephony. it for you. (1) The circuit is of quite standard type and O.K., except for the fact that itis capable of giving " G.G.S.C." (Pengam) asks(1) Whether it considerable reradiation.(2) The alterations sug- is better to connect low resistance telephones in series gested are quite optional.(3) There is very littleor parallel when operated from a step-down trans- to choose between them. former.(2) How should a separate heterodyne be connected, and how can he tell if his apparatus is " C.R.W." (Malabar Coast) asks (1) For areradiating when using autodynereception. (3) comparison of two transformers.(2) If one would Windings for frame aerial 5" square, to be equivalent be more selective than the other.(3) What is the in wavelength effect to one consisting of two 70" mostefficientinter -valvetransformercoveringa wires; and (4) Which is the better of two circuits, range of 600 to 20,000 metres.(4) If potentiometer one giving potentiometer control to the H.F. valves control of H.T. potential is as efficient as cutting outand the other to the rectifier valve only, and whether or putting cells in the circuit. Zenith valves can be used with his set. (1) The first instrument should give somewhat When using a step-down transformer,better finer adjustment to correct value, but there will results are usually obtained with the telephones in probably not be much difference between them. parallel. --When highresistance telephonesare (2) To cover such a big range several entirely connected directly in the H.T. lead, they should distinct transformers are desirable.(3) No single be in series.(2) To operate a separate heterodyne transformer is efficient over such a large range. such as described by Mr. Coursey, it is only necessary Over shorter ranges we are unable to discriminate to slightly couple the wavemeter coils with the between the products of our various advertisers.tuning inductance of the receiver.Even the use (4) Very wasteful owing to the rapid runningof a separate heterodyne, if coupled to the aerial down of the battery through the potentiometercircuit, may give rise to slight reradiation.All resistance, unless this is exceedingly high, which autodyne or heterodyne receivers when adjusted is undesirable from several points of view.Ad- to the oscillating point, that is when they are justment of H.T. voltage is very seldom required. capable of the reception of C.W., cause reradiation. " J.H.E." (County Durham) asks (1) If itThe extent of reradiation depends on the potential is possible to add one stage of H.F. to a circuit ofof the H.T. battery, and consequently the value which he encloses diagram.(2) Why does the set of the plate current, the type of valve, and the howl when the primary switch is off the studs.(3) Ifextent of coupling between grid and plate circuits. ,t is possible to receive FL on a three -valve set without (3) Use 11 turns of bell wire or single flexible aerial.(4) Why he gets signals on a one -valve wire.It is not possible to construct a frame aerial sat and the H.T. switched off that will give a wavelength variation equal to that (1) See Fig.4, page 467, issue for July 8th. of a two -wire aerial for a given change of inductance (2) Owing to the breaking down of the grid circuit or capacity.For reception over a wide range of tie result may be a true oscillation or a sequence ofwavelength, you might wind on your frame in (3) It should beaddition, many turns of single No. 22 D.C.C., and rapid discharges from the A.T.C. arrange for connecting in or out of circuit by means possible on an indoor aerial or a good frame. (4) (4)Thisisnot uncommon.Some valves will of switches which obviate dead end effects. function without H.T., but in a much less sensitive Where a number of H.F. valves are used, itis always advisable to arrange potentiometer control way. for the grids of the H.F. valves, mainly in order to " IN DOUBT " (Staines) has constructed thepreventself -oscillation.Separatepotentiometer American short-wave receiver described in the June control is desirable for the rectifier valve, which 3rd issue, and is unable to obtain satisfactory results, should be of a type specially designed for use as a and he asks if the component parts of his outfit are detector.Your circuit consisting of three H.F. correctly constructed. valves, one detector and L.F. valve should be From the information you furnish, and your draw - admirably suitable for the reception of telephony Lags, everything would appear to be in order,and telegraphy. We have no information concern and without describing to some extent what ing the type of valves to which you refer. 638 THE WIRELESS WORLD AND RADIO REVIEW Annual. 12, 1922 " L.H." (Mansfield)isusing a three -valve "ROBBRIDE " (Tottenham).-(1)Circuit receiver, comprising one H. F., one rectifier, andshown is correct, except that a blocking condenser one L.F.He is not obtaining satisfactory results,should be inserted across the telephones ;also, and asks us to suggest the probable cause of his trouble. a parallel A.T.C. is undesirable at short wavelengths. There is little doubt that the trouble lies in the (2) Yes, it is quite suitable.(3) You should receive design or constructionof the intervalve high London broadcasting easily.Dutch concerts only frequency transformer.The spacing of the primary weakly.(4) Any resistance not less than 2,000 and secondary windings, and the direction of wind- ohms. ing, is important.If you bridge the primary with a small condenser for tuning, it is advisable not to "W.H.S." (Sutton -on -Sea) gives a list of ap- run on the primary and secondary windingsparatus and asks if this is complete, and how to simultaneously.If your transformer is wound in connect up the various pieces.(2) Is it necessary a groove, it is as well to wind primary and secondary to have a licence before purchasing apparatus. in opposite directions, taking the finishing end of (1) The apparatus suggested would be sufficient, the inner winding to the plate, and the beginningbut a grid condenser and leak would be an ad- end of the secondary winding to the grid.We would vantage.Connect up asindiagramFig. 17. suggest that you construct a number of interchange-(2) No, but a licence must be obtained before the able transformers, experimenting with short-wave apparatus is used. high frequency amplification first.Build up a transformer on a piece of 1" ebonite rod, putting on 600 turns for primary, and 600 for secondary, each being single layer and separated from each other by a single layer of empire cloth.If you make these two windings in the same direction, the terminating ends of each winding will be taken to grid and plate. The wire used should be about No. 40 S.S.C. and will be suitable for use on wavelengths between 500 and 700 metres. "D. McN." (Dublin) has constructed a single valve receiving set with reaction, and is unable to obtain satisfactory results, while his tuning inductance alone works quite well with crystal. From your description everything would appear to be in order.The only thing we can suggest is that you might try reversing the connections Fig. 7. to the reaction coil.You do not say what circuit you are using, but we think if you were to connect " W.H.D." (Hull) asks re the American short- a variable condenser in series with the aerial wave tuner described in the issue of June 3rd (1) What inductance, and another across the reaction coil, resistance telephones should be used.(2) Value for you would probably get oscillations produced, the fixed condenser.(3) Distanceitwill receive and then the tuning -in of signals will be quite easy. telephony.(4) Whattransmittingstationswork It may be that the wavelength range of the aerial in its limited wavelength. tuning inductance, when joined to your aerial, (1) Notlessthan2,000ohms.(2) About is not sufficiently close to that given by the reaction0.001 mfds.(3) Perhaps up to 50 miles.(4) inductance. Amateur stations about 300 metres and broadcast stations between 350 and 400, but it is not proposed " C.J.M.D." (Mill Hill) asks (1) How muchto erect a broadcasting station within 50 miles No. 30 wire to put on a 4" coil to suit an A.T.I.,of Hull. 5" x 11",of No.24.(2) Which isthebetter arrangement, valve as H. F. amplifier with a crystal " H.K-M." (Newbury) asks for certain in- detector or a single valve used as a detector.(3) Howformation in regard to a modified Reinartz tuner. many ohms will it take to reduce a current from 4 volts Some of the information you require is given in to 2 volts. the article on page 445 of July 8th issue.Your (1) Wind about 5" length of the tube.(2) Theformer being 9" in diameter, we should suggest former arrangement.(3) Volts are the measurethe following values : Grid coil 35 turns, tapped at of electromotive force.A current is measured in 10, 16 and 25.Aerial coupling 15 turns, tapped at amperes.If you will tell us the amount of currentevery three.Reaction 30 turns, tapped at every flowing we could tell you how many ohms would be five.This should cover the broadcast band easily. required to reduce the pressure from 4 volts to 2 volts, but not otherwise.You should buy an " TELEPHONIST " (Llanwrda Caom) en- elementary text -book on electricity and study itcloses a diagram of set and asks for suggestions for carefully. improvements to enable him to receive broadcasting telephony from all stations in theBritish Isles, " N.G." (Barry).-(1) Use about lb.of The Hague and Eiffel Tower. No. 26, make coils up to 4" diameter, and connect The circuit shown is quite O.K. except for the as many as necessary in series for both A.T.I. anode circuit of the first valve.The grid condenser and reaction coils.(2) Sliding the coils over eachshould be connected on the valve side of the tuned other will be satisfactory.(3) One tap per coil circuit, but some reaction would be advisable and a would be sufficient, but probably this will not beparallel A.Y.C. is bad on short waves.300 ohms. essential.(4) 0.001 mfd. appears to us exceesive for a filament resistance. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW xvii

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Head Office : London Showrooms : Clifton Junction,219/229 Shaftesbury Av. Nr. Manchester. W.C.2 8 Volt 80 Amp. Hour Exide Battery. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW 639 " J.A.H." (Farnborough) asks (1) The weight " G.H.G." (Bedford)(1) Referstothein- and gauge of wire required to wind the honeycomb structions given in the issue of June 24th for con- coils described on page 539, October, 1920, issue. structing a buzzer wavemeter to set up oscillations Use No. 28 wire.lib. should be sufficient forof precisely 400 metres, and asks for the dimensions all the coils required, which may have turns rang- of the condensers and inductances to give 1,500 metres ing from 150 to 500.N.B.-We regret that, as weand 2,600 metres.(2) Asks how to add two ad- have replied to a considerable number of letters ditional valves to his two -valve set without materially from you lately, pressure on our space will prevent disturbing the present connections. us doing so again at present. (1) The details given in the article referred to " R.D.M. (Belfast) asks (1) With referencewere determined by careful experiment, and it is to page 35 of the " Construction of Amateur Valve impossible to obtain, by relative calculation, the Stations," how can the secondary 9" diameter fitexact data for constructing these wavemeters. inside the primary 8" diameter as given.(2) IfIt can only be found by direct experiment and tests dead-end switches in the secondary coil as well as in against a standard wavemeter.The data was the primary will improve the set. (3) If a transformergiven for 400 metres, for use by experimenters not and 120 ohm telephones are better than 4,000 ohm in possession of a wavemeter. We would suggest telephones. that you insert six additional plates in the condenser, (1) 9" should read 7" and is a printing error. which will increase its capacity by four times, and (2) Yes.(3) Thereislittletochoose.H.R. add one extra slab coil to the inductance, wound in telephones are slightly cheaper and more sensitive, the same direction as the one already fitted and but L.R. are more robust. spaced 4" away from it for producing a wavelength " INTERFERED WITH " (Leicester) asks of 1,050 metres.For 2,600 metres you might make how to overcome interference due tothe adjacent the condenser with strips twice as wide and twice tramway system. as long, and by using nine plates you willincrease We are afraid we can give you little help as you the capacity to sixteen times that given in the have tried all the usual remedies.The Leicester article, and this large condenser should be used in tram system is notoriously bad in this way.You conjunction with four slab coils.The utility of this might try a directional aerial system as, for instance, apparatus depends entirely upon precise calibra- one giving a heart -shaped diagram with the blind tion. side to the trams, though we doubt if this would " C.H.S." (Wolverhampton) submits a circuit give good results, or H.F. chokes across the aerialof a two -valve receiver with high frequency inter - circuit ;also iron screening of your L.F. circuits. valve coupling and a coil coupled to the H.F .transformer for producing reaction effects and 'wishes to " S.S.R.C." (Stoke-on-Trent) asks (1) The know windings for primary, secondary and reaction wavelengthused forCroydontelephony.(2) If he can receive Paris telephony.(3) coils for this arrangement to tune to 350/500 metres. more valves by means of a " Ford " spark coil When working to this arrangement you are re- used as a transformer.(4) The cause of a loudcommended to provide for a moderately loose hissing note in the telephones. coupling between the windings of the transformer. (1) About 900 metres.(2) Possible, but some- The primary which is connected with the plate cir- what doubtful.(3) No, the windings are quite cuit and bridged by a small value variable condenser unsuitable.(4) We cannot say for certain, but it (0.0003 mfds. ), should consist of 170 turns of No. 28 is probably due to a defective cell in the H.T. D.C.C. on a 2" former, and this should be wrapped battery. at the ends beyond the winding to support the " J.H.S." (Finchley) sends a diagram of hiswindings on another former at a distance of about 4" away.The secondary wound on this outside five -valve set, and asks (1) For switching arrange- former should also consist of 190 turns of No. 32 ment for switching in one to five valves.(2) If The the diagram is correct.(3) If the set can be im- D.C.C. coinciding with the primary winding. proved. reaction coil can be made to slide outside the (1) The switching arrangement shown in Fig. 5,secondary and should consist of 200 turns of No. page 62, April 8th issue, can easily be extended to 32 S.C.C. suit a five -valve circuit such as yours.(2) Circuit " H.C.P." (Birmingham) asks(1) To what is correct except that blocking condenser in the wavelength will a certain coil tune.(2) The capacity anode of the third valve should be across the iron - of variable condensers suitable for the above.(3) If cored coil only, and not reaction coil as well. (3) he could receive 2 MT and PCGG with the above The set would be somewhat improved by a potentialcoil in a three -valve set.(4) If shellacing the wire adjustment of the first three valves. will affect thecoil. " H.P.A." (Jersey) asks (1) For a four -valve (1) The primary circuit will receive up to about 5,000 metres without a condenser.Up to 10,000 circuittofulfilcertainrequirements.(2) How (2) Primary to alter a certain set for short waves.(3) If trans-metres with a condenser as below. 0.001 mfds., secondary 0.0005 mfds.(3) Probably former coupling isbetter than condenser coupling the coils are much too big and wound with on short waves. not ; (1) and (2) For short wave work we shouldtoo thin a wire.(4) It makes it less susceptible recommend circuit as shown in Fig.5, page 62, toatmosphericchanges,andusuallyslightly April 8th issue, with the addition of a further H.F. affects the tuning range. valve, the switching being extended on the same " LEARNER " (Walsall) asks for winding lines as shown.(3) Yes.(4) A wide range of details for a set of honeycomb coils. wavelengths, includingshortwaves. A plug-in Try valuesasfollows,adjustingfinallyby arrangement to enable either condenser couplingexperiment, but the values you suggest appear or transformer coupling to be used is very con- very inconvenient.30, 40, 70, 85, 150, 250, 550, venient. 650. 640 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 " KO SINE " (Whitehaven) asks how H.F. " FINE ADJUSTMENT " (Douai School) currents are changed into L.F. currents. asks with regard to a Reinartz tuner he is constructing An adequate discussion is out of the range of these (1) If the wavelength depends on the aerial or grid columns and we should advise you to buy a book circuit, and how to calculate the dimensions of the such as Bangay's " Elementary Principles," which coil.(2) How can another valve be added to the will give you some idea as to the wireless theory. tuner for H.F. amplification.(3) Would such a As you suggest, the valves used for H.F. and L.F.set with a 100' x 60' high aerial receive 2 NT and amplification are the same, and generally the samePCGG at Addlestone,Surrey.(4) If a crystal valves are used for rectification.The difference in detector can be used with a Reinartz tuner. action is in each case due to the circuits employed. (1) Chiefly on the grid circuit.About 5" x 4" Very roughly speaking, the large number of H.F.of No. 20, with 0.0005 mfd. condenser will be O.K. pulses of current corresponding to each spark are(2) See the article in the issue of July 8th.(3) passed through a rectifier, which may be a valve or Probably.(4) Not efficiently. crystal, by which all the negative half -cycles are wiped out.The series of positive half -cycles, if V passed through a high impedance, such as an iron - cored transformer,behaveasone L.F.pulse through the transformer. " ANDREAE COLLEGIUM "(Bradford) asks (1) How to add another valve through a resistance capacity to a circuit sketched, so that he can switch over quickly from one valve to two.(2) Whether English broadcasting stations could be heard on one valve at Rouen. (1) Use a spherical reaction coil.Preferably couple the switch shown with a switch to break the filament of the second valve(Fig. 8) when not required, and use separate filament resistances for each valve.(2) Very doubtful. " A.W." (Plumstead) encloses a diagram of circuit and asks (1) For criticism.(2) Capacities of condensers suitable for the set.(3) Wavelength li11111 of set. 7Nri (1) Not very efficient.We prefer the circuit of Fig. 3, page 5.01, issue July 15th.(2) Closed circuit condenser 0.0005 mfds., grid condenser Fig. 8. 0.0002 mfds.(3) Wavelengths up to 4,500 metres with anadditionalaerialloadinginductance. " A.M.H.C." (Shoreham) asksrereaction Without this only up to about 2,700 metres. coil on page 33 in Alan Douglas's book, how many tappings are necessary, as the diagram shows five " READER " (Royston) refers to Fig. 7, pageand the letterpress stipulates 34.(2) If an illus- 276, May 27th issue, and asks (1) The capacitytration can be given showing the attachment of the of the reaction condenser.(2) If honeycomb coils reaction coil.(3) For a sketch of the circuit. are suitable for coupling the valves.(3) If he is (1) Apparently 34 were intended, as page 33 infringing any patent by sellino a receiver using this distinctly says that it is the secondary taps which circuit. are visible in the illustration. 34 is, however, (1) Up to about 0.0001 mfds.(2) Not veryrather a large number.(2) We think the letter- suitable, but something might be done with them press gives a very fair description.One or two inspecial circumstances.(3) We believe thatrods are passed right through the cheeks of the capacity reaction as well as magnetic is covered by inner coil, and are arranged so that this coil can existing patents. slide on them.The rods are fixed in any convenient way parallel with the base carrying the primary " J.S." (Byfleet) wishes to know (1) and (2) coil.The coupler may be used in the circuit of How to arrange a " B Mark I " set for short wave Fig. 4, page 11, or in many of the circuits given reception.(3) The wavelength range of his tuner, in these columns. wound with 92 turns of No. 24 D.C.C. on 4" former for primary and 175 turns of No. 36 D.C.C. on 3" SHARE MARKET REPORT. former for secondary. (1) and (2) See December 10th, December 24th Prices as we go to press on August 4th are :- and January 7th last issues.(3) When connected Marconi Ordinary ..22 3 0 to a single wire aerial 100' in length, the maximum Preference .. .. 2 0 7i wavelength to which the set will tune will be Inter. Marine.. .. 1 8 0 approximately 900 metres.For telephony recep- Canadian 10 0 tion we recommend you to construct two special coils, the exact dimension of which can easily be Radio Corporation of America found by experiment specially suitable for use on Ordinary .. 19 3 your aerial. Preference .. 13 AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW x ix WHY DID THE GRID LEAK ? A Prize for the best Answer. Watch these Advertisements for Winners. Write on a separate piece of paper (one side only). Endorse " Competition " top of left-hand corner of paper.

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BertramCl, Rx, A3, telephone transformer, two A coils, 24 80 5 Day & Co., Ltd., q & ro, Charing Cross, S.W.x. 6ovolt H.T.Perfectcondition, brand new, 28 88 5 ownerbuildinglargerset.What offers ?- 28 4 2 5 1 ALLARDICE, " Ravensbury," Caterham Valley 30 52 Surrey. Wireless Expert, ready for the wireless boom, 32 6 84 8 First-class Postmaster -General's VariableMicaCondensers. -New,accurate 34 79 9 1 Certificate,ex-adjustments.0. 0005, 9s.; 0.001, r2s. 6d. Money 36 92 11 12 perience in various parts of the world with latest 38 11 10 13 instruments, commercial educadbn, correspondencereturnedif dissatisfied. -THOMAS,Redbourne, 17 typewriting, desires position where above wouldSt. Albans. 40 1624 17 23 be of value. -F. F. WARNER, High Lane, nr. Rigging. -Flexible steel cable, blocks, fittings in Prices at per lb.Postage Extra.Earth Cli s. Stockport. stock. Stays with insulators, strainers,etc., 6d. each.7 22 Aerial Wire, 7/- per 100 ft. made uptoinstructions. Prompt delivery. EVERYTHING FOR WIRELESS INSTOCK. Galvanisedsteel cable,6-strand, r so -wire. Huge Purchase. -Wireless Transmitter, Type 7s.3d., r7 -wire7s.6d., r 7 -wire,9s.3d. No. r, fitted with high class variable spark gap,per loo ft.Delivery F.O.R. London.Also few LESLIE DIXON & CO., condenser and tuning,rSterling spark coil,good second-hand one and two -valve Receiving 9, Colonial Avenue, Minories, E.1 Helix mounted on ebonite panel, terminals andSetsandaccessoryparts.-' S.A.CUTTERS," (nearAIdgate Sta tion. Telephone Avenue 4566. externalfittingsmounted onebonitepanel.6x, Lee Park, Blackheath S.E.3. Internalfittingsin mahogany case. Range, Great Success. -Morse Code easily mastered with roo-5oo metres, work on 4 to 6 volts.Testedthe' LittleBrick"(Prov.: Pat. 13846). before dispatch and sent complete at 17s. 6d. each,Sends any message any speed, and will last a plus ad. for packing and postage.-CADNEYlifetime.Price, complete, 6s. post free.Further BROS., Alpha Mews, Alpha Road, New Cross,particulars stamped envelope.-GRIBISHAW (Dept. S.E.24. W), Leigh Street, Golbome, Lancs. EBONITE " A" TYPE 4 PRONG Aerial Wire. -Our Speciality 7/22 Hard Drawn StrandedCopper,guaranteed,too',5s.3d. ; VALVE HOLDERS 540',7s. ; rooyards,i3s.Carriage paid.- FAIRBROTHER & Co., Vulcan Street, Leeds. 1 /9 each, post free. VELO Complete Wireless Receiving Station, including HIGH QUALITY GUARANTEED RECEIV- tuner,crystal) detector, aerial, telephones (4,000 WILKINSON, ING SETS. ohms), insulators, ready to fit up.Guaranteed to receive speech, music and Morse.75s., no offers, LONSDALE RD. KILBURN, N.W.6 ValveSets complete witn everyaccessory, first P.O.secures. -H.,x6,LordshipPark, TRADE SUPPLIED. Established 1900 including'Phones,Valves,Accumulator, London, N.i6. Battery, Aerial, Insulators ready for im- Brand New Mk. Tuner, 4'w105.rod. mediate use and go.rantP, d to give best B Mk. P 2 -Valve Receiver, C4 xos.-W. SEED, results. Crigglestone, Wakefield. Single Valve Set £11 lls. Instrument Boxes of every description.Splendid Two -Valve Set .. £14 14s. finish.Enquiries invited. -SMITH, Terling, Essex.1 KEYSTONE WIRELESS SUPPLIES Designs of Receiving Sets, Motors, Generators, WHOLESALE ONLY. Three -Valve Set .. £17 17s. etc., supplied.Sound advice given. Calls arranged if desired.Note new address-Pt:max, Buckhurst Ebonite. cabinet work, engraving, expert It will be found highly advantage ens to purchase designers in amplifiers. these complete sets, but all accessories can Hill, Essex. Slab inductances, be supplied singly if required. " Multiwave "TuningCoils. -Setofnine basket coils, etc.Switch arms. contacts. 200-25,000metres.Shellac impregnated,silk - Terminals, Scales. Intervalve Transformers, uncased. 21/- taped mounted complete with table tuning stand, Low Prices Offices: High Finish. Intervalve Transformers,in Ma - chart,35s.Specificationstamp. -RADIO COIL Co.,dperators0, Maybank Avenue, Harrow. 33, Trinity Road, TOOTING, S.W. hogany Case and Terminals . 26/ - Uniform and Bridge Coat, " condition Telephone Transformers, uncased.. 17/ - New." Suit five feet eight or nine. -Write, JAMES Telephone Transformers,inMa- MURDOCH, 17, St. John Street, Prestwick, Ayrshire. hogany Case and Terminals .. 21' - Small Parts Supplied from Stook. -Condenser plates,crystaldetectors,terminals,spacers, Prompt delivery given of all parts and enquiries washers, nuts, contact studs and stops, valve legs. and price lists sent by return. List free.-FRASER, Sentinel House, Southampton Send us your enquiries for Row, London. H. C. DALY, Special Line, Wireless Girder Masts Light and Strong, 3o' f,r, 35' 225. 6d., '40' 25s.,45'3oBOXES, CABINETS, 22 Walbrook, London, E.C.4 SO'35s.Cash with order, carriage forward. -1 F. ARMSTRONG, Weybridge. SPREADERS, CONDEN- To the Trade. -Selling Agenciesavailable. B.A. Screws, Nuts and Washers, assorted gross, 25.,lists2d. -J. H. BENNETT, Station Road, SERS and parts, LEAD -IN- Willesden Junction. For Sale. -Ebonite -r. 3/16", }" and r, any TUBES, and all accessories, size cut. fi"3s. 6d. per square foot, other sizes in proportion. Carriage paid on ros. lots.Scrap to the Trade. Ebonite Sheet suitable for condensers, insulators, HEATH & Co., Ltd. etc., 3s.perlb.,postage8d. NewHart Instrument Weeks, New Intharn, S.113.9 Accumulatorsin2 -volt units --2v. 4o amp. (1) COMPETITIVE PRICES 14.s. 6d., (2)28s.; 2V. 6oamp.(a)175., PROMPT DELIVERIES are prepared to undertake in their fully (2) 33S. 2V. 80aMp.(I)20S., (2) 38s. equipped works -Wireless Apparatus Carriage 'forward.Aerials -Rubber covered on and Parts for the trade. Quotations given wind-up reels, with z R.A.F. ebonite insulators, The Central Aircraft Co. 25.6d.each,postage 9d.Valveholders--Best to Blue Prints.Immediate attention. quality, Is. 9d. ;cheaper quality, is. 6d., screwed 179 High Rd., Kilburn, N.W.6 Phone -Lee Green Jol. Wire-Polan-r, Lyndon.. legs." Ora" Valves -15s. each,Postage 3d.- RENSHAW & MARSDEN, Penny Street, Blackburn. Phone -Hampstead 4403-4 8018.

ti AuciusT 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxi THE WIRELESS WORLD EXCHANGE AND MART

SITUATIONS WANTED. ELECTRADIX RADIOS Ex -Chief Telegraphist. R N.-Young man desires Instrument Wire s postFitting, Instruction.Thorough knowledge Hundreds of Head wireless,allbranches,practical,theoretical. Sets in Stock.All FROM STOCK Last post staff instructor.Expert operator.- with cords.Ster- KING, x6, Bell Green, Lower Sydenham, S.E. ling Brown Phones, S.W.G. S.C.C.D.C.C.8.3.0.D.S.C. En. Marconi Standard Ex C.P.O. W/T (29)12 years experience all s,000 ohms, 51/ - 47 -- 110!-120/- 41/- grades, thorough knowledge theory and practical pair ;4,000 ohms, 48 97/- working, including high power shore stations, - 107/- 28/- desiresemploymentanycapacity, selling, 52/- pair; Brown's 46 84/- 80/- 20/- A 120 ohm L.R. - Demonstrating,etc.,whereaboveexperience head 'phones, 40!- 44 50/- 66/- 16/- necessary.-E.J.M.; 8, Speranza Street, Plumstead, S.E.I8. pair,Sullivan'sL,R. 48 -- 40/- 52/- 18/- Amateur, with four years' experience, requires ditto, with 6ft. 42 81/- 88/- 9/- employment.-Box DAY'S cord plug and jack, -- A.3, BERTRAM 22/-. 41 - 80/- 82/- 8/- ADVERTISING OFFICES, 9 and Io, Charing Cross, HighRes.Head S.W.x. 40 14/- 17/- 18/- 22/- 8/8 ft-Lieut. R.E. (29),Single, over ten years' Sets,1,300 ohms, 89 12/6 15/- 17/- 21/8 6/- experience 26/-; 4,000 ohms, Wireless,Navy,Army,Marconi. 80/- complete, 88 11/- 18/- 18/- 19/- 5/8 Thorough up-to-date knowledge of Wireless, both theoretical and practical.Expert lecturer and Second-hand So - 87 10/- 12/- 14/6 17/8 4/11 demonstrator.Seeks employment with Wireless ohm head - sets 88 8/6 10/- 18/9 15/- 4/8 guaranteed, 15/,Single L.R. Receivers, 4/6. W," I, Oatlands Drive, Weybridge. Cords for double 'phone, new, 2/6 and 8/9. 86 7/9 9/8 12/9 14/- 4/6 Used, 1/6.4 Way Plugs, 2/-. 84 6/10 8/- 11/8 18/9 4/4 SITUATIONS VACANT. Microphone Transmitters, breast plate, 1E/8 ; 88 6/2 7/6 10/6 13/- 4/3 Wireless.-PatentAgentrequirestechnical Hand, 2/8.Insets, 9d. Aerials.-Wire and every accessory in stock. 82 6/10 7/2 911 12/10 4/2 Assistant with thorough knowledge of wireless. ExperienceinPatent Work desirable.-Write Condensers.-Fixed and variable in all sizes, 81 6/6 6/10 8/9 11/6 4/- giving full particulars and salary required to Relays. G.P.O., 21/-; Weston MX., £2 15s. 80 5/- 5/4 7/9 9/10 8/10 Box515,SELLS ADVERTISING OFFICES,Fleet MorseInkers,45/-.Soundersetsfor Street, E.C.4. making rectifiers, 12/6 each. 29 4/9 5/- 7/8 9/8 8/8 Panel SwitchFlushFitting,D.P., 3/6. 26 4/8 4/8 7/2 9/- 8/6 BOOKS. Plugs and Jacks, 1/6 pair. 6o volt Battery. 27 4/2 4/5 '7/- 8/6 8/5 eiv. units, inpolished mahogany ease, six RadioMagazines,allthelatest." Radio sockets, two plugs,17/6.Finest set ever Prices per lb. Bobbins free. World,"'W. ; PopularRadio," roiel. ; offered. Orders of £2 or over, Carriage Paid, G.B. Radio Broadcast,"Is.6d. ;" Radio News," Receivers, all new.Marconi Trench, 5o D.C. as.6d.";" Science and Invention,"Is.9d. ; Cost £40.Complete, 15 101. Terms-Cash with Order. " Scientific American,"as.6d. Post Free.- Amplifier Receiver, Mark II, s valve, with INTERNATIONAL NEWS COMPANY. LTD., 15, Bream's variablecondenser,£710s.Singlevalve FINE WIRE SUPPLIES, Buildings, London, E.C.4. panel, 35/6.3 -valve Amplifier, Hark IV. £8. H.T. Motor Generators to x,000 volts, £15. (A. E. DAVIS) TRADE ENQUIRIES. x kW 220 to 25 volts, £80. EVERYTHING FOR WIRELESS. 41, Arlingford Road, Manufacturers and Factors.-Catalogues and Call at our Electrical Showrooms and inspect. Brixton, S.W.2 Terms, for all wireless goods desired by wireless LESLIE DIXON & 00., specialists in excellent Northern District. Agencies Near Aldgate Station, Met Ey.First Turning considered.-Box LI, BERTRAM DAY'S ADVERTIS- on leh in Minories. ING OFFICES, 9 and io, Charing Cross, S.W.I. PURCHASE YOUR WIRELESS Wireless Repetition Work for trade.-LIBERTY REQUIREMENTS THROUGH ENGINEERING CO., LTD., Acton Town Station. W.3 RADIOPHONE TUNERS, 200-1,400ms. 88/ - The Viper Re -Covering Co., Ltd. WANTED TO PURCHASE. Valve Panels for above ..21/- 7/8, POULTRY, E.C.2. Wanted to Purohase.-Mark 3* Short Wave -0005 Variable Condensers ..18/6 (i minute from Bank) Tele. : City 1897 Tuner.State condition and price.-Box H.r, BERT RAM DAY'S ADVERTISING OFFICES, g and to, Above 3 make an Ideal Receiver. Marconiphones, Sterling and R.F.H. Sets, etc., Charing Cross, S.W.I. Broadcast Concert Coilspair 2/ - can be supplied. Place your ordersNOW. Grid Leaks and Condensers 8/6 MISCELLANEOUS. Fixed Condensers .. 2/6 Expert Advice for the Amateur.-Designs and 5 -Plate Condensers 6/6 THE UNIQUE N.M.C.(WirelessPatents) diagrams, information on allwireless matters. .. Two -valve Receiving Unit, combining Advice on faults and difficulties.Prospectus post 2 -Valve H.F Amplifier Panels32/ - Filament Resistance,Aerial,Tuning In- free.-G. P. KENDALL, B.Sc., Wireless Consultant, ductance, Aerial Tuning Condenser, Grid Moortown, Leeds. Get our New Bargain List. Tuning Inductance and Oscillating Condenser, Printing.-Memos, Billheads,Cards, Price complete in polished case, 12" x 6" x 6", Lists,etc.,very lowprices,samples free. £6 Ss. less Valves. VICTORIA PRESS, 368, KIIIIISiOrd Road, Warrington, AMATEUR SUPPLIES, The Set to obtain maximum efficiency. 184, COTEFORD STREET. N.M.C. 4,000 W., Double Head Gear, 35/ - TRADE: Inductance Tubes. TOOTING, LONDON, S.W. All Experimenters' Supplies in Stock. WirelessExhibition-Willbeheldonthe N. M. CO., 145, Northcote Road, 24th, 25th, 26th Aug., by the South London Wire- Trade Supplied. London, S.W.11. less & Scientific Clubat St. John'sInstitute OUR SPECIALITIES. Larcom Street, S.E.17 (2 mins. Southwark Town PHONE TRANSFORMERS in polished Hall). Special Attractions. AdmissionOne Mahogany Case, engraved ebonite top, Con- CONNOLLY, BROTHERS Shilling, inc. tax.Trade and Amateur Exhibits denser incorporated, 21/-.Unmounted, 14', WIRELESS APPARATUS MANUFACTURERS, especially invited. Sec. W. ANSELL, 67, Larcom L.F. Intervalve Transformers, 18/-..0005 V. LOSTOCK RD., URMSTON, MANCHESTER. Street, S.E.17. Condensers in Polished Mahogany Case, scale Spares & Complete Components at Trade Prices. Wireless ManufacturerofBritishPatented and Brass Pointer,17/6.All own manu- Examples 5o' x 6' Double Wire Aerial, 4o' portable crystal set desires retailers or dealers to factures. Mahogany Cases made to order. Lead in, ready for fixing, 17/6.7/22 Stranded negotiate for output.Sample seen by appt.- Lowest Prices. Wire, per foot.2" Reel Insulators, 41d. NVrite W.M., 54, New Oxford Street. WOODMASON, each. e X 12" Wound Inductance Coil, 4/9. Mallard Valves, Brown's Phones, Speakers, 28's Enamelled Wire, fib., 2/-, rib., 3/6. Batteries, Aerial Wires 7/22, 13 ft.Poles, and Electrical and Wireless Engineer, CARRIAGE PAID ON ORDERS OVER £2. Sundries.-G. R. ALEXANDER, The Motor House, COLCHESTER, and at IPSWICH. Hale, Al trincham. D 2 xaii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 THE WIRELESS WORLD EXCHANGE AND MART

WHOLESALE S.A. CUTTERS " WIRELESS SUPPLIES Manufacturers of The Year Book HIGH CLASS CUTTING TOOLS and Send on your ELECTRICAL GEAR of Requirements

We Sell at Low- BURNDEPT Wireless est Rates con- Apparatus Always in Stock. LTC) sistent with Good Quality Also 4 Little Titchfield Street. Telegraphy OxfordCircus, HEADPHONES LOUD SPEAK- and LONDON, W.I. LET US ERS, RELAYS, CABLEWIRES, l'11.(ne : GERRARD 6123QUOTE YOU MASTS, FLEXIBLE STEEL CABLE FITTINGS Telephony

Write for Quotations WhetherR E as a sourceS ofIJ practical I imformationT S 1922 for the Amateur or as a valuable medium for COMPLETE INSTALLATIONS, every Advertiser, thebest resultsare Inv ariably obtai W. 91 ACCESSORIES, PARTS, ETC. 1,476 Pages. Demy 8vo. through thened"livireless World BERTRAM DAY & CO., LTD. DemonstrationsofAll PRICE NET. Complete Advertising Service, Apparatus by Appointment. 15/. 9 and 10 CHARING CROSS. S.W.1 (Postage Inland 1/-.Abroad 1/4) London Office Open Shortly. L.F. TRANSFORMERS- 15/- 61, LEE PARK, CONTENTS- H.F. do. with 4 tappings- 251- RecordoftheDevelopmentofWireless Vario meter - - -12/6 BLACKHEATH S.E.3 Telegraphy-NationalandInternational 2 -Valve Note Magnifier -40/ - Wireless Laws and Regulations-Directory of the World's Land and Ship Wireless Send Stamp for List. Stations-International Allocation of Call CLARKE, Letters-Alphabetical List of Call Letters- SPECIAL OFFER Meteorological Section-International Time 41,HatchlandsRoad,Redhill. Complete setof parts foriSingle Valve Receiver and Weather Signals-National Resumes ready to assemble with Cabinet and Tuner, ofProgressinWirelessTelegraphy- 17/8, with all orders received in 7 days we Particulars of Wireless Telegraph Patents, will include set of tuning coils, 300 to 2,600 spas-Aviation Section-Tabular Listof metres. Aviation Stations-Useful Data Section- EBONITE MIDLAND RADIOMANF. CO., Wireless Terminology-Conventional Signs usedinWirelessDiagrams-Companies 43,Dame AgnesStreet.Nottingham. Engaged in the Commercial Development VALVE HOLDERS. KNOBS. of Wireless Telegraphy-Biographical Sec- Panels andPieces cuttosize. tion-Literature on Wireless Telegraphy and Telephony-Dtrectory of the World's Prompt Delivery. Amateurs and F. ARMSTRONG, Wireless Societies-Directory of Wireless Weybridge. CollegesandSchools-ListofLicensed Trade Supplied. Send your enquiries. Phone: Wey, 620. Wireless Girder Mast Works Amateur Transmitting Stations-Code Sec- C. OLIVER, 207E ,ikt 14.1 MHOAR4 AV! tion-Special Articles on " TheEarthing London Agent: Wilkinson, Lonsdale Road, Resistance of Antenna.," by Dr. Miessner Kilburn.Agent for Lancashire, Yorkshire, " The Recording of Wireless Signals,"by Cheshire, Shropshire, Staffordshire and North Dr. Abraham-" The Birth and History of Wales :Fred Moore & Co., 46, Park Lane, Long DistanceWirelessTelegraphy "- Liverpool. " The Rectification Effect in its Reaction to FOR SALE. Agents Wanted where not represented. the Composition and Structure of Crystals." HONEYCOMB COILS. A valuable feature Of use present issue is the specially drawn map, which gives, for the In setsof Eight Coils, Wave Range with .---BUILD YOUROWN SET- first time, a simple means of finding the dis- 001 Condenser, 300 to 7,000 Metres.Price, tance and true direction of Wireless Stations £1 7s. Unmounted, £2 10s. Mounted. Half the pleasure in Wireless lies in building in all parts of the World, from London as Send for Lists. your own Instruments.Send stamp today the centre. These coils are HAND WOUND, and combine for our completelists,and getto work - maximum efficiency with lowest possible self - yourself. capacity.There is a big demand for these coils, but at present they can be supplied from ELECTRICAL SUPPLY STORES, The Wireless Press, Ltd. stock by .-- 5,AlbertTerrace, King Cross, HALIFAX. I Dept W W ), 12-13, Henrietta St., London, W.C.2 CHAMP, KAY & CO., -WE SUPPLY THE PARTS- 95.Saltisford, WARWICK. AuGusT.111 12, 1922 1111110THE WIRELESS WORLD ANDRADIO REVIEW OUR PRICE FOR THIS OUTFIT

CARRIAGEcit. EBONITE 7 15 0 PAID

Cheap shoddy ebonite increasesmanu- Read the specification of the Wonderful facturing costs, besides endangering your

REPUTATION. DON'T WAIT F. & B. Single Valve Set untilyouare" BITTEN "before

writing for samples of our RELIABLE, Well finished wood base upon which is mounted Inductance Coil and Slider, CONSISTENT qualities, which we are Valve Bite Mullard Valve, Filament Everything offering with every, confidence of giving Resistance, Grid Condenser and Leak, Fixed Condenser, with all necessary ter - SATISFACTION.. Included, minals and connections made, and insulation to all back connections. Illustrations of Mouldings sent No 6 Volt 20 ampere Accumulator for the willingly. low tension, and a 60 volt high tension enquiries attended to promptly. Extras battery. 100 feet of3/20'saerialcable with Moulding N.0. -Our latest to necessary insulators leading in tube and -AERIAL INSULATOR- earthing clip.Pairofdoublehead receiver 4,000 ohms total resistance in- Buy cluded. We also supply a very reliable Radio Ebonite Supplies, Crystal Receiving Set,everything 4 LITTLE COLLEGE STREET, included £4 15 0 LONDON,(Minute from Cannon Street E.C.4 Station) OrdersExecuteclin Rotation, send at once to save delay Tel. :-CENTRAL 4711. FOX & BRATBY, LTD. SHEETS, RODS, TUBES, MOULDINGS .74 -ail Order Department,34 DUKE STREET, 'AMPLE ;STOCKS AVAILABLE. ST. JAMES', PICCADILLY, S.W.1 X A £20,000 DEAL IN WHICH EVERY BATTERIES WIRELESS AMATEUR MAY PARTICIPATE OF MERIT. "BROWN " "A" TYPE RADIO HEADPHONES Guaranteed new and unused. NOT re -conditioned.

120 8,000 ohms. ohms 42/6 49/6 Maker's Maker's Price Price 58/- 66/-

SULLIVAN 8,000 ohms,...36/6 Why pay the full price and wait weeks for delivery when we can supply from stock atless than trade price 2 Terms eash:with order. Postage 1/- extra. Approval for 7 days. 15 Volt Strip Connection 3/6, postage 6d Trade enquiries for quantities solicited. 15 8 -terminal type, 71 or 15 volts ... 3, 6 15 Wander Plug, 3 volt variation ... 4/- Sd

FULLER" BLOCK" TYPE AC- 86 99 Pt tt 60" .. t9 ... 14/6 CUMULATORS 4 volts, 4 amp., 32,'6 Fully Illustrated List Of Wireless Goods, Post free. 441. the only practical battery for wireless. H. D. BUTLER & CO., LTD. THE CITY ACCUMULATOR CO. Office : BANK BUILDINGS, 222, GT. DOVER ST., S.E.I 79, MARK LANE, E.C.3. (Opposite Boro Tube Station) Work.:- - CANONBURY. LONDON, N.I Phone :- Avenue cx.Telegrams :' Tyche, Fen, London.' TelefthaxeHoibsoz9. Telex. "Ingenuity,'Phose London." THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922

THE FELLOWS HEADPHONE PRICE 301- Complete with cord Stock resistance 4000 ohms Other resistances to order

TheseHeadphonesarehighlyefficient,wellfinishedand British throughout.

We also Manufacture-

Complete Valve ReceivingSet ;Crystal Sets ; Valve Holders ;Ebonite Knobs ;Grid Leaks ; GridCondensers(mounted andunmounted) ; Valve Legs ;Condenser Vanes ;Variable Con- densers ;Filament Resistances ;Valves ;High TensionBatteries : Accumulators ;&c.,&c.

Write for List. Deliveries from Stont.

FELLOWS MAGNETO CO. LTD. CUMBERLAND AVENUE, PARK ROYAL, N.W.10. Telephone : WILLESDEN 1560. Telegrams : QUIXMAG. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW XXV

UNITS,' COMPONENTS Ooz AND SUNDRIES . ^a z TUNER PANEL. u 'S 0 Containing'ooi mf.VariableCon- .n 3 denser, Fine Tuning Condenser and Coil vs c c_ Fitted with G Stand for Honeycomb Coils. o>"/8d' 71".n° O Series -Parallel Switch...£5 0 0 X -CO HIGH FREQUENCY 42J >X('I. o C.) AMPLIFYING PANELS eai rz- For Two ValvesandTransformers. w W r Fitted with Double Tuning Condenser. c 0 £3100 --- e NOTE MAGNIFIER. znt OSto U With Transformer ... £3100 -o '4 - . OiLT4 All above supplied with walnut or mahogany c cases,mattfinishebonitepanels,gold O ,;ZL E lacqueredbrasswork.Condenserswith c bevelled dials. 0T0 C1:12

lid gja g C) Send stamp for List of Condensers and Parts, and y000= t, q).° 4,) E all sundries for Wireless. c ;'1 - LL,

n'Canufacturers: >.) '47; t; ; Zi (;)in 71 0iv -; V- KERR & THOMAS, WN BARR HILL WORKS, 2.40as1700 00 g o 69 DALBEATTIE, SCOTLAND. > `,1 L° 3 (..) v1U

NVIRF.:1,ESS CRYSTAL RECEIVING SET. Specification.-Solenoidtypeinductancewithtappings, 0005 variable eondenser, perikon detector or galena, the whole ISHEET, ROD AND TUBEstockedin being assembled on r ebonite, and mounted in a highly polished cabinet.This receiver is ideal for the reception of telephony. qualitiessuitableforall Wireless work. Wavelength,180/1,800metres approx.Price, complete with Phones(4,000) ...... 25 12 8 KNOBS(Moulded), various patterns stocked CRYSTAL RECEIVING SET. Specification.-Doubleslidetuninginductance,galena detector with dnstproof case, blocking condenser, the whole CONDENSER DIAL AND KNOB. being assembled on a highly polished mahogany base, being an ideal receiver for the reception of telephony.Price, complete I3" and 4' dia.-Cr-100°

with phones (4,000) .. - - ..14 10 0 Filament Switches, under panel type, ebonite .. .. 319 Watch this Advert.

Aerial Insulators ...... 3d. Valve Legs with two nuts .. ..per set of 4 10}d. for new Ex -Govt. 2 -valve Receiver (less valves etc.) .. £75 0 mouldings. Variable Condensers (21 plate) ...... 17/-

H.T. Units, 15v...... - 3/3 & 3/9 H.T.Battery Boxes, complete with switch and fuses, etc. 6/6 Condenser Spindles with knob Grid Condensers ...... 2/6 Valve Holders ...... each 1/ - Fuller Inert Cells, liv. Ali Condenser Plates per doz. 1/6 Crystals .. .. per piece 6d. Zincite ...... per piece 9d. Valve Pins with nut .. per doz. 1,9 Enquiries Sollalted Single -valve and 2 -valve panels Accumulators for Valves.. ..from16 6

Dutch Concert Coils . per pair 4/6 Inductances wound on formers .. - .. 4/9 WHOLESALE ONLY. Aerial Wire, 7/22...... per 100 ft. 5/9 Microphones with replacable in.sets . .. 2/6 H.T. Leads (red and black) .. :. each 4d. Phones, new (4,000 m.), double.. ..30: - Ebonite Knobs ...... each 6d. Switch Arms, laminated with bush .. .. 2/ - AMERICAN HARD RUBBER CO. Carriage Free on £1 and over. ,BRITAIN) LIMITED C. S. SWAN, 191 Bishopsgate, 13a,FORE STREET, LONDON,E,C.2 (NEXT TO BRANDON S). Teleg. 'Eboniseth, Ave., London." 'Phone: Central 12764 and 65 Windsor Road, Leyton, E.10 E. C.2 xxvi - THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 66

VertgeagDRY CELLS BATTERIES werethefirstinthefield,andtheirfinequalities make thempeculiarlysuitedforwirelessinstallations. THE UNIT ' DRY CELL HIGH TENSION BATTERIES " Build up your batteries as you build Any size or voltage withany tappings up your Marconi sets." or sockets at 3 or 6 volt intervals foruse with wander plugscan be supplied Unlimited flexibility in size, voltage and to order. intermediate tappings. Each cell is fitted with brass screw terminal and looped With i3 Sockets wire, and they are efficiently insulated No. W. 19, 36 volts, 24 cells, 3/6each. to prevent current leak. Size 61 x 21 x 3}.Weight 2 lbs. 8 ozs. Wander plugs for use with above. 1/-perpair. No. UW1 7/6 dozen With 2 Spring Contacts.As illustrated. EMF. volts Weight 31 ozs. No. W.1 r, 15 volts, II cells, 3/6 each.Size 9} x x Dimensions 2} ins. x I 5/16 ins. Diam. Weight 1 lb. 2 02S. Art catalogue of standard sizes and list of accumulators for valve filament supply sent on request. Dept. D.L. The EVER -READY Works. Hercules Pl., Holloway, LONDON, N.7

" SEMAPHORE " Wireless HIGH QUALITY High Tension Dry Batteries Ref co er Iv1 Sets :: CONDENSERS ::

ihan3IPPcsmal '001mt. 24- '0005 mf. 18l. TOO mf. 14 - TERMINALS. - The 15 volt Complete with scales, post free. Batteries are supplied (unless other-VoltsNumber Price Each wise ordered) with 2 Brass Connect- of Cells Carriage paid UNIT ing Strips as ill ed.All the othersizes have2 Insulated 15 11 IA. 8/3 COIL Plugs.Brass Sockets are fixed to HOLDERS every other Cell so that Tappings30 22 8/6 can be taken at each 3 volts. 36 24 9/3 Other sizes can be supplied and50 36 13/6 quotationsgivenon receiptof 60 44 1616 enquiries. Made of Ebonite and brass throughout 90 66 24/6 withexcellent gun metal finish. Fixed Unit In order to prove that " SEMA-100 72 26/6 ... 4/2 Shows method of PHORES" are THE BEST and Moving Unit ... 5/8 fixing. induce a trial, we have reduced our Prices post free. price for IS -volt to 3/8 each. Trade supplied promptly Terms on applioation. ASHLEY RADIO SEMAPHORE, Ltd. , TACKLE -1V 69, Renshaw Street, LIVERPOOL 28, John Street, Bedford Row, London, W.C.I. Telephone : Telegrams : 4628Bank. " Rotary. Liverpool." Telephones . . MUSEUM. 5422 and 5423. Telegrams . . ARWELIDITE, HOLB. LONDON. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxvie

():FER PROMPT DELIVERY of complete Receiving Sets and all apparatus required by the Amateur Experimenter.

ONE TO THREE VALVE SETS COMPLETE. " K.B." UNIT SYSTEMS. COMPLETE SETS OF PARTS to build Valve Panels, Condenser Panels, Variable Condensers, etc. AERIAL WIRE H.T. BATTERIES TERMINALS, INSULATORS VALVE HOLDERS &c., &c. FILAMENT RESISTANCES SWITCHES EBONITE SHEET, ACCUMULATORS KNOBS ROD AND TUBE Trade Enquiries Invited. Catalogue post free, 4d. VISIT OUR SHOWROOMS (open 9 a.m. to 7 p.m.), WHERE YOU CAN " LISTEN IN " ON OUR RECEIVING SETS AND INSPECT OUR LATEST PRODUCTIONS. THE "K.B." RADIO EQUIPMENT COMPANY HEAD OFFICES &SHOWROOMS 109 HIGH ROAD, KILBURN, LONDON, N.W.6. WORKS : QUEEN'S PARK, N.W. Bus Services 8, 16, a8 and 51 pass the door. 3 minutes Kilburn Park Statton (Baksrloo Railway).

SKINDERVIKEN BUTTON. A Supersensitive Microphone. Known all over the world and patented in every civilized country.Over 60,000 ACCUMULATORS sold.ENGLISH Manufacture. Make up your own Loud Speaker. Absolutely Guaranteed Best Quality Transmit your GRAMOPHONE musk to any room in your house. CELLULOID CASES The only practical Microphone for use in Detectiphone Sets. Price 5/- each 4volt40 amp. 18/6 4 volt80 amp. 28/2

(for use with Receivers Special Low Resistance 4 60 21/6 4 100 30/- Skinderviken Buttons) 10/- eash 6 40 26/3 6 80 .. 37/3 Special Gramophone Attachments 1/-

Write for 16 page BOOKLET fully illustrated and containing 6 60 31/9 ! 6 100 41/6 much useful information forallinterested inFle=10 PACKING FREE. Transmission.ed. Post free. SPECIAL PRICES TO TRADE Sole Proprietors : forquantities on application. MIKRO LTD., 274/6, Pentonville Rd., London, N.I ,Opp. Ulna'. Cross 121[0 )Itlr Station). SPECIAL OFFER SENSATIONAL REDUCTIONS. 6 volt 40 ACTUAL AMP. SET three glass cells SLAB INDUCTANCES, Let of 8, 91- sealed tops in well -made TEAK crate, a hand- 00JAH make 10/-, post 9d. 3 -plate VERNIER CONDENSERS, 6/-, post 9d some set @ 49/6. L.F. TRANSFORMERS, 19/6, post 6d.PHONE. 4 volt 24 amp., celluloid cases, 11/9, postage 1/- TRANSFORMERS 13/6, post 6d. 2 16 ebonite cases,3/9 each, post free FILAMENT RESISTANCES for panel mounting, AERIAL WIRE, 5/- per 100 ft. Coil. 3/9, post 3d. The POPULAR H.T.BATTERY 36v. 4/9 post 1/ - ALL SIZES of ACCUMULATORS QUOTED FOR CATALOGUE FREE WITH URDErt. Dynamos, Motors, Electrical Accessories. Write for Lists. RADIO. ELECTRICAL & MECHANICAL SUPPLIES. SCIENTIFIC SUPPLY STORES F. Yates & Son, Ltd. Wholesale Electricians 144, Church Street, Kensington, London, W.8 8. NEWINGTON CAUSEWAY, ',NONE (One minutefrom Notting 11111 Gate Station.) Phone -Park4276 NOP LONDON, SE -1. xxviii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922

The London Telegraph Training College, Ltd. Telephone ESTABLISHED WESTERN26%. Morse House, Earl's Court, S.W. 25 YEARS. OFFICIALLY RECOGNISED BY THE WAROFFICEAND POSTOFFICEAUTHORITIES CABLE AND WIRELESS TELEGRAPHY. PARENTS desirous of placing their sons in either of the above Services and of affording them the best training facilities should apply for particulars of Courses and the methods of instruction which place this Institution in the first rank.Cable Telegraphy offers at the present time excellent prospects to youths from 15 years of age and upwards, and the College has exclusive facilities for obtaining posts for qualified students in the leading Cable Companies at commencing salaries of £150 to £300 per annum, with yearly increments of £12 to £25, and ultimate possibilities of obtaining positions as Supervisors, Assistant Superintendents, Managers, etc. In the Wireless Telegraph Service the commencing remuneration at the present time is approximately £150 per annum, and Operators, when qualified by obtaining the Postmaster- General's Certificate of Proficiency, are nominated by the College for appointments. NoCorrespondence Classes orBranches. DAY AND EVENING CLASSES. Prospectus containing all information will be forwarded on application to THE SECRETARY (Dept. H.), 262, Earl's Court Road, Earl's Court, London, S.W.5 Sole Proprietors of the "Scott" Training Disc, which contains useful formulre and other information for Wireless Telegraph Operators and is invaluable to Army Signalling Officers for range finding, etc. Price, complete with instructions for use, 1/-.Postage 2d.

Present Purchasing Powerofa Pound is equal to Pre -War Value when you purchase PETO P -UNITS SIMPLICITY WITH MAXIMUM RESULTS Unit No. 8 lieutNo. 5 UnitNs.4

PUS -SCOTT N9.5.

No. 3 - H.F. Unit Amplifying No. 5-Low Frequency Unit (can Unit (Transformer extra). No. 4-Detecting Unit. be used on any other set as note magnifier), with transformer. Price 37/6 Price 37/6 Price 45/ - No connections to puzzle over, just push as many units asyou can afford against each"pther, slip the little rods through and turn a screw and there you are. SETS OF PARTS can be supplied to build any of the above. For prices see our ILLUSTRATED CATALOGUE with lists of transmitting times and wavelengths.(til. post free. DON'T FORGET THE NEW ADDRESS:- PETO SCOTT,Featherstone House, 64, High Holborn, London, THE CONDENSER KINGatilt at 17,Frome Road, Wood Green. W.C.1. AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW XXIX IMPORTANT NOTICE- Specially designed A. C. COSSOR, Limited, hereby give notice that the order of Mr. Justice Russell of the for 1st March, 1922, continually advertised by the Marconi Co., was an order ARRIVED AT Broadcasting BY CONSENT. Being engaged at the time in the production of an improved and different type of valve, A. C. COSSOR, Limited, did not consider the patents in question of sufficient importance to warrant the expense of litigation. A. C. COSSOR, Limited, respectfully leave the public and the Trade to judge whether the constant repetition of the notification of the judgement referred to is necessary or HEADGEAR expedient in the circumstances. RECEIVERS A. C. COSSOR, LIMITED Designedand manufactured by Aberdeen Works, Aberdeen Lane, leadingTelephone Manufacturers. Backed by many years' experience. Highbury Grove, N.5 Highestefficiency, concentrated magnetic field,instantaneously WARNI N G. adjusted to the ears, comfortable in wear, either receiver detachable MARCONI'S WIRELESS TELEGRAPH CO., LTD., from headband, protected term- v. inals, light weight, twin series cord. A. C. COSSOR, LTD. Marconi's WirelessTelegraph Company, Limited, GIVE NOTICE that an ORDER was made A.T.M. LOUD A.T.M. Crystal in the High Court of Justice, Chancery Division, SPEAKING DetectorSets by Mr. Justice Russell on the 1st March, 1922, RECEIVERS restrainingMessrs. A. C. Cossor, Ltd., from Highest Grade. infringing the Marconi Company's Letters Patent Threetypesof Maximum Efficiency. Nos. 28413 of 1913 and 126658, except so far as amplifyinghorn, ModerateCost. Messrs. A. C. Cossor, Ltd. manufacture for H M . Government. Messrs. A. C. Cossor, Ltd., were further ORDERED upon oath to DESTROY allarticles Ask yourdealerfor and apparatus (other than those constructed to A.T.M. the order of H.M. Government) made or used by them in INFRINGEMENT of these patents, Broadcasting Apparatus and TO PAY THE MARCONI COMPANY DAMAGES AND COSTS. The M -O Valve Company, Limited, of Osram Automatic TelephoneManufacturingWorks, Brook Green, Hammersmith, London, W.6, is the only firm in this country licensed to Co., Ltd. manufacturethermionicvalvesunderthe patents belonging to the Marconi Company. Head Office & Works : London Office : Any valve similar to those generally known Milton Rd., Edge Lane, 6o Lincoln's Inn Fields as the " French type " constitutes an infringe- Liverpool. W.C. a. ment of the above patents whether manufactured in this country or imported from abroad. Marconi House, Strand, London, W.C. 2. X X X THE WIRELESS WORLD AND RADIO REVIEW AUGUST12, 1922' North Wales Wireless College & AmateurSupplies COLWYN BAY. 'Phone 407. Most Complete Stock of all Wireless Students prepared under ideal conditions Instruments and Accessories. Wireless and Cable Operators as PROMPT DELIVERIES. POSTAL AND RESIDENTIAL TUITION. SPECIAL POSTAL COURSE FOR AMATEURS. LIST BY RETURN.rid. STAMP. PROSPECTUS POST FREE. " DIOPLION " INTERVALVE TRANSFORMS DON'T READ THIS If you

111Z111111111111111 21- Actual size Price, 2/6 per dozen, plated ; brass ;small type, 9d. per doz. One valve detector panel complete with filament resistance Are the result of 18 months care- valve holder, and grid leak and condenser, fitted with fulresearch, and will be found insulated terminals, mounted on solid ebonite base in mahogany instrument case .. PRICE25/- equal to any.They are sold on Leading -in Tube, ebonite, R.A.F. pattern with brass rod the " money back " principle, and and fittings. .. PRICE 3/6 Aerial Real Insulators, tested to 25000 volts PRICE 4 we areconfident that once you Accumulator Charging Resistances PRICE Universal Tuners.These tuners have been designed to have made atest,your future tune in Marconi concerts, broadcasting, and Dutch supplies will all be " DIOPLION " Concerts, so that a baby can use them.Wavelength range, 300-1,500 metres, with .0005 m.f. condenser, types. PRICE 4,000 ohm phones, new patent 3 -magnet type, fitted IMMEDIATE DELIVERY cat, be cords and tags, complete with nickel plated head bands .. PRICE NV- given to EARLY APPLICANTS Transmitting Keys,G.P.O.pattern,fitted platinum contacts PRICE 5'- and the trade should take advan- Valve Holders, fitted in solid ebonite, fixing case drilled tage without delay. fitted with valve earthing clip.. .. PRICE 2/8 Grid Leaks and Condensers, mounted on solid ebonite PRICE 5/ - WELIERCETLERSICSALLtd&. Instrument Cases, solid mahogany, rxr x 24", highly finished, fitted ebonite panel, undrilled PRICE 8/ - MITCHELL'S Postage extra on all the above prices. The trade supplied. Enquiries solicited. McDermott Road, Peckham, S.E.15 614,olt:OR. RD. (Retail Store, 188, Rye Lane, S.E.15) J. LI POWSKY,

eir LONDON, E.3 'Phone : East 3345 ACCUMULATORS ETe I HAVE IN STOCK ALL NEW STOCK & GUARANTEED. 4 Volt 23 Amp. Celluloid - - - - 11/3 each. Postage if. 5000 BROWN'S 4 Volt 4o Amp. - 17/6 6 Volt. ao Amp. - 25/8 PAIRS(120 ohms) " A " PHONES 4 ,,60 ,, - 21/3 6 ,, 6o ,, - 31/-

, 80 - 27/- 6 8o - 36/- NEW AND UNISSUED 4 Packing 1/6 extra. Packing 2/- extra. 7/22 Aerial Wire 6/- per no ft. POST A F. Mullard Ora Valves 15/- each. FREE'it"' PAIR 15 Volt Siemens H.T. Batteries /- Accumulator Charging Board 37/8 CASH WITH ORDER Voltmeters, Watch Pattern, o/x2 Volts- - - 6/ - CASH WITH ORDER.Goods despatched per return. WILKINSON, Lonsdale Rd., Kilburn, LOWKE & SONS, Ltd., Northampton. TRADE SUPPLIED(Same address since 1900)N.W.6 PHONES (PGitruk=leleel)30/- CRYSTAL SET 40/ Special Wireless Telephones, 4,000 ohms, 30/- post free.Receiving Set on Mahogany base, double slide Tuning Inductance, Fixed Condenser, Crystal Detector, Terminals, 40/-post free. Terminals complete, 2/6 doz. Valve Legs complete,2/6doz.Contact Studs complete,2/-doz. Postage extrs. I. K. STEVENS & Co. WirelessSection, 32a, Chester St., Grosvenor Place, S.W.1 Auous12, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxxi

c GENUINE& ORIGINAL ;At NEW :Mc VALVE H ELLESEN DRY B ATTERIES 4A-8 UNIVERSAL KNOWN THE WORLD OVER AS THE BEST While retaining the superior detecting qualities of the " Soft " R.M.R. Valve is an efficient Amplifier. L.T. 4 Volts. H.T. 30 to 45 Volts. Y ruOv. IC Rectifies Amplifies CODEWORD: CODEWORD: " WIRIT" Size 61x 2i " WIRIT ' 36 volts. SPECIAL TRADE & WHOLESALETERMS. Oscillates CODEWORD VOLTS DETAILS PRICE " WIRON " x5 Screw terminals " WIRTO " z3 Strip 4/4/-- 1716 "WIRIT" 36 2 wander plugs 8/6 FREE. " WIRIN " 6o 14/- POSE ALL LISTS FREE ON APPLICATION. A. H. HUNT, LTD. R. M. RADIO, LTD. H.A.H. Works, Tunstall Rd., Croydon, Surrey. 5, Regent Square, Gray's Inn Road, W.C. 1

The Construction of " The Model Engineer911 A specialpaperfor youngEngineers.Apprentices. Students endAmateursinterestedin Mechanics. Amateur Valve Stations Electricity and Model Making. It contains practical articlesby experiencedwritersonE'ectricaland By ALAN L. M. DOUGLAS Mechanicalsubjects,Locomotives.Motor Cycling, Model Aeroplanes and Wireless Telegraphy. 78 pages. 55 Diagrams and Illustrations. Published Ierr Thursday. 5.1. po,r free. "Junior Mechanics & Electricity" The paperfor beginners ofallagesinMechanics. PRICE NETT. Electricity and Model Making.All the articles are written in simple language so that everybody can read 16 Itis well illustiatedThere is and understand them. also a Queries and Replies section, from which much (Postage 2d.) valuable information can be obtained. Published on tst of each month. 4,1. post free. The aim of the author in compiling this SOME USEFUL BOOKS. PracticalLessonsin Small Accumulators ..cold volume has beentoplace withinthe Metal Turning .. r'q Electric Bells At Alarms mid reach of the amateur who isinterested Engineering Mathe- Electric Batteries ..told maticsSimply Ex. SmallDynamosand inWireless Telegraphy and Telephony plained 2 Motors .. told Practical Dynamo and Induction Coils for a Handbook which will enable him to MotorConstruction I'q Amateurs .. obtain data that he has otherwise diffi- Practical Induction Small Electric Motors told Coil Construction.. t9 AlternatingCurrents md cultyinacquiring,inorder that he Petrol Motors Simply Windmills and Wind forhimselfaisparatus Explained .. , Motors.. top) may construct Workshop Wrinkles Wireless Telegrarhy which he desirestomake,butdoes and Recipes .. t's Simply Explained ..told not quite know how to design correctly. Ebert' Boy's Book of Electricity, 3d. Elyty Boy's Book of Engines,3d. Book List sent post free on receipt of card. The Wireless Press, Limited PERCIVAL MARSHALL & CO., 66m, FARRINGDON ST.. LONDON, E.C. 12-13, Henrietta Street, Strand, London, W.C.2 xxxii THE WIRELESS WORLD AND RADIOREVIEW AUGUST 12, 1922 HIGH GRADEEBONITE SHEETS RODS TUBES MOULDINGS "Bakelite," "Wittonite" &Fireproof Mouldings Suitable for Electrical, Wireless and MechanicalRequirements. ENQUIRIES INVITED THE GENERAL ELECTRICCO., LTD., Insulation Dept., MAGNET HOUSE. KINGSWAY,LONDON. W.C.2 DEC IUD!, MAIL Insulation Works WITTON and COVENTRY.

CONDENSERS. '0003 Variable Air Condensers.... 12/6 IRELE 0005 SS 15/- '001 V. 1.0 24/- '00005 Vernier .... 416 00001 4/6 High Resistance Phones 12 I0 0 RECEIVERS Filament Resistances ....3/6 & 5/- Contact Studs ....doz. 1/6 REWOUND Switch Arms .. 2/6 4000 Ohms Mullard Ora Valves. Parts to buildyour own sets. AND UPWARDS B. L HOUSTOUN, Regent 4911.66, ENDELL STREET. W.C.S. PERI 2--SET G TURNOCK 41 HIGH ST ASTON BHAM Castagnoli Instruments WIRELESS cannot be bettered for Take advantage of our 14 years' experience of Wire- less. Build your own receivers.We can supply all Efficiency and Workmanship. parts, and show you how to do it. JAMES FRASER & CO. (le collaboration with E.T.C. Address as below) SCHOOL INSTRUCTION Day, Evening and Postal courses in Wireless, Valves, etc.P.M.G. (Exam.), and amateur classes.Also Cable and Telegraphy. Prospectus from 'Phone :North 1036. Principal ELECTRICAL TRAINING COLLEGE, Radio House, Manor G'dns, Holloway, N.7

WITH GOOD APPARATUS YOU CAN GET GOOD RESULTS For the "Broadcasts." ---You Require this Receiver. A high-class 2 -Valve Amplifier Receiver, fittedwith THE " W.P. " Variable Air Condenser, two Filament Rheostats,and an internal new type variable High Frequency Air Core Transformer,extremelyefficientonall wavelengths 200-4,000 metres and over. Morse Practice Key Well Made. First-class Finish. Thoroughly Reliable PRICE £6 10lessvalves. Write for Hillstrom? 1.1,t Post Free. Price7/6 Post Free GORDON CASTAGNOLI MANUFACTURER OF WIRELESS APPARATUS THE WIRELESS PRESS, LTD. 15, Rayne Road, Braintree,Essex 12-13 HENRIETTA STREET. LONDON. W.C. 2 AUGUST 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW AUCKLAND'S Undoubtedly thefinestresultsare obtainable by using Tuned High Frequency Transformers. We can now supply from stock Inter- changeable (Standard 4 -pin type) Transformers wound as under : No. 1 150-600 5/- 6/- 2 380-800 Demonstrations 3 570-1,300 6/6 41,000-2,175 7/- at Showrooms I 51,600-3,200 7/6 62,200-5,600 8/6 It is essential that these Transformers be tuned by a '0002 Condenser. G. Z. AUCKLAND & SON 395, ST. JOHN STREET, LONDON, E.C.1 Manufacturers of Radio Apparatus Factories: ISLINGTON. N. Phone-CLERKENWELL 3173. Telegrarns-"ZAUCKADIO, LONDON. -

If You Want to Buy BE UP-TO-DATE READ THE CHEAP WIRELESS TRANSMISSION Buy OF PHOTOCRAPHS EX -GOVT. SURPLUS By MARCUS J. MARTIN. 143 pages. 139 Diagrams and Illustrations. STOCK. 250 TONS Price 5/- net. Post free 5/6 TO SELECT FROM THE WIRELESS PRESS. LIMITED, Dirt. W.W WIRELESS MANUFACTURERS 12/13, HENRIETTA ST. STRAND, LONDON W.C.2 please inspect our SMALL PARTS WIRELESS AMATEURS beforemaking yoursetscome and view our stock. Questions and Answers THE COUPON ElectricalDisposals Synd. To accompany Questions Office : 6, MARKET PLACE, OXFORD CIRCUS sent induring the week Warehouse : 84a, Glengall Road, Peckham commencing Aug. 12th, 1922. Phone-Museum 643 TECHNICAL ADVICE FREE VOL. X, NO. 20. call in and see us about it. See Conditions on Page 633. We have so Years' experience THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 ALL-BRITISH WIRELESS EXHIBITION&CONVENTION willbeheldatthe HORTICULTURALHALL WESTMINSTER : LONDON : S.W.1 SEPT.30TH TOOCT.7TH (SATURDAY) (SATURDAY) Thiswillbethemostrepresentative Wireless Exhibition everheldin GreatBritain. THECONVENTIONwillbeheldunder theauspicesoftheWIRELESSSOCIETY OFLONDONandallaffiliatedsocieties. APPLICATIONSforstandswillonlybe acceptedfromBRITISHAlliedand KindredTrades. ge IMPORTANTPUBLICWARNING. In view of certain misleading statements at present circulating, itis desired to emphasize that this will be the first and only Wireless Exhibition held this year carrying the full support of the entire Trade, the latter by common consentbeingpledgedtoparticipateinnoother similar gathering. ApPlicationsshould be addressed to THEORGANISERS BERTRAMDAY & CO.,LTD. WIRELESSPUBLICITYSPECIALISTS 9and10,CharingCross,S.W.1 Gerrard8063/4 AvousT 12, 1922 THE WIRELESS WORLD AND RADIO REVIEW

2. Allconnections I. Perfect insulation shown in diagram of grid connection en ready made for you sures silent operation. and brought out to terminals.

'PO OA V III

3.To add an amplifying stage, connecttoterminals andinsert valve.

4. Tapped holesin two sides and base make fitting easy.

Themost important detail improvement yet made inWireless Receiving Sets. THE ELWELL AMPLIFYING UNIT Comprising valvesocket and ironclad This patented amplifying unit, when pro- intervalve transformer, mechanically and vided with a valve and connected as marked electricallycombined in oneunit: on the terminals, is all that is necessary to give one stage of amplificationto your existing set. No soldering is necessary. The unit is easily attached to panel or shelf, or Exclusivedesign covered bypatents. will stand alone. British made and guaranteed throughout. The self..contained permanent connections are a big practical advantage, whilethe perfect insulation of the grid connection will To secure early delivery order at once. appeal to all amateurs troubled with " noise."

Price 39,6 only, for complete amplifying unit, less valve. Enquiries for all wireless components invited. C. F. ELWELL, LTD., CRAVEN HOUSE, KINGSWAY, LONDON, W.C.2. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 12, 1922 I BROADCASTINC-1

SULLIVAN PATENT TELEPHONERECEIVERS for RADIO TELEPHONY AND TELEGRAPHY Of High and Uniform sensitivity andDISTORTION=LESS being thus specially adapted for receivingspeeches, neW3 and concerts from 'BROADCASTING and otherstations Windings highly insulated, durable and reliable in all climates and under allcon- ditions of service.This was strikingly evidenced during theGreat War when avesselcarrying "SULLIVAN" phones shipped to the order ofan Allied Government was sunk through misadventure, but atalater date was successfully raised and her cargo salvaged.The Telephones themselveswere found to have sustained much damage throughthe action of sea water, but the coils provedto be perfect electrically and mechanically notwithstandingtheir long immersion, andallwere again brought into requisition. IMPORTANT .NOTICE These Telephone Receivers must not becon- fused with the old and comparatively insensitive" SU LLIV AN " phones, sold by the Disposals Board and still being retailed by certain dealers, nor with those new but equally insensitive Radio Telephone Receivers of Continental and other origin bearinga misleading resemblance to my present pattern.

WHITE METAL HEADBANDS SUPPLIED IF DESIRED Without public advertisement of any kind, over one quarter ofa million sets of " SULLIVAN" phones have been made and sold for " Wireless" alone. Trade Terms on Application. DEMONSTRATION AND SHOWROOMS AT LIVERPOOL HOUSE, MIDDLESEX STREET, LONDON, E.1. (Twominutes'walkfromLiverpoolStreetandBroadStreetStations)

Works. Office., "LIVERPOOL HOUSE" WINCHESTER HOUSE MIDDLESEX ST.,LONDON,E.1HW SULLIVAN LONDON,EC.2., ENGLAND e Avenue 4871 TS 1.t..2 "lampoon -1%emen.Lonoco.:' Phone: London Wall 3518 lay y2, , Printed by Sanders Phillips & Co., Ltd., Chryssell Road, London, S.W.9, forthe 141., giProprietors and Publishers, The Wireless Press, Ltd., 12-13, Henrietta Street,London, sa W.0.2 ;Sydney, N.S.W., 97, Clarence Street ;Melbourne, 422-24, Little Collins StreetNew York, 326, Broadway. 19th AUGUST, 1922. THE PRICE 6DNET. WIRELESS WORLD AND RADIO REVIEW

Registered at the G:P.O; VOL. X. No. 21. 19th AUGUST, 1922. as a Weekly Newsparer. THE TINGEY UNIT SYSTEM HAS PROVED ITS ' EFFICIENCY Write for ILLUSTRATED, CATALOGUE which contains an article on Wireless Made Easy and a Complete List of all Wire- less Goods in Stock WRITE FORILLUSTRATED CATALOGUE 3d. POST FREE

£ s.d £ s.d. C 1. CONDENSERS. One pair mounted in case. 5 00 I 1. INDUCTANCES. B. Coil -1,000-8,500 metres R. RECEIVER (for R. Valves).. 4 176 with approximate calibration .. Price1 176 I 1. INDUCTANCES. C. Coil -5,000-24,000 metres R P. RECEIVERS (for Mullard Valves) . 4 76 with approximate calibration .. ..Price32 6 R.S. SINGLE VALVE RECEIVER.. .. 3 100 J 1. JUNCTION BRACKETS (8 styles) from 3,- to 6/6 each R.V. UNIT H.F. to follow R.S. Unit .. ..2 00 P 2. BROWN'S PHONES (D Type), 126 w. Per pair286 A 2. MULTI H.F. AMPLIFIER UNIT, Choke and BROWN'S RELAY UNIT (mounted in case), for rapid

resistance type.. . .. 3 150 attachment to Tingey Units. No loose connections (2.000 ohms input) A 3. MULTI L.F. AMPLIFIER UNIT ..3 15 0 .. ..6 15 0 BROWN'S RELAY (without Tingey adaptation) .. 626 MULTI H.F. AMPLIFIER UNIT, without in- A 4. " ORA " MULLARD'S VALVES .. ..each0 15 0 .. 2 10 0 ductances or variable condenser .. P 1. INDUCTANCE PLUGS .. 04 0 A 24. COMBINED UNIT, tuned or stand-by position3 150 T 2. INTERCHANGEABLE TRANSFORMERS (300 0 0 T 1. MULTI TELEPHONE TRANSFORMER UNIT2 to 24,000 metres) .. . each 6/- to IS/ - 11. INDUCTANCES.A. Coil -200-1.600 metres TINGE? (3 -Valve) RECEIVER, 1 valve H.F., 1 Rect. with approximate calibration. Price 1 50 1 L.F. (without valves) .. 8 100 COMPLETE RECEIVING SETS(VALVE) From £14. Showrooms Open 8 a.m. to 8p.m. Saturdays 8 a.m.to/p.m.

Offices&Works Offices&Showrooms Phone W. R.H. TINGEY. HAMMERSMITH 1916 92 Queen St. Teleges. Hammersmith. "T1NtOIDAR LONDON SPECIALIST /N WIRELESSLondon . W.6 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19,1922 MAGNAVOX THE WOLD'S FItriNCEST

RADIO LOUD brings it MAGNAVOX SPEAKER tellsit. No. 111293 Broadcastingfaith/ullyreproduced (14" Horn). withmarvellous clarity and volume Sterling Telephone & Electric Co., Ltd. YOUR TELEPHONE HOUSE, 210/212, Tottenham Court Road, London, W.1 ENQUIRIES Telephone No.: 4144 Museum 17 lines) Telegrams : Cucumis. Wesdo, London INVITED. Works :DAGENHAM, ESSEX. BRANCHES :NEWCASTLE -ON -TYNE :9,ClaveringPlace. CARDIFF :8, Park Place.

This Book Will Help IF YOU WANT A YOU. GOOD BOOK ON RADIOTELEPHONY The moregenerallyuseful GET formula'andmethods of measurement for inductance TELEPHONY and capacity are brought together in a convenient form in WITHOUT WIRES The BY Calculation and Measurement PHILIPR.COURSEY,B.Sc.(ENG.), A.M I .E.E. of Price 15/. Nett Inductance and Capacity ( Postage 9d.) By It contains a complete collection of information on the various schemes, proposed and tried, relativeto the W. H. NOTTAGE, B.Sc. electrical transmission of the sound of voices through space without wires. Price Nett. An excellentlistofreferencesto 3/6 papers and articles, forms a complete ( Postage 5d.) bibliographyofthe whole subject. The Wireless Press, Ltd., THE WIRELESS PRESS, LTD. Dept, W.W., 84. Dept. W.W. 8/4 12-13,HenriettaStreet, London, W.C.2 12-13, Henrietta St., London, W.C.2 GAMAGES\i - r19, 1922 THE WIRELESS WORLD AND RADIO REVIEW iii LEAD IN AMATEUR WIRELESS FIRST IN 1908 --FOREMOST TO -DAY Exceptional Offer of 'PHONES

BRDWN'S DoubleHead- piece496 Receivers, 8000 ohms. Ditto,120 ,`.1115.-- IMPROVED TYPE OF FILAMENT RESISTANCE The above has been produced by us to meet the present demandforacheapyet 4216efficient Filament Resistance suitable for mounting to the SULLIVAN'SDouble Head- purchaser's own instruments. piece Receivers, 8,000 ohms. Itiseasilyattached, and when fixed is very neat and attractivelooking. The Resistance is wound on an air core in a grooved Ebonite 3616 former. When mounting Withoutleads.In perfect allthatisnecessaryisto condition and absolutely new. drill a hole in the panel for the spindle and three holes LOW FREQUENCY All sent pest free. for the fixing screws. Remove the ebonite knob and screws from theresistance,insert AMPLIFIER the spindle and collar through The single stage low frequency the centre hole in the panel Amplifierhereillustratedcan and attach firmly by means be easily connected to any valve ofthescrews. Replace or crystal receiving set, thereby knobtocomplete. To increasing the efficiency of the indicate the " Off " position receiver by 30%. With the use a mark should be made on ofthis instrument,signalsare the panel to correspond with renderedvery thearrowontheknob. distinct,and These resistances are suitable many otherwise inaudible messages for one, two, or three valves. are sufficiently strengthened as to become Size 2r wide by 2'high. readable. This Amplifierisparticularly suitedfor the receptionof telephony and PRICE S/6 music owing to the absence of noise usual with multi -valve amplifiers. The transformer used is the finest on the market, and the design and finish of the FULL VALUE whole instrument are up to our usual high standard of FOR MONEY excellence. Length 8', width 6", height 3k'. We areoff, r,ng ALWAYS this fine piece of apparatus at the extraordinary low price of 42/-Post Free. "WESTON" MOVING COIL RELAYS WRITE NOW FOR OUR This well-known instrument is one of the most sensitive relays obtainable.It consists of a very delicate permanent WIRELESS magnet (" Weston "), moving coil instrument movement and is provided with a platinum circuit closer in place of CATALOGUE a pointer.The contact screws are adjustable and are so Fullyillustrated.giv:ngall arranged that the contact closer can be set to move through details and prices.indispens- an arc ranging from r to less than 1 -tooth.It is highly able to the man who wants the recommended for all classes of work where an extremely best apparatus atthe lowest sensitive relayis required;the attention of wireless prices.A copy willbe gladly enthusiasts being especially drawn to same for the purpose of experimenting in wireless recording.We are now sent POST FREE ON offering this beautiful REQUEST. instrumentatthe 10W price of L./ - GAMAGES, HOLBORN, LONDON,

A 111 THE: WIRELESS WORLD AND RADIO REVIEW Al-1:1ST 19, 1922 W. H. PORTER & CO. GENTS' MAKE 44, Church Street, BIRMINGHAM. FITMENTS

WHOLESALE ONLY. SEND FOR OUR ALWAYS STATE QUANTITY AND FULLEST PARTICULARS SUNDRIES RE THE ARTICLE YOU WISH TO BE QUOTED FOR, PAMPHLET AND IF POSSIBLE SEND A SPECIMEN. Condensers-best and cheapest on the market.Ebonite parts and fittings. Specially made moulded parts and fitting to special designs. MAKE USE Filament Resistances. OF OUR Grid Leaks and Condensers. STOCKS Head 'Phones. Loud Speakers. Intervalve Transformers. Telephone Transformers. Valve Holders. ASK US Turned and Moulded Knobs and Fittings. TO QUOTE Coil Holders and Sockets. FOR YOUR All Brass -turned and Pressed Parts a very special department. Ebonite Dials. WHOLESALE REQUIREMENTS Condenser Parts. Aerial Wire. Condenser Scales. GENT & Co. LTD. FARADAY LEICESTERWORKS Switch Arms. LONDON :25, Victoria Street, S.W.l. NEWCASTLE -ON -TYNE: Tangent House, 52, Blackett Street Complete Telephony Receiving Sets.

H.F. TRANSFORMERS TO FIT VALVE SOCKETS. The THOR No. 0 Range150 Metres - 5/6

No. 1 0 9 300 - 6/ - Goes one

No. 2 9 P 600 - 6/3

No. 3 , 9 1200 - 6/9 Better

No. 4 1800 - 7/6 Strength,efficiency,sound workmanship,andvalue No. 5 ,. 2500 Of 8/3 are four outstanding features of the No. 6 ,, 6000 - 9/9

No. 7 9 9 8000 - 12/ - T H 0 R Filament Resistance

No. 8 24000 - 14/3 Although on the market for such a short time, some There is good latitude on these Coils for higher and lower ranges. makers are already offering inferior imitations. Protect yourself by insisting on the genuine Thor. Ask H.T. BATTERIES (Fully Guaranteed) your dealer about it-ask him to show you the THOR. 15 Volt strip connection 3/6 post 6d. Price only 6/ -

15 3 -terminal type 36 6d. Stocks held by London Representative : Mr. J.O. Maddock. 15 Wander plug 3 - x x, Bayham Road, Bedford Park, W.4. volt Variation -4/- 6d. Purchasing agents wanted where not If unobtainable locally, Showing the represented. 7/6 1/- 36 ,, send P.O. to- Phosphor_ bronzeBlade 1 60 ,, 14/6

1/3 108 22/6 Fully Illustrated List containing over 100 illustrations. post free 4d. H. E. Ashdown H. D. BUTLER & CO., LTD. (Birmingham) Ltd. Office :Bank Buildings, 222,GreatDoverStreet, Perry Barr, Birmingham BOROUGH,S.E.I (Opposite Boro Tube Station) 'Phone:Northern 559. Works :Canonbury. London. N.7 Tel. Segment, Birmingham. Telephone: Hop 3029.Telegrams :Ingenuity. Phone, London. Code :A.B.C., 5th Edition, Western. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW

The Name "BURNDEPT" GUARANTEES Cent. Per Cent. QUALITY & EFFICIENCY. BIRMINGHAM: MANCHESTER: 133 NEW STREET. 61, BRIDGE STREET, DEANSOATE. LIVERPOOL: L3URNDEPT LEEDS: 10, SOUTH JOHN STREET. 48, Or. GEORGE STREET. ; - -d777. - LONDON OFFICE & SHOWROOMS 15 Bedford Street. Strand. W.C.2. THE BURNDEPT ULTRA IIIRECEIVER (New Series Mk. 4) The mostPerfectallpurposeReceiver ALL the well-known features THIShigh - classreceiving of the previous series are re- sethashadmorerefine- tained,viz.,separate valve ments added, further improv- control - independent use of ingH.F. Amplificationfor valves,etc. A telephone very short waves-we now transformeris incorporated claim to obtain the maximum so that eitherhigh or low 'H.F. amplification it is possi- resistancephonescan be ble to obtain from one valve used at option. from 140 to 20,000 metres.

ILLUSTRATED CATALOGUE Burndept III Ultra Receiver ILLUSTRATED CATALOGUE Post free, 6d. Price - - £25 Post free, 6d. Returnable with first Order. (less valves) Returnable with first Order. This Catalogue gives full details of our one, two, three and four Valve Receiving Sets Absolutely complete and ready for Signals, Telephony and Music (Prices range from £21) LONDON SHOWROOMS' LONDON SHOWROOMS! 15, BEDFORDS. 16, BEDFORD ST , STRAND, W.C.T.2 BURNDEPT LTD. STRAND W.C,2 Manufacturers of Wireless Apparatus Aerial Works & Eastnor Works, BLACKHEATH, LONDON, S.E.3 NI MI MI CRAY INSTALLATIONS, LD. electrical & Mechanical engineers, W. A. C. SMITH

'Phone 72b, High Street, 'Phone 236, Argyle Street, 288 288 Southampton SOUTHAMPTON. Southampton GLASGOW, HAMPSHIRE AGENTS for"BURNDEPT"are Sole Scottish Agents for the Wireless Apparatus. Transmitting and Receiving Sets in Stock. Famous Burndept Receivers All Accessories for Amateur use. Call and inspect our 'Stock. when full Particulars and

Demonstrations will be given. A2 vi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

" Transform " Engraving Costs toProfits.

MHE present high costs of engraving are I reduced to a minimum with Taylor - Hobson Engraving Machines. The speed and efficiency of these machines make themaprofitablesection of every plant. They turn out high quality work on hard or soft surfaces at a fraction of the old cost. They are invaluableforrapid mass production. General Engravers everywhere have adopted these machines for all styles of engraving. Cutter at Work. Send a Tort Card for full particulars. TAY1.0104AYLOV0135011.1Z" 74a, NewmanStreet,London, W.1 Works :LEICESTER.

RADIO INSULATION AS SPECIFIED AND USED BY THE BRITISH ADMIRALTY

BRITISH MADE PAXOLIN BRITISH MADE

TUBES DISCS PLATES, &c. MANUFACTURED IN ALL FORMS, SIZES AND THICKNESSES BY THE MICANITE & INSULATORS Co.LTD. EMPIRE WORKS WALTHAMSTOW LONDON, E.17

TELEGRAMS :-" MYTILITE. PHONE. LONDON." TELEPHONES -WALTHAMSTOW 738, 739 AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW vii DUBILIER A New Condenser for Wireless Receivers With Clips for Grid Leak.

Y P e THE DUBILIER TYPE 600 AICp Gtiii,atk DUBILIER MICA CONDENSER (ADFNQI-R CO 0921)00

The illustrations show two types of this new condenser for wireless receiving circuits.The condensers have the same perfect mica insulation, the same high efficiency and the same permanence of capacity as the larger Dubilier Mica Condensers Without Clips for Grid Leak. used in wireless transmitters.Distortion when receiving telephony is often due to bad design of the components of the receiver-therefore use efficient Dubilier Condensers in your receiver B to obtainthebest outof your set. CONDENSER(11211 t PRICES: Capacity between 0'0001 and 0'001 mfd -2/6 each

97 7/ 0'001 0'005 - 3/- (inclusive) ,THE WAY TO DUBILIERS. Condensers complete with Grid Leaks - 7 6

TRADE TERMS ON APPLICATION.

Both types of condenser (with or without clips GOLDHAWA ROAD for a grid leak) arefitted with screw terminals as well as tags for making soldered connections.

THE DUBILIER CONDENSER CO. (1921), LTD., DUCON WORKS, Goldhawk Road, Shepherd's Bush, London, W.12 Telephone-Hammersmith 1084. Telegrams-Hivotteon, Phone, London. Code-Marconi International. viii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

EXPER IENC.E

HIGH -FREQUENCY Specially designed AMPL I FICATION for 100 to 20,000 METRES Broadcasting IMPROVED ADJUSTABLE REACTANCE COIL, SELF -TUNED. SPECIALLY DESIGNED FOR SHORT WAVELENGTHS HIGHEST EFFICIENCY.

HEADGEAR RECEIVERS This is the high frequency unit that every wireless experimenter has been waiting for.The fact that it bears our,name is 'a Designedand manufactured by guarantee that it will do all that is asked of it. ADVANTAGE OF HIGH FREQUENCY AMPLIFICATION leading Telephone Manufacturers. All serious wireless experimenters will appreciate the great Backed by many years' experience. advantages of high frequency amplification before rectifying. It makes signals far below audible strength easily readable and permits additional audio frequency amplification (after Highestefficiency, concentrated rectifying) without rfndering the receiving set unstable. THE TAPPED ANODE REACTANCE COIL. magnetic field,instantaneously This coil, originally developed by Mr. W. A. Appleton, our research director and specially designed for short wavelengths adjusted to the ears, comfortable has now been still further improved by a finer sub -division of the tappings to obtain the best efficiency for broadcasting. in wear, either receiver detachable NEW AND IMPROVED DESIGN. from headband, protected term- The coil is sectionally wound and cylindrical in form as this design allows greater mechanical strength in the winding inals, lightweight, twin series cord. at the tapping points than does the earlier disc type. loo TO 20 000 METRE RANGE. Twelve tapping points are provided covering a range ofwave- lengths from zoo to 2o,000 metres. CONSTANT REACTANCE VALUE. A.T.M. LOUD A.T.M. Crystal The tappings have been selected to keep the reactance value SPEAKING DetectorSets approximately constant for all wavelengths. NO TUNING CONDENSER NEEDED. RECEIVERS Highest Grade. No tuning condenser is necessary as the capacity of the winding Threetypesof Maximum Efficiency. renders the coil self tuned. HIGHEST EFFICIENCY. amplifyinghorn. ModerateCost. This type of coil gives a higher efficiency on short wavelength, than any other method of intervalve coupling. DELIVERY- Immediately from stock. Ask yourdealerfor PRICE -Tapped Reactance Coil as specified ..£15 Al TwelveTpoint switch for use with same.. 160 Radio Instruments Limited Broadcasting Apparatus Managing Director :J. Joseph, M.I.E.E., late Manager to Mr. H. Sullivan.Chief Designer :W. A. Appleton, M.E.E., M.I.R.E., late Admiralty Technical Research Officer. Automatic TelephoneManufacturing ONLY ADDRESS. Works, Offices & Showrooms Co., Ltd. 12a, Hyde Street, Head Office & Works : London Office : NEW OXFORD ST., W.C.1 Milton Rd., Edge Lane, 6o Lincoln's Inn Fields We have the largest wireless works in Central London. We are wireless engineers of established reputation. Liverpool. W.C.z. Our name on wireless apparatus is a guarantee of satisfaction

I.P.S. 7A. Auot-sT19,1922 THE NVIRELESS WOHL1) AND HAM() REVIEW ix .42k. riAk. "DUROS" CELLS The only accumulator suppliedina charged state. They retain their charge for very long periods. Stocked by all leading dealers in " Wireless Supplies." 58a, BUCKINGHAM PALACE ROAD, WESTMINSTER, S.W.1 E. G. LIND & CO., THE WIRELESS WORLD AND RADIO REVIEW THE OFFICIAL ORGAN OF THE WIRELESS SOCIETY OF LONDON A MAGAZINE DEVOTED TO WIRELESS TELEGRAPHY AND TELEPHONY CONTENTS Valve Manufacture ------641 More About the Armstrong Super -Regenerative Receiver- - - - 648 An Amateur -made Two -valve Set in Buckinghamshire.By A. F. H. Baldry - 652 An Experimental Station at Yeovil.By L. W. C. Martin - - - - - 654 Contents continued on next page. BATTERIES FOR WIRELESS High Tension Block Accumulators Fuller "Chad" Batterie

FullerPlate and Patent Block Cells (a and 6 -volt sets) are eminently suitable for Wireless Work.

Block Accumulators, unlike the ordin- Designed for use in supplying the ary Plate Type, retain their energy anode (sheath) circuit of thermionic reception purposes. for12-18 months on one charge. valves for Unequaled for use with Wireless Expert tests inevery case confirm theStandard Thermionic Valves. Standardised itssuperiority over sizes-Iand 3A.H.capacity. Battery usually employed. Last much longer than ordinary Dry Price Type No. of cellsVoltage. Capacity Cells, free from risks of leakage and short circuits. A ra/Z xz 24 A.H. 14 150 A so/Z 3o 6o A.H.£1000 Type No.of cellsVoltage CapacityA.H. Price r approx. 5/- A 12/K 12 24 3 A.H. IS 150 8 12 A 15 I approx. 7/- A 30/K 30 6o 3 A.H. £12 10 0 ro 4} approx. 11/9 B 8 12 EBONITE-Rod, Sheet and Tube so 15 4approx. 113/ - FULLER'S UNITED ELECTRIC WORKS, LTD. (If [TRIM w.1 WOODLAND WORKS, CHADWELL HEATH, ESSEX. Telegram.:Fuller, Chadwell Heath." Telephone :Ilford 171 (4 lines). London Telephone Area. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

MEN IN THE WIRELESSSERVICES DESIRING RAPID ADVANCEMENT should train in swe time with the College which ensures this " U.E C." (Regents Park, London, N.W.1 ) has in Twelve Years secured hundreds of successes by I Individual Postal Training for Engineering Examinations and Professional Work. I State YOUR ambition in confidence, to-SECRETARY'S DEPT. (Desk W.). I UNIVERSITYENGINEERING COLLEGE, WESTGATEON-SEA, KENT, and expert advice with the New prospectus. No. 8, wi I be sent you without obligation

CONTENTS(Continued)

Croydon Aerodrome Wireless Station - - - .. - - 655 Experimental Station Design.By F. H. H. (Continued) - - - 659 Notes - _. - - - .. - - - - - 663 Correspondence ------665 Calendar of Current Events ------665 Wireless Club Reports- - - - .. - - - - - 666 Questions and Answers------670 Share Market Report - - - - - , - - - - 676

HOLLOW STEEL MASTS FORAERIALS These masts are light, strong, easily erected, and will lasta lifetime.All lengths over lSft. are made in sections and each mast is supplied completewith baseplate, finial, rope cleat, pulley sheave, guy clips, three steel guyropes and strainers, painted one coat ready for immediate erection.Being made of steel, no lightning conductorsare required PROMPT DELIVERY. PRICES F.O.R. FOR CASH WITH ORDER, EACH 10ft. ... 32/6 15ft. ... 42/6 2Oft. ... 45/- 25ft. ... 57/6 3Oft. 84/- 4Oft. ...126/ - OtherLengths supplied at equally Low Prices. Trade Inquiries Invited THE WIRELESS STEEL MAST & ACCESSORYCOMPANY Lombard Street West, West Bromwich Telephone No. 447 AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW THE IDEAL WIRELESS SET CAN BE BUILT UP ON THE MARCONI SCIENTIFIC UNIT SYSTEM F you invest in this series of unitsyou need not scrap any of your gear Iwhen you wish to improve your set. Units I, 2 and 4 form a nucleus which will giveyou all the broadcast programmes and all telephony and telegraphy between30o metres and 26,009 metres.

NUCLEUS SET

This nucleus consists ofa Variable Condenser ;a Retroactive Tuner ;and an Amplifying Detector. If you want greaterrange add Unit 3, a High Frequency Amplifier. If you want greater audibility add Unit5, a Note Magnifier. If you wish touse low resistance telephones add Unit 6, a Telephone Transformer. THE FULL SYSTEM,

FULL DETMLS AND FREE ADVICE upon the combination most suitable for your special needs willbe sent onreceipt of your enquiry by THE

MARCONI SCIENTIFIC INSTRUMENTCO., LTD. 40 DEAN STREET, SOHO, W.1 TELEGRAMS :THEMASINCO. WESTOENT TELEPHONE : : GERRARD 774.5 xii THE WIRELESS WORLD AND RADIO REVIEW AucusT 19. 1922

" Delighted with results obtained AN IDEAL VALVE from the ONE VALVE RECEIVER purchased ACCUMULATOR yesterday.With telephones on table we heard 50 Amps "broadcast" telephony in adjoining room although door was closed." 2 volts 10/- The abo,tiau ,fractfrom unsolicited letter receimi 4 .. 20/- St 71,k. Carriage - These panels are all carefully tested on short wave- 2 volts length telephony.They are suitable for receiving telephony or telegraphy.Price (without valve) E4 4 2/- 6 3/ - ONE VALVE PANEL Dimensions of each cell, MAGNAVOX LOUD SPEAKERS. 8 x 4 x 3 Weight without Acid, Immediate delivery if ordered now. 51 lbs. Junior Magnavox P; ice £10 10 0 Senior Magnavox Price £200 0 BROWN -STERLING 'PHONES. 6 Volt 50 Amp Multi -magnet Head Telephones (with cords). Accumulator 2,000 ohms..51/- 4,000 ohms..52/ - 120 ohms..48/- Consistingofthreeas illustrated, in strong wooden container, with Wales' Speciality :SPHINX H. T. Batteries leather strap handle, These batteries compare most favourably under test with other well knov.11 35/ - makes.Standard 15 volt II cell battery. Price: 3/6 a, h (Postage 3/- extra). Send for Illustrated Catalogue (W), post free, 6d. L,T2EBRO WIRELESS ENGINEERS 13-14, GT QUEEN ST.KINGSWAY.LONDON.W.C.2 Phone GERRARD 576 Telegrams ZYWATESENG WESTCENT

ESTAB. CONFIDENCE FECONOMIC 1896 WIRELESS VALVES SIMPLY EXPLAINED By J OLIN SCOTT TAGGART, F. Inst .P. is the very latest book on valves. If you are not confident that your knowledge of the valve is complete and accurate, you Telephone : LECTRII should buy this book immediately.There are 134 pages and MUSEUM 1055. E 56 illustrations.Last week's " Wireless World " tells you LIMITED I more about it.It is selling at the low price of 2/6 NET and 3/- NET doth bound.

Large This, and our other publications are sold by Wireless Dealers of standing or they may be obtained, by return, POST FREE,

Selection From RADIO PRESS LIMITED, Publishers of Authoritative Wireless Books, of " 34/35,NorfolkStreet,London, W.C.2 Variable WIRELESS VALVES SIMPLY EXPLAINED

Air Condensers AS AN ADVERTISEMENT WE

OUR 82 PAGE RADIO REQUISITES ARE OFFERING 500 (ONLY)

CATALOGUE, OVER 200 ILLUSTRA- TIONS INCLUDING CRYSTAL AND :GET

VALVECIRCUITS. R HEAD -PHONES MAILED BY BEST ENGLISH MAKE 8000 OHMS

RETURN FOR 4d. S CASH WITH ORDER I S AT 35/.PER PAIR T POSTAGE 11- EXTRA N C Angell's Wireless Supply Stores E 95 HIGHBURY NEW PARK,LONDON, N.5 S THE WIRELESS WORLD AND RADIO REVIEW THE OFFICIAL ORGAN OF THE WIRELESS SOCIETY OF LONDON Vol.. X.No. 21. AUGUST 19TH, 1922 WEEKLY Valve Manufacture A BRIEF DESCRIPTION OF THE SIMPLER PROCESSES ADOPTED IN THE MANUFACTURE OF M.O. VALVES NOW that valvesaresoextensively given.The inception of the present company used for transmission and reception,for manufacturing valves, which carries on and by their use the production andbusiness at the Osram-G.E.C. Lamp Works, detection of continuous waves and the trans -Hammersmith, is due to a combination of

Valves of the " R" type connected to the pump whilst the operator controls the potentials applied to the electrodes. mission of telephony are rendered possible,the experiences of Marconi's Wireless Tele- it is perhaps surprising that so little informa-graph Company, Ltd. and the General Electric tion is available dealing with the manufacturingCompany, Ltd., who have combined together processesadoptedinthisnewindustry.the valve business and manufacture under Before describing the methods of manufacture,the title of the M.O. Valve Company, Ltd. an explanation of the term " M.O." may be The first consideration in valve production 642 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 is the selection of materials having suitablesoftening temperature, and high non-conductive properties.The glassissupplied by thepropertiesat moderately high temperature. glassworks in the form of bulbs, tube and rod, If these conditions are not met, serious trouble of such dimensions and shapes as are required.will arise, due to electrolysis and the liberation Its composition must be such as will renderof gas, which will either prevent a good vacuum it suitable for the particular set\ Le in whichfrom being obtainedor else result ,in the

Tl:e " R" Valve.Left.Ready for preliminary pumping. Right. Foot tube with electrode supports. it is to be employed.The nature and com-rapid deterioration of valves through poor position of the glassis of the greatest im-vacuum after they have been put into service. portance, and successful valve manufacture The variousmetalsemployedinvalve is largely dependent upon this.The essentialconstruction must alsobe of the highest features, particularly with respect to trans-degree of purity, and capable of being effectively mitting valves, are that bulbs and tube shall gas -freed.Nickelisat present almost ex- have a uniform thickness of wall,a high clusivelyemployedinanodeconstruction, AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 643 and is supplied in rolled sheets of the thicknessleads pass through the pinch, which is that of o2 mm., in the form of wire and flat strip.part of the valve at which the electrode con- Nickel is also used for making the supports nections enter, and in the case of small receiving fortheelectrodes,thoughunderspecialvalves forms the point of attachment for the circumstances molybdenum, or " nichrome,"electrode supports. isto be preferred.Molybdenum is not so In all valveone cr more the electrodes

Machine for clamping electrode supports and leads in the foot tube. soft as nickel under heating, and consequentlyis supported from a flanged glass foot tube, makes a stile'. support.Nichrome is almostwhich is subsequently welded to the neck of as good in this respect, and has a furtherthe bulb.Foot tubes vary considerably in advantage in the fact thatit can be moresize and type, dependent upon the form of easily gas freed.Platinum is used solely forvalve in which they will be used. making a vacuum -tight seal where the electrode In the case of receiving valves of the ordinary 644 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 type, such as the " R " valve, the foot tubeThese operations are carried out in a vacuum is prepared from a short length of suitablefurnace, the wires referred to, together with glass tube, cut to a predetermined length.the other parts, being packed in a nickel tray. One end is heated and spread out in the formThe furnace has a fused silica heating chamber of a flange.The wires that are to pass throughin the form of a tube.After the internal the foot tube are first cut to the requiredmetallic parts have been thus treated, they length, each complete " wire " consisting ofare placed in the foot tube on a machine three parts welded together, the external leadswhich rotates in front of a series of blowpipe being of copper.The part that is to form theflames, and when sufficiently hot, two flat seal is of platinum, and the internal support ofjaws are brought up and completely embed nickel, molybdenum or nichrome as the casethe wires in the glass in their correct position may be. relative to each other. Welding is done .by means of a fine hot In the case of special valves and many types blowpipe flame.The copper wire is fusedof transmitting valves, the arrangement of the

An assembling bay, where filaments, grids and plates are fitted.

directly to the platinum strip ;the other end" pinch " cannot be conveniently accomplished of the platinum strip, after having a smallby machine methods, and has to be largely amount of copper fused to it,is welded toeffected by hand.In such valves the two the nickel. filament leads usually share the same pinch, Itis, of course, necessary, before sealingwhilst the anode and grid leads may each in, to thoroughly clean the whole of the interiorhave a separate one.The effect of electrolysis metallic parts of the valve, to remove fromin this connection is that owing to the high their surface all impurities which may havetemperature the glass becomes conductive, accumulated through constanthandling inand current passes between the electrode leads the course of manufacture, and further theyin the pinch, with the consequent liberation must be gas -freed as far as is possible beforeof gas from the glass.In the case of valves the actual bombardment to which they willof very high power, such as will be operated subsequently be subjected during exhaustion.by voltages of Iopoo or more, the method of AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 045 bringing the grid and filament leads together In the case of small valves, the grid is through the same foot tube cannot well bekept straight and the spacing correct by lacing employed, and so in valves of this type theit to a stiff support called a " damping wire," three sets of leads are kept as far apart ashaving two loops or eyes made in it, and spaced possible.The anode lead is taken from onethecorrectdistanceapart,corresponding foot tube, the filament leads throughtheto the total length of the finished grid.The opposite one, and the grid lead through anends of the damping wireare afterwards additional sealing tube in the bottom of theattached to the vertical grid support wire, bulb, but as this part of the bulb is morewhich is mounted on the pinch.To prevent liable to metallic deposit than the necks are,vibration in use, the individual turns of the itisessential that precautions be taken togrid helix are each bound to the damping ensure perfect insulation between this deposit wire. and the grid lead. Grids for larger valves require more than- a

Machine for sealing in the mounted electrodes.

There are two types of grid, one composed ofsingle support.In such cases three support a wire wound into a helix, the other being ofwires are laid along a mandrill in which a wire mesh formed into a hollow cylinder.light screw thread has been cut.The grid The helical grid is used when liberal spacingis wound over the supports, and the operator is required, while mesh is more suitable, andsews each turn to each of the three supports, also more convenient from a manufacturingusing for the purpose a needle threaded with point of view, for valves in which close gridfine molybdenum wire, and making the helix spacingisrequired. A mandrillismadefollow the screw thread on the mandrill. having a diameter equal to that required forAfter lacing, the end turns may be arc -welded the grid, and on this the wire is wound in ato prevent slipping.Close -meshed grids are long helix.The overall length of each gridcut to size, and after being bent to the required is predetermined, and the number of turnsshape, the ends are stitched together with which it shall have per centimetre, and also molybdenum wire.Some forms of grid are the number of turns in that length. open-ended, while others have the top ehd 64& THE WIRELESS WORLDAND RADIO REVIEW Auousr 19, 1922 entirely closed.The former are used in lowBlanks are stamped out in the various sizes power valves which are not intended to operate required, and formed up into cylinders by on very high tension circuits, and they haverolling them round mandrills.Anodes of smallreceivingvalvesareplaincylinders having a projecting tongue which is afterwards arc -welded to the anode support wire, which is satisfactory, owing to their small size and weight.With larger valves a tripod arrangement is adopted, the anode being blanked out and holes punched forrivettingtothree supportlegs.Largeanodesarestiffened by rolling ribs round them, and in some cases by also turning the edges over. The valve filaments are all of drawn Tungsten wire, but there are some slight differences between the wire used for receiving valves andthatfortransmitters.The filaments are accurately cut to size on gauges and jigs, and the correct mounting positionlocated by means of a sharp bend, so as to ensure correct length between support points.Fila- ment wires are thoroughly cleaned before they are sealedin,so asto remove from their surface all impurities, by being heated

Detector Type R.4.B. Filament v _1 s 3.8, filament amps. a 65. Normal anode volts, 5017o. Designed for use as a detector or low frequency amplifier. the loop end of the filament supported by a wire which may be fixed to the grid foot tube, or it may terminate in a closed stud, forming part of the anode foot tube at the other end of the bulb, and designed to ensure goodinsulationbetweentheanodeand filament. Gridswith domed endshaveasmall diameter opening left in the centre, into which is fitted a flanged button of highly insulating, heat-resi3ting m 1:eri al.ThishasasmallLow TemperatureEmitter, Type L.T 3. diameter hole throughitscentre, throughRequires a filament potentizl cf only 1'8 volts which the filament tension wire passes toand passes a current of 0.11 amperes. An aspring.As previouslystated,nickelis efficientdetector,oscillator, highandlow generallyusedformakingvalveanodes. frequency amplifier. AtrausT 19. 1922 THE WIRELESS WORLDAND RADIO REVIEW 647 in dry hydrogen to a bright red heat.Thistungsten, and good electrical contact ensured. treatment not only cleans the surfaces, butThe projecting ends of the filament may in removes springiness and kinks from the wire.special circumstances be bent back and arc -

A Power Rectifier; Type U Am.

The mounting of the filament is effected bywelded to the supports, an operation which first flattening out the ends of the supportingrequires considerable skill. wires by pliers having specially shaped jaws. The hooks are then tightly pinched over the(To be concluded in issue of 26th August, 1922.) 848 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

More about the Armstrong Super -Regenerative Receiver

THE article which appearedinour iscapacitive, due tothe capacity between issue of July 29th regarding E. H.the grid and plate of the tube itself, and the Armstrong's new circuit hascreated magnitude of thiscouplingisdetermined widespreadinterest.That article was theby the value of the variometer inductance. first information on the subject to be published The effect of regeneration is to reduce the in this country, and as that was prepared effectiveradio -frequencyresistanceof the in haste from the very little ptactical informa-receiving circuit to a very low value.This tion divulged by Mr. Armstrong when hethe operator can prove to his own satisfaction described the apparatus before the Instituteby actually inserting several. hundred ohms of Radio Engineers, it does not contain thein the tuned grid circuit.He will find that practical information which would enable the by increasing the regenerative coupling between circuit to be tried out.In the July issue ofgrid and plate circuits, he will obtain the same The Wireless Age there appears an articlesignal as if the resistance were not present. which gives some more practical data whichIn other words, in regeneration we have a may at least serve to help in solving practicalpowerful method of annulling the resistance difficultieswhich no doubt amateursareof a receiving circuit.In this way it can be experiencing in endeavouring to operate thereduced to as low as a few hundredths of an circuit. ohm.This low resistance accounts for the We give below an abstract of the articlesharpness of tuning obtained on a regenerative appearing in The Wireless Age, and this wereceiver-very often a variation of only half hope to follow in an early issue with a detaileda degree on a tuning knob is enough to lose description of how to build up the set anda signal which is otherwise of several hundred operate it.The author of the article, Mr. A.times audibility.This helps to explain the Ringel, opens up the subject with a considera-presence of vernier adjustments on all good tion of the theory of regeneration. types of such receivers. THEORY OF REGENERATION. As the coupling is increased still further, Before describing the principle involved inthe resistance of the circuit is lowered and this new extension of regeneration, we willlowered, with consequently greater amplifica- consider the behaviour of an ordinary re-tion.When the resistance approaches zero, generativereceiver.Incomingsignalsarethe valve commences oscillating at a frequency applied between the grid and filament of thedetermined by the tunedcircuits.These valve.These oscillationsareamplifiedin oscillationsare identicaltothose obtained the valve, and as a result, we get very muchin continuous wave transmitters, except that greater variations in the plats circuit.If thethey are much feebler.Although the signal plate circuit is coupled back to the grid circuit,received is very much louder, its quality is the reinforced oscillations are fed back toentirely lost.If it is a spark note, it becomes the grid and are once more re -amplified by the hoarse and mushy, losingitscharacteristic valve.In this way we can build up a verynote-and speech and music, although their weak signal until it is of sufficient amplitudepresence is apparent, become absolutely un- to give a loud sound on detection. intelligible gibberish.If no signals are coming This process is called regeneration.Thein, the presence of oscillations can be detected amount of amplification is controlled by theas follows coupling between the grid and plate circuits. 1 . As the regenerative coupling is increased In the case where a reaction coil is used in the to the oscillating point, a sudden rushing plate circuit, the extent of regeneration depends or hissing, is heard in the phones. on the magnetic coupling between the reaction 2. Touching the grid terminal of the coil and the grid coil.Where a variometer valve with the finger will produce a dull is employed in the plate circuit, the coupling thump in the phones-and removalof AucarsT 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 649 the finger will cause a similar thumpingthe amplitude will be proportional to the actual noise. amplitude of the speech waves at the moment of application.No matter how small this THEORY UNDERLYING SUPER -REGENERATION. initial voltage is,it will at once commence As explained before, much greater signalto build up to an infinitely large value.So strengthisobtained when regenerationis much for pure theory.In actual practice, increased-but thisisallupset when theif we go to the negative resistance circuits, valve breaks into oscillation.In his super -we cannot secure the above results, because regenerative circuit, Armstrong increases thethe circuit breaks into oscillation at the slightest coupling so that the valve is far beyond theshock, thus paralysing the tube. oscillation point, and the effective resistance THEORY OF THE SUPER -REGENERATIVE CIRCUIT. of the circuit is made even less than zero-the Armstrong takes advantage of regeneration circuit is made to have a negative resistance.to the limit of a valve, and still prevents it from And he stops the oscillations so that he canoscillating.He has discovered that he can take advantage of this negative resistance andstop oscillations in a negative resistance circuit thus obtain powerful signals. either by introducing resistance in the circuit Before going any further, let us divergeat definite intervals or by reducing the amount a bit and delve into the theory of variousof regeneration so that the circuit resistance tuned circuits containing (i) positive resistance, becomespositiveand negativealternately. (2) zero resistance, and (3) negative resistance. In both cases the effect is to give the circuit In the first case, when continuous oscillationsfirst a positive and then a negative resistance. areimpressed,afterashortbuilding upThis alternation is sufficient to prevent oscilla- time,theoscillationsattainand preservetions.During the negative resistance period

"lull

I'll', Fig. I.Control of regeneration by varying the H.T. supply. adefiniteconstantamplitude.When thewe can make full use of the very great amplifica- impressed oscillations are removed they dietion produced-but justasthecircuitis away to zero.The greater this resistance,about to start oscillating of its own accord, the longer it takes to build up the oscillationswe introduce a positive resistance.During and the faster they die off-and vice versa.the positive resistance period, the circuit, of In the second case, when continuous oscilla-course,cannotoscillateand theresulting tions are impressed, they keep on steadilyamplification of the incoming signals is much increasing in value, depending on how longless than before. they are applied.If the source of oscillations This variation between positive and negative is removed, the circuit keeps on oscillatingresistance may be made at any frequency de- at the same amplitude it had when the voltagesired, provided that it is less than that of the was removed. incoming oscillations.No doubt it could be In a negative resistance circuit, if oscillationsdone mechanically by connecting a resistance are applied, they continue building up to anin the tuned grid circuit, regenerating beyond extremelygreatvalue,regardlessastotheoscillationpoint,withtheresistance whether the voltage is removed or not.How-shortcircuited, and then alternatelyshort ever, at any given time after the e.m.f. is im-and open circuiting the resistanceat any pressed, this amplitude, although very large,desired frequency.Variation in regeneration is always proportional to the initial appliedmay be accomplished in a similar manner by amplitude.Thus,if we havecontinuousmechanically varying the plate voltage of the waves modulated by speech or music applied,regenerating valve sothat the grid circuit B 4 650 1HE WIRELESS WORLD AND RADIO] REVIEW AUGUST 19, 1922 resistance is alteraately positive and negative.energy they are required to handle.For the Then again, we may use a combination ofreceiving circuits, the coils and condensers both methods. should be of values suitable for tuning to the But movingmechanicalpartsmay bewavelength range desired.In the oscillatory dispensed with and vacuum tube oscillatorscircuit, the coils should be quite large-with employed to produce this variation in circuitan inductance of the order of too or 200 resistance or amount of regeneration.Thesemillihenries. (Honeycomborduo -lateral methods are illustrated in the diagrams. coilsNo.1250or150o,approximately.) Pie -shaped coils used in spark transformers, SUPER -REGENERATION BY PLATE VOLTAGE having1,500to2,000 turns,aresuitable VARIATION. here.The condensers are ordinary 43 plate Fig. t shows how the amount of regeneration variable air condensers. is varied by varying the plate voltage.The The system shown in Fig. I should present first valve is the regenerator, which introducesno great difficulty in operating or adjusting. negative resistance in the grid circuit.In-The condensers and coupling in the oscillator coming signals are coupled to the grid circuit,are adjusted until a very high pitched whistle amplified in the first valve and fed back tois obtained.Then the receiving and regenera- the grid by means of the reaction coil.Thetive circuits are tuned to the station to be re- reaction coupling is made large enough toceived in the usual manlier.In fact, the carry the circuit beyond the oscillating point.operation should be much easier than that of The second valve acts as oscillator of any fre-the average receiver. quencydesired.Generally,oneof about to,000 cycles is suitable.The amateur and experimenter will recognise the usual oscillating circuits.The coils and condensers should be so selected as to give this frequency (which corresponds to a wavelength of about 30,000 metres). Note that the plate oscillatory circuitis also in the plate circuit of the first valve. The plate voltage of this regenerating valve is thus varied at a frequency of 1o,000 cycles. When the oscillations are such as to make the plate more positive, regeneration is increased beyond the oscillating point, and the signal amplitude increasestoa very great value.Just as the valve is ready to burst Fig. 2.Control by positive resistance in the into oscillations of the circuit frequency, the grid circuit. applied frequency reduces the plate voltage to a low value, and thus reduces regeneration and introduces a positive resistance in the SUPER -REGENERATION BY RESISTANCE VARIA- grid circuit-effectually cutting off any sign TION. of free oscillation.A very high degree of Fig. 2 shows a method whereby a positive amplificationisthus obtained during thoseresistance is introduced into the tuned grid half cycles of the ro,000 cycle oscillationscircuit of the regenerating valve.Incoming when the plate is made more positive. signals are applied to the grid of the first The grid circuit of the first valve is coupledvalve and amplified by regeneration due to the to an aperiodic coil in the grid circuit of thereaction coupling.The second valve acts as last valve, which acts as a detector.Rectifica- a 1o,000 cycle oscillator-and these oscillations tion is accomplished by applying a negativeare also impressed on the grid of the first potential to the grid, instead of the usualvalve.The regenerationiscarried beyond condenser and leak.But it is really immaterialthe normal oscillation point of thisvalve. :which method is used. ThF first valve may beDuring that half cycle, when the local oscilla- an amplifyingvalve.Butitisdesirable,tions make the first grid negative, no grid though not essential, tohave power valvescurrentisdrawn and theeffectiveradio for the oscillator and detector, because of thefrequency resistance of the circuit is negative Aucmax 19, 1922 THE WIRELESS WORLDAND RADIO REVIEW 651 because of the super -regeneration.The in-circuits are used to produce the necessary coming signal is built up to very great ampli- Io,000cycleoscillations.The condensers tude during this interval.Just as the firstC1 and C2 should be of fairly large capacity, valve is ready to go into oscillation, the localsay oooi microfarad, in order to provide a oscillations are reversed and tend to give theby-passforthe incoming high frequency first grid a positive potential.In this case,signals-since the latter would be blocked a stream of electrons commences to flow fromby the high inductance coils L1 and L2 (of the filament to the grid and this. is equivalentabout 200 millihenries each). to connecting a resistance of several thousand The received signals are super -regenerated ohms across the tuned circuit.The effectiveas usual during that interval when the io,000 resistance of this circuit is thus increased untilcycle oscillation applies a negative potential it is no longer negative, but positive, and thusto the grid, and at the same time tends to chokes out free or self oscillation in the re- increasetheeffectiveplatevoltage.The ceiving circuits.Of course, we obtain veryoscillationsin the gridand plate circuits high amplification in the negative resistancemust be of the proper phase, so as to produce periods.In the circuit shown, the first valveboth the above effects at the same time. During acts as the detector.Evidently Armstrongthishalf cycle,theeffectiveresistance of prefers to use a grid cell instead of condensercircuit L C is made negative, resulting in and grid leak to obtain rectification. considerable regenerative amplification.Just

1= fi -=T i ,1,_1____._ =- L, 0t, L,39.,-tczI - ---,--

Fig. 3.A combination of the methods shown Figs. i and 2.

Only two valves are used in this arrange-as L C is on the verge of self oscillation, the ment, thefirstperformingtwo functions,polarity of the applied io,000 cycles reverses, regenerator and detector, the other acting onlyso that the grid is made positive and the plate as an oscillator.Since the only thing thatvoltage is lowered; The former causes grid controls the amount of amplification is thecurrenttoflow,thus introducing positive limit of the valve, better results could be resistance.The resuctioninplatevoltage obtained by using power valves instead ofdecreases the amount of regeneration and thus ordinaryreceivingvalvesincaseswhere aidsinincreasingthepositiveresistance. extraordinarily great intensityisrequired. Under such circumstances, of course, free oscillations are completely choked off. SUPER -REGENERATION BY COMBINED RESIST- In this arrangement, both regeneration and ANCE AND PLATE VOLTAGE VARIATION. io,000 cycle oscillation are performed within Fig. 3 shows a method of varying the re-a single valve. A second valve, the grid of sistance in the tuned grid circuit and platewhich is coupled to L, acts as the detector. voltage simultaneously. The adjustments both for tuning and local The circuit L C is tuned to the incomingoscillation are very critical.Hence this circuit signals and these are impressed on the gridis not suitable for use by the average experi- of the first valve-the signal being amplifiedmenter because of the great pains necessary by regenerationinthe manner describedin order to secure super -regeneration. above.In series with L and C, we have another tuned circuit L1 C1 coupled to L2 C2, which PRACTICAL SUPER -REGENERATIVE CIRCUIT. isinseries with the reaction coil.These Fig. 4 shows a practical two -valve circuit. 652 THEWIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 It is essentially the same as that of Fig. 2. The first valve is the regenerator and the second the local oscillator.Free oscillations in the receiver circuit are stopped by those half cycles of the local oscillations which make the first grid positive. The unusual feature in this arrangement lies in the use of the oscillator valve as the detector of the signals which are amplified by super -regeneration by the first valve. The amplified signals are impressed upon the grid of the oscillator valve, which rectifies them, intheplatecircuit,thusl_makingL.them Fig. 4. A practical two -valve circuit. audible.

An Amateur -Made Two -Valve Set in Buckinghamshire By A. F. H. BALDRY.

AvHILE nothing out of the ordinarysmall ebonite panel measuring approximately isclaimed forthisset, either in4 ins. by 24 ins. let into the centre of the front design or resultsaccomplished, itside of the cabinet. is thought that this description may be of The long wave reactance has two tappings interest to fellow amateurs in the fascinatingbrought out and controlled by a small switch hobby of wireless. The apparatus consists of one rectifying and one note -magnifying valve with L.F. transformer mounted on an ebonite panel measuring II ins. by 9 ins. and enclosed in a polished wooden cabinet ' ' ins. by 9 ins. by 44 ins. With the exception of the usual items, L.F. transformer valves, phones, etc., the set is entirely amateur -made. There are two sets of inductances incorporated, together with reactances, which are so connected with a four -pole switch that either may be used at will.The inductance formers both measure 3 ins. diameter, and were made of ebonite with reactances measuring 24 ins. diameter, arranged to turn within.The set Circuit Diagram of Mr. Baldry's Set. being divided into two sections, it was found that by making six tappings in the shortwhich enables varying amounts of reactance wave inductance, an effective range of 200 to be used.This feature has been of consider- metres to i,000 metres was available.Each able use at times. tapping was brought out to a brass contact The variable condenser (A.T.C.) is of the stud turned up out of the solid.A similarair dielectric type and consists of 21 plates, process was adopted with the long wave I fixed and ro moving, cut from aluminium inductance, twelve tappings being made insheet approximately 1/64in.thick.Great thisinstance.Thisgivesan approximatecare was exercised in ensuring that the vanes range of i,000 metres to 12,000 metres.Each should be absolutely flat and true, this being valveiscontrolled by a separate filament effectedbycarefulpressingwhileunder resistance which are both mounted on agentle heat. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 653 Allinternal connectionsare made withfitted to enable an instant change over from No. 20 S.W.G. rubber -covered, which wasphones to loud -speaker. The panel on the right found to be sufficiently stiff for the purpose. carries a three -valve L.F. amplifier which is still The switchboard was gradually assembledincomplete. as the occasion arose, and the various switches The aerialusedisastandard P.M.G. and instruments were mounted on a polishedaerial of 140 ft.. twin wire carried on two masts teak board measuring 2 ft. 6 ins. by 2 ft. 6 ins. 5o fthigh, the whole being very carefully by I in.All terminals were fitted in / in. insulated.

The complete Receiver, showing Plugs and Jacks. ebonite plugs, thereby reducing capacity effects Resultsareverygood,allContinental to a minimum.At the top of the board willstations coming in clear and strong, whilst be seen a single pole change over switch which Croydon and 2 MT telephony can be heard enables the aerial to be connected to earthcomfortably on the loud speaker. PCGG is when not in use.The instruments consistclear, but not so strong.The set being situated of two voltmeters for measuring H.T. and near .Marlow -on -Thames, considerable inter- L.T. voltage and one amperemeter. Theference is caused at times by Leafield, which double pole change over switch in the centre isis but 23 miles distant. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

An Experimenter's Station at Yeovil

By L. W. C. MARTIN.

N the left of the photograph (Fig. I), The first valve can be either H.F. transformer, mounted in the box, is a short andtuned anode, or resistance -coupled. long wave tuner.The short waves Two transformers (H.F.) can be seen in are received on a variometer type of inductancethe photograph, one of which is in position. enclosed inside the box, with five tappings, andThese I have made from 30o to 2,800 metres. tuning from 200 to i,600 metres ; also mountedAbove this wavelength I use resistances of in the box are two variable condensers of50,000 ohms. 0.002 mfd. and o000s mfd. respectively. The long wave coils are of the plug-in The second valverectifies ;both these type, with tappings mounted on the side ofvalves are " V.24 " and have been in constant the box, basket coils being used for wavesuse for eighteen months. The two "R" up to 5,000 metres and lattice wound coilsvalves are note magnifiers, and are controlled for above that wavelength and up to 24,450.by one rheostat. For portability all tuning coils will pack away in In the diagram of connections I have pur- the box through the small door seen in the front. posely omitted plugs and switches to avoid A change over from short to long wave coils,complication, except in the diagram of the also series to parallel of condensers, is effectedtuner. by one plug (2 pin) as shown in the circuit The amplifier has a hinge at each end of the diagram, Fig. 2, thus doing away with twobase, and a box -like cover fits over the whole double -poledouble -throwswitches,which and is secured by two screws. would take up rather too much room.There The H.T. battery is shown on the extreme is another 2 -pin plug for reaction coils. right.With the four valves in use, and a The amplifier is I, 2, 3 or 4 valves, all cutting very good indoor aerial, WII (New Brunswick), out of valves being done by plugs ; also various 13,40o metres,iseasily readable withthe circuits can be tried in a few moments bytelephones onthe table when there is no changing about the plugs. jamming by Carnarvon.

Fig i.The Tuner is on the left, and the Detector -Amplifier, using " V. 24" and " R" valves, on the right. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 655 PCGG can be heard anywhere in the room If I use my outside aerial and one more with a gramophone horn attached on one valvevariometer coupled to the first valve earpiece of the telephones.Croydon needof amplifier, PCGG can be heard anywhere not be mentioned. in the house.

000IµF 1. MT 0002µF

p --11100005 par C> C> C> r C>

.-NAA/rt

01 - LT SHORT 0

Fig. 2.Circuit diagram showing Switching Arrangements for Short and Long Way.? Tuning.

Croydon Aerodrome Wireless Station THE EQUIPMENT OF THE LONDON TERMINUS. OF CIVIL AIR ROUTES. THE wireless telephony station of theis, of course, to take bearings on aircraft Croydon Aerodromeisperhaps thewhilst in flight, and these are transmitted most familiar ofallstations whichto the aircraft through the medium of the the amateur in this country hears. wireless telephone. Visits have been made to the station by Fig.i shows the mast which carries the a good number of wireless societies in theD.F. receiving station and the hut in which the London area, thanks to the courtesy of theinstruments are located.The apparatus seen Air Ministry, but the accompanying photo-in Fig. 2 is the standard Marconi direction graphs of the station are published as beingfinder and receiver.On the right of the thought to be of general interest, especiallypicture may be seen a wavemeter, and just to those who are familiar with the station onin front of this the telegraph key. the wireless telephone but have not had the Immediately in front of the main instrument opportunity of visiting it. can be seen a row of eight switches, which At the Aerodrome there are two stations, serve to control various circuits. one the direction -finding station and the other One serves to start up the main generators the radio -telephone station which. is used forfor the transmitter.Another serves to put communication with aircraft. into connection with the land -line telephone The purpose of the direction -finding stationthe table microphone seen in the picture, 656 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 19, 1922 which is the microphone used for the trans- The main aerial, that of the transmitting missions by wireless telephone.In this waystation,issupported betweentwolattice it is possible to relay ordinary land -line tele-masts as shown in the illustration (Fig. 4). phony through the local telephone exchange The main generating unit consists of an direct to aircraft in flight, and in this wayA.C. motor which is run by the supply mains,

rig.i.The Mast carrying the D.F Aerials. passengers may be kept in communicationanctdrives an A.C. generator.The generating with the ground whilst travelling. plant is duplicated so as to avoid any risk of Fig. 3 illustrates the transmitting apparatus,a breakdown in the service. D C. generators which consists of a Marconi ikW. telephonyfor battery charging are also in duplicate for transmitter. this reason. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 657

Fig. 2.The Direction Finder and Receiver.

Fig. 3.The Main Transmitting Apparatus. .6581 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

Fig. 4.The Aerial and Mast of the Transmitter. Progress of the Broadcasting Scheme. At last a definite scheme for broadcasting hasannum. For two years the apparatus will be been agreed upon for the London area, and it islimited to types submitted for the approval of the hoped that this will be put intooperation onPost Office by members of the company, but to Monday, August 21st.It is hoped to commenceavoid anything in the shape of a monopoly the in the provincial areas in six or seven weeks' time. Postmaster -General has laidit down that any There will be a broadcasting centre for London. bona fide British manufacturer of wireless apparatus The apparatus is in readiness.All that remains tonlust be allowed to become a member of the be done isto secure the Postmaster -General's.toioadcasting company, simply by taking a £1 approval of the company's memoranda and articlesqualifying share.The licence of the company will of association.The, board of directors of the new be subject to the maintenance of an efficient service. company will proceed to deal with the provision Towards the expenses of the broadcasting company, of the provincial stations. the Pest Office will contribute a portion of the The Postmaster -General has laid down severallicensing fees paid for receiving sets, and a further conditions under which the broadcasting companycontribution will be paid out of the purchase will work.Profits are limited to 74- per cent. permoney on each set sold by the manufacturers. ATTOUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 659 ExperimentalStation Design Continued from p. 585, August 5th, 1922. These articles, which will appear in alternate issues, are intended not only to be a complete guide to those new towireless, but to give explicitdetailson the constructionofallthe components of the experimental station.Actual designs will of necessity in some instances be somewhat crude, in order that they may be made up without elaborate workshop equipment. Practical working instructions will be given where necessary for the help of those unacquainted withthe moresimpleprocessesof instrumentmaking. Of course, where good workshop facilities exist, the designs may be readily modified. Economyismade anessential feature,bearingin mind always that wherelow-priced component parts can be obtained their use has been embodied in the designs. For those who do not desire to make their own apparatus, the descriptions will assist them in selecting the equipment for their stations. The information contained in the first few articles under this heading is to help those new to wireless and whose first aim is to build a simple set capable of receiving broadcasted telephony and consequently may cover ground already familiarto many readers. Thesucceeding instalments, however, will advance by easy stages, and in the course of the series the construction of an elaborate station will be evolved. X. LOW FREQUENCY INTERVALVE TRANSFORMER. As a step in the construction of aend pieces.Two circles, each 1in. radius, notemagnifyingunitadesignis are marked on the ebonite with dividers, and required for the intervalve transformer, the ebonite sawn in two.The four corners and the following materials will be required.of each piece are then cut away, going to Polished ebonite sheet 28 ins. by 4f ins. bywithin 1'16 in. of the line.If a lathe is avail- 7/16 in., 1 lb. No. 22 S.W.G. soft iron coreable the next step will be to drill the holes

f.+

\ I MP' (\I

7 Fig. 1.Ebonite end plates with rounded corners.

wiresin91 -in. to to -in.lengths, apiecein the centres and mount the two pieces on a of black fibre 6 ins. by 12 ins. by/32 in. inspindle for turning down to size, and at the thickness, two 6 B.A by 4 in. round -headedsame time rounding the edges as shown in brass screws with nuts, 5 ounces No. 46 S.S.C.,Fig. 1.' Withoutalathe,however,itis a small piece of scrap hard brass sheet aboutquite easy tofileaccurately down tothe 18 S.W.G.,odd pieces of silk ribbon and ascratched circle.Having done this, set the few feet of insulated wire, 28 to 34 S.W.G.,dividers to s in. and make another circle on 12 ins of empire cloth 6 ins. wide. one side of each piece.Again resetting the The firststepisthe construction of thedividers to s in., rest one kg just on to the

gla 660 THE WIRELESS. WORLD AND RADIO REVIEW At0u§T 19, 1922 face on which this circle has been made and slightly moistened with oil to prevent rusting. run a scratch line round the edge.ThisWith a little care it is easily possible to securely gives two scratch lines, one round the outsidefix the end discs in position on the core. edge and another as a circle on the face. This being done the core is wrapped twice Carefully file away down to these lines, thusround with empire cloth.It should be cut to makingabevel.Having gone accuratelyabout 213-6 ins. in width, and tiny cuts nearly to the line and so constructed a new face* in deep made at intervals of in. long. of equal width all the way round, remove theThis will facilitate the edges spreading and sharp edges as shown in the sectional drawingbuilding up against the ebonite, and so obviat- in Fig. i.The hole can now be made throughing the possibility of the primary winding the centre, and if a hand brace is to be used,pulling down in contact with the core.For itis advisable to put a small hole throughthe purpose of providing a short flexible lead first, followed by the 7/16 -in.drill. Twothree strands of instrument wire of about other holes are made in each piece for the3o S.W.G. are twisted together.'One wire leads at the positions shown.All of theseis left about 6 ins. longer than the other two, holes are rounded, the small ones with theand at the point where the two terminate, the

Fig. 2.The core, consisting of soft iron wires, with ebonite end plates securely wedged in position. point of a large drill and the large ones eitherlonger wire is scraped bare of insulation and with the point of a drill or a rose bit.Thetwisted with the bared ends of the two shorter small holes are slightly drilled out at both pieces.The jointshould be soldered by ends to prevent damage to the wiresIt isusing a little resin as flux, and with the tip of advisable also to run a fine file lightly and evenly a well tinned iron.The end of the long round the sharp edges of the discs to preventwire is joined to the end of the wire with the very fine wire with which the transformerwhich the transformer is to be wound, taking is wound from becoming damaged shouldvery great care not to burn or overheat this it come in contact with the end pieces duringfine wire. winding. Winding is somewhat difficult for the man The end pieces are now mounted on anot in possession of a lathe, but with a little bundle of core wires (Fig. 2), and it is most patiencethe winding can besuccessfully important thatallwires shall be perfectlyaccomplishedwith some improvisedar- straight and parallel.Should there be anyrangement.As a suggestion the core wires may crossing over of wires in the core the endsbe mounted as a spindle in upright wooden may become slack when the wires are bentbearings.To prevent friction on the wood round.Itisadvisable thatthe wires becausing the wires to grip and so displacing AUGUST 19, 1922 THE WIRELESS' WORLD AND RADIO REVIEW 661 them, they should be wrapped very tightly Fine wires such as are used for winding with a piece of 22 gauge brass sheet at thelow frequency transformers should not be bearing pointsA driving handle can bepurchasedinreelscarrying more than 4 made from a strip of ebonite with hole andto 5 ounces, or great difficulty will be experi- slot for gripping the core wires to the designenced in unwinding owing to the momentum shown on p. 584, August 5th issue.A 3/16 in. which a heavy reel will gather as it spins. brass rod fixed through this with nuts will The primary is wound on up to a diameter serve to revolve the arm and spindle.Theof 13/16 in.This can be measured by means reel from which the wire is being unwound of callipers, but care must be taken not to damage must becarefully mounted so as toturnthe wire by sharp edges.Kinks must be quite easily, or otherwise the wire will notavoided, and should breaks or kinks occur be sufficiently strong to revolveit.If thea joint must be made by cautiously twisting winding is being done in the lathe the reeltheendstogetherandlightlysoldering, must be particularly free and should be plugged wrapping the joint with a piece of thin silk with a rod with pointed ends which run inbefore continuing.The wire must be wound

Fig. 3.Side view of finished transformer.The dotted lines indicate the position of the ebonite ends. holes in the ends of screws.When a stopon evenly by slowly running from end to end is made during winding the reel should not inordertoavoid any comparatively big beallowedtorevolve onwithimpetusdifference of potential between consecutive it may have gathered.Care is also necessaryturns.On completing the primary it should when starting, by not attempting to makebe tested for continuity with a milliameter thereelsuddenlyrevolverapidly.Startordelicategalvanometer andafour -volt slowly, and gentlyspeed up and steadilybattery. slow down before stopping.These difficulties Three layers of empire cloth with frilled do not apply when hand winding, but one must edges are wrapped over the primary winding be careful not to turn with a jerky motion.tothoroughlyinsulatethetwowindings When winding by hand a smooth brass rodfrom one another and form a good bed for through the centre of the reel will usuallythe secondary.One end of the empire cloth provide a bearing without too much friction.is held in place with the leading out wire of 882 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 the secondary, whilst the other end must beebonite pieces, on. which their ends should tightly tied off with another piece of wire torest, and are held in position by means of two prevent the empire cloth springing open beforefibre bands which should be placed over the sufficient turns are put on to hold it down.wires so that they clamp them down on to This latter piece of wire must of course bethe ebonite discs and completely hide the removed, and on no account buried in with the freeends. To give strength tothejoint winding.The secondary is wound on up to a in the fibre bands small brass plates are made diameter of if ins., and more care is neededwhich are clamped together with the 6 B.A. than when winding the primary owing to thescrews and nuts. increased diameter and consequently higher The transformer is held to its base with speed at which the wire runs from the reelanother band of fibre, and it is advisable to to bobbin. On completing to the requiredmount thetransformer permanently on a diameter the winding is wrapped with empirewooden base, holes in the corners of which cloth of exact width to fit between the cheeksserve for fixing to bench or panel. without turning up at the edges. A single This transformer has a turns ratio of ap- layer of thread put on over the empire clothproximately i : 2, and a resistance ratio of t :4. will hold it down and entirely protect the wire.Although in transformer' design higher ratios Next a strip 68A are sometimes of fibre is cut (110 used,frequent- totheexact lynobetter width between results are ob- the ebonite end tainedowing pieces and yet toinsufficient not so tightly primary turns. fittingasto A t:t trans - force them former with an apart,forit efficient prim - mustnot be a r ywinding overlooked willgivefar that there is a superior re - great danger of sults to a I :4 breakingt h e transformer winding if the which has not cheeks bend sufficientpri- outwards at all mary turns.

or moveon The direction the cores. The in which the fibre is wrap- / windingsare ped round and Fig. 4. End view of Transformer when mounted. connected up tiedoffat in the ampli- eachendwiththread. Thispieceoffying circuitisimportant, firstinorder fibre is for keeping the end pieces perfectly togettherightdirectionofpotential spaced and for preventing them crushing influctuation to the grid of the valve connected as the core wires are bent round. to the secondary, and secondly to obtain the The core wires must now be spread outcorrect capacity couplingbetween the two from a point at the exact centre at either endvalvesand makinguseof thecapacity and bent down evenly all round and inter-between primary and secondary windings. laced.Figs. 3 and 4 are sufficiently indicativeBothwindingsareput oninthe same of what has to be done and it is quite worthdirection. Thebeginningendofthe while making an effort to get all wires evenlyprimary is marked " I.P.," and the finishing distributed and free from bends other thanend " O.P.," the beginning end of the secondary at the centre and edges of the end pieces." I.S." and its finishing end " 0.S."" I.P." Bends once made in the soft iron wires areis taken to H.T. +, " O.P." to plate, " I.S." hard to remove. to grid and " 0.S." to L.T. The wires should reach just beyond the F. H. H. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 663

Notes

Imperial Chain Station at Bourne. miles from Paris, the largest station was opened Proposals have been made to erect near_Spalding, at St. Assise, Melun, on August 7th.Although Lincolnshire, a transmitting station to operate asonly one transmitting plant out of four is at present a link in the Imperial Chain.Its receiving stationin operation, the other three are expected to com- will be at Banbury. mence work in a few weeks. Eight steel masts, each 800 feet high, will support There are 17 masts, each 800 feet high, and when the antenna; at Bourne.The masts are designedthe station is in full working condition it is hoped to take a horizontal pull of ten tons at the topto transmit 500 to 600 words a minute by sending and a wind load of 60 lbs. per square foot.They five or six messages simultaneously. will form a square with the station in the centre. Thermionic valve sets are to be installed, capable of transmitting continuously 90 words a minute in direct communication with Poona, Johannesburg and Perth (Australia). At Banbury the new station is to be built on similar lines to the one now in existence which receives for Leafield. Ifthe above proposals are carried through, Bourne will be the largest station in this country. Special Arrangements for Aviators. An Air Ministry notificationto airmen states that when meteorological ' and wireless facilities, in addition to or different from those normally available, are likely to be required, either :(a) For a special individual flight ; or (b) for regular services on new routes ; or (c) through changes in the routine services of aviation companies operating on recognised air routes, particulars should be forwarded (marked URGENT) to the Director of Civil Aviation (Room 550), Air Ministry, Adastral House, Kings- way, W.C.2. In case (a) one week s notice should be given, with full particulars of the route, the proposed date and time of flight, and of the W/T or R/T equipment of the aeroplane. In case (b) the period required for making any necessary arrangements before the commencement of the contemplated service will vary according to circumstances, but the necessary details should be supplied as early as possible. In case (c) at least 48 hours' notice (Sundays excluded) of proposed changes should be given. Dutch Concert. Authority has been given by the Dutch P.M.G. for Concerts to be broadcasted from PCGG, The Hague, on 1,300 metres when the new aerial is erected toward the end of this month. Until August 20th, by reason of the Daily Mail assistance, transmission will take place from 8.40 to 9.40 B.S.T. nightly, in addition to the present programme, and the power has been increased to 1 k.W. Suggested Association for Ireland. We have received a letter from Mr. H. L. Fletcher, Mona, Shankill, Co. Dublin, who states that having obtained permission fromtheauthoritieshe is desirous of forming a Wireless Association for Ireland.He would be glad to receive communications from likely members, and secretaries ofMiss E.Scarborough,ofMessrs.Scarborough, existing clubs. Mitchell & Co., who won a prize for the very latest Sainte Assise Opened. in carnivalcostumes. She went toaballas Near the Forest of Fontainebleau, less Than 30 " The Wireless World." 664 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 19, 1922 An Amateur Station at Guildford. APOLOGY The telephony from 2 HX is familiar to amateurs in the Guildford district.The power used for" IMPORTANT PUBLIC WARNING " transmission is only 4 watts and so the range is not We regret that in the advertisement columns of very wide.Power for the valve is taken frrim a 600 -volt generator, hand -driven, located under theour issue of the 12th August we inadvertently bench, and the system of modulation is by gridpublished a statement under the above heading control.Receiving side consists of detector valve, which we now realise was a very injurious one to the followed by two L.F. amplifiers.Tuning is accom- forthcoming Exhibition of the Radio and Wireless plished by means of a set of lattice coils described Exhibition and Convention which is to be opened by Mr. Philip Coursey, in the Wireless World, in December, 1920. at the Central Hall, Westminster, on September 2nd. By kind permission of the Postmaster -General, We desire to express our regret at the inaccuracy much experimental work has Leen carried out on ofsuch advertisement and for any injury or the low power, also a good deal of local demon - damage occasioned.

2 HX, an Amateur Station at Guildford. stration work.Signals have been reported asAustralian Wireless Service. good from stations as far as 35 miles away. Most of the apparatus is home-made by Mr. It is stated in the Commonwealth of Australia F. A. Love, and seems to be fairly efficient, besides Gazette that the control of wireless service in the having provided many happy hours in the con-Commonwealth has been transferred from the Postmaster -General to the Prime Minister " with struction. such of the existing staff as the Prime Minister may require for the economic and efficient working Ramsgate 's First Concert. of the service."The Wireless Telegraph Act, The first wireless concert at Ramsgate was held 1905-1919,is now administered by the Prime a few days ago at a fete in Ellington Park. Minister as from June let, 1922. Mr. F. Harrison, of Rochester Cottage, High Street,St.Lawrence, whoisan enthusiastic amateur, is making an effort to form a local society. Sale of Apparatus. A Committee of the Council of the Electrical A Tuner for All Wavelengths. Contractors' Association is investigating the subject, In our issue dated July 29th, on page 543, afrom the contractor's point of view, of whose paragraph commencing " The A.T.I. Section," atbusiness it is to sell and equip receiving stations. the bottom of the right-hand column should precedeSo far the Association thinks that if complaints the paragraph above it commencing " For the and disappointments are to be avoided the business purpose of tuning." should remain in technical hands. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 666 ultra -radio frequency.Such a choke may well Correspondence consist of about 20 turns of wire ona }-inch form. Their use is desirable only when a multiplicity of Freak Reception. tubes is used in parallel. K. B. WARNER. To the Editor of THE WIRELESS WORLD AND RADIO REVIEW. TheAmericanRadioRelayLeague. note in the July 29th issue of your paper a letter from Mr. Stevenson with reference to harmonics from EAB.I have had the same effectCalendar of Current Events from EAA (Aranjuez) calling POZ. The wave-Sunday, August 20th length would be somewhere about 350-400 m.I TransmissionofDailyMailConcertfrom could not be certain, as I took no notice of it at the 2.30 to 5 p.m. and from 8 to 9 p.m. on 1,085 metres time.In this case I did not tune to the fundamental by PCGG The Hague, Holland. wavelength at all, but the signals were quite clear PADDINGTON WIRELESS AND SCIENTIFIC SOCIETY. and readable, using1rectifier and a L.F. note Field Day. magnifier. Curiously enough, these effects were received at Tuesday, August 22nd about the same time as with Mr. Stephenson- Transmission of Telephony at 8p.m. on 400 about 2200 B.S.T.I do not know if the effect is metres, by 2 MT Writtle, near Chelmsford. due to this particular period at night.I too haveThursday, August 24th noticed that the French coastal stations come Transmission of Daily Mail Concert at 8 to 9p.m., in very strongly about this time-recognisable by on 1,085 metres, by PCGG The Hague, Holland. the call beginning with " F," and have often had ILFORD ANDDISTRICT RADIOSoctErv. GRL jammed out by them. At St. Mary's Hall, High Road, Ilford.Lecture Isthere any explanationforthis" freak " on " Short Wave Reception,withSpecial reception reference to Damped Waves," by Mr. E. E. Hale. COURTNEY DRUMMOMD. Tuesday, August 29th Transmission of Telephony at 8 p.m.on 400 metres by 2MT Writtle, near Chelmsford. 2 PF Heard on Indoor Aerial. Wednesday, August 30th To the Editor of THE WIRELESS WORLD SOUTH SHIELDS Y.M.C.A. WIRELESS SOCIETY. AND RADIO REVIEW. 7.30 p.m.-Fowler Street.General Meeting. SIR,-It may interest 2 PF to know that IThursday, August 31st received his music and read his speech here in RADIO EXPERIMENTAL ASSOCIATION, Leicester, using three valves, and an indoor aerial ; NOTTINGHAM AND DISTRICT. horizontal part nine feet long and lead to instru- Meeting. ments five feet long. W EST LONDON WIRELESS AND EXPERIMENTAL He was working to 2 FN on Sunday, July 30th, ASSOCIATION. at 1845 hrs. G.M.T.2 FN comes through much At Belmont Road Schools, Chiswick, W.First louder, of course, by reason of his position. meeting after vacation. The aerial is about eighteen feet from ground CROYDON WIRELESS AND PHYSICAL SOCIETY. level, in the centre of the town, and close to the Meeting. electric traction routes. T. S. SKEET. Eastbourne College Wireless Club. Leicester.

The Reinartz Transmitter. To the Editor of THE WIRELESS WORLD AND RADIO REVIEW. SIR,-I am pleased to note the interest of The Wireless World and Radio Review in the circuit arrangements of Mr. John L. Reinartz which has been presented through QST.As the author of this article in June QST, which is reproduced on pages 447 and 448 of your issue of July 8th, however, may I point out an error in your Fig. 1 ? The choke coils as shown in QST were radio chokes, but in your diagram you have shown them with iron cores, which is incorrect.The one in the anode supply is to prevent the radio frequency oscillations from by-passing through the source of power and as nearly as possible should be resonant to the Eastbourne College Receiving Set. oscillating frequency.The choke in the grid lead The Club whose apparatusis shown above, isthe customary very small inductance whichholds its meetings on Tuesday evenings.It has American amateurs use in power tubes for thefifteen members.Next term the Club hopes to purpose of choking out parasitic oscillations at anobtain a transmitting licence. 0 2 666 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

Wireless Club Reports NOTE.-Under this heading the Editor will be pleased to give publication to reports of the meetings of Wireless Clubs and Societies.Such reports should be submitted without covering letter in the exact form in which they are to appear and as concise as possible, the Editor reserving the right to edit awl curtail the reports if necessary. The Editor will be pleased to consider for publication papers read before Societies. An Asterisk denotes affiliation with the Wireless Society of London. Derby Wireless Club.* experimental portion of his investigations could be Hon. Secretary's address, " The Limes," Chellas- carried out by switching only. ton, Derby. The principles of electro-magnetic and electro- In a series of eight lectures, extending over the static reaction, by which the anode circuit current last twelve months, Mr. E. Fowler Clark, B.Sc.,and voltage respectively are utilised via suitable B.A., A.M.I.E.E., has described the results asinductive or capacity coupling to inject into the progressively obtained, of a very thorough mathe-grid oscillatorycircuit assisting components of matical and experimental investigationofthevoltage and current, were then indicated, and, behaviourof an ordinary hard three -electrodeon a straight line valve characteristic and zero thermionic valve as applied to radio reception. grid current basis, the phenomena associated with As a preliminary, the first lecture consisted of achanges of the variable quantities, including those description of up-to-date ideas of charges, direct relating to the limits of oscillation, which had been and alternating currents, unilateral conductivity,arrived at mathematically and confirmed experi- potential, electric and magnetic strains, energymentally, were pointed out. transformations, ether waves, and electronic emis- Finally, Mr. Clark described, with the necessary sions from hot bodies, in terms of the electronic explanations, the results of experimental work on nature of electricity and of the atomic constitutionthe production oftheoscillation with various of matter. values of grid and anode potential, also of grid The second lecture dealt with inductance andleak potential in the case of the grid leak, indicating capacity, the various arrangements of tuned aerialthe conditions in which the phenomenon known as receiving circuits, types of transmitted waves and " overlap " would occur. received oscillations and impulses and the utilisation Mr. Clark consented to give further lectures, of the maximum induced alternating potential to describing from time to time his further experiments actuate detecting devices, also with the advantagesas they progress. of the closed secondary oscillatory circuit. Hounslow and District Wireless Society.* Mr. Clark then proceeded to describe, with the Hon. Secretary, Mr. A. J. Rolfe, 20, Standard aid of a series of very carefully taken experimentalRoad, Hounslow. curves, the various characteristics of the two and On Saturday, July 22nd, a demonstration was three -electrode hard valves and the methods by given at the Isleworth Hospital Fete, all members which, utilising suitable features of these character- assistingin erecting the apparatus and aerial. istics, the rectification effect necessary to convert Special permission was obtained from the P.M.G. intermittentradio oscillation trains into audio -enabling Lieut. Walker (2 OM) of Brentford, tQ frequency telephonic impulses could be obtained, transmit music.This he did in his usual style. coupled in the second instance with amplification. Everything went off well and a good sum was Bend and grid leak condenser rectification were handed to the Hospital Fund. considered in detail and particularly the effects of On Thursday, July 27th, a public demonstration experimentally varying the applied anode and gridwas arranged at the Council House.This being potentials. the first night of the Daily Mail broadcasting from Following this, and as a preliminary to theHolland, nearly 700 people were present and recep- consideration of the valve receiving circuit withtion was very good indeed, except for the usual loaded anode circuit to which it is analogous, aninterference.Afterwards, Lieut. Walker gave a alternating current circuit consisting of inductancevery stirring address to the audience, pointing out and capacity in parallel, supplied from an alternatorthe Society's work in the district, and stating further through a resistance, was considered.The changes that after the success that evening in receiving occurring in the magnitudes and phases of the total the Hague concert, support was desired more than and branch currents as first the inductance and ever.He also promised to transmit when he got then the capacity in the circuit is increased, under home.This he did at 9 p.m.His music was the action of the alternator P.D. or that impressedextremely loud and was heard in the street on the on the grid, as the case may be, were illustrated bySociety's Brown H.1 loud speaker.Councillor means of a vector circle diagram, attention beingW. J.Heath, J.P., chairman for the evening, drawn to the oases of tuning and over -tuning of thereceived a message transmitted for hisspecial varied (anode) circuit. benefit by Lieut. Walker, and enjoyed the experience Reception of spark transmissions on a tunedas much as the audience.At 9.30 p.m. the Society's anode circuit withcrystal rectification and nofirst public demonstration closed down. reaction, on the above principle, was then referred On Saturday, July 29th, another demonstration to, after which Mr. Clark diverted to describe,was given at the Hounslow Hospital Fete.Lieut. with the aid of distributed diagrams, his circuitWalker again obliged, and at 9.10 p.m. Marconi arrangements, by which nearly the whole of theHouse (2 LO) was picked up, where a local singer AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 667 was performing.This demonstration wentoff the Society with the necessary permit, a party of without any trouble and a further good sum wasmembers were enabled to pay a visit to the Council's handed to the Hospital. generating station atGreenwich on Saturday, The members are well pleased with a briskJuly 29th. A guide took the party round, and the week's work.If any gentleman would care to join visit proved an afternoon's thorough enjoyment. the Society, he should write to the Secretary. The active membership of the Society is steadily increasing, and now stands at 52, nearly all of whom Stoke -on Trent Wireless and Experimentalhave receiving permits, while there are eleven Society.* transmitting licences including the two possessed Hon. Secretary, Mr. F. T. Jones, 360, Cobridgeby the Society itself. Road, Hanley. The Society's latest step on the road of progress At a meeting of the Stoke-on-Trent Wireless andis the completion of affiliation to the Wireless Experimental Society, held on Thursday, August Society of London. 3rd, it was decided to admit the members of the Y.M.C.A., in whose building the Society have made Wireless and Experimental Association.* their headquarters, at areduced annual subscription. Secretary,Mr.Geo.Sutton, A.M.I.E.E.,18, A Committee meeting has been called, to hurry Melford Road, S.E.22. forward as rapidly as possible the erection of the The meeting on Wednesday, July 26th, was very aerial and the fitting up ofthe new club -roomwell attended, and general queries were very fully to suit the Society's needs.It is hoped to havedealt with for the edification of the newer members. everything ready by the end of the month, and to The Chairman started a very interesting discussion have a formal and probably public opening. on multiple aerials, and aerials used multiply. That involved finding out what would happen The Gloucester Wireless and Scientific Society*were several aerials in close proximity used at the Hon. Secretary, Mr. G. T. Peck, 45, Denmarksame time on the same wavelength, and how Road, Gloucester. interference could be prevented by having their At a meeting held at headquarters on July 3rd,ends connected together, thus forming parallel Mr. B. T. Gowing demonstrated with a two -valveoscillatory circuits which, if oscillating, would do setoforiginaldesign.The resistance -capacity circuit used-the outcome of much experimentalso at a common frequency.Mr. Voigt followed up work-worked well over all wavelengths, even asby describing what would happen in almost every low as 300 metres, and Mr. Gowing seems to havepossible arrangement of three stations working overcome the usual drawback of the resistance -near each other on the same, separate and connected capacity circuit, i.e., inability to work below 1,000aerials.Most of the points, although not practic- metres.During the course of the evening some veryable for the amateur, were of exceptional interest. good signals were obtained on the club's aerial. On Wednesday, August 2nd, the application and At a meeting of the Society on July 31st, Mr. advantages of two -slide inductances over single slide C. Minchin gave a second lecture on " Dynamos." inductances was explained. The Chairman then des- This proved to be very interesting, the lecturer cribed practically every practicable form of detector, producing several formers and coil -winding machinesgiving useful information for the handling and use used in the manufacture of dynamos. of the multitudinous combinations of crystals and Although during the summer months the Society'spointing out as far as possible how each may be activities have been somewhat curtailed, it is hopedidentified. A competition was announced for the best wireless gadget.No limits were placed, except that anyone interested in amateur wireless willthat it had better be some little valuable article. communicate with the Hon. Secretary, who will Communications and enquiries to the Assistant be pleased to answer all enquiries at the aboveSecretary (Mr. W. J. Joughin),21, Troughton address. Road, Charlton, S.E.7. Ilford and District Radio Societynj Hon. Secretary, Mr. A. E. Gregory, 77, Khedive Lion Radio Club, Shoreditch. Road, E.7. Hon. Secretary (pro tern. ), Mr. A. V. Turner, At the request of several of the members, Mr.35, Aske Street, Pitfield Street, N.1. E. E. Hale had prepared a lecture on " Don'ts." The above club is in the course of formation and This he delivered on Thursday, July 13th, with histhe Secretary would be glad to hear from amateurs customary vigour and in a systematic manner,in the district who are likely to become members. commencing with the aerial and working throughHe would also welcome catalogues and literature the set to the telephones, emphasising the thingswhich might be of interest to the members.In- that an amateur should not do under any circum- tending members should write or call at the above stances, and criticising the experiments that, while address. permissible, are from a beginner's point of view best left alone.The discourse proved most in- Otley and District Wireless Society. formative without being redundant in any way, Hon. Secretary, Mr. Y. C. Weston, 24, Guycroft, and was greatly appreciated. Otley, Yorks. Mr. A.J. Thompson lectured on Thursday, On August 3rd, at 7.30 p.m., the second meeting July 27th, and demonstrated " Aerials, Earthswas held at the Cafe, Queen's Hall; Otley. and Wiring."The lecturer condensed his informa- After the minutes of the last meeting had been tion exceedingly well, and his explanations of theread and passed, two lectures were given. Mr. N. different types of aerials in use with their respectiveWeston lectured on " Electrostatics,' and Mr. Dey merits and demerits were of high value. lectured on the subject of " Signalling." By the courtesy of the Electrical Engineer to Several new members were enrolled. A further the*,L.C.C. Tramways, who had kindly providedmeeting was held on August 17th. 668 TILE WIRELESS WORLDAND RADIO REVIEW AUGUST 19, 1922 The North Essex Wireless Society. and the reception of C.W. and spark signals was Hon. Secretary, Mr. F. T. Smith, Headquarters,loud and clear. 15, Rayne Road, Braintree. Also a one -valve set was demonstrated and music A field day was arranged for August Bankand telephony from several amateur stations were Holiday for members, atMr.Lagden's station,listened to with interest, including 2 MT, who Gt. Leighs.The object of the experiments wasare to be congratulated on their splendid trans- to prove tothose possessing reactioncircuits mission. exactly what an amount oflocalinterference Several new members were enrolled and others their misuse caused. are heartily welcome.All particulars from the Using the above gentleman's station as a base, Hon. Secretary. a temporary station was erected about 300 yards away.The result was that those present were Clapham Park Wireless Society able to learn how to reduce their re -radiation to a (Embracing Streatham Hill, Balham, and minimum.As a forcible proof to those who might Tooting Districts). have been careless about tight -coupling, a micro- Hon. Secretary, Mr. J.C. Elvy, 3, Fontenoy phone was placed in the anode circuit of one Road, Bedford Hill, S.W.12. receiver and both music and speech were received A very successful inaugural meeting was held clearly and loud in the other receiver.Single valveunder thechairmanshipofMr.J.C.Elvy, sets were used in both cases, and it is thought that A.M.I.E.E., etc., Consulting Electrical Engineer, by mutual agreement, arrived at through these at the Studios, 67, Balham High Road, which were experiments, there will be much less local inter-graciously lent for that purpose by Mr. M. P. Prout, ference in the district.At the conclusion Mr-Cantab., at 8 p.m. on August 1st, 1922. Lagden kindly entertained the members of the After a brief conversazione, the fifteen present, Society to tea and was accorded a hearty vote ofnamely, Messrs. J. Gray, C. A. Griffiths, W. W. thanks for his kindness.Before leaving, musicMillar, M. P. Prout, J. C. Elvy, A. E. Redburn, was transmitted by 2 ZV, and this concluded aW. Brierley, R. H. J. McCue, H. R. Knott, H. E. highly successful and satisfactory day. Austin, A. L. Beedle, R. McCue, F. H. Austin, V. L. Natusch, R. G. Rippon, sat down to business. Southampton and District Wireless Society.Mr. J. C. Elvy was elected Hon. Secretary.Mr. Hon. Secretary, Mr.T.Cutler,24,FloatingM. P. Prout was elected Hon. Treasurer. Bridge Road, Southampton. Elected to serve on Committee :-Messrs. J. Gray, W. A meeting of the above Society was held onBrierley, A. L. Beadle, R. H. J. McCue. July 26th at the Assembly Rooms and a pleasant In furtherance of an endeavour to secure a evening was spent. representative of each sub -districttofacilitate The members of the Society did exceedinglyfutureorganisation,further nominees may be well with their amateur constructed sets in receivingselected for Streatham Hill and Battersea portions the broadcasted concerts from the Hague on July of area concerned. 27th.The best attempt to hand is that of Mr. Lush, The next item dealt with was a suitable title of Fitzhugh, Southampton. Using a four -valvefor the club.The proposed word " Scientific " L.F. constructed set he was able to hear the wholewas omitted as it was agreed that the abbreviated of the concert all over the large room without thetitlewould notprecludedealingswithother aid of a loud speaker. Mr. Lush states the musicsubjects should members so desire on occasion. was louder than FL, which goes to show the The decision therefore is as above. excellent results obtained.Congratulations from It was decided to hold meetings every Wednesday all the members of the Society are offered to Mr.at 7.30 p.m. in winter, and alternate Wednesdays Lush. in summer at 7.30 p.m.,i.e., fortnightly up to A further meeting, held on Wednesday, AugustSeptember 30th next, the next meeting being fixed 2nd inst., resulted in one of the largest attendedfor August 9th. meetings of its members yet recorded.As members The question of subscriptions arose, Mr. M. P. are steadily increasing, great things are being looked Prout generously offering to extend the loan of forward to during the winter.It has not yet beenthe premises till further notice, and after discussing definitely decided to engage the present club -roomvarying ratesforjuniors and seniors,it was for a further period of six months as it is hopedprovisionally decided that the subscription be 7s. 6d. to obtain another room.Therefore, the improve-annually, payable in advance, as from August 1st ment of the club aerial is at present at a standstill. of each year, and within one month.Entrants The following were elected as members onin last six months of the year to pay 4s. sub- July 27th and August 2nd :-Col. Neade, Messrs.scription, to carry them up to following July 31st. Bovey, Southard, Smith, Hirst, Dickenson. All entrants after the first fifty enrolled to pay All amateurs in Southampton and district can2s. 6d. entrance fee in addition. be supplied with particulars of the Societyon After a hearty vote of thanks had been accorded application to the Secretary. to Mr. M. P. Prout for material assistance rendered by allowing use ofhisstudios as provisional The Hornsey and District Wireless and Modelheadquarters ; also to Mr. J. Gray for offering to Engineering Society. institute buzzer practice as an appetiser at 7.30 p.m. Hon. Secretary, Mr. H. Davy, 134, Inderwickeach meeting and to the Chairman for so ably Road, Hornsey, N.B. conducting the Society through its initial stages, On Tuesday, August1st,1922, a successfulto which suitable references were made, the meeting meeting was held at 29, Felix Avenue, Weston Park,was brought to a close at 9.30 p.m. Crouch End. The question of aerial and other equipment for A two -valve resistance -capacity set was tried out the Studios, has already been touched upon. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW 669 Aberdare and District Wireless Society. A hearty vote of thanks was passed by the meeting Hon. Secretary(pro tern.),Mr. J. Owen Lewis, to Mr. Carpenter for his kindness in giving such Alltyblacca, Danyderi Street, Godreaman, Aberdare. an interesting demonstration. A meeting of wireless enthusiasts of the Aberdare Over thirty new members were enrolled, bringing Valley was held at the Cwmaman Public Hall on the total up to 70, and the Club is now looking Thursday, July 27th, when it was unanimouslyfor a larger room. decided to form a Society under the above name. Meeting every Wednesday night 7.30 to 10 p.m. Mr. A. E. Hay ((2 KG), of " Glendale," Collegeat above address. Street, Aberdare, was elected to the chair, and Guildford and District Wireless Society. under his able guidance, a very profitable evening Hon. Secretary, Mr. Rowland T.Bailey, 46, was spent.A membership of nineteen was regis- High Street, Guildford. tered, but in view of the fact that about 18 to 20 On Saturday, July 29th the members of the prospectivemembers wereunabletoattend,above Society gave some demonstrations in aid it was decided to hold an official inaugural meeting ofChiddingfoldHospitalSaturday Fund.On at a later date. the whole the day proved successful.Mr. F. A. In the meantime Mr. Hay, Mr. J. Owen Lewis, Love, of Guildford (2 HX) very kindly gave three Mr. Parry and Mr. Duffy were appointed to act astransmissionsof musicintheafternoon, and Chairman, Hon. Secretary, and a committee ofat 7 p.m. gave out cricket results, etc., from the two,pro tern.,until the first official meeting, whichevening newspaper.A call from Marconi House is to be heldin Aberdare on Thursday evening,(2 LO), and the reception of their three concerts August 10th, at 7 o'clock. at 5, 6 and 9 p.m. also added to the success and The Society is extremely fortunate in havingpopularity of the demonstrations.A four -valve secured the active interest of Mr. Hay, who, asset, the property of Mr. R. C. Patrick, a member the founder of the South Wales Wireless Society, of the Society, was used, and in spite of being is well known as the pioneer of amateur wirelesstransported ten miles, performed the duties ex- work in Wales, and who has achieved some recordspected of it most admirably. It is hoped the efforts in amateur transmission. proved beneficial to the Hospital Fund. The Society has beenofferedthe use of an The Society is still anxious to swell its member- excellent lecturehallin the main thoroughfare ship, and therefore the number of sets ;a good piece of Aberdare, and it is anticipated that the meeting of advicewould be for everyone starting on the fields which will be held there on August 10thwill of wireless to become a member of the nearest be very successful, as at the beginning of AugustSociety, where they will findfirst-class advice upwards of fifty applications for membership are given willingly.Any amateur in the neighbourhood to hand, and all local electrical workers are keenlyis heartily invited to come to the Society's room in the new society. at 46, High Street, Guildford, on any Monday A vote of thanks was tendered to Mr. Ray of evening at 7 p.m. the Cwmaman Public Hall for his kindness in having The Fulham and Putney Radio Society. placed a room free of charge at the disposal of Hon. Secretary, Mr. J. Wright Dewhurst, 52, the, meeting. North End Road, West Kensington, London, W.14. Candidatesformembershipcanobtain ull The monthly meeting of the above Society was particulars from the Hon. Secretary. held at their temporary headquarters, 232, Putney Bridge Road, on Thursday, August 3rd.There Walthamstow Amateur Radio Club. was a fair attendance and several new members Hon. Secretary, Mr. R. Cook, 49, Ulverstone were enrolled.Amongst other businessit was Road, Walthamstow, E.17. proposed that as soon as the question of suitable A most successful wireless demonstration was accommodation was settled, that the Society become given on July 25thatthe Club headquarters,affiliated to the Wireless Society of London. A Y.M.C.A., Church Hill, Walthamstow. very interesting discussion on wireless topics took Over 400 were present and greatly enjoyedplace amongst the members and several gave their the short lectures given by Mr. Oswald Carpenterexperiences with wireless during the late war. (ResearchDept.),oftheMarconi'sScientific Instrument Company, Ltd., and also the music At the next meeting it was arranged to have a which was received from various sources.Mr. three -valve set (lent by Mr. Houstoun) working Carpenter informed the audience that this was the to receive some amateur transmissions. firstdemonstrationofthe" Magnavox " loudSutton and District Wireless Society, Surrey. speaker and the " Magnavox " power amplifier Hon. Secretary, Mr. E. A. Pywell, " Stanley before an English wireless society. Lodge," Rosebery Road, Cheam, Surrey. Several times during the various items of music The Secretary begs to announce that, owing to Mr. Carpenter had to shut down owing to thea considerable increase in the number of members, jamming fromvariousinexperienced amateursa larger room has been engaged for the meetings. in the neighbourhood. This necessitates a change of meeting night from 2 MT, who gave us a special call, came throughThursday to Wednesday, commencing on 9th very loudly and distinctly, and could be heard August (8-10 p.m.). with ease all over the large hall. This new room is in the same building, namely, Mr. Carpenter also brought with him some very the Adult School, Benhill Avenue, and, with the interesting lanternslides, showing some of theincreased facilities, a special effort will be made earlier stations and also the modern ones, including to help the beginners. one of Senatore Marconi endeavouring to fly a kite Will all in the district interested in wireless, both inNewfoundland whenthefirsttransatlanticbeginners and experts, attach themselves to the wireless message was sent. Society and thus ensure its continued success. 670 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 Questions and Answers _ .NOTE.-This section of the magazine is placed at the disposal of all reader* who wish to receive advice and information on matter. pertaining to both the technical and non -technical sides of wireless work.Readers should comply with the following rules :-(1) Each question should be numbered and written on a separate sheet on one side of the paper, and addressed " Questions and Answers," Editor, THE WIRELESS WORLD AND RADIO REVIEW, 12/13, Henrietta Street, London, W .0.2.Queries should be clear and concise.(2) Before sending in their questions readers are advised to search recent numbers to see whether the same queries have not been dealt with before.(3) Each communication sent in to be accompanied by the " Questions and Answers " coupon to be found in the advertisement columns of the issue current at the time of forwarding the questions.(4) The name and address of the querist,which is for reference and not for publication, to appear at the top of every sheet or sheets, and unless typewritten, this should be in block capitals. Queries will be answered under the initials and town of the correspondent, or, if so desired, under a " nom de plume."(5) In view of the fact that a large proportion of the circuits and apparatus described in these answers are covered by patents, readers are advised before making use of them, to satisfy themselves that they would not be infringing patents.(6) Where a reply through the post is required every question sent in must be accompanied by a postal order for the amount of le., or 3s. 6d. for a maximum of four questions.(7) Four questions is the maximum which may be sent in at one time. " H.E.P." (North Greenwich).-We gatherof action to the grid and L.T. minus of the valve. from your remarks that you have added a L.F. The closed circuit should then be connected to the to your crystal set.The further improvement you plate, and one of the telephone leads.A condenser request could be obtained by adding a H.F. valve,having a value of about 0.002 mfds. should be con- one of various suitable circuits being as shown innected across the telephones. A suitable con- Fig. 1. The circuit should then give the results denser will be found inside the set already connected required. to the short circuited telephone terminals.The other telephone lead is then taken to H.T. plus, H.T. minus being taken to the filament battery. This tuner is usually provided with two contacts, which are closed when the change -over switch is placed in the tuned position. As you will be making use of the closed circuit whilst the switch is over on the other side, you will need to short circuit these two contacts.This tuner is quite good for giving reactioneffectswhensocorrected.(2) The position of the tap should be variable, and it is better to use an additional coil wound in the same direction as the secondary inductance, one end of which is connected to the L.T. battery and the other taken across to the grid of the oscillator valve. The oscillator must be arranged to give wavelengths of the order of 30,000 metres-that is, just above audible frequency.(3) It is regretted that we are unable to advise you further in the manipulation of this circuit, as very little data concerning the dimensions of the coils is at present available. " P.H." (Coventry)isconstructing a three valve receiver built up on the unit system, and wishes to know whether his panel wiring, as shown in his Fig. 1. diagram, is correct.(2) The values for the grid leak, grid condenser, and telephone condenser.(3) Whether the set could be used in conjunction with the tuner " F.W.S." (Nottingham)wishesto know described in theissueofJuly 15th,and(4) (1) How to convert a Mk. III long wave tuner to Whether we consider it advisable for him to abandon give reaction effects.(2) Whether in attaching his the unit system he has devised and adopt that described

Mk. III tuner for use as a component of the Armstrong in recent issues. super -regenerative circuit, he should make connection (1) Your circuit diagram is quite in order, but it between the oscillator valve, grid coil, and the A.T.I. isdifficult to trace out precisely your practical by means of a variable coupled inductance, or bywiring diagram.However, it appears to possess connection to the top of the coil.(3) Should theno special merits over the designs put forward in oscillator valve grid coil tune to the same wavelength the articles to which you refer, and we strongly as the A.T.I. of the tuner. recommend you to follow these articles as a guide (1) Isolate the closed circuit, which can be donefor the construction of a long range multivalve by placing the change -over switch in the stand-byreceiving station.The advice given is in every position.The telephone terminals should be short way reliable and complete, and should you experience circuited, and leads taken from the opposite sidesany difficulty in making up the apparatus, we shall of the crystal detector, which should be put out be pleased to assist you. Atrausx 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW STERLING No. 1 CRYSTAL WIT RECEIVING SET Specially designed for use in connection with the Wireless Telephony Broad- casting Scheme, and is suitable forarangeofabout 25 miles.

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Telephones: Telegrams: Gerrard 3039. The Radio Waveora Co. Wychwood, Western 847. 168 Regent Street, London, W.1 Phone, London, xiv THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

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INFORMATION THAT IS VALUABLE TO YOU SEA, LAND is to be found inevery issue of and AIR "CONQUEST" (The Monthly Magazine of Popular Science) THE AUSTRALIAN The wonderful contents of the AUGUST ISSUE MONTHLY JOURNAL include articles on of 110W TO ERECT YOUR WIRELESS AERIAL Aviation, Radio -Tele- Wireless Notes-The Way of an Eagle- How Bells are Made-Some Difficulties in graphyRadio -Telephony the Theory of Relativity-The Cannibal Ladybird-A Scientist's Diary-Strange Locomotives-Useful Hints for the Home -Home ExperimentsinScience-Is Price Annual There Vegetation on the Moon-Wanted: 1/9 Subscription A Popular Science Theatre-Questions Post Free 21/ - and Answers-Ancient Hawaiian Rock Pictures, etc. AB..NDANTLY ILLUSTRATED. PRICE : 1 /- THE WIRELESS PRESS LIMITED Obtainable at all Bookstalls and Newsagents, or Post Free 1 3 12/13, Henrietta St., London, W.C.2 from The Milano, CONQUEST, 12-13, Henrietta St.. W.0.2 A big Shdlingsworth!Get your copy to -day. AUGUST 19 1922 THE WIRELESS WORLD AND RADIO REVIEW 671 " SPARKS " (Bingley)describeshisthree - (1) (2), (3) and (4) It is difficult to suggest the valve set and asks for a wiring diagram for same,cause of the apparatus not functioning correctly, so that one or both of the H.F. valves may be cut out. as the diagram you give is quite correct.The addition of a variable condenser having a maximum value from 0.0005 to 0.0015 mfds. and connected in V series or parallel with the aerial circuit would be found helpful, as it is quite probable that the range c of the tuning coil and the aerial circuit as it stands C> CO C>C> does not come within that of the closed circuit coil. C> A condenser having a maximum value of 0.0005 C> mfds., may with advantage be connected across the reaction coil.As you do not define the actual results given by the set as it stands, we can hardly locate the fault.The variety of valve you use may be the cause of the trouble, as it may be of the slightly soft variety, and require a potentiometer to control the potential of the grid.We think if you make the addition of the condenser suggested, you should have no difficulty in bringing in signals, presuming no internal fault exists on the valve -111111-vAN, panel, which being of reliable make, we do not look to as a source of trouble. " G.A.H." (Farnborough) has a number of Fig. 2. accumulators which he wishestolay aside, and enquires what condition they should be in in order Without knowing the nature of your switches wethat no deterioration may result. cannot give the exact information required, but The cells, whether charged or uncharged, should your circuits might be arranged approximately as be completely emptied of acid and filled with dis- in the diagram (Fig. 2). tilled water, and allowed to stand for several days. " N.L." (Co. Down) submits two circuit dia- This should then be tipped away and the accumulator grams, one comprising six valves with resistance left standing wrong way up, in order that all moisture capacity coupling, followed by two note magnifiers, may drain from the plates.When the interior has and the other a four -valve set with H.F. transformer become dry, the stoppers should be replaced to coupling, all inductances being tuned by means ofprevent dust entering the interior. condensers, and asks which circuit is the better for " C.H.B." (Fleetwood) asks (1) For alternative the purpose of receiving telephony.(2) What type diagram to Fig. 5, page 15, April let issue, sub- of H.F. transformer we should recommend.(3) stituting connections for single slide A.T.I. with Whether the values of condensers and resistances reaction.(2) If A.T.I., wound on a tube 84" x 4" are suitable for use with " V24" or " R " valves, with No. 30 S.S.C., is suitable.(3) Approximate and what values should be used with " Ora " valves. wavelength of same. (1) Both circuits will give you very satisfactory (1) See diagram (Fig. 3), but an alteration of results, and the relative merits can only be con- this nature will quite spoil the set.The remainder sidered with regard to ease of manipulation.In of the set as in the diagram referred to.(2) We your No. 1 circuit it is not an advantage to tune both primary and secondary of H.F. transformers, V as it makes manipulation very complicated, and the connecting condenser across the secondary of a H.F. transformer drops the potential whichis applied to the grid of the next valve.In construct- L ing an outfit to your No. 2 circuit, you should take great care to ensure that the values of condensers C> and resistances are precisely correct.(2) H.F. C) transformers of the Sullivan type can be relied upon C> as quite suitable for use in your No. 1 circuit.(3) C> The values of condensers and inductances are all quite correct for use with " V24 " and " R " valves, these valves having been specially designed for use C2> in the circuits in which you propose to connect C> them.It is very important that all valves shall be C> of identical properties. T " M.H.C." (Wendover) submits a plan showing 101 the layout of his apparatus, comprising three inductances and single valve panel, and asks (1) Why he is unable to receive signals though the panel itself it, O.K., having been tested on another set.(2) If Fig. 3. the wire as shown by him is correct.(3) Whether another variable condenser would be helpful, and if should prefer a coil of larger diameter wound with so, where it should be connected.(4) What should thicker wire.(3) Up to 4,000 metres with a normal be the capacity of such a condenser. P.M.G. aerial. 672 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 19, 1922 " UNCLE TOM " (Bournemouth) asks (1) For a diagram of a two -valve transmitter for C.W. and telephony.(2) Data for wiring transmitter. (3) If more valves can be added without dismantling set.(4) Values of condensers and resistances. (1) See diagram(Fig.4).(2)Itdepends largely on the aerial.Try about 40 turns on a former 3" diameter for the A.T.I., and 80 turns on a 2" diameter former for the reaction.(3) Not V

Fig. 6. " R.J." (Christiania) sends a diagram ofa circuit for transmitter, and asks (1) If circuit is correct. (2) How can he add another valve to his single valve receiver. (1) The circuit will do, except that for transmission by arc, D.C. must be used with electrodes of copper and carbon.Consult a good text -book, as there are many technical points to be considered JV AA. before successful radiation can be obtained.(2) See diagram (Fig. 6). 1111- III " J.H.W." (Newbury) asks (1) For connections for a resistance coupled to L.F. amplifier.(2) How to add a panel as H.F. resistance amplifierto a Fig. 4. single panel shown. usefully, except in parallel with the oscillating valve.(4) For grid condenser 0.001 mfds., with 250,000 ohms.Feed condenser try 0.0005 mfd. " P.H." (Coventry) asks (1) Wiring data for a detecting, H.F. and L.P. set of panels, using the same H.F. and L.F. batteries. (2)Would single layer coils for short wavelengthsandduolateral coils for long wavelengths give a range of from 250/30,000 metres.(3) Should reactance be used, and if so how wired. (4) What valves should be used for the different stages of the multi -valve circuit. (1) Many different methods are possible, one Fig. 7. of which we give in diagram Fig. 5. (2)Yes.7::(1) The connections for a L.F. amplifier are (3) Reactance can be used and will give greaterexactly the same as for a H.F. amplifier of this type, selectivity. For method of wiring, see the diagram.but largervaluesofcoupling condenser,say (4)" R " valves may be used throughout, or0.0005 mfd., and smaller values of grid leak, say "V 24" valves for amplifiers and "QX" for rectifier. megohm, are suitable.(2) See diagram:(Fig. 7). V

!!c> '-'VVVV"- -'VV \/- ge

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111111111111111111 xvi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 THE " BROWN" LOUD SPEAKERS WITH NEW IMPROVED CURVED HORNS. The requisites of a Loud Speaker are pure tone, clear articulation, and good volume of sound.The " BROWN " Loud Speaker possesses these qualities, and they are enhanced by the new improved curved horn. THE AMATEUR does not always need the full sized Loud Speaker (Ha) as used in Lecture Halls, and a small type (H.z) has been designed to meet his more modest home requirements. THE NEW HORN used with both H.1 and H.z, is constructed on thelogarithmiclawofincreasing openings and isacousticallyperfect. PRICES : II.1 (Large) Low Resistance, s20 ohms £650 H. 2 (Small) ff £300 The " BROWN " Standard Pattern (withupright funnel) Low Resistance, tzo ohms £5100 (High Resistances for all patterns 2/6 to 5/- extra) Catalogues post free onapplication. MANUFACTURERSSSOLE G. BROWN, LTD., H.I(Large) Height2I. SHOWROOMS: 19 MORTIMER STREET, LONDON, W.1 TeaIp_hone: Museum 4950 Works : Victoria Road, North Acton, London, W.3 Sole .Agent for the Argentine : Telegrams: " Sidkownix, London,"Telephone: Chiswick 1469.Horatio D. Guerrero, Las Heras 2.48o, Buenos Aires Brown's Wireless Apparatus can be purchased from all Wireless Suppliers. EARLY DELIVERY of Telephones and Loud Speakers can now be given. WIRELESS CONSTRUCTION PARTS TO BUILD YOUR OWN SETS Our Famous " Atlantic " 3 Valve Receiver Grid Leak and Condenser for remounting 3/6 and Amplifier, Panel Type, range 200 to Fil. Res. and Valve Holder on Ebonite .. 6/6 3,000 metres, i H.F., I Rect., r L.F., 2 Variable Condensers, 3Fil.Res., 3 Valve Holders, 2 Fil. Res. on Ebonite .. 12/6 Coil Holders and Plug in Coils .. 175/- Concert Coils, for Marconi Concerts, etc. Pair 2/- Full Set of Parts for the above .. 125/-Set of Basket and Slab Inductances, Our " Super Atlantic " 4 Valve Receiver includes our Concert Coils - and Amplifier, designed especially for 50o to 8,000 metres, Set of 6.. 6/6 telephony, Panel type as above, r H.F., Rect., 2 L.F., 2 Variable Condensers, 500 to 20,000 metres, set of 7.. 8/9 Coils and Coil Holder, Price, tested on Ebonite Plugs for Mounting Slabs, etc.. 2/- aerial .. 215/ - ooi Semi -Variable Condensers .. 17/6 Full Set of Parts.. ..175/-Cabinet Concert Tuners .. 38/- 3 Valve Amplifier, 1 H.F., 1 Rect., 1 L.F., Double Slide Crystal Receiver .. 42/ - Skeleton Variable Condensersforre- same as our " Atlantic," less Inductances and Variable Condensers .. 110/- mounting, 25 plate 12/6, 31 plate 14/6, 43 plate 18/6.The finest Condensers 3 Plate Vernier Condenser .. 4/6 made.

5 /1 . 6/ - Get oar NEW LIST FULL OF GOOD THINGS. AMATEUR SUPPLIES ASSOCIATION, 134, Coteford Street, Tooting, Works :196, High Street, Merton. LONDON, S.W.17. AUGUST 19, 1922 THE WIRELESS WORLDAND RADIO REVIEW 673 " P.W." (Maidstone)asks(1) Number of Where D is diameter of coil in ems., n= No. of -moving plates 21." in diameter required for con- turns in ems. struction of condenser having a capacity of 0.0005 mfds.(2) For a diagram embodying one H.F. L = length in ems. and k is a constant depending amplifier, rectifying valve and one note magnifier, on 1, a few values of which are given :- and also dimensions of condenser. V

IIII 'Iii Fig. 8. d d (1) If the spacing between the successive moving K K plates is 5/64", and the gaugeis No. 20 S.W.G., then ten will be required.From this information you can easily calculate the number required and 0.1 0.96 10.0 0.20 your spacing washers will be of different dimensions. 0.25 090 0.50 0.82 The thickness of air space in the particulars given 0.75 0.75 1.0 0.69 above to the thickness that you propose to adopt 1.5 0.59 2.0 0-52 is inversely proportional to the number of plates 3.0 0.43 5.0 0.32 required.See Fig. 8.A.T.C., 0.001/0.0015 mfds.; " P.L. " (Teignmouth) asks (1) W hat wavelength reaction tuning condensers, 0.0004 mfds. ;grid and system is the GFA meteorological report and condenser,0.0003mfds.;thecondenserthat the R.A.F. news sent at 08.35 G.M.T.(2) Why do bridges the primary of the transformer, 0.001 ; some C.W. stations " splutter."(3) What is the H.T. condenser, 0.01/0.25 mfds. system which makes its dots and dashes on different H.F. primary notes.(4) If GBL (Leafield) is an arc station, tuning condenser, 0.0003 mfds. maximum. and if so, is the note which fills the spaces between the dots and dashes the carrier wave. " CURIOSITY " (Cambridge) asks (1) For (1) Formerly 1,400 m., but from 1st July 4,100 m., a diagram of a four -valveset, using a Reinartz and in cases of breakdown reverts to 1,400 m. Tuner. (2) MaximumwavelengthaReinartz (2) " Spluttering " in a C.W. station is generally Tuner can be made to work upon.(3) Formula due to a badly adjusted arc as generator of the for calculating the inductance of single layer coils. C.W.(3) This is the general method of keying (1) See diagram (Fig. 9)(2) No exact figuresan arc, by changing the wavelength.By suitable are available.We doubt, however, if the tunertuning one of the notes may be made inaudible, would be very much use about 1,500 metres. the other is then easily read.(4) Yes, the second (3) L mhys. -y2d2n2Lk note is the spacing wave-quite a different thing 1,000 from the carrier wave of a telephone set. V

I a

Fig. 9. 674 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 19, 1922 " A.11." (Bradford) wishes to purchase wireless " K.B." (W.1) asks (1) How to convert a B receiving outfit, and asks us to advise him with regardMark II receiver for the reception of short wave to the relative merits of apparatus supplied by varioustelephony.(2) Which is the more suitable for the manufacturers. construction of a frame aerial, wire having 105 It is regretted that we cannot advise you with strands of No. 42, or single No. 18.(3) The capacities regard to the relative efficiency of the variousof the aerial tuning and grid condensers in the B outfits you mention. You should, if possible, in- Mark II set. spect the apparatus, and if purchasing from a firm (1) Remove the small tuning coil from the of not long standing, a demonstration of the set instrument and bring out four leads for the purpose in use on an aerial similar to your own would helpof connecting to two coils which you must arrange to satisfy you as to its merits. external to the set.The 4 megohm leak must also "C.W.N." (Wandsworth Common) asks be removed, and the four wires which terminate on for a diagram of a certain two -valve set. one of the leak terminals should be carefully tied See diagram (Fig.10).A set of this typetogether and wrapped with insulating tape.The would not be very efficient, and would hardly beother lead may be removed from the set. A small worth the complication and expense involved. circular condenser may also be removed, or at any V

0000J --o -\"~-, -(000 0 000P- I T -ON -^A^A,,A,

Fig. 10. " A.T.G." (Whetstone) has a loose coupledrate taken out of circuit, but the lead which formerly tuner with primary 6" in diameter by 9" long and goes to the coil and from thence up to the valve secondary 5" in diameter by 7" long, and asks for holders muststillbeleftconnected through. windings for tuning up to 3,000 metres. Construct two coils as described on page 328 of Wind primary with No. 24 D.C.C. and secondary June 10th issue, and these are connected to the four with No. 26 D.C.C., making tappings at 4", 1" leads which were formerly joined to the inductance 14", 2", 24", 34", 44", 54", 64", 74", and 9" on thecoil of the set.One coil is connected to the lead primary; and at 4", 1", li", 24", 3", 31", 41",which passes from the valve holder, and also the 54", and 7" on the secondary.This tuner may notright-hand tag of the three when the instrument is work efficiently on wavelengths below 400 metres,viewed from the inside with the filament resistance for which two special coils should be constructed. on the left.The other two tags-that is, the left- " H.H.J." (Sydenham) has a tuningcoil hand pair-are connected to the other coil, and when 6" in diameter by 44" long, wound with 220 turnsin use these two coils are placed over one another. and tapped for 10 turns, and asks (1) Whether itFor short wave telephony reception a condenser would be suitable for the reception of Paris sparkhaving a maximum value of 0.0005 mfds. should be signals when coupled to a crystal detector.(2) Theconnected in series between the aerial lead and the best type of crystal for use without potentiometer, andaerial terminal of the instrument, whilst another (3) Should resistance of telephones be 4,000 ohms,of similar value should be connected across the or whether ones of lower resistance might be used. coil which is joined to the plate circuit.(2) The (1) We do not think that your coil will tune toflexible wire would probably be found more suitable, 2,600 metres.It is impossible to advise you as toas it will lie closer to the sides of the frame, and the wavelength to which a coil will tune withoutit is more easy to arrange strands of flexible wire knowing the dimensions of the aerial to which it isparallel to one another.If you take the trouble connected.In making tappings on a coil, equalof fixing small pieces of ebonite with spaced holes distances should not be spaced off.They should bedrilled in them at intervals along the outside of made at increasing intervals along the coil.(2) the frame, you may be able to use the No. 18 by Silicon and artificial galena used in conjunctionpassing it through the holes.(3) The aerial tuning with a light iron wire can be recommended, also condenser would have a value of something less than many of the special crystals at present on the market, 0.0001 mfds.This value is not specified, as it is particulars of which can be seen in the advertisementadjusted according to the value of the inductance columns.(3) A minimum resistance of 4,000 ohms to which it is connected.This set is not usually is advisable. fitted with a grid condenser, and the leak which is AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW

ghe carat Commercial eless telephone 8ePvieginGreatg3ntain u8ed for (Dommunications between the offices of the Aersey Docks CC llarbour Doard in Liverpool and the Oar '4q1u-shi,r) beyond the mouth of the Jt(ense Size Marconi apparatusin each case is operated by the ordinary (.7!..i-trliourDoard staff and has been in continual use since its installation over a year ago. "eilling up" is performed by means of the- 0 0itiaironi wireless bell0 0 AlARC0V7:1? WIRELESS TELEGRAPHCO.. art MAROON HOUSE. STRAND, LONDON, WC.2 Telephone: CITY 8710. 177:n

D AUGUST 19, 1922 xviii THE WIRELESS WORLD AND RADIO REVIEW "BRITWIRE " CONDENSERS. OWING to the demand for a good condenser, which at the sametime is cheap, we are now manufacturing a BalancedCondenser for panel mounting, replacing the imported condensers hitherto sold.The plates are die-cast into the supporting columns, and are counterbalanced so that they will remain in any position whenmounted on an upright panel. At present only two capacities are being manufactured,viz. :'0005 and '00 I, but other capacity condensers will be made in due course.Orders booked and executed in strict rotation. PRICE WITH EBONITE REVOLVING SCALE : '0005 ... 17/6 '001 25/-

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WE.specialize in the manufacture of batteries forfilament current supply to Valves and high-tensionbatteriesfor application of Anode Potential. We can supply these batteries in glass, ebonite or celluloid containers to any desired voltage. Exide batteries can be relied upon for wireless work and retain their charge over very longperiods. Prices and Particulars on Jpplication.

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Head OliCce London Showrooms : Clifton Junction,910/210 Shaftesbury Av. Nr. Manchester. W.C.2 6 Volt 80 Amp. Hour Exide Battery. AuausT 19, 1922 THE WIRELESS WORLDAND RADIO REVIEW 675 shown across the aerial and earth terminalsis for sions and arrangement.It is quite easy to wind the purpose of flattening the tuning. a number of coils of increasing dimensions, and by " W.E.P." (Sussex) asks (1) For instructionsa very simple experiment you will soon discover as tothe best method of constructinga balanced the wavelengths to which they will tune the aerial. capacity for use in conjunction with his telephonyThen working on, you might make many coils, transmitter, and (2) Whether there would beany equal in size to the largest, and by connecting them appreciable loss in running the aerial of the earthup in series you can keep on building up until the connections of transmitter and receiver toa double maximum wavelength range is attained.(2) 30 pole change -over switch, together with the aerialandmoving and 31 fixed plates, spacing washer 5/64", earth leads. plates 20 S.W.G., radius of moving plates 14". (1) As you are no doubt restrictedas to space, It would have been better had you stated the it may be very difficult for you to arrangean efficient dimensions of the plates and washers you can capacity.It should consist of a number of insu- obtain, and then we could have told you the number lated wires placed near the ground and runningyou would need.(See article on Condenser Con- beneath the aerial.For good work you may findstruction in issue of August 5th.)(3) Enamelled that you need at least six or eight such wires,atwire is better, because the enamelling protects the least as long as the aerial wires, and spacedas wide surface and prevents it being broken up by corrosion. apart as possible, say a minimum of 8 feet.As your Bare wire can, however, be used, and will give quite setisinstalled on the second floor, you mightgood results. (4) A map of the wireless stations possibly arrange a row of insulators along a distantof the world was formerly published in the " Year- wall, and run out a number of wires, fanlike. With Book of Wireless Telegraphy and Telephony," but this lower capacity and big dimensionsyou will owing to the difficulty of including all the stations find that by its use you will need to adda fewon one map, it has been subdivided into a number more turns of inductance in the aerial circuit ofof smaller maps, drawn on various scales.The the transmitter, in order to workon your presentlist of regular transmissions published from time wavelength.(2) With a valve transmitter thereto time by this journal is supplied with the issue is no objection to you arranginga china -based of August 5th. switch for the purpose of switchingover from " C.L.H." (N.W.2) asks for windings for an transmitter to receiver.There is one variety inaperiodic resistance, H.F. transformer with optimum which the arms of the switch are well spaced, whichwavelength of 900 metres.He intends to incorporate is quite suitable.Alternatively you might removethe transformer with a seven -valve H.F. amplifier. the arms and contacts from the usual pattern As you will need to make several transformers, switch and remount them on an ebonite base,it is essential that a design must be adopted which fitting a new ebonite bridging piece between thewill ensure that all are of precisely the same dimen- two levers, as in many switches at present on market, this is made of black fibre of uncertainit will fluter out signals on wavelengths on which insulating properties. the others function most efficiently, consequently " F.J.L.' (Plumstead) is constructing a two- primaries and secondaries should consist only of wire aerial with mid point lead-in, and is unable to a single layer, and be wound with No. 44 S.B.C. bring down the leading -in wires directly from the " Eureka 'wire.Both primary and secondary middle of the aerial, owing to the projecting edge ofshould consist of 650 turns on a 2" former, separated the roof, which is likely to foul one of the leads, and from each other by a single layer of empire cloth. asks whether equally good results will be obtained if The direction of wire is important, and if both one wire is brought across almost directly to the other, values are made in the same direction, the finishing and thence down to the instruments. 'ends should be taken to grid and plate. A point to be considered is that an equal length " H.C." (Manchester) asks(1) Why he is of wire must be in each limb of the aerialup to the unable to receive telephony on his single valve receiver, point of joining, and as you are unable toarrange whilst he is able to receive Morse quite strongly from this, we would suggest that you join the two aerialFL.(2) Number of plates required for constructing wires straight across in the middle, andrun you an aerial tuning condenser, the moving plates being leading wire from the mid point of this connecting24" in diameter.(3) The cause of the loud shriek wire.If there is still any tendency to foul theobtained in the telephones while tuning. (4) Details edge of the roof, the lead-in wire may be tied backfor the construction of a H.F. transformer for use a little out of the perpendicular.What you muston 200-2,500 metres, making use of the No. 29 and avoid is joining together two leading wires of unequal 36 wire he has in his possession. length, or the aerial will prove inefficient, particularly (1) We notice that you connect your aerial for short wave reception. tuning condenser in parallel across the aerial tuning " V.E.C." (Walsall) asks (1) For dimensionsinductance.With the type of condenser you are of coils for wavelengths between 500 and 14,000 metres using, this takes the minimum range of your set for use in conjunction with an aerial tuning condenser well above that on which telephony is usually of 0.0016 mfds.(2) How many condenser plates are transmitted.Particulars as to dimensions of aerial required to give 0.0015 mfds. and also 0.004 mfds.would have been helpfulingiving you exact (3) Whether bare copper wire is more efficient than instructions, but in any case, your present aerial enamelled for aerial construction, and (4) Where hetuning inductance istoo large for short wave can obtain a map of the world showing the locationreception.You should construct two special coils of the wireless stations, also stating the times offor short wave work, of about 34" and 4"lin diameter, transmission and wavelengths. one turning or sliding inside the other, and having (1) It is not possible to advise you exactly as to4" of the winding of No. 24 D.C.C. ;or alternatively the number of turns required to tune your aerialyou might construct coils to the instructions given to given wavelengths without knowing its dimen- on page 328 of June 10th issue.It is very helpful D2 Auousr 19, 1922 676 THE WIRELESS WORLD AND RADIO REVIEW with short wave work to tune the reaction coil byminus, and if this is done, the variable condenser bridging it with a variable condenser, and the oneshould be connected in series with aerial circuit, that is at present connected in your long wave setand another connected across the secondary winding. should be suitable for the purpose. (2) YouAlthough you complain that the results you obtain neither state the thickness of your new condenserare not entirely satisfactory, we do notthink it plates nor of the spacing washers, consequentlyeasy with your equipment to obtainsignals from we cannot advise you as to the number of platesPCGG sufficiently strong for the operation of a required, but if the plates happen to be of 20 S.W.G. loud speaker. and the spacing washers 3/32 of an inch, you will require about 24 movable and 25 fixed to give a capacity of 0.001 mfds.You may findit an advantage to build such a deep condenser, and SHARE MARKET REPORT. one having similar capacity may be found quite suitable if your aerial dimensions are fairly great, Prices as we go to press on August 11th are :- and a smaller condenser, moreover, will permit of finer tuning.(See article on Condenser Con- Marconi Ordinary .. ..£2 6 7i struction in issue of August 5th.)(3) This is due Preference .. 2 3 6 to the use of too tight a coupling between aerial and 8 9 reaction circuits, and the tuning condenser across Inter. Marine.. 1 1010i the reaction coil should permit of critical adjustment PP Canadian .. to the point where the noise just ceases.A modification of grid condenser and leak may make the Radio Corporation of America :- reaction adjustment less critical.(4) 200 to 2,500 19 3 metres cannot be obtained by the use of one trans- Ordinary .. former.Using your No. 36 wire, you might Preference .. 13 9 construct a transformer having 280 turns each for primary and secondary, of mean diameter of 11", the two windings being separated by a wrapping of insulating material.The one that is connectedMarconi Annual Report. in the plate circuit should be bridged with a small At the Annual General Meeting of Marconi's variable condenser.The direction of winding is important, and if your transformer is wound in aWirelessTelegraphCompany,Ltd.,heldon groove, the two windings should be in oppositeAugust 15th, the report of the directors and state- directions, and the end of the primary and thement of accounts were rendered for the year beginning of the secondary-that is, the two leadsended December 31st, 1921. that pass out between the windings-should be It was pointed out that owing to the many taken to grid and plate. matters which still remain unsettled, the accounts " J.E.L." (Letchworth) asks for a diagram ofonce more do not reflect the true strengthof the Company's position. athree -valvecircuitcomprising one H.F.,one The Credit Balance of Profit and Loss Account detector, and one L.F., suitable for the reception offor the year amounted to £275,361 7s. Bd., which, telephony, and in particular PCGG, 2 MT, 2 LO,added to the balance brought forward from the and Croydon, and sufficiently strong for operatinglast account, leaves to the credit of Profit and Loss a small pattern Brown loud speaker.A circuitAccount a sum of £1,093,928 9s. Ild., subject to diagram is submitted, and it is stated that it is very From difficult to obtain strong signals with a loud speaker. Corporation Profits Tax and Income Tax. Your circuit would appear to be in every way this have to be deducted the following dividends satisfactory, except that perhaps you might getOn Preference Shares, 7 per cent. paid on January better results by connecting the aerial tuning31st, 1922, £17,500;on the Ordinary Shares an condenser in series with the inductance, whichinterim dividend of 5 per cent. paid on January will permit of the use of more turns in the A.T.I , 31st,1922,£131,5553s.7d.,together making and consequently a bigger potential will be bridged£149,055 3s. 7d., leaving available for distribution a balance of £944,873 6s. 4d. off.You did not describe the construction of the The directors recommended payment of further H.F. transformer, and it may be in this instrumentdividends for the year ended December 31st, that inefficiency arises.The two windings should 1921 :-On the Ordinary Shares,10 per cent. not be put on simultaneously, but should be separate (making 15 per cent. for the year), £265,543 Os. 10d.; and insulated from one another, and with this on the Preference Shares, 5 per cent.(making 12 form of construction it is an advantage to bridgeper cent. for the year), £12,500,together making the primary winding with a small value variable £278,043 Os. 10d., leaving a balance to carry forward condenser.The direction of winding is important, and if both primary and secondary are wound in to next account of £666,830 5s. 6d. the same direction, the finishing ends should be taken to grid and plate, and the beginning endsW. T. Henley's Dividend. to H.T. plus and L.T. minus of the potentiometer. The directors of Messrs. W. T. Henley's Telegraph The detector valve should be of such a type asWorks Company, Ltd., Blomfield Street, London will give efficient rectification, and one of theWall, E.C.2, have declared a dividend on the slightly soft variety, or a " Q " controlled withPreference Shares at the rate of 4-1 per cent. per a potentiometer may considerably improve yourannum, less Income Tax, for the half -yearended results.It is an advantage to loosely couple theJune 30th last.Also an interim dividend on the aerial inductance with a secondary inductance,Ordinary Shares of ls. per share, less Income Tax, which is taken to the first valve grid and L.T.both to be paid on September 1st next. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW XIX

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Glasgow Depot : 15, Woodside Terrace. Newcastle Depot :17. Sandhi& XX THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 THE ONLY WAY TO PREVENT SURFACE LEAKAGEatop IS TO FIT COWL INSULATORS 100% EFFICIENCY GUARANTEED The "Crystor Cowl" Insulators are unique-made of the best quality Ebonite, they are absolutely essential to every aerial.Fit them NOW, and immediately you willincreasetheefficiency of your receiver. CRYSTOR COMPLETE AERIAL OUTFITS Single Wire Aerial Two - WireAerial Containing 2 Crystor Cowl Aerial Containing 4 Crystor Cowl Aerial Insulators, I Crystor Cowl Lead-in Insulators, I Crystor Cowl Lead-in (vertical or horizontal), 100 ft. Best (vertical or horizontal type), 100 ft. Quality strandedcopper Aerial BestQuality stranded copper Wire, 100 ft best Hemp Rope and Aerial Wire, 100 ftbest Hemp

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Horizontal Wall for Window LEAD IN Dia. of Cowl 24". Dia. of Shank 4" Length on the Curve 13". Price10/6post free.

AERIAL INSULATOR Length of B..(ciy 3". Dia. It Length Overall 4" Vertical Root 2/6 each.Set of four 10,- post free. WIRELESS LEAD IN SUPPLIES CO. Dia. of Cowl 24" 64 Mortimer Street, Dia. of Shank 4" LONDON, W.1 Length Overall 11" Price 10/- post free. PhoneMuseum 2672 .At ST19, 1922 E WIRELESS WORLD AND RADIO REVIEW x xi i HELARGEST STOCK B'HAM WIRELESS of 4 B.A. TERMINALS IN ENGLAND. COMPONENTS CO. 2 Booth St., BIRMINGHAM. Actual size 6per dozen, plated, 3,- brass; Condensers.001, ; 0.0005, 10,6 ;0-0003 8 -.Vernier Price, 2 Condensers, 3/6.Perfectly made and for Panel Mounting. 2 B.A. Single, 9d. per dozen, Lilt valve detector panel complete with filament resistance Ebonite Dials with Scale, 2 - each. valve holder, and grid leak and condenser, fitted with Filament Resistances, 2 6 -the best made and finest article on insulated terminals, mounted on solid ebonite base the market for Panel Mounting. in mahogany instrument case PRICE 25/ - Grid Leak and Condenser, 2,-.A special design and superior Leading -in Tube, ebonite, R.A.F. pattern with brass rod

to any other make. and fittings. PRICE 3/6 WESTERN ELECTRIC HEAD 'PHONES. -4,000ohms, Aerial Real Insulators, tested to 25000 volts PRICE 4 26J- per pair.The finest 'phone on the market.Orders Accumulator Charging Resistances PRICE25/ now taken in advance. Delivery in four to six weeks. Universal Tuners.These tuners have been designed to WESTERN ELECTRIC LOUD SPEAKERS. --4,000ohms, tune in Marconi concerts, broadcasting, and Dutch Concerts, so that a baby can use them.Wavelength £2 5s.Switch Arms, 2,- each. range, 300-1,500 metres, with -0005 m.f. condenser, Aerial Wire, 7 22, 4'- per 100'. PRICE 7/- Engraved Condenser Scales, 9d. each. 4,000 ohm phones, new patent 3 -magnet type, fitted Condenser scales, 9d. per doz. cords and tags, complete with nickel plated head bands PRICE 35/ - Sleeving all colours, 4d. per yard. pattern,fittedplatinum Insulators, lld, each. Transmitting Keys,G.P.O. contacts...... PRICE 5/- Valve Legs, lid. each. Valve Holders, fitted in solid ebonite, fixing case drilled Terminals, 4 B.A.. 21d- each. fitted with valve earthing clip .. PRICE 2/6 Grid Leaks and Condensers, mounted on solid ebonite Square rods, screwed both ends for condensers, 5" 2ld. each PRICE 5/ - 31" 2d. eat, 21" 11d. each. Instrument Cases, solid mahogany, 9' x 6' a 21", highly Round Rods screwed both ends, 31" 2d., 21' lid. each. finished, fitted ebonite panel, undrilled PRICE 8' Washers, 3d. per doz. small, 4d. per doz. large. yes age extra on all the above prices. Com date Single Valve Receiving Set with Icons, less valve, The trade supplied. Enquiries sot 'Phones, Batter/ aid Aerial. £6 5s. 614,OLD `FORD RD. Two -Valve Set, £7 10s. J. LIPOWSKY, Bo Carriage extra. Catiwiti!order. LONDON, E.3 'Phone : East 3345 SENSATIONAL REDUCTIONS. MITCHELL -PHONE SLAB INDUCTANCES, :,et of 8, 9/- 00JAH make 10/-, post 9d. HEADGEAR. 3 -plate VERNIER CONDENSERS, 6/-, post 9d L.F. TRANSFORMERS, 19/6, post 6d. PHONE olk TRANSFORMERS 13/6, post 6d FILAMENT RESISTANCES for panel mounting, Overm000pair dis- 319,post 3d. tributed to the trade The POPULAtt H.T. BATTERY 36v 4/9 post 1/ - inthreemonths, CATALOGUE FREE WITH , nDEet. is sufficient guarantee to quality.Al- RADIO. ELECTRICAL & MECHANICAL SUPPLIES. though not quite as illustration (a new SCIENTIFIC SUPPLY STORES mechanical im- 8. NEWINGTON CAUSEWAY, provement being Pit Mr fitted) they are NIP -in LONDON, SE I. ..X comfortable, highly efficient,and sold a money back WE ARE THE ONLY FIRM WHO SUPPLYINSULATING TUBING COMPLETE 35/- Pair. baonsis. WITH TINNED COPPER WIRE AT 6d. PER YARD. IMMEDIATE DELIVERY FROM STOCK, and the trade should grasp the opportunity with- SET OF 7 BASKET COILS (UP TO 4.,000 METRES), 8/-. INDUCTANCE SWITCHES -5 STUD 7/8, 19 STUD 12/6. out delay.GOOD DISCOUNTS, and the H.F. TRANSFORMER BOBBINS-UNWOUND-2/8. qualityissuch that you willobtain many VALVE LEGS-TURNED AND LACQUERED, 104. PER ' '41 -REPEAT ORDERS. SET. L.F. INTERVALVE TRANSFORMER. 19'6 SHIPPING ORDERS ASPECIALITY. 5 -OHM FILAMENT RESISTANCE, 4 6. SPECIAL.-AGATE CYLINDERS FOR JONSEN RABECK M ITCHELL'S WIRELESS Ltd LOUD SPEAKER., 22/6. Mail Order Office - McDermott Road, Peckham, S.E.15. 126. FORESTROAD, Retail Store,188,Rye Lane, Peckham, S.E.15. EVLINSDALSTON , LONDON,E.8 'Phones: NEW CROSS 1540/x. Price List Post Free. TRADE SUPPLIED. xxii THE WIRELESS WORLD AND RADIO REVIEW AuGusT 19, 1922 THE WIRELESS WORLD EXCHANGE AND MART

TARIFF. Advertisements are accepted for FOR SALE. this Section at the rate of twopence per word, STAR DELTA WIRELESS with a minimum charge of two shillings.The All Wireless and Electrical Goods stocked at SUPPLY COMPANY advertiser's name and address will be charged9,ColonialAvenue,Minories,nearAldgate for, and single letters and single figures will beStation.Handiest place for City buyers-LEstas INSTRUMENTS TESTED FREE. counted as words. Compound words willbeDIXON & Co.Telephone No. Avenue 4166. counted as two words. The House ForAllWirelessAccessories Two 24 B.P. Motor Generators, one 4o' Mast DirectionFinders,DraftingInstruments,etc. Have You Called 1 It Not, Why Not ? ex Admiralty surplus. Half prices. -THE LONDON -WIRELESS AT HOME KLEC RIC FIRM, Croydon. 388a, Oxford Road, MANCHESTER. B.A. Screws, Nuts and Washers, assorted gross Make your own wireless set.We supply all at.,lists2d. -J. H. BENNETT, Station Road, parts.Send two stamps for completklists.of Willesden Junction. For Sale. -Ebonite -r, 3/16", jand r, any I Buy Wireless Gear instruments, parts, sundries, etc. size cut, *" 3s. 6 . per square foot, other sizes in proportion. Carriage paid on los. lots.Scrap of every description. Electrical Supply Stores Ebonite Sheet suitable for condensers, insulators Send your particulars to : 5,Albert Terrace, KingCross, etc.,3s.perlb.,postage8d. New Hart Accumulators in 2 -volt units -2v. 40 amp. (I) WILKINSON, HALIFAX. 145.6d. ; (2)28s. ;2V. 6o amp. (a)r7s., (2)33s.; 2 V. 8o amp. r) 205., (2)38S. Lonsdale Rd., Kilburn, N.W.6 Carriage forward.Aerials -Rubber covered on wind-up reels, with 2 R.A.F. ebonite insulators, SAME ADDRESS SINCE 1900. as. 6d. each, postage 9d.Valveholders-Best VELO quality, as. cheaper quality, as. 6d., screwed legs." Ora 'valves-x5s. each.Postage 3c1.- PURCHASE YOUR WIRELESS EVERY SET TESTED RENSHAW & MARSDEN, Penny Street, Blackburn. REQUIREMENTS THROUGH Aerial Wire. -Our Speciality 7/22 Hard Drawn The name carries a guarantee of the highest StrandedCopper,guaranteed,loo'55.3d.; The Viper Re -Covering Co., Ltd. quality material and workmanship.If you I40',7s.;WO yards,13s. Carriage paid.- purchase a set thus guaranteed you obtain BAIREROTHER & Co., Vulcan Street, Leeds. 7/8, POULTRY, E.0.2. the best value for your money and you are New Wireless List Ready, post free.Write (z minute from Bank) Tele. : City 1897 assuredofobtainingendlesspleasurefor now.-Tuompsos, 5, Westborough, Scarborough yourself and friends. Wireless Masts. -Improved Girder Type. Light Narconishones, Sterling and R.F.H. Sets, etc., VELD.--Single-ValveSetincludingPanel, and strong. 30 to 5o ft. at is. ft. 5o to zoo ft. can be supplied. Place your orders NOW. Tuner (200-1,200 metres), Valve,Phones, at xs. 6d. ft.Cash with order, carriage forward. Accumulator4 -volt,40amp.,68volt. F. ARMSTRONG, Weybridge. Battery, 100' 722 Aerial Wire, Insulators Wireless Instrument Cases, Walnut or Mahogany, andPulleys,Receiving Range -Telephony finest finish, if by 7k," by 4" (outside), 8s.6d. HEATH & Co., Ltd. up to 100 miles.. 211 Ils. Second quality, 7s. 6d.Any size proportion- Instrument Works, New Eltham, S.E.9 VELD. -Double Valve Set(1detector and ately, prompt delivery. Trade inquiries invited.- 1 L.F.) including all accessories.Receiving HITCHCOCK, Colchester. are prepared to undertake in their fully range -Telephony up to 200 miles.£14 14s. Two -Valve Amplifier. -One High Frequency, equipped works -Wireless Apparatus VELD. -Triple Valve Set (1 detector and 2 one Rect.comprising ebonite panel mounted L.F.) including all accessories.Receiving mahogany, 45s.r,000 metre transformer,6s. and Parts for the trade. Quotations given range -Telephony up to 300 miles.£17 17s. Slab coils,9s.set. -E. G., 8r, Church Street, toBluePrints.Immediate attention. VELD. -Crystal Sets.Wavelengths 200-3,000 Stoke Newington, London. metres,including'phones,potentiometer Mark IT Star Receiving Instrument-Quitc Phne-Lee Green301. London.. and aerial 25 15s. new. Never been used.Best offer. -CARTER, Immediate deliveries of all the above and of Gleneagle Mansions, Streatham, London. CONNOLL.V, any parts required for experimental sets. For Sale, -Marconi wavemeter, complete, £5. Intervalve transformers (L.F.) of high finish. Also Weston relay, £2 or nearest offer. -Box WIRELESS APPARATUS MANUFACTURERS, Cased, 26/-.Uncased 21/-. D.3, BERTRAM DAY'S ADVERTISINGOFFICES, LOSTOCK RD., URMSTON, MANCHESTER. Spare Telephones -fine British make, 2,000 9 and ro, Charing Cross, S.W.x. Spares & Complete Components at Trade Prices. ohms, 30,'-. VariableCondenser,ooormid.,23s.6d. ; Examples :5o x 6' Double Wire Aerial, 4o' Sent per return on receipt of your order and copper aerials, 45. 6d. roo' ;reel insulators, 3d. ; Lead in, ready for fixing, 17/6.7/22 Stranded remittance. terminals Is. 9d. dozen _ 4,000 ohm headphones, Wire, 4d per foot.2- Reel Insulators, so. 3os. ;24 S.W.G. enamelled copper, as.6d. lb. each.4" x Wound Inductance Coll, 4/9. From H. C. DALY, Pricelist.--CONWYKIRKHAM, 2,Whitworth 28's Enamelled Wire, Vb., 2/-, 11b., 3/8. Terrace, Rusholme, Manchester. CARRIAGE PAID ON ORDERS OVER U. 22 Walbrook, London, E.C.4 Cabinet Valve Receiver. MI accessories, new, or Authorised Agents.Enquiries welcomed k9.-RAHA, 21, Cromwell Road, London. from the trade. " Eyrelection "WirelessBattery, 15 Volt, THE UNIQUE N.M.C.(WirelessPatents) 3s. 3d. carriage forward.6o -Volt, an. carriage Two -valve Receiving Unit, combining forward.Wide range of voltage tappings on each Filament Resistance,Aerial, Tuning In- SITUATIONS VACANT. size.-EYRE CO., South Yardley, Birmingham. ductance, Aerial Tuning Condenser, Grid Accumulator C.A.V.-4 Volts aoo Amp. Charged, Tuning Inductance and Oscillating Condenser, Wireless. -Agents wanted all over the countrymetal case, nearly new, 12.-MILLARD, 7, Barton complete in polished case, 12' x x 6", to sell London manufacturers British made ap-Street, W.14. 28 8s. less Valves. paratus to private persons during the coming boom. Fifteen Glass Jars, 51" by 41`", inside and xor The Set to obtain maximum efficiency. Broadcasting is developing daily and big salesdeep.Complete with wooden trays, 20S.Three N.M.C. 4,000 W.. Double Head Gear, 35/ - can be made.Gentlemen of education of strictestMarconi Leyden Jars, believed to be one quart. Inductance Tubes. integrity with some electrical knowledge who canAll in good condition, 5s.One 4 -in. spark coil All Experimenters' Supplies in Stock. give sound references and either deposit Fidelitywith platinum contacts polished mahogany base, N. M. CO., 145, Northcote Road, Guarantee Bond or £23 purely as security (re-as new, £3ix's.One transmitting aluminium Trade Supplied. London, S.W.11. turnable).No cheap or foreign apparatus.NoHelix polished mahogany woodwork, as new, salary or expenses.Ten per cent. commission.7s. 6d.-HErwoarx, Moorings, Dovercourt. Commercialtravellerscalling ondealersnot 4 -Valve Receiving Set, complete except batteries, wanted. -Box E.3, BERTRAM DAY'S ADVERTISING300-3,000 metres,x5. -W. A.. SMITH,15,St. Make OFFICES, 9 and xo, Charing Cross, S.W.i. Julians Road, Kilburn. WirelessDoubleHeadphones. -2,000 our own 27s. 6d. complete.Money returned if not satisfied. arch*ohm, SITUATIONS WANTED. -DIRECT WIRELESS SUPPLY, 491 Heaton Road, Arms what Peckham, London, S.E. Experienced Wireless Man, with capital, desires Variable Mica Condensers, New, accurate adjust-veu save.C/CRAW T engagement with progressivefirm.Fullpar-ments, 00005,9s. ;crow,12s.6d.Money P/7 Pfi ticulars on application to-R4rno, 6, The Drive,returnedifdissatisfied.-THomas,Redbourn, Roundhay, Leeds. St. Albans. AUGUST 19, 1922 THE WIRELESS WOR-4) AND RADIO REVIEW xx THE WIRELESS WORLD EXCHANGEAND MART

FOR SALE -continued Strawboard Inductance Tubes 2" to 6" dia., for Crystal Sets, etc. Complete Tingey Receiving Set, consisting of C.i, Rx, A3, telephone transformer, two A Coils, EBONITE!!! Attractive Prices - Quick Delivery 6o volt H.T., perfect condition, brand new, owner I SHEET Enquiries attended to promptly. building larger set.What offers /-ALLENDIEE, " Ravensbury," Caterham Valley, Surrey. 1" 4/-; 6/6;I"10/- Sq. foot A. EATON LEE & CO., BEST PHOSPHOR BRONZE 4. Little College Street, LONDON, E.C.4 Tuner Mark III', New. What offers 1 -Box G.2, BERTRAM DAY'SADVERTISING ;OFFICES,1 AERIAL WIRE Central 471L (Nr. Cannon St. Station.) 9 and zo, Charing Cross, S.W.I. 7 Strand Enamelled 100' 7/6, 150' 10/ - Amateur Selling quantity Wireless Receiving II IN & apparatus, send for list.Bargains. -Box B.P., Porcelain BERTRAM DAY'S ADVERTISING OFFICES, 9 and zo, Reel Insulators EBONITE "Charing Cross, S.W.r. 2" Diem.4d.Each. RELIABLE GRADES ONLY Cylindrical Coil Winding Machine, winds up All Postage Extra. (See last week's Advt.) to 6' diameter by 18' long, :7s., carriage paid. ALL DELIVERY PER RETURN.

Large stocks drills and taps.-R.E.P. ENGINEER- SHEET,ROD, TUBE, ING, Robert Street, Sheffield. Everything for the Experimenter.

PANELS, MOULDINGS WIRELESS AND Small Parts Supplied from Stock.-Concienser HOUGHTON'S Enquirielattended topromptly. plates,crystaldetectors,terminals,spacers,' ELECTRICAL SUPPLIES washers, nuts, contact studs and stops, valve HIGH STREET. BLACKWOOD. MON. legs. List free.-FRASER. Sentinel House, South- RADIO EBONITE SUPPLIES, mampton Row, London. 4 Little College SL, London, E.C.4 Wireless Items toNote. -Aerial Wire,7/22

Central 4712. (Nr. Cannon St. Station.) enamelled, zoo' 5s. 6d. woo' variable condensers R E SUITS Ivorine scale, pointed.Panel or cabinet, each Whether as a source of practical imformation 0111 II M M16s. 6d.o.0005 Fittings, as above, I2S. 6d. each. for the Amateur or as a valuable medium for Crystal cups, lacquered, washer and nut 5d. each, every Advertiser, thebest results are 4s. dozen. Ebonite, all sizes, to 4s. 9d.lnsulite invalibraobly obtughained[[ slides, contact and spring, each 7d. Inductance Wireless World " Enamelled Wires tuning switch, best finish, 5 studs each, 45. 3d. For toll particulars and adver 'sing rates apply to 7 studs 45. 9d.Terminals, large, best, nut and BERTRAM DAY & CO., LTD. for washer, 25. 3d. doz.Valve sockets, set of 4 Complete Advertising Service, rod.Contactstuds,best,nut andwasher, 9 and 10 CHARING CROSS. S W.1 Wireless. is. 9d. doz.No 24'S enamelled wire, 2s.d., to vulcanite any size,3s.9d. lb.Stamp for list Carriage paid over £2.-WRIGHT BROS., Electrical 4042 44 46 47 S.W.G. Engineers, 38A, Cross Street, Sale, Manchester. WE CAN SUPPLY FROM TOOK 6/68/-12/6 19/6 30/- CONDENSER VANES. TERMINALS. AERIALS H.D. Copper. WANTED TO PURCHASE. CONTACT STUDS. 7/22 7/20 SPACERS SPINDLES. PLAIN 100 ft. Coils. Wanted to Purchase. -Mark 3* ShortWave VARIABLE CONDENSERS. 4/-5/- Tuner. State condition and price. -Box ENAMD.5/-6/6 BERTRAM DAY'S ADVERTISING OFFICES, 9 and zo, DETECTORS. Silk and Cotton Covered Charing Cross, S.W.I. POINTERS. Priceson Application. LAMINATIONS, ETC. WRITE FOR LIST. Terms :-CASH WITH ORDER MISCELLANEOUS. Also Spinnings, Stampings and PressiTools POSTAGE EXTRA. made to specifications. Expert Advice for the Amateur. -Designs and diagrams, information on allwireless matters. THE GLENFIELD ENGINEERING HORROCKS ASPIN, Advice on faults and difficulties. Prospectus post free. -G. P. KENDALL, B.Sc., Wireless Consultant, CO., LTD. 12, SCHWABE STREET. Moortown, Leeds. 225, Pentonville Rd., London, N.1 RHODES, MANCHESTER. East Ham, Wanstead, Ilford, Manor Park and Telephone :Holborn 9714. Forest Gate. Amateurs should not fail to come to the RADIORENDEZVOUS.709, Manor Park Northern Wireless Buyers get Broadway (over Lipton).Club open till so p.m. yourrequirements from The Grand nightly. Climax Bargains. 4,00o ohm coupled head'phones,tested Electric Wireless Supplies Depot, Ocean perfect, 225. 6d., half price. Three -valve panel, Road, South Shields. The Wireless Sup- TRADE ENQUIRIES. 43.Valves, xos. 6d. o/ooz Condensers 21S. plies Depot, 2, Market Place, Morpeth. Setvalvediagrams,Is.6d.4v. 24 ah. Aerials Fixed under supervision of a certified Acc/re Its. 6d_, and others, twinbell wire 6s. Large stocks for amateurs making own electrical engineer.Masts, spreaders, wire, etc., Too yards.8v. 2 amps. dynamos, 17s. 6d. sets.Burndept 3 -valve, Burndept Ultra supplied if necessary. -SMITH & GALEY, Builders Cash with order.Postage extra. IV, Tingey 5 -valve sets, on view.Free and Decorators, Lismore Road, N.W.5.'Phone, Hampstead, 5858. CLIMAX ENGINEERING CO. demonstrations. Pay us a visit or send 182 Church Street, Kensington. 2023 Park' Quotations, with particulars required forall your enquiries. parts of apparatus appertainingto Wireless. - The Proprietor of the Patent No. 24231, of 1214,BREWER & BRUNT, Radio Dept., Albert Road, for improved receiving system for continuousHoylake. Your Case Work electric waves. is desirous of entering into arrange- Wireless for All. -Weekly payments or cash. Let us quote you for your wireless ments by way of licence and otherwise on reason-Best make. Cheapest terms. -Stamp, BUSH, casework We are specialists in this able terms for the purpose of exploiting the same119, Sutherland Avenue, London, W.9. class of work and feel sure our work- and ensuring its full development and practical manship and prices will interest you. working inthis country.All communications Muter Cabinet Maker and Electrical and Surgical should be addressed in the first instance to-Instrument Specialist. Finestworkmanship Phone: L.W.2720. HASELTINE, LAKE & Co.,CharteredPatentguaranteed. Strictly lowest terms. Let me quote CARRINGTON &NEWBERY LTD., Agents,28, Southampton Buildings, Chanceryyou. -S. L. GEDGE, 6, Torriano Mews, Torriano 18/21, Norman Bulliags, Old Street, E.0 Lane, London, W.C.2. Avenue, Kentish Town, N.W.5. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 AGENTS 10,000 IMMEDIATE DELIVERY The " Radiophone No. 2 Crystal Receiver" Set The Radiophone No. z Crystal ReceiverSet comprises an Air Dielectric Variable Condenser, *00025 mfds.Variometer type of Inductance wound with double silk covered wire, on Ebonite former.Blocking Condenser o03 mfd. and terminals for Aerial, Earth and Telephones, together with two extra terminals for attaching a valve amplifier if desired. The detector is composed of brass cup containing a selected and tested specimen of " Radiocite."The upper contact works in a stiff ball socket through which a short brass stem with an ebonite handle and a fine contact wire is attached. These parts are mounted on solid ebonite panel the whole enclosed in a highly polished mahogany carrying case. Price as above specification £4 10 With a set of Dictograph Phones £6 0 Super -Antenna Saves Cost of Outside Aerial and Installation Think of the considerable savings effected by eliminating outside aerial and expense of installing same.Yet broadcasting can be received with the greatest accuracy by simply attaching Super -Antenna plug to any electric light socket.Stations 1,200 miles distant can readily be copied, other units being equal. RADIOPHONE No. 2 (Registered Design) Why Use Outside Aerials ? There is always danger of aerial coming in contact with live wire when strung over or near power or lighting wires.Then, too, it is necessary to guard against mishap from lightning and some buildings prohibit overhead aerials, because of Insurance restrictions.The Super -Antenna unit overcomes all such difficulties. Safe-Simple-Efficient. The Super-Anienna is shock proof, will not blow fuses,or damage any receiving set.Has an Price auxiliary condenser of *0005 mfds. which assures bestradioresults.Bestforreceivingwired wireless which, in the near future, will be in use in practically all cities. Mechanically Perfect. 3 5- The Super -Antenna unit tends to reduce static effects because itisscientifically correct both electrically and mechanically.Through a filtering circuit which may be varied by eight separate connections (see below)the power currentis cut off from receiving unit and the high frequency radio currents are permitted to pass through to receiving unit. Endorsed By All Leading Electrical Institutions WIRELESS EXPLOITATION CORPORATION BECK HOLNE, 91, Shaftesbury Avenue, London, W.1. Telephones :GERRARD 1185 Telegrams :" OSOFILMY," WESTCENT, LONDON. 1156 Cables : " OSOFILMY,' LONDON. AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW X X V

htkk, GENUINE & ORIGINAL 720A .44 0.0 PETOP -UNITS H ELLESEN DRY Copied but Never Equalled B ATTERIES TYPES PETO THEMAN OF PARTS KNOWN THE WORLD OVERAS THE BEST still offers his originalproductions. UNIT No. 3.

St.;? I' - .7."-V---"%olfr-

III H.F. tih fec .4, 'cis 4, , , , ..t. AMPLIFYING PET.} SCOT' UNIT. ,t, t.0 it) Set of Patti13/6 1 I', ,eii Cabinet to fit3/6 IL 10' CODEWORD : CODEWORD : IiiI ,., ''' ;60 " WIRIT " Size 61 x 2i X ;. " WIRIT '' 36 volts. i SPECIAL TRADE & WHOLESALE TERMS. CODEWORD VOLTS DETAILS PRICE 'I . "" WIRON " z5 Sc ew terminals 4,- " WIRTO " z5 Strip 4i- UNIT No. 4. ' WIRIT" 36 2 wander plugs 8 8 Co 14, - " WIRIN " - - -._.- ALL LISTS FREE ON APPLICATION. - -4.'ii-----iii A. H. HUNT, LTD. V .:)...'., -4- DETECTING H.A.H. Works, Tunstall Rd., Croydon, Surrey I, .., UNIT. li PETONC40.1"T eis, Set of Parts17/6 1111111111111111M 11111111111111111111 Cabinet...3/6 1 I +re- e , NT

1 11 . r0' .1. -- I LI

I UNIT No. 5. INSIST ON HAVING A ti Nei I FULLER 'BLOCK' TYPE re' 4°1,, "4 L.F. 'b ,I4 AMPLIFYING ACCUMULATOR ', PM- 5,OTT UNIT. FOR YOUR WIRELESS SET! N°5

IThe only Accumulator on the market that will hold its I charge from 12 to i8 months when not in use. Set of Parts33/6 S+ ' fe, 4 -volt 40 amp. hours. 1 126, plus 1/3 carriage Cabinet...3/6 6 -volt 40 £2 89, 1/6 S INote :-These prices are 331% below those of the , L T ,: ..v.. /

actual makers. V fir::.--eire 8,000 Sold. 20,000 stillin stook. Descriptive and Instructive Pamphlet on request from- I ForPrices of finished Instruments-see Catalogue. The CITY ACCUMULATOR Co. (Dept. 88) Noconnections to puzzle over, just push asmany 79. MARK LANE, E.C.3 (Tel. No. Avenue qz) unitsas youcan afford, against each other,slip the ALSO SUPPLIED BY- littlerods through and turn a screw, and there your are. Selfridge/ & Co.. Ltd.,Wireless Section;A. W. Get ourIllustrated catalogue post free 6d., with Carnage, Ltd., Wireless Dept.;Barnsley British listof transmitting stations and wavelengths. Co-operative Society, Radio Section:Richford & Co., 153, Fleet Street, E.C.3.The South WalesI Wireless InstallationCo.. Ltd.,IS, West Bute PETO SCOTT, GendeTnsheeeKing Street, Cardiff. 64, HIGH HOLBORN, LONDON,W.C.1. AGENTS WANTED IN ALL PARTS. Also at 27, Frome Road, Wood Green, xx vi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 A 220,000 DEAL IN WHICH EVERY WIRELESS AMATEUR MAY PARTICIPATE WE SPECIALISE "BROWN" "A" TYPE IN RADIO HEADPHONES Guaranteed new and unused. NOT re -conditioned. EBONITE 120 8,000 ohms. ohms EQUIPMENT 42/6 49/6 FOR Maker's Maker's Price Price WIRELESS SETS 58/- 66/-

SHEETS: TUBES : SULLIVAN 8,000 ohms,...3616 PANELS Why pay the full price and wait weeks fordelivery when KNOBS, CONDENSER COVERS we can supply from stock atless thantrade price ? Terms cash with order. Postage 1/- extra. Approval for 7 days WHOLESALE ONLY Trade enquiries for quantities solicited. FROM STOCK FULLER " BLOCK "TYPE AC- CUMULATORS 4 volts, 4 amp., 32,6 the only practicalbatteryfor wireless. HIGHTENSITE LTD. THE CITY ACCUMULATOR CO. 79, MARK LANE, E.C.3. Normandy St., Custom House, E.16 Pn.ne :Avenue 91. Telegrams :' Tyche, Fen, London.' 'Phone :EAST 3153.

WE WANT YOUR /4.4coo.. '-' t'.... 1 ,g: 14 0 0.ti ? n t' 2 -a "t"--' eq 'V x 0CL0 Z . C3 Z .ii.i 8 -4 0 4- el "a" > ,S) ADDRESS ['l sal°

Therefore we offer all Wireless En- I: ;: C ' 92 . . . Z "50. l t0 9 i 4 n "E> .. -TS 1 ° j"1Z thusiasts the 14 bargains as under 'qlir 0 ? 9:: li "B a 424 0 ci) 10 VI .". W .... AerialWire,phosphor Fixed Condensers,all . "- bronze, stranded, per values, Mica and 1.11 1 ti g Z. 0: ._4J Too ft... .. 5/6 Copper 1/6 Cheaperquality, 4tt (1)k E -1 § a L',2.E "IT, i 6 Phones, 4,000Ohms, . - P. I. i a : > 1;1( 1 Isi : 3/2os .. 8/8 Double.. .. 87/6 Flash Lamp Refill 7d. .k.i *A t: r SquareBrassRod, '..."FPT! 16 Volt H.T. Units 8/9 6d. . I Grid Leaks, all values 2/8 per ft. Cl) a-(3.-t: ,nt. E ;,1 x tO iii t, ''it PolishedEboniteValve Contact Studs, r head, ld 0 0 E -c§e .t.f, rrei,n t-. m Sockets.. 1/4 Ebonite,finestquality, a Valve Legs, set of 4, with per lb... 3/11 aira.) 1 8 ITs w ;slit.". -- r

O'l setofIvorine Tablets,absolutely CC1 c)E"6 tI, ' !--' .0 1:, 7-9',Si free ofcost. gio 6.z.z.1,.:,-;;E "ci THE " BRUNSWICK " CRYSTAL SET,SPECIALLY DESIGNED TO REACH LONG DISTANCE STATIONS, a w 0 ° ":-"l "t 76' t i-ur ALSO " BROADCASTING " STATIONS .. 29/6 Pr- ii., 0 42 - "'"' 4 !I X.4

x To Inductance.Enamelled Wire.Two efficient W CDf-' ; =%4 ; 12 ! E a' r "t Sliders. Copper, Mica and Ebonite Condenser. New type Universal Detector.Polished woodwork.Mounted on Z0t ' "5E cm' 't '''. tOC4 4?t f- il 1 ;1., E-',=, polished baseboard.All brass parts lacquered.Ivorine 8,c: i _. E.Li, 9° ,-; 7 , , te c 4, g sr (3a., ,- ..* tablets :-" aerial," " earth " and " phones."Set of parts od ready to assemble, 22/6.Carriage extra. 1.1 itt: .eF... 0 .,,i .2. N Is 4.4 8 0 441 ww co C 15 esi -lt --.1, -",d 2 11 C E r .--44LLI > 0 0 c xi Nt. '-3 ", ° " 1.64 p.co a-- The SCIENTIFIC WIRELESS CO. 0 ,,, Est4)...F 188, BRUNSWICK STREET (X 43Oyu 0 ,--xti1,, 8 tt .. 6 r,i.....; OXFORD ROAD 0 -Ell .27: ? 01 :4:6 -=:2g4 Zs 1..: ;"-L, 0 . a.,,,:, es - Phone MANCHESTER Cent. 6839 en O 1, >t i:,,,L. t .p, fa.. 3 t- U2 Fs u t''`J ( \I AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxvii ACCUMULATORS"CASTAPHONE" (REG. TRADE MARK) Absolutely Guaranteed Best Quality CRYSTAL W/T CELLULOID CASES RECEIVING SET 4volt40 amp. 18/6 4volt80 amp. 28;2

PRICE 4 60 21./6 4 100 30/-

6 40 26 3 6 80 37,3

6 60 31.9 6 100 41/8 65/- PACKING FREE. SPECIAL PRICES TO TRADE British Valves :-"R." 26/6;" R.M.R.," I5/-. forquantifies on application. S. or E Aerial Wire, 7/22, 100 ft., 6/6 ; 150 ft., 9/- SPECIAL OFFER H.T. Batteries :-36 volt. 8/- ; 60, 14/- ; 75, 16/ - 6 volt 40 ACTUAL AMP. SET three glass cells Ball and Socket Detector, 4/9 ; "Egg" Insulators, 5d. sealed tops in well -made TEAK crate, a handsome set @ 49,6. 4 volt 24 amp., celluloidcases, 11/9, postage1/-

2 16 ebonite cases,3/9 each, post free " HERTZITE " AERIAL WIRE, 5/- per 100 ft. Coil. MOUNTED IN PATENT DETECTOR ALL SIZES of ACCUMULATORS QUOTED FOR 5/6 Dynamos, Motors, Electrical Accessories. rosT FREE Write for Lists. F. Yates & Son, Ltd. Wholesale Electricians RUSSELL AND SHAW, 144, Church Street, Kensington, London, W.8 38, Great James St., Bedford Row, W.C.1 (One Inmate from Notting 11111Gate Station.) Phone -Park 4276

LE`-'L IE m HAS LTD. PROVIDENCE PLACE, WEST END LANE, KILBURN, N.W.6

Telephone HAMPSTEAD 1261 Nearest Tube Station, KILBURN PARK I BAKERLOO) FOR EVERY WIRELESS REQUISITE Illustrated Catalogues 6d.Post Free.

SECOND EDITION.

"THE CONSTRUCTION OF WIRELESS RECEIVING APPARATUS" I HAVE IN STOCK BY PAUL D TYERS. 1/8 NET. From all Wireless Dealers or by return Post Free from RADIO PRESS LIMITED, 5000 BROWN'S Publishers of Authoritative Wireless Books, PAIRS (120 ohms) " A " PHONES 34'35 Norfolk Street, LONDON, W.C.2 NEW AND UNISSUED The huge sales of this book are due to the fact that it contains POST PER the information that the amateur wants.It is essentially a 40/ - PAIR book for the EXPERIMENTER.It explains how the various parts of a valve or crystal set can be made without the use of CASH WITH ORDER a lathe or expensive tools.Ittells you how to make such things as grid leaks filament resistances, etc.etc. The first edition only LASTED about ONE WEEK. WILKINSON, Lonsdale Rd., Kilburn, TENTH THOUSAND. TRADE SUPPLIED(Same address since 1900) N.W.6 xxviii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 WE PUBLISH PRIZE WINNERS, Issue 29th July, 1922 Question :" Whywas Sol annoyed " Core Wire.Soft iron, 2/4 per lb. Terminals. A very neat wireless terminal. Ebonite.Best quality.Any size, rod or Polished complete with nut and washer. One of our Single Valve Panels has been sent sheet, 0/.. per lb. 2/6 doz. to : Mr. C. C. Juoson, Tin Foil.Free from lead.Sheets, 2f." x The White Cottage, Filament Resistances.For Panel mount- 13", 4d, each. Carlton Road, Weymouth, ing with knob pointer and good contact.Valve Sockets.With nutand washer. for the following : A speciality.4/- each. Fine finish, set of four, 9d. " Because he (a Jew) was placed next to the HEAD RECEIVERS. Light,sensitive. Valve Holders.Best quality ebonite, with (H)Ammeter." of good design and superior finish. Tested nuts, 1/4 each. Aerial Wire, 7/22's, Enamelled Hard Drawn and guaranteed perfect.Complete with Wood's Metal, 8d, per packet. Copper. 6/- per too'. cords.140 ohm SIN- each., 4,000 ohm CRYSTALS. Carborundum, Copper, Aerial Pulleys, 2r 1/-, 5' with tackle hook 82/. each., 8,000 ohm 38/. each. Postage Pyrites, Galena, Bornite, IronPyrites and bicket, 2/6. 9d. each.Illustrated pamphlet, Sd. each. Silicon, Manganese, 8d. per packet. Aerial Insulators, Shell Type, 21" x 2r, Inductance Tubes.12"long. Specially 116 each. impregnated, airfkl.,3"7d.,34" 8d., SUPERIOR QUALITY WIRE. British AerialInsulators,ReelType,2"diam. 104., 44' 1/-,5" 1/2, 6" 1/6 each, made.All wire wound free.Post extra. white, 44 each. Postage 9d. each. Single Dble. Batteries. For H. F. Make your own. Flash Inductance Slider Rod.4" square in 13" S.W.G. S.C.C. D.C.C. SilkSilkEnld. Lamp Batteries, 6/- doz. lengths. Not jagged but smooth. 6d. each, 12 1/to1/II4/- 5/4 1/8 Buzzers for Morse practice, new improved Insulating Tubing, 64. per yard. x/rx 2/- 4/- 5/4 1/9 line, best quality, 4/6. 16 2/. 2/1 4/2 5/6 Jiro Condenser Diic;,Ebonite, irdiam.,1/- each IvorineScales. o to,8o'. Engraved 8 2/, 2/2 4/4 5/6 x/r CondenserDials,engraved,finefinish, (Not printed), 1/2 each. 20 2/2 2/3 4/8 6/2 2/6 21* diam., J/9 each. Ivorine Tablets.Set of six.9d. 22 2/6 2/1r 5/- 6/8 2/8 Condensers.Fixed.Exceptional quality. Knobs.Ebonite.xr diameter.Superior 24 3/- 3/6 5/6 7/4 2/8 Made with copper foil.From -000t to finish.Knurled 7d. each. 26 3/7 4/1 6/8 8/2 3/2 oot.2'9 each. LOUD SPEAKERS. Exceptionally 28 4/4 4/7 7/2 9/- 3/6 Condenser Vanes. Not rubbish. Best strong efficient.so ohm, 2,000 ohm, 4,000 ohm 3o 3/- 5/6 8/- xo/- 3/2o aluminium. Fixed3k', Moving21". 22 10s. each. 32 6/- 7/3 9/2 13/- 4/2 1/- doz. Mica.Pure Ruby.Pieces, 3' x 3' x 34 7/- 8/3 11/614/- 4/4 Condenser Spacing Washers. Remember oo2" thick, 6d. each. 36 8/8to/2 14/- 15/6 4/8 they must be accurate.Small 4d. doz. Paraffin Wax. per lb. 38 11/3 13/2 16/- 19/- 5/3 large 6d. doz. Resistan'eWires. " Elsi"i,rand22'S 40 15/- 18/- ,8/6 22/6 6/6 Condenser Screwed Rod.Brass 12" lengths, (t ohm per yard), 24's (r.7 ohms per 42 17/3 21/- 31/614/- 9/ - 2 B.A.or4 B.A. 6d.each,2B.A. yard) and 28's enamelled (4 ohms per At per lb. and 4 B.A. nuts 7d. doz., 2 B.A. and yard), 2d. per yard. 4 B.A. washers 24. doz. Switch Arms Exceptionally strong and Carriage extra.Please remit ample postage, Contact Studs. Studs, not rubbish, 1/6 doz. well made, 2/6 each. balance returned.Orders over (z carriage Copper FoilSheets.9" x aS,4d.each. paid.Money back if not satisfied. J.L. CARTWRIGHT & CO., Manufacturing Electrical and Radio Engineers 'Phone-Cent. 42o9. Dept. W.130/132, LONDON ROAD. MANCHESTER. 'Grams-Pladuram, Manchester. Special Terms to theTrade. Works: BERRY STREET No Catalogues yet. (TEC HIGH TENSION DRY BATTERIES for WIRELESS SETS

NORMAL SIZE, No. W 7o V, 15 Volts W 71 V, 5o Volts GIANT SIZE, No. W 73, is Volta Price5/- Price15/- Price 6/6 SUPPLIED IN TWO SIZES FOR15,50or60 VOLTS. andwithTappingsin3VoltSteps. ALL BATTERIES FITTED WITH PLUG SOCKETS AND MOVABLE TERMINALS. Complete Illustrated Price List on Application. THE EFANDEM CO., LTD., FALLINGS PARK WORKS, DRY BATTTERY MANUFACTURERS WOLVERHAMPTON Annus: 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxix For theyare jolly good- -FELLOWS

FellowsHeadTelephones,. 4,000 ohms.

two earpiecesinlightdiecast nonringing metal. Price 30/- per pair.

Deliveries. Immediate against cash with order.

Manufacture. The samehigh grade workmanship as the Fellows. Magneto.

Send your order to -day.(Cheques, P.O., P.O.O. or M.O. to be crossed LondonJointCity Midland Bank, Ltd.)

grade terms for quantities on request.

FELLOWS MAGNETO Co. Ltd. LONDON, N.W.10. telephone: Tekgrons : Willesden 156o-1. Quittnag, Phone, London.

For all Radio Apparatus and Com- ponents.

To ensurethe earliest attention send this page with your order. SNs WORI.1) AM/ RADIO REVIHW AUGUST 19, 1922 North Wales Wireless College & AmateurSupplies COLWYN BAY. 'Phone toy. Most Complete Stock of all Wireless Students prepared under ideal conditions as Instruments and Accessories. Wireless and Cable Operators PROMPT DELIVERIES. POSTAL AND RESIDENTIAL TUITION. SPECIAL POSTAL COURSE FOR AMATEURS. LIST BY RETURN.rid. STAMP. PROSPECTUS POST FREE. IRELES FOR YOUR AERIAL S too ft.7/22COPPER WIRE, 4 REEL IN- RECEIVERS SULATORS,20yd.1016 SKEIN ROPE CORD, REWOUND MAST PULLEY,COMPLETE Poet tree British 4000 Ohms LEAD- IN -TUBE. Isles. AND UPWARDS Henry J. Brewster & Co. PEPI2/SET 11, Queen Victoria St., London, E.C.4 G TURNOCK 41 HIGH ST ASTON SHAM BKINDERVIKEN BUTTON. A Supersensitive Microphone. TUBE, SHEET, Known all over the world and patented in every civilized country.Over 00,000 WIRE, STRIP, sold.ENGLISH Mallatnoture. Make up your own Loud Speaker. Transmit your GRAMOt HONE make ROD & CASTINGS to any room in your house. IN The only practicalPrice Microphone 5/- for eachuse in Detectiphone Sete. Special Low ResistanceReceivers(for use with PHOSPHOR BRONZE, SkIndervIken Buttrins) 10/- *ask Special Gramophone Attachments COPPER, BRASS,&c.,&c. Write for 16 page BOOKLET hilly illustrated and con= much usefulinformationforallinterestedInII Sound Tram:dation.6d. Post free. CHARLES CLIFFORD & SON, LTD., Sot. Propriaers : MIKRO LTD.,274/6, Pentonville Rd., London, N.l BIRMINGHAM, OPP. Rises Cr.. 'Mod.) Rly Station).

MANUFACTURERS F. WIGGINS & SONS and RETAILERS Telephone promptly supplied with Avenue 2248 Terminals, Screws, Largest Stoek Valve Legs, Spacers, in the World. Nuts, Washers, &c. MICA Prices Right. Quality Right FOR CONDENSERS APPLY FOR TRADE TERMS AND ALL PURPOSES. The ORMOND ENGINEERING Co. 102,103 & 104, Minories, London, E.1 199, PENTONVILLEROAD, LONDON, N.1 Thor,: HOLBORN 1812.

PHONES (PaitruZnnt eed>30/- CRYSTAL SET 37/6 Special Wireless Telephones, 4,000 ohms, 30/- post free. Receiving Set on Mahogany base, single slide Tuning Inductance, Fixed Condenser, Crystal Detector, Terminals, 40/- postfree. Valveholdersin Ebonite,firstqualityonly,1/-. Parisisreceivedquite easilyonthisset. I. K. STEVENS & Co. Wireless Section, 32a, Chester St., Grosvenor Place, S.W.1 Trade Inquiries Invited. Phone-Victoria 5837 kuairsT 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW IMPORTANT WIRELESS Take advantage of our 14 years' experience of Wire- less. Build your own receivers.We can supply all NOTICE- parts, and show you how to do it. JAMES FRASER & CO. (In collaboration with E.T.C. Address as below) A. C. COSSOR, Limited, hereby give notice that the order of Mr. Justice Russell of the SCHOOL INSTRUCTION 1st March, 1922, continually advertised by Day, Evening and Postal courses in Wireless, Valves, the Marconi Co., was an order ARRIVED etc.P.M.G. (Exam.), and amateur classes.Also AT BY CONSENT. Cable and Telegraphy. Prospectus from 'Phone :North 1036. Principal : Being engaged at the time in the production ELECTRICAL TRAINING COLLEGE, of an improved and different type of valve, Radio House, Manor G'dns, Holloway, N.7 A. C. COSSOR, Limited, did not consider the patents in question of sufficient importance to warrant the expense of litigation. THE LONDON RADIO CO. A. C. COSSOR, Limited, respectfully leave Manufacturers of Wireless Requisites the public and the Trade to judge whether the constant repetition of the notification of Valve Holders, all types- 9d. each the judgement referred to is necessary or Rheostats - - - 2,9 expedient in the circumstances. Switch Knobs, screwed - 21d. Condensers, Variable, from 5/- to 21/ - A. C. COSSOR, LIMITED Ebonite Panels cut to any size Buy fromtheactualmanufacturers. AberdeenWorks,Aberdeen Lane, Highbury Grove, N.5 1, Lonsdale Rd., Kilburn, London, N.W.6 Cash with order. Postage and packing extra,

VERNIER ADJUSTMENT FOR SLIDERS Complete with 13 in. bar. AERIAL WIRE Bar and Slider - 4/6 Neat " ON " and 7/22Enamelled Stranded. "OFF" Switches too ft. 6/- TELEPHONE As illustrated - -2,'3 15o ft. 9 TRANSFORMERS SINGLE LAYER COILS

4i in.diam 9 in.long. Wound with 24 Enamel. Unmounted (as illustration), CONDENSER SCALES Suitable for220w Phones. Engraved 0-180° Unmounted 16, - - In Box with Terminals - -18/6 With Knob and Bush - - 3/9 Price 6/6 St. John Street, E.C.1 G. Z. AUCKLAND & SON,395,'Phone - - 3173 CLERKENWELL. Auausr 19, 1922 XXXil THE WIRELESS WORLD AND RADIO REVIEW 'Ward5Goldstone) PE NDLE TON (Ili 511.1.2 Lo

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 CRYSTAL and VALVE RECEIVING SETS, and full range ofElectro Supplies for Wireless INDISPENSABLE TO THE TRADE.

on amCQ Std bi- for ERICSSON PHONES

WHENyou instal yourwireless set-crystal or valve

I -you'll get maximum results if you fit Ericsson Phones-clarity, sensitivity, strength of signals and absence of " click."Specially suited to telephony. Ericsson Phones embody the accumulated experience of telephone manufacture for a generation. I Easy to the bead, light and comfortable.The magnets never lam theirstrengthand " shorts " are non-existent. I I Write for ?articular: The BRITISH L. M. ERICSSON I I MANUFACTURING Co., Ltd. Head Office: 60, Lincoln's Inn Fields, E.C.2 I

41, Telephones

los AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxxiii

They FALL into Position: TELEPHONY RECEIVERS TWO -VALVE RESISTANCE AMPLIFIER.- Will receive all wavelengths from 180 metres to 30,000 metres.Perfect for FOR telephony.Mounted in French polished mahogany cabinet PARTS "K.B." with ebonite top.Perfectly simple, and can be operated by anyone.Finest workmanship and finish. Every instrument tested and guaranteed to give perfect results. CONDENSERS. PRICE 2 -valve£5,3 -valve£6. Points to OkCole. One -valve panel.A very superior instrument.Price 28 -. Illustrated Catalogue, 3d., post free Moulded Top and Bottom Ebonite Plates. LEWIS POLLARD, All Vanes Guaranteed FLAT. MANUFACTURER OF WIRELESS INSTRUMENTS, All Parts clear of Burrs, etc. 209,CunliffeRoad, BLACKPOOL. No Protecting Supports on Top. RESULT. WITH GOOD APPARATUS YOU CAN GET GOOD RESULTS THE g W.P. " Morse Practice Key Well Made. First-class Finish. Thereughly Reliable Price7/6 Post Free THE WIRELESS PRESS, LTD. 12.13 HENRIETTA STREET. LONDON. W.0 2 SOMETHING NEW COLOURED HIGH FREQUENCY TRANSFORMERS Interchangeable type to fitstandard valve holders. These transformers are manufactured from a new insulating material, with equal insulation properties to ebonite, and are supplied in various colours to quickly distinguish the wavelengths. PRICES : The various coloured transformers will improve the appearance of your receiver and relieve the dull monotony of an ebonite For Panel Mounting. In Pol. Mahogany Cabinet. panel.Supplied in white, green, red, amber, and blue. Unwound formers fitted with split pins, Capacity. Set of Parts. Assembled. 4/- to 5/6 EACH, postage extra. The tradesupplied. '0015 27/- 30/- 38/8 '001 21/- 24/ 31/8 LEWIS POLLARD, '00075 17/- 20/- 213/- Manufacturer of Wireless Instruments, '0005 14/- 17/- 22/8 '0003 11/- 14/- 19/- 209, CUNLIFFE ROAD, BLACKPOOL. '0002 8/- 11/- 18/- '0001 7/- 10/- 14/8 '00005 3/8 5/- 9/ - ENGRAVED EBONITE DIAL 3/3 extra Large Stocks now in hand.Complete Sets, Units and Questions and Answers ALL AMATEUR REQUIREMENTS. IMMEDIATE DELIVERY. COUPON CATALOGUE Post free 4d. To accompany Questions (Carriage Extra on Orders under 12) sent induring the week Trade Enquiries Invited. commencing Aug. 19th, 1922. The "K. B." Radio Equipment Company, VOL. X, NO. 21. IfeadOffices 109 High Road, Kilburn, N.W.6 & Showrooms: See Conditions on Page 670. Bus Services -- 3 mutates Kilburn Park Station 8, 16.28 & 51 Pass Door. (Bakerloo THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 WIRELESS Sterling Wireless Receivers Large or Small Contact Studs ...... doz. 1 0 Valve Legs, complete with nut and washer ..each 3 Price 311- pair Hart Accumulators, 4 -volt, 24 amp. hour ..each 14 9 Specification. Postage and Packing extra ...... each 1 3 STILL THE CHEAPEST DoubleHead Telephone FIRM FOR WIRES. Recei ver. S.W.G. S.C.C. D.C.0 Single Silk E bl. SilkEmd. Specially de- 12 1/10 1/11 4/- 5/4 1/8 signedforWire- 14 1/11 2/- 4/- 5/4 1/9 lessTelephony. 16 2/- 2/1 4/2 5/6 1/10 Excellent arti- 18 2/1 2/2 4/4 5/6 1/11 culation.Single 20 2/2 2/8 4/8 6/2 2/6 Pole piece cen- 22 2/8 2/11 5/- 6/8 2/8 tral operation 24 3/- 3/6 5/6 7/4 2/8 diaphragm. 26 8/7 4/1 8/8 8/2 8/2 Caseofalu- 28 4/4 4/7 7/2 19/- 3/8 miniumwith 80 5/- 5/6 8/- 10/- 8/10 swivel a n d 82 8/- 7/8 9/2 18/- 4/2 trunnion 34 7/- 8/8 11/6 14/- 4/4 movement. 36 8/8 10/2 14/- 15/6 4 8 Headbands of 38 11/8 18/2 18/- 19/- 5 3 steel cosiet- 40 15/- 18- 18/6 22/6 6,6 tizcdto pre- 42 17/8 21'- 31/6 34/- 9/ - vent corrosion At per lb. and are adjust- All orders of 1 lb. or over wound on reels free.For less than able. Each set 1 lb. reel 3d. extra. complete with Further Lists on application.Trade Supplied.Postages extra 6 ft. best qual- 2000w, ity flexible First quality at cord,weight moderate prices so oz. Immediate Delivery. Price 31/-.Postage 1/-. J. B. Bower & Co., Ltd. Also4000w.32/, LIBERAL TRADE DISCOUNT. Wireless Manufacturers, RADIO SERVICE CO., LTD. 15, Kingston Road, WIMBLEDON, S.W.19 62, OXFORD STREET, W.1. Telephone : Museum 2136. 'Phone : Wimbledon 1030. Works :Merton Works : Church St., Stoke Newington, N.16. The Construction ofBIN DING CASES

Amateur Valve Stations (INCLUDING INDEX) By ALAN L. M. DOUGLAS 78 pages. 55 Diagrams and Illustrations. VOL. 9

PRICE 1 / 6 NETT. The Wireless World (Postage 2d.) `Price3/6 nett. The aim of the author in compiling this volume has beento place withinthe (Post free 4/-1 reach of the amateur who is interested inWireless Telegraphy and Telephony a Handbook which will enable him to obtain data that he has otherwise diffi- INDEX (SOLD SEPARATELY) cultyinacquiring,inorder that he may constructforhimselfapparatus which he desirestomake,butdoes Price 8d. Post free. not quite know how to design correctly.

The Wireless Press, Limited THE WIRELESS PRESS LTD. 12-13, Henrietta Street, Strand, London, W.C.2 12-13, Henrietta St., Strand, W.C.2 AUGUST 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW XXIV Just Received ! AMERICA'S LATEST PUBLICATIONS FOR THE WIRELESS EXPERIMENTER. HOW TO MAKE COMMERCIAL TYPE RADIO APPARATUS By M. B. SLEEPER. Price 4/- net (post free 4/3). The experimenter will be able to geta world of ideas for the design and construction of his wireless apparatus from thevery clear descriptions and ninety-eight illustrated figures. CONSTRUCTION OF RADIO PHONE AND nPHONE AND TELEGRAPH RECEIVERS FOR BEGINNERS TE.EGRAPH By M. B. SLEEPER. RECEIVERS Price 4/- net (post free 4/3). Each piece of apparatus described was first made, tested and foundefficient before the final design was accepted. Working drawings preparedespecially LEf-Prn for the novice and the man who wants to receive the wireless broadcast. RADIO EXPERIMENTER'S HANDBOOK By M. B. SLEEPER. Price 5/- net (post free 5/3). A book which tells in a very concise way the " Why " of radio andanswers many of the " Practical Questions of the Beginner," and even themore advanced student of Wireless. To follow shortly THE ABC OF VACUUM TUBES USEDIN RADIO RECEPTION By E. H. LEWIS. Price 6!- (post free 6/5). Written particularly for those who know nothing about wireless,but who desire an understanding of the elementary principles ofoperation of vacuum tubes, and various circuits in which theyare used for reception of wireless telegraph signals, music and speech by wireless telephone.

THE WIRELESS PRESS, LTD.,Dept. W.W. 12-13, HENRIETTA STREET, STRAND, LONDON,W.C.2 xxxvi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922 DON'T WORK The IN THE DARK. If you have a Wireless Set and know but little of the principles A B C of its working, you are missing a great amount of the interest OF WIRELESS and pleasure which the man ob- tains who has this knowledge. BY It is nice to get good results PERCY W. HARRIS but where is the satisfaction EDITOR OF "CONQUEST" if you know not how they are (The British nlagazine of PopularScience.) obtained ? The Elementary Price6D.net. Post free8D Principles of THE BOOK for the Wireless Telegraphy IN THE STREET' By R. D. BANGAY, This wonderful little book has been specially prepared for those who are desirous of getting tells in the simplest possible manner, the theory a good knowledge of Wireless withoutdelving and practice of wireless. into text books. The Author makes the subject intelligible to persons who do notpossess much technical knowledge, and at the same time it is brief and No technicalexpressions accurate. to puzzleover. No hard thinking to be done. The book is so arranged as to be useful as No mathematical formulce a reference book for studentsand amateurs. to be elucidated. It is published in two parts What is Wireless?How does it Work? PRICE4/-EACH (post free 4/5) The A.B.C. Will Tell You or combined in one volume Wireless is the Topic of the Day The Up-to-date man needs to be conversant with it. NETT PRICE7/6 An evening spent in reading this book will put (post free 8/3). you in a position to appreciate tothe full the wonders of the latest and greatest of sciences. The Wireless Press, Limited Dept. W.W. The Wireless Press, Ltd. 12-13 Henrietta St., Strand, London, W.2. 12-13, Henrietta St., Strand, London, W.C.2 Arrousr 19, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxxvii

ALL-BRITISH WIRELESS EXHIBITION & CONVENTION will be held at the HORTICULTURAL HALL WESTMINSTER : LONDON :S.W.1 SEPT. 30THTO OCT. 7TH (SATURDAY) (SATURDAY)

This will be the most representative Wireless Exhibition ever held in Great Britain. THE CONVENTION will be held under the auspices of the WIRELESS SOCIETY OF LONDON andallaffiliated societies.

Communications should be addressed to THE ORGANISERS BERTRAM DAY & CO., LTD. WIRELESS PUBLICITY SPECIALISTS 9 and 10, Charing Cross, S.W.1 Gerrard 8063/4 xxxviii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19, 1922

it August, 1922. To THE ORGANISERS OF THE RADIO AND WIRELESS EXHIBITION & CONVENTION

We desire to express our deep regret that the advertisement insertedbyus inthe" WIRELESS WORLD AND RADIO REVIEW " contained a very seriousreflectiononthe Exhibitionto be heldattheCentralHall, Westminster, on the 2ndSeptember,bytheRadioandWirelessExhibitionand Convention. We failed to realise its full significance at the time, but we realise now the injury which it was calculated to occasion to the Radio and Wireless Exhibition.

We undertake not to repeat it and we also undertake to publish this apology in the next issue of the " WIRELESS WORLD AND RADIO REVIEW "inasprominent a manner asour advertisement, and to pay the costs.

BERTRAM DAY & CO., LTD.,

BERTRAM DAY, Managing Director. A.UGUST19, 1922 THE WIRELESS WORLD AND RADIO REVIEW

`C he OHMER INSULATION TESTING SET (COX'S PATENT) This is the lightest, cheapest and best instrument of its kind on the market. It consists of an Ohmeter and Generator mounted in one case.The Ohmeter is of the Electrostatic type, giving extreme lightness.Absolutely unaffected by externalfields.Itreads directly in Megohms and is independent of the voltage or speed ofthe generator. NALDER BROS. & THOMPSON, LTD., 97a, DALSTON LANE, LONDON, E.8.

WARNING. Hoyle's Book Saves Time MARCONI'S WIRELESS TELEGRAPH CO., LTD., The tables and equations are compiled v. in book form andreference to the detailed indexspeedily puts onein A. C. COSSOR, LTD. possession of the information desired. Marconi's WirelessTelegraph Company, Limited, GIVE NOTICE that an ORDER was made NO OTHER COMPLETE BOOK in the High Court of Justice, Chancery Division, EXISTS FOR THE USE OF by Mr. Justice Russell on the 1st March, 1922, restrainingMessrs. A. C. Cossor, Ltd., from RADIO WORKERS. infringing the Marconi Company's Letters Patent Nos. 28413 of 1913 and 126658, except so far as Send at once for a copy of Messrs. A. C. Cossor, Ltd. manufacture for H.M. Government. Messrs. A. C. Cossor, Ltd., were further STANDARD ORDERED upon oath to DESTROY all articles and apparatus (other than those constructed to TABLES & EQUATIONS the order of H.M. Government) made or used IN by them in INFRINGEMENT of these patents, and TO PAY THE MARCONI COMPANY DAMAGES RADIO TELEGRAPHY AND COSTS. The M -O Valve Company, Limited, of Osram By Works, Brook Green, Hammersmith, London, BERTRAM HOYLE, M.Sc., Tech., A.M.I.E.E. W.6, is the only firm in this country licensed to manufacturethermionicvalvesunderthe Price 91 nett. Post free 9/9 patents belonging to the Marconi Company. Any valve similar to those generally known as the " French type " constitutes an infringement of the above patents whether manufac- THE WIRELESS PRESS, LTD. tured in this country or imported from abroad. Dept. W.W. 8/4 Marconi House, Strand, London, W.C. 2. 12,13 Henrietta St., London, W.C.2

Registered -NIPHAN- Trade Mark. As used by II.M. War Office, Electric Supply Companies, Railway Companies. Marconi's Wireless Telegraph Company WATER-TIGHT PLUGSSIMMONDS BROS., LTD. 4.6 & 8. NEWTON STREET. HOLBORN. W.C. and CABLE COUPLINGS a TO MEET HOME OFFICE REQUIREMENTS

11110 ih)))fl

COUPLING CONNECTING CABLES Phones : Telegrams: 2600 Garrard. 12061 CeatraL Mahon. Loudon." SIX WAY TEE CONNECTORS Pateeted is Emrland aad Abroad. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 19,1922

1 2. AU connections I.Perfect insulation shown in diagram of grid connection en ready made for you SUMS silent operation. and brought out to terminals.

I P (DA

+4V

- 4V ILE OP O

3. To add an amplifying stage, connecttoterminals andinsert valve.

4. Tapped holes in two sides and base make fitting easy.

Themostimportant detail improvement yet made inWireless Receiving Sets. THE ELWELL AMPLIFYING UNIT Comprising valvesocket and ironclad This patented 'amplifying unit, when pro- intervalve transformer, mechanically and vided with a valve and connected as marked electrically combined in oneunit. on the terminals, is all that is necessary to give one stage of amplificationto your existing set. No soldering is necessary. The unit is easily attached to panel or shelf, or Exclusivedesign covered bypatents. will stand alone. British made and guaranteed throughout. The self-contained permanent connections are a big practicaladvantage, whilethe perfect insulation of the grid connection will To secure early delivery order at once. appeal to all amateurs troubled with " noise."

Price 39,6 only, for complete amplifying unit, less valve. Enquiries for all wireless components invited. C. F. ELWELL, LTD., CRAVEN HOUSE, KINGSWAY, LONDON, W.C.2. Printed by Sanders Phillips & Co., Ltd., Chryssell Road, London, S.W.II, for the us: Proprietors and Publishers, The Wireless Press, Ltd., 12-13, Henrietta Street, London, W.C.2 ;Sydney, N.S.W., 97, Clarence Street ;Melbourne, 422.24, Little CollitiskW52 Street ; New York, 326, Broadway. 26th AUGUST, 1922. THE PRICE 6D NET. WIRELESS WORLD AND RADIO REVIEW

Registered at tie G:P.O. VOL. X. No. 22. 26th AUGUST, 1922. as a Weekly *mender.

ALWAYS USE HART ACCUMULATORS SUITABLE FOR ALL CLASSES OF allir ELECTRICAL WORK WE SPECIALISE IN HART HIGH TENSION BATTERIES HART ACCUMULATOR CO.,LIT., VISIT OUR:STAND NO. 17 , STRATFORD ALL BRITISH WIRELESS EXHIBITION LONDONE.15 BRANCH OFFICES AT: HORTICULTURAL HALL, Sep. 30th to Oet.7th BELFAST :41, Chichester Street. GLASGOW :107,WellingtonStreet. BIRMINGHAM :174, Corporation Street. LONDON: 36, Victoria St., S.W.1 BRISTOL :37, Victoria Street. MANCHESTER :4, Victoria Bridge. YORK :6, Bridge Street. THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26 1922 STERLING No. 1 CRYSTAL WI RECEIVING SET Specially designed foruse in connection with the Wireless Telephony Broad- castingScheme, and is suitable for arangeofabout 2 S miles. PRICE £7-12-6 VisitourStand No.34.All -British Wireless Exhibition, Horticultural Hall, September 3oth to October 7th. STERLING TELEPHONE & ELECTRIC CO., LTD. 210-212, Tottenham Court Road, LONDON : : : W.1 Telephent 4144Museum (7 lines) Telegrams : " Cucumis,Wesdo,London." Works : DAGENHAM. ESSEX. BRANCHES NEWCASTLE -ON -TYNE :9, Clavering Place. IMMEDIATE DELIVERY CARDIFF :S, Park Place. "Wireless forall" Before you decideon the construction ofyour set. It will payyou to have particulars of- Condensite Celoron For PANELS and OTHER PARTS. This material is waterproof, immune to atmospheric and climaticconditions, will not warp, has high surface and volume restivity, high di -electric strength, low specificgravity. LET US QUOTE YOU SEND PaIRTICULdRSOF YOUR EXICT REQUIREMENTSTO THE MANUFACTURERS

DIAMOND -FIBRE HIGHROAD WORKS SOUTH TOTTENHAM. N 15. Y/holesale Manufacturers CHADWELL HEATH, ESSEX. of Wireless apparatus. Trade Enquiries Invited. iv THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922

The New SHEET, ROD AND TUBE stockedin Precision qualitiessuitableforall Wireless work. BURNDEPT KNOBS(Moulded),various patterns stocked Variable CONDENSER DIAL AND KNOB. I3 and 4' dia.-W--100° Condenser Watch this Advert. The design ofthis instrument is such that it can be produced for new in large quantities at a reasonable price, whilst retaining a high mouldings. 1 standard of technical excellence. SPECIFICATION.Vanes of hard thick aluminium: Bearings metal to metal.Contact to moving plates by phosphor bronze soldered strip.Adjustable operating tension.Spacing between plates sufficient Or pressure up to coo volts.Built upon Bakelite. Suitable for mounting on any panel from l to It" thick, by drilling clearing hole for spindle and 31,-holes for fixing screws. Each instrument supplied complete with "a- 'high-class engraved and polished Ebonite dial and substantial knob assembled, and the necessary fixing screws.The maximum capacity is 000d and the minimum capacity negligible. Enquiries Solicited We recommend this size condenser as being the most suitable for both A.T.I. and secondary tuning.Itis the same condenser WHOLESALE ONLY. which is built up into all our newI BURNDEPT tuners.

AMERICAN HARD RUBBER CO. (BRITAIN) LIMITED I13a, FORE STREET, LONDON,E,C. 2 Teleg. ' Eboniseth, Ave., London." 'Phone : Central 12754 MINIMMIN Our Motto ! Satisfaction

No. 141 No. 142 PRICES. Filament Resistances, Smooth Action.. 4 - Sound construction, easy tomount.

No. 141.For Panel mounting...... 22 Grid Leaks (Tubular enclosed), 2 Meg. No. 144. A smaller size condenser capacity ooc275 for high Crystals(Selected),Zincite, Bornite,Silicon,Galena, frequency amplification, Vernier tuning, reactance tuning, etc. Carborundum, C. Pyrites, etc... 13d. No. 144 for panel mounting only.The specification of this Crystal Cups, with side fixing screw 6d. condenser is precisely the same as No. 141. 21 12 Brass Square Rod, 12" x i" x 6d. Inductance Formers, 12" x 3" .. 6d. No 142.Mounted complete on Ebonite Panel and inpolished Inductance Formers, 12" x 4" .. 9d. walnut case .. £2 15 Inductance Formers, 12" x 5" .. 1;- Sliders with Plungers .. 6d. Fusible Alloy for Fixing Crystals .. 8d. THE TRADE ARE INVITED TO ASK Aerial Wire Stranded, 7/25.. .. per 111111 ft.3/6 FOR QUOTATIONS FOR QUANTITIES Aerial Insulators, Egg, Porcelain 8d. Aerial Insulators, Reel Type .. 4d. Visit our Stand No. AllBritishWirelessExhibition, Aerial Pulleys, Aluminium, with cord.. 1/6 HorticulturalHall,September3othtoOctober7th. Condenser Vanes, Aluminium (accurate) .. per doz.1/10 Condenser Spacers, Large (true to .001").. per doz. 5d. Condenser Spacers, Small (true to -0011.. per doz. 3d. Condensers, Tops and Bottoms (Bushed) each 1/- LONDON SHOWROOMS : Condenser Ivorine Scales, 0-180 deg. .. 9d. Switch Arms, Laminated with Bush, etc... 2'3 15, BEDFORD ST., STRAND, W.C.2 Brass Studs, r high r dia... .. per doz. 1- Brass Studs, I" high x r dia... per doz. 13 Brass Studs, f" high x X" dia... .. per doz. 16 Hellesden 36v. H.T.Batteries,with plug.. ..each 86 Telefunken and A.E.G. Valves Tested .. 10'6 Ltd. Headphones, Double, excellent for speech and Music, BURNDEPT 2,000 ohms, 30/-.4,000 ohms, 32 6. Panels, Tuners, etc. Aerial Works and Eastnor Works Postage extra. BLACKHEATH VILLAGE, S.E.3 The ESSEX WIRELESS Co

All , BURNDEPT Apparatus is duly licensed under (Office andShowrooms) Marconi Patents for amateur use in Great Britain. 499, Grove Green Road, Leytonstone, Ell Telephone : WANSTED 749.(i minute from station G.E.R.) AL-NusT 26, 1022 THE WIRELESS WORLD AND RADIO REVIEW V

The Name "BURNDEPT" GUARANTEES Cent. Per Cent.QUALITY & EFFICIENCY. LIVERP3OL: MANCHESTER 10. SOUTH JOHN 61, BRIDGE STREET, STREET. DEANSGATE. 0 BIRMINGHAM : LE,RJRNDEPT LEEDS: 133 New S 48, GT. GEORGE STREET.

LONDON OFFICE & SHOWROOMS 15 BedForcl Street. Strand. W.C.2,. Burndept I. ReceiverWE HAVE A COMPLETE Burndept II. Receiver STOCK OF ALL WIRE- LESS ACCESSORIES BURNDEPT (Patent)Coils- COIL HOLDERS- TUNING PANELS - CONDENSERS AMPLIFIERS - ACCUMU- LATORS - HIGH-TENSION BATTERIES- HEADPHONES VALVES- MASTS-SPREAD ERS-AERIAL WIRE- INSULATORS - SWITCHES. Etc., Etc.

Size 9k" x 7k" x 4r Size 11k" x 9A"41' ILLUSTRATED CATALOGUE. ONE VALVE (W.) OPTIONAL SINGLE Post free 6,1.; to all who apply and mention DETECTOR SET. "TheWireless World ".This givesfull detailsof our one. two, three and four -valve NOTE MAGNIFIER. RECEIVING SETS complete and ready for PRICE: use. Also details of all accessories. PRICE : (With 'Phone Transformer) PRICES from£2 1 (With 'Phone Transformer) £5 0 0 £12 10 The Trade are invited to ask for Quotationsfor Quantities. LONDON SHOWROOMS: 15, BedfordStreet, Strand, W.C.2 Visit our Stand No.12a. 111 British Wireless Exhibition, Horticultural Hall,Sept. 30th to Oct. 7th AERIAL&WORKSBLACKHEATH BURNDEPTLtd.EASTNOR WORKSVILLAGE S.E.3 All BURNDEPT Apparatus is duly licensed under Marconi Patentsfor amateur use in Great Britain. The Baynton High Tension UnitRegd. No. 11896/22 Containing 45 Cells

ADVANTAGES : (A)Esch Battery can be separately Tested. (C) No soldering required, exhausted Batteries (B) Exhausted cells replacel at tie cost of a few penes. replaced by unloing 2 meas. (D) Four Ta2teing, or more it required. (E) A neat Polished Box, with Ebouile _lopand Braes Terminals. PRICES : 75 volts .... 27/5 SEND FOR ONE TO -DAY ALL BURNDEPT AP - 75 volts .... 32/6 The Best Value on theMarket PARATUS IN STOCK SoleManufacturers-C. S. BAYNTON & SON,153, New Street, BIRMINGHAM.

A 2 vi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922

A New Condenser for Wireless Receivers With Clips for Grid Leak.

TYRE 600 THE DUBILIER TYPE 600 MICA CONDENSER DURILIER MICA CONDENSER CONDENSER C011921N-" The illustrations show two types of this new condenser for wireless receiving circuits.The condensers have the same perfect mica insulation, the same high efficiency and the same permanence of capacity as the larger Dubilier Mica Condensers used in wireless transmitters.Distortion when Without Clips for Grid Leak receiving telephony is often due to bad design of the components of the receiver-therefore use MICA CONDiNCEP efficient Dubilier Condensers in your receiver U 8 I E toobtainthebest outof your set. CONDENSER CO (:9211 LTO PRICES: Capacity between 0'0001 and 0'001 mfd- 2/6 each

17 1? 0.001 0'005 3/- (inclusive) THE WAY TO DUBILIERS.

Condensers complete with Grid Leaks - 7/6

TRADE TERMS ON APPLICATION.

Both types of condenser (with or without clips for a grid leak) arefitted with screw terminals as well as tags for making soldered connections.

4 Visit our Stand No. 36. All British Wireless Exhibition, Horticultural Hall, September 30th to October7th. THE DUBILIER CONDENSER CO. (1921), LTD., DUCON WORKS, Goldhawk Road, Shepherd's Bush, London, W.12 Telephone-Hammersmith 1084. Telegrams-Hivolteon, Phone, London. Code-Marconi International Aut:usT 26, 1922 THE WIREL ESS WORLD AND R.1I )10II E VIEW vii

ELECTRICAL AND Mechanical Engineers Contractors to the Admiralty, War Office & Air Force

Manufacturers of . . . MARCONI'S WIRELESS DISC DISCHARGERS. ROTARY CONVERTERS. DYNAMOS. ELECTRIC MOTORS. TRANSFORMERS. BOOSTERS. BOX HIGH VACUUM PUMPS.

COMPLETE ELECTRIC LIGHT INSTALLATIONS For Country Houses and Yachts. Lighting Sets for Motor Cars and Aeroplanes. Estimates Free. AN EFFICIENT STAFF FOR REPAIRS

Inventors' ideas carefully and skilfully carriedout fromthepreparation of detailed drawings to the completion of the finished article :: W. MACKIE & CO ESTABLISHED1882 THE PALACE ENGINEERING WORKS 12 9, 131, 13 3, Lambeth Road, London, S.E. 1 TELEPHONE 182 HOP THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 IF YOU REQUIRE EXPZR IffIVCE HIGH -FREQUENCY A LIGHT MAST OR AMPLIFICATION 100 to 20,000 METRES IMPROVED ADJUSTABLE REACTANCE COMA: SELF - AERIAL SPREADER TUNED. SPECIALLY DESIGNED TO GIVE THE HIGH- EST EFFICIENCY ON THE SHORT WAVELENGTHS USED IN BROADCASTING. WRITE TO McGRUER HOLLOW SPAR CO. LTD. COMMERCIAL ROAD, LAMBETH, LONDON. S.E.1 Visit our Stand No. 37.All Britt -.11 V\Exhibition, HorticulturalHall,September3oth W October7th. This is the high frequency unit that every wireless experimenter 'Fiume Wires : has been waiting for.The fact that it bears our name is a HOP "OLLOSPARSH guarantee that it will do all that is asked of it. 718 WATLOO, LONDON.' ADVANTAGE OF HIGH FREQUENCY AMPLIFICATION. All serious wireless experimenters will appreciate the great advantages of high frequency amplification before rectifyng. It makes signals far below audible strength easily readable and permits additional audio frequency amplification (after rectilying) without rendering the receiving set unstable. THE TAPPED ANODE REACTANCE COIL. This coil, originally developed by Mr. W. A. Appleton, our research director, and specially designed for short wavelengths, has now been still further improved by a finer sub -division of the tappings to obtain the best efficiency for broadcasting. NEW AND IMPROVED DESIGN. The coil is sectionally wound and cylindrical in form as this design allows greater mechanical strength inthe winding at the tapping points than does the earlier disc type. too TO 200,000 METRE RANGE. Twelve tapping points are provided covering a range of wavelengths from too to 20,000 metres. TRADE MARK CONSTANT REACTANCE VALUE. The tappings have been selected to keep the reactance value approximately constant for all wavelengths. NO TUNING CONDENSER NEEDED. No tuning condenser is necessary as the capacity of the winding renders the coil self -tuned. HIGHEST EFFICIENCY. The WHITECROSS This type of coil gives a higher efficiency on short wavelengths than any other method of intervalve coupling. COMPANY, LIMITED DELIVERY- Immediately from stook. PRICE --TappedReactanceCoil as specified, WARRINGTON :: complete with wiring diagram.. 25/ - Twelve point switch for use with same.. 16/ - Audio -frequency Intervalve Transformers each 25/ - Telephone Transformers .. ..each 20' - Manufacturers ofAllDescriptions of Radio Instruments Limited

Managing Director: J. Joseph, M.I.li I late Manager to Mr. H. Sullivan.Chief Designer : W. A. Appleton, M.E.E., WIRE ROPES M.I.R.E., late Admiralty Technical Research Officer. ONLY ADDRESS.Works, Offices & Showrooms AND WIRES 12a, Hyde Street, NEW OXFORD ST., W.C.1 We have the largest wireless works in Central London. We are wireless engineers of established reputation. Our name on wireless apparatus is a guarantee of satisfaction. AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW ix WIRELESS EQUIPMENT LTD. Tel Telegrarnes RADIO ENGINEERS AND MANUFACTURERS WIREQUIP GERRARD WESTCENT 6785. :: APPARATUS AND SPARES :: LONDON WRITE FOR OUR ILLUSTRATED LISTS OF SETS AND COMPONENT PARTS, 3d. POST FREE Head Office :90, CHARING CROSS ROAD T ONDON, W.C.2 Visit our Stand N,14. All!' rit Hyliibition, Horticultural Hall, September 30th to October 7th THE WIRELESS WORLD AND RADIO REVIEW THE OFFICIAL ORGAN OF THE WIRELESS SOCIETY OFLONDON A MAGAZINE DEVOTED TO WIRELESS TELEGRAPHYAND TELEPHONY CONTENTS A Broadcast Receiver.By A. J. Bull ------677 Valve Manufacture (continued) ------683 The Trans -Continental Wireless Station of Sainte Assise - - - 689 A Suggestion for the Experimenter.By G. P. Kendall, B.Sc. - - - 693 Contents ecmlinual on next page.

SIEMENS PRIMARY CELLS & BATTERIES DRY AND FLUID for the High -Tension Circuit of Wireless Apparatus using Thermionic Valves.

'Descriptive Pamphlet (Supplement 1to Catalogue No. 600) will be sent on application to the Manufacturers : SIEMENS BROTHERS & CO.LTD. WOOLWICH, LONDON, S.E.18 Telegrams : " SIEMENS WOOLWICH... Telephone : CITY 6400 Visit our Stand No. 48. All British WirelesaFvhibition, HorticulturalHall, Sept. 30th to Oct. 7th THE WIRELESS WORLD AND RADIO REVIEW AtictuaT 26, 1922 NOW IS THE TIME to acquirea soundtheoreticalandpractical knowledgeof THREE ELECTRODE VALVES, (as applied to C.W. Radio -telegraphy andRadio -telephony), by means of my POSTAL INSTRUCTION COURSE PerfectlySimple 2 Lt.E.REDPATH, atay I Send you Particular3? 19, Niger St., BARROW-IN-FURNESS

CONTENTS(Continued) WirelessWithoutanAerial: A NewLineofExperimentforAmateurs. By Percy W. Harris 694 Notes - 696 Correspondence 698 Book Reviews - - 698 Calendar of Current Events 699 Wireless Club Reports - 700 Questions and Answers - 703 Share Market Report - 710

THE WIRELESS WORLD AND RADIO REVIEW is publishedweekly on Saturdays. All correspondence relating to contributions shouldbe addressed to THE EDITOR, THE WIRELESS WORLD AND RADIO REVIEW,12-13, Henrietta Street, London, W.C.2. No responsibility can to taken for MSS.or photographs sent without stamps to defray cost of return postage. Editorial and Publishing Offices 12-13, Henrietta Street, Strand,London, W.C.2. Telegraphic Address :" nadionic,Rand,London." Telephone No.:Gerrard2807. Advertisement Managers, Bertram Day & Co., Ltd.,9 and io, Charing. Cross, S.W.I. Telephone No.: Gerrard 8063 and 8064. SUBSCRIPTION RATES.- 28s. per annum, post free. Single Copies 6d., or post free 7d. Registered at the G.P.O. for transmission by Magazine Postto Canada and Newfoundland. HOLLOW STEEL MASTS FORAERIALS Those masts are light, strong, easily erected, and will last lifetime.All lengths over 15ft. are made in sections and each mast is supplied complete withbaseplate, finial, rope cleat, pulley *heave, guy clips, three steel guyropes and strainers, painted one coat ready for immediate erection.Being made of steel, no lightning conductorsare required PROMPT DELIVERY. PRICES F.O.R. FOR CASH WITH ORDER, EACH 10ft. ... 32/6 15ft. 42/6 2Oft. ... 45/- 25ft. ... 57/6 3Oft. 84/ - 40ft. ... 126/ - Other Lengths supplied at equally Leto Prices. Trade Inquiries Invited THE WIRELESS STEEL MAST & ACCESSORYCOMPANY Lombard Street West, West Bromwich Telephone No. 447 AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW zi VALVES DELIVERY FROM STOCK. RECEIVING.

Filament Anode Type. Voltage. Voltage. PRICE. R 4 6o £1 6 1-6 R4B 4 5o 1 10 0

V24Q- 5.2 36 1 4 0 5.2 50 1 40 (150 as amplifier) QX 5.2 50 1 40 SPECIAL LOW TEMPERATURE VALVES.

Filament Filament Anode Type. Voltage. Current. Voltage. PRICE. L.T.I .8 4 36.-50 £2 10 0 L.T.3 I'8 TRANSMITTING. Filament Anode Type Voltage. Voltage. PRICE. A.T.2 5 5.5 UP TO1,000 g 1 1 00 A.T.4ox 7 13000 215 0 Visit our Stand No. 32. All British Wireless Exhibition,Horticultural Hall, September 30th to October 7th THE MARCONI SCIENTIFICINSTRUMENTCO., LTD. TELEGRAMS: THEMASINCO. WESTOENT 40 DEAN STREET, SOHO, W.1 TELEPHONE: GERRARD 774 xii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 Ff7`7.6,Specialities. The SPHINK High Tension Battery

TheIdealValve Accumulator 6 Volts 5o Amp. In wooden case with leather strap handle. 6 Volts5o Amp. PRICE 35/ - r6 Volts. A battery especially designed with the object of giving Carriage 3/- a constant voltage for a maximum period. PRICE 3/6 each.Carriage Paid. 4 Volts 5o Amps. PRICE 24/ - Carriage Visit our Stand No. 15.All British Wireless Exhibition, Horticultural Hall, September 3oth to October 7th. We have Magnavox Loud Speakers in stock.Immediate delivery if ordered now. Send for Illustrated Catalogue of complete Wireless Sets and Component Parts Post Free-Threepence. Zr2M220 WIRELESS ENGINEERS 13-14, GT. QUEEN ST,K1NGSWAY. LONDON.W.G.2. Phone. GERRARD576. Telegrams.ZYWATESENG.WESTCENT

Wireless Telegraphy & Telephony. EBONITE AND Special offer of Aerial Fittings. VULCANITE 150 ft. 7/22 Best H.C. Copper Aerial Wire. 2 Ash Spreaders, 6 ft. X 7/8 in. diameter. 4 Brass Spreaders Bands with two eyes. 4 White Porcelain Reel Insulators 2 in. diam. TUBES-RODS-SHEETS 2 GalvanisedPulley Blocks with Hooks. 1 Lead-in Insulator 9 in. long with Soldering LARGE Shoe and Terminal. 100 ft. Stout Manilla Rope. STOCKS Complete Outfit. BRITANNIA RUBBER AND 301- KAMPTULICON CO., LTD. CARRIAGE PAID IN GREAT BRITAIN. 7, NEIN/GATE ST., LONDON, E.C.1 Telephone : Telegrams : RADIO SUPPLIES 2168 Central Britannia, London (Dept. ), 236, HIGH HOLBORN, W.C.1 THE WIRELESS WORLD AND RADIO REVIEW THE OFFICIAL ORGAN OF THE WIRELESS SOCIETY OF LONDON

VOL. X.No. 22. AUGUST 26TH, 1922. WEEKLY A Broadcast Receiver By A. J. BULL. ISUPPOSE that during the last few weeks In the design of the instrument provision is quite a number of people associated withmade for reaction, but since it is understood that the technical side of wireless telephonyreaction for broadcasting receivers is likely to have been rung up by telephone and a conversa-be prohibited bythePostmaster -General for tion similar to the following has taken place :wavelength ranges up to about 500 metres, it " Hullo Brown !Good morning !I hopeshould be borne in mind that provision is made that your cold is better."" Good morning !for the reactionterminalsof the instrument Yes, thank you " (and mutters to himself, tobebridged across by a brassstrap for " Now how on earth did he know that I had reception on these wavelengths. had a cold ?I haven't seen him for a year.) Although the finished design is that of a Well !What can I do for you ? " three -valve instrument, there is no need to " I want your advice about the constructioncomplete the instrument before experiments of a valvereceiver which will enable me to in the reception of signals can be commenced. pick up all the broadcast stations, and also the Provided that the dimensions of the box Dutch concert on a very poor aerial. and consequently that of the ebonite panel is "As I already possess a few odd parts fromadhered to, one valve and its circuit (Fig. 2a) ex -service apparatus, I would like to build thecan be built in the panel as shown in Fig. 2b. set myself, and make use, if possible, of thoseThis single valve circuit, with the addition of parts.I want really a first-class instrument,an aerial,etc.,of course,willenable the but cash being limited, I should like to buildowner to become acquainted with the doings thesetupgradually,andtocommenceof the nearest broadcast station. receiving signals from the moment I purchase the first valve.At the same time I would like With the introduction of the second valve the finished instrument to be complete inand its wiring, additional experiments are of itself, excepting of course for the H.T. andcourse rendered possible, and finally, with the L.T. batteries." inclusion of the remaining valve, simultaneous " Righto, Jones.Iwill see what I can doH.F. amplification, detection, and note magni- for you." fication become available. * * * To those who wish to commence operations It is the intention of the writer of this articleimmediately with a single valve, and desire to give details and working particulars of ato possess a three -valve instrument complete three -valve amplifier, which can be built upin itself ultimately, and not made up of a by anyone from odd component parts that arenumber of units which have to be wired at present available at dealers of second-handtogether to function as a single instrument, and new apparatus ;and at the same time tothis design should prove of special interest. produce a finished instrument of high efficiency The finished instrument, as shown in the which will enable experimenters to receive from photograph (Fig. 1), will also be found useful various broadcasting stationsthat may be tothe keen experimenter who desiresto erected in the British. Isles, and also from someinstantly compare methods of reception, or of those on the Continent. to demonstrate the advantage of employing 678 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 26, 1922 a particular method when receiving from a When reaction is required the strap short certain station. circuiting the reaction terminals is opened. For instance :- The circuits employed (Fig. 3) are well Supposing theexperimenter'sstationis known and therefote need no explanation. situated about ioo miles from the MarconiThe condenser used (o000s mfds.) in the telephony station(2 MT) atWrittle ; byH.F. circuit, is perhaps rather larger than that operating the switches provided on the instru-usually employed for the purpose, but in- ment whilst this station is transmitting, radioductances for the most important waves to the frequency and audio frequency amplificationexperimenter, possibly the broadcast waves, can be compared, the advantage of reaction,can be suitably constructed, or purchased, and the disadvantage of carrying reaction toowhich will permit of the condenser functioning far demonstrated, etc., also strength of signalssomewhere nearits minimum value.The can be noted with one, two, or three valvesadvantage of the larger condenser over that in circuit. more commonly employed, viz., o000i mfd.) The following table indicates the positionwill be found when it is desired to receive of the switches for valves in use :- wavelengths above 2,50o metres, as the wave Position of Two-way Switch H.F. Valve Detecting Valve. L.F. Valve. Dewar Swith. turned to Detecting Valve Up Right Detecting Valve L.F. Valve Neutral Right H.F. Valve Detecting Valve Up Left H.F. Valve Detecting Valve j L.F. Valve Neutral Lef t

Fig. r.The complete instrument. AUGUST 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 679, range of each coil is considerably increased.transformer once did duty in a heterodyne For example, Igranic coil No. 600, of 19,7oowavemeter. microhenries inductance, tunes, with a o000i The switch which can be seen on the front mfd. condenser, from 2,500 to 4,200 metresof the instrument is an ordinaryland -line approximately. telephone listening key, sometimes described By a simple calculation, viz., A = 1885 % LCby dealers as a " Dewar " switch. where L is in microhenries and C in micro - The reader should now have the impression farads, it will be seen that the range of thisthat no particular make of parts is essential. coil is increased with a o0005 mfd. condenser,Some makes are, of course, preferable to others, to 5,83o metres approximately, and the lossowing to their better design and mechanical in efficiency due to reactance of the condenserconstruction. withtheselowerfrequenciesisscarcely When purchasing componentpartsitis noticeable to the experimenter. advisable to have the full size design (given on the next page) and dimensions of the panel (Fig. 4) at hand, so that the dimensions of variousparts may be checked.Sufficient space, however, has been allowed for any moderate variation in size of the parts that are likely to be offered to the experimenter. Afterthevariouspartshave been got together,the wooden box shouldfirst be constructed.This is made of j in. material Fig. 22.Simplified connections of single valveand measures outside 14 x 7i x 4 ins. circuit with switch to shirt circuit reaction leads.in height, thefront being screwed on by means of four suitable1 -in. brass screws. ORIGIN OF SEVERAL OF THE PARTS EMPLOYED The ebonite top to the box should next be IN THE INSTRUMENT. prepared. As has already been stated, it is intended that this instrument shall be made up of component parts which are available at dealers, or which amateurs may already possess, and so a brief description of some of the parts from which the set shown in the photograph was constructed by the writer will now be given. - LT + - HT +

Fig. 3.Simplified circuit diagram. This should be unpolished,1 in. in thickness, and secured in position by ten-in. brass screws Consideration must now be given to full scale design and any alterations made to the design Fig. 2b.Single valve wiring diagram. which may be considered necessary, owing The filament resistances and valve holdersperhaps to difference in size of one or two of the were originally designedfora R.A.F. d.f.component parts purchased, to the dimensions amplifier, and purchased very cheaply.Theshown in the diagram.It may be anticipated H.F. condenser and twelve terminals are fromthat the transformers will vary in size, and the well-known Mark III receiver.The ooo1also that the diameter of the holes in the mfd. fixed condenseracross theintervalvefront of the box through which the three 680 THE WIRELESS WORLD AND RADIO REVIEW AIIGIIST 26, 1922

LT ATJOUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW 681

INTERVALVE HT + TRANSFORMER

0.03u,F

0000E

DIC'BAI A e0 a) L tE

, 682 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 filament spindles pass, may vary in diameter,should be taken that there is no stretching but these slight alterations should not presentor shrinking of the paper.After the necessary any difficulty.The ebonite panel can nowdrilling has been done, the panel can be laid be unscrewed from the box and the positionaside for a moment. The front of the box of all holes marked ready for drilling on theshould now be unscrewed and the hole cut underside of the ebonite. to receive the Dewar switch, and the three

Fig. 4.Dimensions of the panels (top and front). The design on pp. 68o-681 is drawn full size.holes drilled for the reception of the filament If a copy of this diagram is carefully gummed tospindles.The next step is to screw the com- the underside of the ebonite panel, the positionplete filament resistances and Dewar switch of all holes to be drilled, and also the disposition in their respective positions, and fasten the of wiring, etc., is clearly defined, but great careebonite panel to the front of the box only by AUGUST 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 683 three i-in. wood screws.By means of nineinsulationoverthewire.Thisinsulation 4 BA screws,in. long, the three valve socketsis commercially known as sleeving, and costs are secured in position.For the drilling ofabout 4d. per yard.It is in the form of a the holes a 7/64 -in. drill is recommended, andtube and fits closely over the wire. if a 4 BA tapered tap is not available, each Here a word of caution is earnestly given. screw may be made to cut its own thread inDo not rush the wiring.It does not pay. the ebonite.This method gives quite satis-Any extra time- spent in wiring and in the factory results.It is advisable at this stage indisposition of the various parts is time well the construction of the amplfier to wire thespent.Space the wires as far apartas is filament circuits.This should preferably beconsistently possible, so asto reduceto a done with tinned bare copper wire of aboutminimum the capacity between one wire in No. 20 gauge, as there are a number of solderedone circuit and another wire in another circuit. connections to be made. A good method toIf this is not done inter -oscillation between the follow with the wiring is to bend each wirecircuits may result. tothe shape required and then passthe (To be continued.)

Valve Manufacture A BRIEF DESCRIPTION OF THE SIMPLER PROCESSES ADOPTED IN THE MANUFACTURE OF M.O. VALVES (Continued from p. 647, Aug. 19th, 1922.) THE dimensions of the electrodes are(receiving valves, the point of sealing is annealed of considerable importance, both with(%beyai rieladcinagsbthesetossealedpendwhicheisbulablloinweadgatso- regard to characteristic and rating, and in the case of transmitting valves of definite3 1cool down by slow stages, but the seaming watt rating, the energy that can be handled isend of the tube is next melted into the body of approximately calculated on the basis of thethe bulb by attaching it to the exhaust system ratio of the rated watts to the anode area. on the pumping tables. The disposition of the anode with regard After the bulbs have been fitted with the to the container, the leads and the pinch,interior electrodes, they are given a preliminary requires considerable attention in valve design,exhaust and sealed off.Those which prove and also the length of anode with regard toto be free from leaks are later sealed on to the length of filament must be carefully con-glass tubing which forms part of the exhaust sidered, in order that even heating may resultsystem on the pumping tables, and a control over the whole anode during bombardment.cock is so turned for a sufficient length of The grid dimensions and spacing are calculatedtime to obtain the first degree of vacuum . to maintain definite characteristics in specifiedThe cock is then turned to another position, operating conditions, and in the case of trans- when the table exhaust system is arranged in mitting valves the spacing may be variedthree stages,i.e., mercury diffusion pump, throughout the length of the grid, accordingrotary oil -box pump, and motor -driven re- to the extent to which it enters the field ofciprocating pump. Thelatterisbacking electronic action.The filament diameter andthe box pump to a pressure of I mm. The length arecalculated on thebasis of thebox pump is in turn backing the diffusion emission requiredata temperature whichpump to a pressure of ooor millimetres, and allows of a reasonably long life, allowancethe diffusion pump iscapable of reducing being made for the cooling at the ends and athe pressure in the valve to something below certain decrease in diameter which occurso00000i mm. during bombardment. The pressure is indicated by the McLeod The sealing -in of the mounted electrodesgauge. A liquid air trap is placed between is effected by the use of a special machine,the high vacuum side of the diffusion pump and great attention is required with regard toand thevalvesundergoing exhaustion,to the annealing of the glass.In the case of smallprevent thepossibility of mercury vapour a 684 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 getting back intothis part of the system.grid potential, the extent of which is a clear Electrical or pressuretestsare appliedto indication of the pressure in the valve and determine the exact condition of the valveof any evolution of gas from the heated during exhaustion.The current in the valve electrodes,Thistestisnotcarriedout

Transmitter type M.T.6.Designed to operate with anode potential of io,000 volts and dissipating 400 watts. anode circuit is adjusted so that the energywhile the valves arestill connected to the dissipated would be the amount that would bepumps, because in this case the gas would be desired to test the valve.This current is cleared by their action as it was evolved.The kept constant by increase and decrease oftest is applied by dissipating a definite wattage AUGUST 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 685 in a specified time, and then comparing thethen turned off and the oven allowed to cool gauge readings at the beginning and end ofdown to a definite temperature, when itis thetest, which will, of course, show theremoved and the valves again connected up amount by which the pressure has increasedto the several terminals on the inside of the

Large Transmitting Valves being exhausted.The pumps are on the left and the remote control switch on the right. during that time owing to the evolution of gas.cage, thus connecting anode, gridand fila- When the requiteddegree of vacuum hasment to their respective circuits, after which been obtained, an oven is brought down overthe cage is placed in position, and then bom- the valves andleftthere untilasuitablebardment can be commenced.This is done temperature isreached.The gas heateris slowly and withgreatcare,theoperator 686 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 26, 1922 watching for the appearance of the blue glowpreliminary bombardment. The processis indicating ionisation.In the early stages ofthen repeated, commencing again with the bombardment, theblue glowwillappearfirst valve, until it is found that the glow is before there is any visible sign of the anodeaccompanied by visible heating of the anode.

1 Type T25o.Requires an Anode Type T3o. A low power Transmitting Valve Voltage of 2,000, anddissipates dissipating 3o watts. I -kW.Overall length 28o mm. heating.As soon as the glow appears, theExperience alone on the part of the operator filament current is reduced to zero, and thecan show how long it is safe or wise to allow next valve proceeded with in a similar manner,the filament current to be maintained while there and so on until the entire batch which theis blue in the valve.Two things may occur : operatorismanipulating has receivedthiseither a rapid increase in ionisation, resulting AUGUST 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 687 in a flash over between anode and filamentto valve users.Itisthis extreme care in which would destroy the valve,or a serioustestingthatassures one thataparticular wasting of the filament due to bombardmentvalve can be relied upon to function correctly of positive ions.Even an experienced operatorin a particular circuit, and for the purpose may produce valves which, though being goodfor which it is required, and the M.O. Valve as far as vacuum is concerned, may have theirCompany, fully appreciating the importance filaments wasted to such a degree as to causeof the standardising of the various types of them to be rejected on subsequenttests,valves,have laid down an extensive and on account of the required filament voltageelaborately equipped Test Room.Every valve being too high.Further, itis clear that ifduring manufacture bears a registered number, this did not happen to be the case, such wastageand records are kept showing theresults would result in a short life for the valve ingiven on test. service. The next and last .tage in manufacture is Before completing the bombarding processthe fitting of the cap with, in the case of the and sealing off, the valves may again be heated" R " valve, a four -pin socket.The capping in the oven to further ensure the absorptionand the soldering -off of the valve leads is of all the available gas from the glass. executed with the same care that is shown in The operation of sealing off after bombard-the other stages of manufacture, and in this ment is one that requires skill and care.Itcase with the object of maintaining insulation will be realised that in the baking process theduring soldering and the correct spacing of glass cannot be brought up to its softening -the leads in the socket.The valves are then point on account of the low pressure insidemarked with type number and manufacturing the bulb, and consequently there is a com-details, and are ready for the market. paratively large amount of gas in the glass, Particulars are given below of the more which is not released during the process, sofamiliar types of valves manufactured by the that when the blowpipe is applied to the sealingM.O. Valve Company, Ltd.The purposes tube to seal off, gas will be liberated, and if afor which the various valves are suited is too careless operator heats a larger surface than iswide a subject to enter into here, but a few absolutely necessary, or prolongs the operationbrief notes on the action of the more important for too long a time, the pumps will not bereceiving valves may be helpful. able to clear the liberated gas quickly enough, The " R " type is the well-known French and so it will be sealed inside the valve, soform of valve, and is extensively employed that it will not pass the subsequent tests. for general reception purposes.It gives good The electricalequipment used invalveresults as a detector, L.F. amplifier, or oscil- manufacture isone provided with alargelator, and is one of the best all-round valves range of voltagesin both alternating andfor use where it is not desired to employ a continuous current, ranging from to to 20,000special type for a specific purpose. volts, for the purpose of supplying anode, grid The " R.4B "isintended for use asa and filament potentials, and for operating thedetector or for low frequency amplifying.It usual indicators, lamps and automatic switchhas a long life, and its filament voltage is gear. well within the capacity of a 4 -volt accumulator. The careful testing of valves is of the utmost The " R.4c " is very similar to the " R.4s " importance.Tests are made to determineand operates on the same filament and anode the emission foragiven filament -current,voltages, but has a slightly more open grid filament -plate -current,filament -grid -current,and lower impedance.It gives silent amplifica- and plate -current for given fluctuations oftion, and has a long life. grid potential.The valve isalso carefully The tubular " Q " valve is for use chiefly as scrutinised as to the concentric arrangementa rectifier, though it can be used as an amplify- oftheelectrodes.Asmentionedearlier,ing valve and for all general receiving work. only those valves are passed which come within The " QX " is an efficient rectifier, and is certain specified standards, which allow of onlyalso employed as an amplifier after several a smalldeviationfromtheprescribed stages of H.F. amplification.It is also suitable characteristic.This assures that all valves ofas an oscillator. a particular type can be relied upon to have The " V.24 " is intended chiefly for use as certainpropertiesandbeinterchangeablean amplifying valve, both at high and low with one another-a very important propertyfrequency, and also as a low -power oscillator. 683 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 The " F.E.I " is a four -electrode valve. such highly efficient valves on the market. Particular reference should be made to aThe credit of tackling the problem of the new type of valve which has been developedthermionic valveinthe proper way and by the M.O. Valve Co., in conjunction withmanufacturing in quantity belongs to them by the Research Laboratories of theGeneralrightundisputed,particularlyduringthe Electric Co., the great advantages of which War.This work-one of those aspects of will be apparent to every valve user.In thewar work almost unknown to the public-had case of an ordinary " R " valve the filamenta very direct bearing upon the result of the

A Test Bench where Valves are examined and data recorded. is run from a four -volt accumulator, and takes struggle,asvalvescouldonly be manu- a current of about o7 amperes.The newfactured in a factory where there were already valve has a special filament, not of the coatedhighlyskilledworkers accustomedtothe type, which requiressomethinglessthanintricacies of incandescent lamps, and itis 2 volts on the filament, while the current isvery doubtful whether we should have been in some cases as low as oo6 amperes.Valves able to hold our own in the under -sea warfare, of thistype,itisunderstood, are almostand to carry on the war in the air with anything ready to be put on the market in large quantities,like success, without the resources of this the first production in all probability being'company being at our disposal. valves running at 1.8 or 2 volts with a filament current of say oo6 to ox amperes. It will be apparent that these valves can be run from small dry cells. A description of valve manufacture would We areindebtedtotheGeneralElectric not be complete without making mention ofCompany, Ltd., and Marconi's Wireless Tele- the enormous amount of research work whichgraph Company, Ltd., for assistancei nthe has been conducted by the M.O. Valvepreparation of this article and the loan of the Company, so that they are now able to placeillustrations of the various valves. AuousT 26. 1922 THE WIRELESS WORLD AND RADIO REVIEW 689

Fig. The station building of the Continental transmitter. The Trans -Continental Wireless Station of Sainte Assise THE foundation stone of the wirelessof Bordeaux, the Paris station being about stationofSainte Assise, known astwice as powerful. ParisRadioCentral,waslaidon The Compagnie Generale de T.S.F., who January 9th, 1921, and the first message washave constructed and who now operate the transmitted from this station on the morningstation, have carried out the work on a grand of July 4th, 1922, at r i o'clock G.M.T. scale.The site of the station is on the plateau The stationcalled up Marion, U.S.A.,of SainteAssise,about twenty-fivemiles on a wavelength of 14,3oo metres. Communi-from Paris (Fig. 2).The area covered by the cation was immediately established, and handstation is bounded on the north by the road operation was then replaced by high speedfrom Seine Port to Sainte Leu, on the south automatic transmission. and west by the Seine, and on the east by During the afternoon, Senatore Marconi,the railway from Melun to Brunoy.The from his yacht Elettra, in the neighbourhood siteis approximately level, and the soilis of New York,reportedexcellentsignals. sufficiently moist at all times to ensure an A further telegram of congratulations afterefficient earthing system. Many conditions moredetailedobservations,wassentbywere laid down by the French Ministry of Senatore Marconi on the following day. Posts and Telegraphs when the erection of the Since that date, observations from all partsstation was sanctioned, and it was some time of the world signify to the very high efficiencybefore thissite was selected which would of the station.Sainte Assise was formallycomply with them all. opened on August 17th, 1922. There are two main buildings which serve Previously, the wirelessstation of Croixto house the station, and these are occupied d'Hins, near Bordeaux, which was opened atas follows :- the end of 192o, has claimed the honour of (r) Two valve transmitters of 5 kW. each, being the most powerful wireless station of forshortdistancecommunications,the the world.The power of the new Sainte aerials being supported on a tower about Assisestation, however, now eclipsesthat 33o ft. high. 690 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 26, 1922 (2) A " Continental "station(Fig.x), may also be used independently for duplex consisting of four high frequency alternators transmissions. with an aerial input of 25 kW., for European (3) An " International "station,con- services. sisting of two Soo kW. high frequency The aerial, which is of the " double cone " alternators and two of 25o kW. each. type, consists of four independent networks, In this case the aerial consists of a double and is supported by a single tower 83o ft.network suspended horizontally by sixteen in height. towers, each 83o ft. high.

Fig. 2. Map showing the location of the Transmitting Stations at Sainte Assise, and the sites of the Receiving Centres.

. The earth system consists of 240 square Two sources of power supply are available, yards of copper plates and ten miles_ ofone a power distribution network, and the other buried copper wires. an emergency installation of three Diesel en- The four alternators (Fig. 4) can be rungines each of i,800 H.P. The station can trans- independently, or they can be used inmit either with one machine of 25o kW., or combination to increase the output.Theywith two such machines coupled, or similarly AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW 691

Fig. 3Room from which the transmitter is controlled.

Fig. 4.High Frequency Alternators. 692 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922

Fig. 5.A view of the operating tables in Paris. with one or two machines of 500 kW., or itde Grevelle, by means of high speed Baudot may conduct two simultaneous transmissions.and Hughes telegraphic apparatus.The re- The stationsarealldesigned to handlecording apparatus for reception is all located traffic ata speed of atleasttoo words aon the same operating tables (Fig. 5), and the minute, so that with all six working trans-arrangements are very similartothoseat mitters at the same time, 36,000 words anRadio House, London. hour may be transmitted. The receiving stations are distinct from the Both the transmitting and receiving stationstransmitting centre, and these are located at arecontrolledfromtheBureauCentralVillecresnes, 22 kilometres S.S.E. of Paris, at Radioelectrique, Rue Montmartre, Paris, in theEssonnes, 3o kilometres south of Paris, and centre of the business quarter.In additionValenton,18kilometresS.S.E.ofParis. this office is connected with the two principalThe location of these places may be seen from Paris telegraph offices of the Bourse and Ruereference to Fig. 2. DO NOT FORGET THESE DATES ! SEPTEMBER 30th TO OCTOBER 7th, 1922 The Wireless Exhibition and Convention AT THE HORTICULTURAL HALL WESTMINSTER, S.W. AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW 693 A Suggestion for the Experimenter By G. P. KENDALL, B.Sc.

DURING the war a telegraph instru- The principle upon which the instrument ment was evolved which had amongworked was the conversion of the very small othercharacteristicsthatofextra-continuous current into an intermittent current ordinary sensitiveness to minute direct currents.consisting of brief pulses of much greater It is the purpose of this contribution to suggestvolume,separatedbycomparativelylong that the investigation of the properties ofintervals during which the line current was similar circuits would be a promising line forbeing stored up in condensers.The pulses, the experimenter who isinterested in theof course, followed each other at a suitable problem of C.W. reception without valves,note frequency.The relation of line current orat anyrate,without localoscillations.to receiver current will be more clearly seen The sensitiveness of the instrument referredfrom Fig. 1, where the two are represented by a to was achieved entirely by means of a corn -dotted line and a full line respectively. How it was done will be understood from the simplified circuitofFig. 2,inwhichis an iron core choke L, a i mfd. condenser, and an interrupter R running at, say, Soo cycles per second.The mode of operation isas TIME follows :-Suppose the key K to be closed Fig. I, at a moment when the interrupter is " making." The line current will pass through the choke, bination of filterand interruptercircuits,the interrupter and the receivers.The next and not by the use of any type of relay ormoment the interrupter contacts open and amplifier. As an instance of itsefficiencythe current can no longer flow through the this should suffice :-A certain signal officer was in the habit of demonstrating its powers by an experiment in which the sending battery A consisted of an orange into which were struck an army knife and fork, while the " line " was a chain of twenty men holding hands. It can be imagined that the current obtained from such a combination of feeble cell and high resistance line would be very small, yet on being applied to the terminals of the set (L) Fig. 3. (R) it produced good strong signals in the receiver, which was a rather insensitive pattern of onlytelephones, but is forced by the choke to go on flowing somewhere, and therefore charges thecondenser. The linecurrentisthus more or less maintained until the interrupter contacts close again, when the flow through the telephones is resumed, greatly augmented by the discharge of the condenser.Repetition of the cycle then occurs, and continues so long as K is Fig. 2. depressed, producing a note in the telephones. The suggested use of this type of circuit zo ohms resistance.It was said, though theis the detection of the minute d.c. which appears writer never had the opportunity to put theat the terminals AB of Fig. 3 (L) when receiving statement to a rigid test, that signals couldC.W. A circuit which would probably give be received through a line resistance of agood results when connected to the respective megohm with only a single dry cell at theterminals of Fig. 3 (L) is given in Fig. 3 (R.) The sending end. success of circuits of this type depends largely c 2 694 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 26, 1922 upon suitable values for chokes and condensers, various ex -government telegraph sets now and itis here that a little experimenting is on themarket.These buzzers (known required.The following data isgivenas as the D Mark III Type) can be easily starting points arranged to buzz on one contact only, ooos mfd. leaving the other free for use as an inter- T = 120 ohm Brown telephones (pro- rupter.Of course, a motor -driven one can bably better than H.R.). be used if available. C2 and C3 = 1 tor mfd. (try 1 mfd. The crystal detector employed should be first, then larger values). a Perikon, or, failing that, some other combina- Li and L2 = Say, j x 3 in. core andtion which does not need a potentiometer. i oz. of No. 42 D.S.C. wire. The above values are likely to require a R = Interrupter, preferably one of thegood deal of modification, but as they stand army double contact buzzers, which canwill probably give considerably better results be obtained quite cheaply from one of thethan the pre-war " tildter " circuit.

Wireless Without an Aerial A NEW LINE OF EXPERIMENT FOR AMATEURS By PERCY W. HARRIS.

THE aerialproblem, which presentsoperates on any electrical circuit from 32 to certain difficulties even to those who120 volts D.C. or A.C."Similarly we have have their own ground on which tothe " Marble Antenna," which " completely experiment,isparticularlytroublesometoreplaces all ordinary wire aerials and outside theflatdweller.Possessors of multi -valvewiring A beautiful ornament suit- sets can of course utilise a frame or loop, andable for office or library," and so forth.Price a certain amount of successisobtainable 3 dollars. with wires slung across the room. But neither The writer has no direct knowledge of the of these expedients gives results comparableconstruction of these wonderful new instru- with those given by an outside aerial. ments, but he can make a shrewd guess. American wireless literature has recentlyIn any case, he has succeeded in duplicating contained announcements of experiments by the results with the simplest possible apparatus, Major -General Squier and others wherebyand the results of his experiments are hereby an outside aerial is dispensed with entirely,offered to other amateurs. the electric light mains being utilised instead. The first clue was obtained from the latest The idea is certainly attractive, and alreadyadvertisementofaerialreplacingdevices. severalfirmsareadvertisingattachmentsWhen one of the leading condenser companies under fancy names for connecting ordinaryadded such a device to their list, it certainly wireless apparatus to the mains.Particularlyseemed likely that a condenser formed part with alternating current supply, it might beof the equipment.Having two or three ex- imagined that this connection would occasioncellent Navy -type ooor variable condensers, a terrible howl in the 'phones, but such isthe writer wired them, two of them as in not the case. the accompanying diagram, connecting one to The current American wirelessjournals ineach wire of the mains, by means of an ordinary particular contain several such advertisements.plug attachment, the other sides of the con- We have, for example, the " Super -Antenna"densers being attached to a common wire taken (price $2.80). " It is fool -proof and shock -proofto the aerial terminal of the set. The receiving and can be used effectually in place of over-apparatus was that described in recent issues headantenna. No powerisused when(a four -valve set for short wavelengths), and operatingwitha Super -Antenna." " Itthe tuned anode circuit was set for 600 metres, AtrGun. 26 1922 THE WIRELESS WORLDAND RADIO REVIEW 695 as there is always " something doing " on Series tuning condenser 00002I mfds. this wave. Burndept shortwave coil No. 4. Without daring to put thephones on, Atmospherics were about the same strength the writer switched on the valves, expectingas with the outside aerial, and switching off a terrible howl. There was neither howl northe light (or what would have been the light signal. Various adjustments of the aerialif there had been a lamp in the socket) reduced tuning condenser in parallel were tried withthe strength of the signal to about a tenth no result.The condenser was then placedof its previous value. inseries,and almostimmediately North Foreland came in loud and clear on three valves. Tuning with the series condenser was extremely sharp, and a vernier would have been useful.Other channel stations, such as FFH (Havre) were also heard with the phones on the table. For the initial experiments the two con- PLUG TO MAINS densers on the mains were both carefully set at maximum. Any alteration of the values was found to alter the tuning very considerably. When retuning was effected, the signals were practically the same strength with the condensers reducedtonearly minimum, and wide differences in the two values were tried without altering the general effect, other than the tuning. As a guide to other experimenters, it may 0 00I/ur 0.001/t F be said that to get ships signals it is necessary MAXIMUM to use a condenser in series with a coil which, MAXIMUM attached to an ordinary external aerial, would need a small condenser in parallel. A No. 5o plug-in coilneeds o0005 approx. in series 0-001/1F for tuning, and two ooor mfd. condensers on the mains to give North Foreland at about MAXIMUM half its capacity. Experiments were thentried on shorter waves, and Major Parker(2 ON) may be interested to hear that his tests with 2 KT. and N2 50 Luton on Monday evening, August i4th, were COIL very useful." The Lost Chord," " Vesti la Giubba," and other selections, as well as the familiar " Hullo, Hullo,Hullo ! " were audible all over the house on four valves and the loud speaker, whilethreevalves and the loud speaker were good enough for the occupants Diagram, showing Circuit. of the room. The coil and condenser already found satisfactory for 600 metres, were used, A few experiments have been made on and tuning was effected alternately on the mainslong waves, and Stavanger and Nauen suc- and the set, to see what difference was found.cessfully received, but on the night these ex- Again the tuning was found very critical,periments took place static was extremely bad although wide differences in the mains con-on outsideaerialand the mainsequally. densers, when compensated in tuning, wereThe first impression is that the efficiency is not found equally satisfactory.As an example,so great on long waves. On short waves such excellent results on 2 ON were obtained withas 600 metres and the concert band, this the following adjustments :- method seems much superior to any indoor Mains condenser o000imfds. aerial so far tried.There seems no noise Mains condenser 2 .. 0'0005 mfds. whatever from the mains themselves. 696 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 Notes Imperial Patent Rights. inthiscountryforthe apparatus to enab'e A conference was held at the Patent Office, electricbatteriestobe chargedfromA.C. London, to consider the practicability of institutingcircuits, known as the Homcharger, are Messrs. a system of granting patents which would beAshworth and Smith, Bridgewater House,60, valid throughout the British Empire.The Chair- Whitworth Street, Manchester. man was the Comptroller -GeneralofPatents, Designs and Trade Marks, Mr. W. Temple Franks, South London Club's Exhibition. and representatives from allover the Empire, Under the auspices of the South London Wireless except Newfoundland, were present. and Scientific Club an exhibition is being held at A report of the conference (obtainable fromSt. John's Institute, Larcom St., Walworth, S.E.17. H.M.S.O., Is. ld., post free) has just been issued,The Exhition opened on Thursday at 2 o'clock and in which it states that an agreement. was reached,closes on August 26th at 10 p.m.One of the without calling witnesses, that a British Empire specialfeatures of this exhibition is a wireless Patent, otherwise a patent which would be operative controlledairship in operation by the inventor throughout the Empire, would be desirable pro- Capt. de Villiers.Other attractions are a wireless vided it in no way affected the autonomy of the controlledtorpedoboat,broadcast receptions, Dominions and India, or the rights and facilitiesnumerous trade and amateur exhibits, and frame which an inventor at present enjoys in these coun-aerialtransmission and reception. St. John's tries.With this object they decided on a scheme Instituteis two minutes walk from Southwark for the establishment of a central office for the Town Hall and the same distance from the Elephant reception and examination of applications for, and and Castle.Admission to the exhibition costs One the grant of, patents.Until it should be possible Shilling.Refreshments areobtainableonthe to introduce the full scheme a provisional schemepremises. was adopted.The conference was of opinion that whether or not the schemes suggested were found Radio in Northern Canada. to he practicable, it was of the highest importance Broadcasting, both in the United States and that both the procedure -and practice in respectCanada, has made life in the Porcupine Goldfields of the grant of patents should be uniform throughout very different.Concerts, market reports, educa- the Empire. tional lectures, etc., are now received. Demonstration at Broadstairs. Vacuum tube sets are used, and one amateur A demonstration and concert were conductedespecially has had exceptional reception from in the Pierremont Hall, Broadstairs, a few days American amateurs over long distances, using very ago.The apparatus used was constructed by small power tubes. Mr. P. F. Cotton, and the Brown loud speaker The largest gold mine, the Hollinger, is equipped was lent by the makers. with an expensive tube set, and another large The function, which was organised by the Broad - mine is installing one also. stairs and St. Peters' Echo, was the outcome of A mining student of Queen's University, Kings- experiments which have been proceeding for some ton, Ontario, says that wireless telephony is greatly time.Perhaps one of the most persistent amateursappreciated in these parts and all out-of-the-way in that district is Mr. A. H. Pound, who sinceplaces, but that disappointment was expressed 1909 has carried out research until, with the co-when advertising began to creep in. operation of Mr. Cotton and the influence and practical aid of the local newspaper mentioned Secretary of the Norwegian " R.A.K." above, a public demonstration was attempted and Mr. Kaye Eystein Weedon points out that he met with complete success. is not, himself, the Honorary Secretary of the The precaution was taken of warning the audienceN.R.A.K. (Norwegian Wireless Amateur Club) as that owing to the close proximity of the North stated in our note on " Conditions in Norway," in Foreland station, interruption might take place. July 22nd issue. As the North Foreland Station is only 2,000 yards from the Pierremont Hall, there was some interrup- PCGG on August 17th. tion, but not so much as to disappoint the audience. Broadcasting of the Daily Mail concert from the Esperanto and Internationl Wireless Trans-Hague was suspended on August 17th on account missions. ofthefuneralofViscount Northcliffe taking Perhaps in the near future we shall hear more ofplace on that day. Esperantoinconnectionwithwirelesstrans- Senatore Marconi's tribute to Lord Northcliffe. missions.Dr. Pierre Corret, Editor, La T.S.F. At the annual general meeting of Marconi's Moderne, who is an enthusiastic supporter of this Wireless Telegraph Company, Limited, Senatore language, proposes to make transmissions from Marconi said :" It is with very deep regret that his station in Paris in Esperanto.An interestwe learn of the death of Lord Northcliffe.No man is also being taken in the subject by the Americanin this country has done more for journalism and Radio Relay League, probably in view of the possi-the dissemination of news. We feel we have lost bility of international amateur transmissions of a valued and respected friend, for Lord Northcliffe the future. always followed and took the keenest interest in Agents for the Homcharger. the development of wireless telegraphy and wireless We are now able tostate that the agents telephony." AUGUST 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 697 British Wireless Relay League (B.W.R.L.). Princess Road, Manchester.Suitable agenda will Mr. Y. W. P. Evans, Hon. Secretary of thebe drawn up and distributed to those in favour of Manchester Wireless Society, has obtained per-the League.Suggestions will be welcomed, and mission from the Postmaster -General to form a any assistance will be appreciated. British Wireless Relay League, which a great many Teletype in American Aeroplanes. amateurs possessing transmittinglicences have An announcement is made by the United States been looking forwardto.Mr. Evans willbe Navy Department that an apparatus has been pleased to hear from those interested with a viewperfected for the use of airmen in communication to forming such a League as early as possible.with the ground.Signals corresponding to letters With a good organisation, and assuming that thestruck on a keyboard are automatically sent out forthcoming transmitting tests between the Man- by the wireless set and are received on a special chesterWirelessSocietyandtheAmerican type of instrument corresponding to a typewriter. Amateurs are a success, there is a possibility of the German Demand. scheme providing a means of opening up a vast German inhabitantsof Swakopmund, South- fieldfor the experimenter.Letters should beWest Africa, have demanded the re-establishment addressed to Mr. Y. W. P. Evans, 2, Parkside Road, of a wireless station. 2 FG. THE TRANSMITTER AND RECEIVER OF Mr. L. H. McMICHAEL.

The main panels represent to the left-hand side a five -valve receiving set, 2 high frequency, r detector and :2 low frequency, with the necessary meters and arrangements for using either coils behind the panel or external tuning coils.The loud speaker speaks for itself. The right-hand side of the main board contains the transmitting set and the lower pair of valves are for rectifying 3,000 A.C. current, the upper pair of valves for transmitting, one a power valve and one a control. Two microphones are available, as will be seen, for use with the change -over switch. The whole set is mounted in an ex -Marconi ship's oak cabinet.The lower portion can just be seen, and it has two doors which open, and inside are housed the transformers, chokes, condensers, accumulator charging rectifier and the accumulators.To the left on the wall, under the distributing board, is a five -valve set, and to the right of that the T.F. three -valve set.A most efficient instrument.Change -over switch for transmitting and receiving is to the right of this again. 698 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 report being very easilyfollowed.Croydonis Correspondence not bad, but PCGG and 2 MT are of practically To the Editor of THE WIRELESS WORLD no use up here until H.F. amplification is added. AND RADIO REVIEW. On long waves the longest range yet is NPM time signals, about 9,500 miles.Might I take this SIR,-Since the last letter I wrote, an acknow- as good for such a combination of valves as I employ ledgement of which I received to -day, in answer to-1 rectifier and 1 L.F. note magnifier ? Mr. Stephenson, I have often been able to pick up the harmonics from EAB on 430 m. that he refers to. A. C. DRUMMOND. On comparison with the fundamental I find this much stronger than the harmonic, but not to the degree that one might expect after comparing the strength of harmonics from GBL. With reference to this last station, the signals Book Review from GBL are readable on the 19th harmonic, THE SIGNAL SERVICE IN THE EUROPEANWAR just below 450 m., using two valves, one rectifier OF 1914TO 1918(FRANCE). By R.E. and one L.F. note magnifier. Priestley,M.C.,B.A.(lateMajor,R.E.). I enclose a photograph of my station, which is Published by the Secretary, the Institution of entirely home-made, with the exception of valves, Royal Engineers, and by the Signals Associa batteries, phones and instruments and such details tion.(Chatham :W. & J. Mackay rk Co., as studs and terminals.In your paper I have Ltd.) noticed, in reply to correspondents, that you have The aim in the preparation of this book has been been giving advice about engraving and fillingto present a full yet concise history of the British ebonite. Signal Service in France during the greatwar. The work covers the evolution of signal policy, organisationandpractice from the date that British troops first landed in France uptothecessationof hostilities. The preparation of such a volume could only be the result of a vast amount of work on the partof the compiler,coupledwitha keen observationexercised over a long period of practical experience of the lessons of the war asaffectingthe signal service. Itisobvious thatone difficulty which must have beenexperiencedwasto sort out from an immense amount ofavailabledata, that which was suitable to be utilised in the preparation of such a history. In my set this was done by engraving bymeans All those who were associated with the Signal of the usual hand -tool, and filling in bymeans of Service during the war cannot fail to appreciate white water colour.This makes a very good to the full the opportunity which this book affords finish, and the paint is not liable to fall out. Oil of going over again the account of the activities paint, ofcourse,is better, and both methods of the Signal Service in all aspects of the campaign, are cheaper than filling with special wax. this tittle being able to appreciate thereason for Since the photograph was taken a condenserevery fresh move in organisation or practice as it (0.0005 mfds.) has been fitted across the reaction. became necessary with the changing aspects of the Behind the tuner in front is a change -over switch,Army's activities. changing from the tuner in front to the one on the No attempt has been made in this volume to deal right.This large tuner may be used for wave-with the work of individual signal units, and the lengths of from about 5,000 to 30,000 m., and is tapped below 5,000 m., but not used on theseauthor rightly suggests that such a course would ranges. have been undesirable. Tuning on short waves is done with basket The book contains several illustrations of interest, coils, sometimes using those with spaced windings, whilst at the end a number of charts are given or " Lokap " coils. illustrating the distribution of signal units and I find the basket coils best organisationforcommunicationsatdifferent for this work, however. stages of the war. The best telephony received here is FL, which comes infairly strong and clear, the weather AUGUST 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 699 A New Publication. Calendar of Current Events Underthetitleof" JournalofScientificSaturday, August 26th. Instruments," there has just appeared a preliminary SOUTH LONDON WIRELESS AND SCIENTIFIC CLUB. number ofa monthly publication produced by Last day of Exhibition, opened on August 24th, the Institute of Physics with the co-operation at St.John's Institute, Larcom Street, Wal- of the National Physical Laboratory. worth, S.E. 17. The publication will deal with the principles, construction and use of scientific instruments ofTuesday, August 29th. all kinds. Transmission of Telephony at 8 p.m. on 400 The new journal is introduced in a foreword to metres, by 2 MT Writtle, near Chelmsford. the first number by Professor Sir J. J. Thomson,Wednesday, August 30th. President of the Institute of Physics.Referring SOUTH SHIELDS Y.M.C.A. WIRELESS SOCIETY. to the purpose of the new journal, he states that it 7.30 p.m.-Fowler Street, General Meeting. has long been recognised by many workers that aThursday, August 31th. journaldealing with methods of measurement RADIO EXPERIMENTAL ASSOCIATION, NOTTINGHAM and the theory, construction and use of instruments AND DISTRICT. would have a great value as an aid to research in all 7.30 p.m.-At Room 74, Mechanics Institute, branches of science and industry.There is at Nottingham.Meeting. present no publication in the English languageWEST LONDON WIRELESS AND EXPERIMENTAL which covers this ground.Descriptions of instru- ASSOCIATION. ments and methods of measurement are given in At Belmont Road Schools, Chiswick, W.First journals devoted to particular branches of science ; meeting after vacation. but in such publications results are of primary importance, and little space can be afforded toSaturday, September 2nd. descriptions and detailed drawings of instruments. CROYDON WIRELESS AND PHYSICAL SOCIETY. It frequently happens that instrumental methods Meeting. are valuable for researches of quite a differentMonday, September 4th. character from that for which they were developed, ILKLEY AND DISTRICT WIRELESS SOCIETY. and workers who may be interested in apparatus 8 p.m.-At Regent Café, Cowpasture Road, as distinct from results obtained may never see the Ilkley, Morse practice. publication in question, even if they know of itsTuesday, September 5th. existence. Transmission of Telephony at 8 p.m. on 400 It is proposed that a journal on the lines suggested shall be produced by the Institute of Physics, which metres by 2 MT Writtle, near Chelmsford. will ensure that the management shall be absolutelyFriday, September 8th. independent.It will be managed by a Finance LEEDS AND DISTRICT AMATEUR WIRELESS Committee appointed by the Institute, on which SOCIETY. the Department of Scientific and Industrial Research 8 p.m.-Lecture on " Automatic Telephony," and the National Physical Laboratory, assisted by Mr. H. Mortimer. by a Scientific Advisory Committee appointed by BELVEDERE AND DISTRICT RADIO AND SCIENTIFIC the Institute of Physics. SOCIETY. The expenses of the Journal will necessarily be 8 p.m.-ErithTechnicalInstitute.General considerable, as a high standard must be established Meeting and enrolment of members. and maintained, and it is doubtful whether receipts will cover expenditure, at any rate to begin with. Neither the Institute of Physics nor the Department The Broadcasting Company of Scientific and Industrial Research has funds available to meet a deficit.Steps are being taken The following statement has been issued by the to raise a guarantee fund for the purpose. Committee of Manufacturers who are at present Before it can be finally decided to publish theengaged in creating the Broadcasting Company :- journal, it will be necessary to have some indication The Committee have observed that a number as toitsprobable circulation, and prospectiveof unauthoritative statements have been made readers are asked to notify their intention to sub-with regard tobroadcasting, and desire it to be scribe.It is proposed that the journal be issuedknown that until the British Broadcasting Company monthly, and be similar in style to the preliminary is registered, and the Board of that Company number.The price will be 2s.6d. (postage 2d.has been appointed, no authoritative statement, extra%, or 30s. a year, post free. in so far as the Broadcasting Company is concerned, It is estimated that with a circulation of aboutcan be made with regard to the future of broadcast- 1,000 there will be a deficit of some £2,000 per ing. annum, while a circulation of about 3,000 will The Memorandum and Articles of Association render the journal self-supporting. of the Company are in course of preparation, and as soon as these are approved, the Company willberegistered,and the Board appointed. Thereafter a full statement will be issued." Book Received (Signed) GEo. PELLS, CONSTRUCTION OF NEW TYPE TRANS -ATLANTIC Secretary (pro km. ) RECEIVING SETS.By M. B. Sleeper. (New The British Broadcasting Company. York :The Norman W. HenleyPublishing August 17th, 1922. Compy.Pp. 113.7i" x Marconi House, W.C.2. 700 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 Wireless Club Reports

NOTE.-Under this heading the Editor will be pleased to give publication to reports of the meetings of Wireless Clubs and Societies.Such reports should be submitted without covering letter in the exact form in which they are to appear and as concise as possible, the Editor reserving the right to edit and curtail the reports if necessary. The Editor will be pleased to consider for publication papers read before Societies. An Asterisk denotes affiliation with the Wireless Society of London.

The Wallasey Wireless and Experimentalrian, submitted for inspection a home-made loud Society.* speaker, an adaptation of a motor car petrol -filler. 'Hon. Secretary, Mr. C. D. M. Hamilton, 24, On July 20th, Mr. Taylor demonstrated the Vaughan Road, New Brighton, Wallasey. capabilities ofa home-made -but very well -con- On July 27th the first General Meeting of thestructed and compact one -valve set. Society was held. The Hon. Auditor read the On August 3rd Messrs. J. V. Potter and D. B. balance sheet, which showed the Society to be in a Taylor, after considerable trouble and patience, most satisfactory financial condition. evolved an ingenious three -valve amplifier which It was arranged to print the syllabus for the should equal if not excel the well-known four -valve coming winter session, and also to publish a reportvariety, as the clarity and intensity of the signals on the Society's work in the form of an annualheard by means of this instrument amply justify magazine. the claims made on its behalf. The meeting night, until further notice, will be The Executive Committee, whilst fully realising every alternate Thursday, the next meeting beingthat mere numerical strength is not everything, on August 24th. encourage the bashful but enthusiastic amateurs, Members will be advised by post when fieldknowing that the making of sets is half the battle, meetings are arranged.Friends of the membersand fosters the initiative of members. wishing to attend the meetings will be advised One of the many problems which the Society is of the dates on notifying the Hon. Secretary. tackling is the evolving of a circuit, the use of which The rules of the Society do not permit of visitors will prevent badly manipulated amateur stations attending more than two evenings or field meetingscausing interference, which at the present time is during any one session. causing so much trouble and annoyance. All communications should be addressed to the Leamington, Warwick and District Radio Hon. Secretary. Society. Hon. Secretary, Mr. F. A. Sleath, 31, Archery Blackpool and Fylde and Lytham St. Annes Road, Leamington Spa. Wireless Society.* The first General Meeting of the above Society Hon. Secretary, Mr. C.Sheffield Doeg, " The was held attheheadquarters, onThursday, Poplars,"6, SeventhAvenue,SouthShore, August 3rd.In the absence of the President, Blackpool. Captain Smith -Clarke,M.I.A.E.,M.S.A.E.,the This Society is now well established.Member- Vice -President, Mr. G. H. Champ, carried out the ship is still going up steadily, and an Assistantduties of Chairman, and opened the meeting with Hon. Secretary was appointed a short time ago a brief resume of the Society's position and future to help to cope with the business side of the Society'sarrangements.For the time being, lectures will affairs. be devoted to constructional items and buzzer In June last a branch was opened in the South- practice. West Area of the Fylde District for the benefit Mr. Marriott was then called upon to give a of members who otherwise would have to covershort address, and he compared the crystal and upwards of ten miles to reach the Blackpoolvalve receivers, dwelling on the limitations of the headquarters. former.Mr. Marriott next described the five -valve Although Blackpool is comparatively of humble receiver kindly lent for the occasion by Messrs. proportions, the Society finds support from a Champ and Kay.The set was then switched on district quite as extensive as either Manchesterand almost immediately station 2 KO (Mr.C. or Liverpool. Baynton,Moseley) was heardtransmittinga This departure when made was very muchgramophone selection. overdue ; 25 members were automatically transferred An attempt was next made to receive the Daily from the Blackpool headquarters, and this numberMail concert, but it. was only possible to hear a has since been doubled by new members joining.tremendous carrier wave, and when this was tuned Both a transmitting and receiving licence has beenout, the speech was barely audible in the phones. applied for. More selections were received from 2 KO, and with A transmitting licence for the Blackpool head- the aid of two loud speakers, the music was heard quarters is daily expected, and when it arrivesin the furthermost corners of the room. a broadcasting service is to be inaugurated for the The meeting terminated at 9.30 p.m. with a benefit of its members and others, and also forhearty vote of thanks to the Committee for their an interchange of messages with the Lythamarrangements, to Messrs. Champ and Kay for the St. Armes Station. loan of apparatus, and to Mr. Marriott for his On July 13th, Mr. B. D. Taylor, the Hon. Libra- address. AuGusT 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 701 Manchester Demonstrators. The headquarters are definitely fixed at the A group of the demonstrators at the first of a Y.M.C.A., Claypath, Durham, where a receiving series of popular lectures the Manchester Wirelessstation will be very shortly installed. Society are giving, in order to give the public a Affiliation with the Wireless Society of London better understanding ofthe instruments used,will probably be completed very shortly. especially in broadcasting.In the centre of the A question box is to be fixedin the clubroom back row is Mr. Y. W. P. Evans, the Hon. Secretary for the benefit of members who prefer not to speak and one of the pioneers of wireless, who gave aat the meetings. A full list of officersisbeing most interesting and instructive lecture, assisted prepared.Membershipcardsarenowready. by Messrs. Lamb, Gregory, Barraclough, E.G. After the announcements, a lively discussion Davies and Hall, who are also shown in the group. took place, during which it was decided to have

The Durham City and District Wireless Club.a half hour's Morse buzzer practice at each meeting. Hon. Secretary, Mr. Geo. Barnard, 3, SowerbyMr. Kelly (Hon. Treasurer) presentedthe club Street, Sacriston, Durham. with a very fine loud sounding buzzer of the open The third meeting of the above clubwas held intype.His kind action was greeted with hearty the " Rose and Crown " on Friday,. August 4th. applause.Mr. Nurthen, who is on the Committee, Considering the fact that a large number of thehas undertaken to take charge of the buzzer class, members were on holiday, the attendance washe having had considerable transmitting experience. quite large.Several new members were enrolled. The Chairman made some very interesting remarks. The meeting was a great success.The chairHe was glad the lecturer had mentioned Dr. Gilbert was once again taken by Mr. F. Sargent, F.R.A.S.,as one of the founders of electro-magnetism, and of the Observatory, Durham, in his usual charac- pointedoutthewonderfulachievementsof ft teristic fashion.After the minutes were read andBritishers in the science of wireless. passed, a lecture given by Mr. G. Barnard on " The A further meeting took place in the Y.M.C.A., Electro-magnetic Theory and its Application toClaypath, on Friday, August 18th,at 7p.m., Wireless Telegraphy," proved very interesting towhen a lecture was given by Mr. G. Barnard on the members.He commenced at the very beginning " The Production of High Frequency Oscillations." so that no one would be left behind.At the ter- The Hon. Secretary invites all who are interested mination of the lecture a hearty round of applause to attend the next meeting, or send names and was given, after which the Hon. Secretary madeaddresses of any person, either sex, desirous of some important announcements, among whichbecoming members, so that he may submit them as were the following :- candidates for election to the club. 702 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 The Liverpool Wireless Society. Ladies who are interested in this subject are Hon. Secretary, Mr. C. L. Lyons, 76, Oldhallparticularly invited to join.Particulars of mem- Street, Liverpool. bership may be had on application to the Secretary, A very successful and interesting meeting ofwho will also be pleased to receive offers from any the above Society was held at The Royal Institu- gentlemen willing to give a lecture or demonstration, tion, Colquitt Street, Liverpool, on Thursday last,or to read a paper before the Society on any branch the 10th instant. of the subject, either technical or practical. The early proceedings were devoted to the answer- ing of the question box which had been passedFulham and Chelsea Amateur Radio and round, and Mr. Hyde explained away the difficulties Social Society. of the questioners in his usual inimitable manner, Hon. Secretary, Mr. R. S. V. Wood, 48, Hamble illustrating his answers by very clear blackboard Street, Fulham, S.W.6. diagrams. An informal meeting took place on Tuesday, An advisory committee was then elected, con-August 1st, at 8.30 p.m., at the Stanley Ward sisting of Messrs.S. Lowey (whose four -valve Conservative Club,428, King's Road, Chelsea. station was described in the August 12th issue of Mr. Oliver, the Chairman, explained the reasons The Wireless World and Radio Review),C. J.of the meeting.Discussion was then invited as Williams, W. A. Robinson, Hyde, Forshaw, Hender- to the advisability offorming a local wireless son, Balmer and Coulton. society,and finallythefollowingproposition A vote of thanks was passed in favour of Mr.was proposed by Mr. Scutt and seconded by Mr. J. M. Wilkie, in recognition of his very able workPaterson :" That this meeting take the necessary on behalf of the Society when occupying thesteps to form an Amateur Wireless Society in position of Hon. Secretary, which position he hasFulham and Chelsea."This was carried unani- unfortunately found it necessary to resign, andmously. a new Secretary (see above) was elected.All On thepropositionofMr. Cox and members and interested readers are requested toseconded by Mr. Wood, Mr. Oliver was voted to note carefully the name and address of the newthe chair, and agreed to act for the time being. Secretary. Mr. Glockler was voted to the vice -chair. Mr. Wood The evening was concluded by Mr. A. W.was elected Secretary, all the propositions being Robinson bringing into operation a " Burndept "carried unanimously. A committee of manage- three -valve receiving set (one H.F., one rectifier, ment was then formed of the following gentlemen : one L.F.) very kindly lent to the Society for theMessrs. Scutt, Flood, Fildis, Martin, Paterson and evening by Messrs. Burndept's Manchester agent, Roberts,thiscommitteebeing elected unani- Mr. Barraclough. Very successful results weremously. A discussion took place on a suggested received of both telegraphy and telephony, whichtitle, and that above was agreed upon. were perfectly audible to all present, and which, It was then agreed that the next general meeting in view of the fact that the instruments werebe called after the committee had sat to consider operated in conjunction with an indoor aerialthe necessary rules and details. A vote of thanks of but moderate dimensions, reflected great creditwas proposed by Messrs. Gray and Gauntlet to upon both the operator and the manufacturersthe Stanley Ward Conservative Club for lending of the set. their room.Messrs. Martin and Roberts proposed Anothermeeting washeldattheRoyala vote of thanks to the chairman, both of which Institution, Colquitt Street, Liverpool, 7.30 p.m.,were duly carried, the meeting being closed with Thursday, August24th.All amateurs in theexpressions of appreciation on the forming of a district not already members of the Society arelocal wireless society. cordially invited to join, and are assured of a con- Ladies included, there was an attendance of 70. tinuance of entertaining and instructive meetings. West Hartlepool Y.M.C.A. Radio and Ilkley and District Wireless Society. Experimental Society. Hon. Secretary, Mr. E. Stanley Dobson, " Lorne Hon. Secretary, Mr. S. Tillotson, 34, Tristram House," Richmond Place, Ilkley. Avenue, West Hartlepool. The third meeting of the above Society was held A Society has been formed with the above title, at the Regent Café, Cowpasture Road, Ilkley,and though but a fortnight old the membership on August 10th. is 36. A grant from the Board of Management In the absence of the President, Mr. F. Lawhas enabled the Committee to purchase com- occupied the chair.It was decided to arrange aponents with which to build a three -valve set, the programme of lectures and demonstrations forerecting to be done by the members under the direc- the coming winter session, and all members aretion of the technical advisers, Messrs. C. Kenyon asked to co-operate in this and also in procuringand Wm. Garrett.In the meantime these gentle- permanent headquarters, which arethe mostmen have kindly loaned their own apparatus for important requirement of the Society. the use of the club, and a successful lecture and In order to enable those members who wish todemonstration was held on July 21st.Classes listen in to the Hague concerts, it has been necessaryare held every Tuesday at 7.30 p.m., and instruction to transfer the monthly meetings to the secondis given in the elements of electricity and Morse Monday in each month, and the Morse practicereading. classes, which are now in full swing, will be held The club has erected an aerial, etc., which is on the intermediate Mondays. open to members for individual use at any time. The membershipisstillsteadilyincreasingApplication for membership is to be made to the and new members are welcomed at any of theGeneral Secretary or the Hon. Secretary of the meetings. Society.The age limit is 15 years. AUGUST 26 1922 THE WIRELESS WORLD AND RADIO REVIEW 703 Questions and Answers NOTE.-This section of the magazine is placed at the disposal of all readers who wish to receive advice and information on matters pertaining to both the technical and non -technical sides of wireless work.Readers should comply with the following rules :-(1) Each question should be numbered and written on a separate sheet on onesid eof the paper, and addressed "Questions and Answers," Editor, THE WIRELESSWORLD AND RADIO REVIEW, 12/13, Henrietta Street, London, W.C.2.Queries should be clear and concise.(2) Before sending in their questions readers are advised to search recent numbers to see whether the same queries have not been dealt with before.(3) Each communication sent in to be accompanied by the " Questions and Answers " coupon to be found in the advertisement columns of the issue current at the time of forwarding the questions.(4) The name and address:of the queriet, which is for reference and not for publication, to appear atthe top of every sheet or sheets, and unless typewritten, this should be in block capitals.Queries will be answered under the initials and town of the correspondent, or, if so desired, under a " nom de plume."(5) In view of the fact that a large proportion of the circuits and apparatus described in these answers are covered by patents, readers are advised, before making use of them, to satisfy themselves that thiy would not be infringing patents.(6) Where a reply through the past is required every question sent in must be accompanied by a postal order for the amountof Is., or 3s. 6d. for a maximum of four questions.(7) Four questions is the maximum which may be sent in at one time. " H.A." (S.E.10) has a two -valve receiving set be of the " Q " type, or one specially recommended comprising one detector oscillator valve and one low to function as an efficient detector. frequencymagnifier,with which hesuccessfully receives 2L0, 2MT and 2FQ, and is desirous of " M.B." (Plumstead) has a four -valve receiver, either amending hiscircuitor adding additionalincluding one H. F. amplifier, which gives quite good amplifiers in order that he may be able to receiveresults with a transformer designed to amplify on PCGG. wavelengths between 600 and 1,200, but is unable to Your circuit is quite in order, excepting that it is get good amplification between 300 and 800 metres. not necessary to connect a variable condenser One probable cause of the trouble is, as you across the primary of the intervalve transformer,suggest, that as the set tunes up to a wavelength and this condenser can be made good use of by of 2,000 metres it does not function efficiently on connecting it across the ends of the reaction coil such a low wavelength as 3,000 metres.Two special marked " S " in your circuit diagram. A smallaerial coils should be made for tuning at this wave- fixed condenser should be connected across the I.Plength.You do not give dimensions of the short and 0.P., having a value between 0.001 and 0.002wave intervalve H.F. transformer you use, but we mfds., and may consist of 15 plates interleaved would suggest that you construct one having 180 with mica 0.002" in thickness, and having an over-turns for primary and secondary, wound on a 1" lap of 1" by 1".Seven will project at one end ofebonite former, and separated from one another the condenser and eight at the other.The tuningby a single layer of empire cloth.The windings range of the coils would seem to be sufficient whenshould be in the same direction, and the finishing connected to your two -wire aerial to tune to 1,070 ends taken to grid and plate.This should be metres, the wavelength of PCGG. The additionbridged with a low capacity variable condenser. of a high frequency amplifying valve and anotherFor short wave work you may find it helpful to note magnifier would assure you of good receptionbridge the reaction coil with a low value variable from this station, particularly as we now under-condenser, and also the aerial tuning condenser stand that its power has been increased.A suitable must be connected in series with the aerial inductance circuit is given in Fig. 1.The rectifier valve should for efficient short wave reception.

r""

0 AERIAL CIRCUIT \ 0

Ili- -ill Fig. 1. 704 THE WIRELESS WORLDAND RADIO REVIEW AUGUST 26, 1922 " C.H.C.G." (Otford) encloses a sketch ofa " N.P." (Whitstable) asks rethe pocket set three -valve amplifier and asks (1) Fora method ofon page 747, March 4th issue (1) If it is a mistake using one, two or three valves at will.(2) Which isto have the A.T.I. of No. 36 and the reactance of better, to tune the anode winding or the grid winding No. 26.(2) If the telephones are shown in the of the above arrangement with variable condensers. right position in the diagram.(3) If the positive (3) If three or four lengths of 1" gaspipe wouldterminal on the telephone goes tothe positive of make a satisfactoryearth.(4) If permission isH.T. battery, and whether a long or short dash is required to use more than one valve. used for the positive of batteries in diagrams.(4) A (1) The second method is quite O.K.The first suitable capacity for the aerial condenser. method is also O.K. if arrangementsare made to (1) For general purposes, yes ; but for a " stunt " break the grid coil of the particular valve to whichreceiver of this type the windings givenmay be S is plugged at any time. (2) There is little difference,necessary to get the required wave range, even at but the anode is somewhat preferable.(3) O.K. the cost of loss of efficiency.(2) Yes, but they if the pipes go well down into' damp earth.(4) Ifmay alternately be on the other side of the H.T. the addition of further valves is not covered bybattery.(3) In the circuit shown, to the positive youroriginalapplication,you shouldobtain of H.T. A long thin stroke represents the positive sanction from the P.M.G. of a cell.(41 0.0005 mfds. maximum, minimum " EUREKA " (Durham) asks (1) Ifa circuitas small as possible. sketched is suitable for general purposes.(2) If " K.R." (Bradford).-There does notappear circuit in No. 1 can be altered as in sketch No. 2. to be much to choose between the two aerialssug- (3) If material enclosed is suitable for panels, etc.,gested.The aerial between the houses is probably instead of ebonite. slightly the better.The amplifier suggested would (1) All right, except that the condenser shownbe of no use in conjunction with your set, butyou across the reaction coil would be better acrossmight add any one of the various L.F. amplifiers the telephone transformer.(2) Yes, with similaron the market or described in back issues.There comment to the above.(3) Yes, unless it is to bewill probably be very little telephony withinrange used under very damp conditions, when the surfaceof a two -valve set in Bradford until the broadcast leakage will probably be more serious. service is inaugurated. " IGNORAMUS " (Probus) asks (1) If the " J.H." (Southsea).-It is useless to try and P.M.G. limits the length of aerial foramateurs. bring your wavelength up much by just addinga (2) If so, what is the length.(3) Will the efficiency loading coil to the aerial, although you mightget of an aerial of given length be altered by anotherup to 1,100 metres in this way with your present method of suspension.(4) The advantages of a coils.To get ranges above this we should recom- basket coil over a solenoid. mend using a set of slab coils, connectedup as in (1) and (2) Yes.The length from the lead-inyour diagram, but cylindrical coils should not be insulator to the far end, measured along the wire, used inside each other as shown.(2) 0.0005 mfds. must not exceed 100'.As many wires may be usedis sufficient up to 3,000 metres.(3) Up to 1,100 as desired.(3) A single line is best.Divided upmetres your windings might be as follows-A.T.I. into shorter lengths is undesirable.(4) It is some- 5" x 4" of No. 24, closed circuit and reaction coil what more portable ;also losses in the coils areas you suggest. somewhat smaller owing to the shape of the coil, G.C.C." (Gateshead) asks for adviceon a but this increased efficiency is not great enoughto be two -valveset which behaves in an unsatisfactory of much importance. way. We can see no real cause for behaviour in this " J.D." (S.E.18) asks (1) Ifa crystal receiverway. A condenser across the telephones would and valve magnifier give louder signals thana single valve with reactance.(2) Why his set will not workimprove the set, also we should omit the permanent without a grid leak and condenser.(3) Wiringconnections between the switch arm and P.5. data for A.T.I. We think it likely that the transformer winding has (1) Yes, as reactance is also used in this crystala break, or disconnection in it.Try out all con- and valve set.(2) The set worked quite well asnections thoroughly.As a rule it is inadvisable to originally given.Possibly you have got the wrong use windings given for pocket sets in general purpose value for H.T. or unsuitable potential on the grid.sets, as such windings have generally to be made Try reversing the reaction coil.(3) The set willquite inefficient in order to get thenecessary be unsatisfactory without a variable condenserportability. in the closed circuit. For the A.T.I. use 100 turns " 0.T." (Bridlington) sends sketches and asks with a slider, and for the closed circuit 4"x 21" (1) If he can improve his aerial.(2) Why his set of No. 26. starts oscillating when he gets tuned -in for Croydon, etc.(3) If we can give a wiring diagram for his " CONWAY " (London) asks re the American set. short wave tuner in June 3rd issue (1) If he will be (1) Yes.Raise the aerial further above the roof. infringing patents by making up some of these sets (2) This is apparently due to too much reaction. for friends.(2) Whether the condensers need be If by tuning -in you include the adjustment of the fixed or variable. reaction coil, behaviour is quite normal as signals (1) Seeing that his circuit uses magnetic reactionimprove with additional reaction until the set you will be infringing patents if you sell sets of begins to oscillate.(3) We cannot say how your this type. We cannot undertake to give completeapparatus is connected internally, and therefore advice relating to patents.(2) Neither of thecannot give wiring diagram, and as the set gives condensers need be variable, but somewhat betterspark stations and telephony, except for the howling results would be obtained if the grid condenserwas trouble, there is probably very little the matter variable. ! with the connections as you at present have them. Atrousx 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW

PROM PTDELP7ERY HIGHEFFICIF2I CY CROCROSS WOUND COILS LOWPRICES "Chew coils have been so designed that the overlap of range used is large enough to enable them to operate with success in when shunted with a .000s condenser is sufficient to enable sets not employing autodyne reception. some other number to be used for reaction purposes. Used in crystal sets they replace the old style cumbersome There is no need therefore to purchase a double set. cylindrical inductances. When used in the aerial circuit the wave lengths obtainable These coils can be supplied either mounted or unmounted. from each coil will be lengthened by an amount which will All coils are nicely taped and mounted coils are fixed to depend upon the properties of the aerial in use, this in ma.iy standard British gauge ebonite push fittings. instances approximating about Igo metres. Each of these coils is tested in an oscillatory circuit before The self -capacity of these coils is extremely low, and the wire despatch. PRICES.

I (Subject to Trade Discount.) Ranges when used with root Ranges when used with 'am I Postage extra Sizes. Sim. variable condenser in parallel, variable condenser in parallel. In closed circuit. In closed circuit. Unmounted. Mounted. Each. Each. s. d. s. d. No. No. ' Metres. Metres. 6 4 0 1 1 1 175 - 400 175 - 300 4 6 2 2 250 - 550 250 - 400 2 0 2 3 4 9 3 3 , 325 - 550 325 - 750 4 4 450 - 950 3 0 5 9 450 - 1200 5 5 550 - 1100 3 6 6 3 550 - 1500 6 6 850 - 2000 850 - 1650 3 9 6 6 7 7 1350 - 3000 1350 - 2250 4 6 7 3 0 8 8 1500 - 4000 1500 - 3000 5 0 8 8a 2000 - 6500 2000 - 4800 5 3 8 3 8a

1 8 6 9 9 3000 - 9500 3000 - 6750 I 5 6 If taken in complete set of to coils as above £8 0 0 per set mounted, or £1 150 per set unmounted. Note.-A new coil holder is now available which is strong and simple, and has been speciallydesigned by us to secure the best results with modern narrow low -capacity coil,.Manufactured by 230, UPPER THAMES STREET, LONDON, E.0 4 CROGGON cSzCO., LTD., Also Manufacturers of Enamelled Aerial Conductors, prices on application. Telegram. :-CROGGON, CENT.LONDON. Trade for over 35 years. Telephone:-CITY44711. Manufacturers of Electrical Apparatus to th MAGNAVOX THE WORLD'S FI7\EST RADIO LOUD bringsit MAGNAVOX SPEAKER tellsit. Broadcastingfaithfullyreproduced No. R1282 with marvellous clarity and Tolume (18' Hornl. YOUR Sterling Telephone & Electric Co., Ltd. ENQUIRIES TELEPHONE HOUSE, 210/212, Tottenham Court Road, London, W.1 INVITED. Telephone No.: 4144 Museum (7 Imes).Telegrams: Cucumis, Wescle, London. Works :DAGENHAM, ESSEX. BRANCHES :NEWCASTLE -ON -TYNE :9, Clavering Place. CARDIFF :8, Park Place. ziv THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 For theyare jollygood- -FELLOWS

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EP, AUGUST 26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 705 " R.R." (Paris) asks for a design of an efficient quite satisfactory. " V24 " or French "R " valves may receiver suitable for reception on wavelengths from be used for amplifying, whilst a " Q " should be 180 to 30,000. used for detecting.The H.F. detector and L.F. The use of resistance capacity coupling for shortvalves must be controlled with separate filament wavelengths is not efficient, although small varia- resistances, and itis an advantage to provide tions of the condensers in the grid circuits according potentiometers for controlling the grid potential to the wavelengths on which it is desired to receive of the H.F. and rectifier valves.Separate tappings will improve the results.Your process of calculating might also be arranged for the various valves to the value of this condenser as being directly proportional to the wavelength which it is desired to receive is quite incorrect.The chief consideration is the high impedance of this condenser on short wavelengths. We would recommend you to adopt three to five valves, according to the degree of amplification desired. The circuit shown (Figs. 2 & 3) embodies two H.F. valves, one detector, and two L.F., and can be thoroughly recommended for general Fig. 3. use, but if you so desire you can omit one H.F. and one L.F. valve.The type of H.F. transformer you mention can be thoroughly recommended, give them just the correct anode voltage required. and it might be mentioned that the efficiencyIf you adopt four -pinsocketsfor interchanging of many H.F. transformers israther doubtful,the H.F. transformers, the resistance capacity unit owing to the system of winding adopted. We domay also be built up to plug in for use on wave- not see why you should not construct such trans-lengths above those provided by the transformers. formers yourself, winding them on 1" ebonite rod,The construction of the set described embodies with single layer primary and secondary, insulatedno special difficulties, but we shall be pleased to from one another with a single layer of empireadvise you further should you have trouble during cloth, the finishing ends being taken to grid andi ts construction. plate, and both windings being in the same direction. " F.A.W." (Brixton).-(1) The inductance of Wind with No. 40 S.S.C., and for wavelengths up the coil is about 7,000 mhys., which should tune to to300 metres use 180 turns for each winding;2,500 metres-or more with a parallel condenser. for 600 metres, 600 turns ;for 1,000 metres, 1,300 (2) To get best value for reaction for different turns ;for 1,500 metres use 800 turns, and this timeconditions of wavelength and aerialresistance. on a 2" ebonite rod.Beyond this wavelength (3) This can be done and might give some results, resistance capacity coupling with fixed condensers is but initial L.F. amplification would be better.

Pi (I) 52 Fl Si St-c, °0001p0000yo -Irop

0-0004.1'7-..' \ 2 -fTh c 0

Fig. 2. 706 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 " C.N.G." (Felton) asks how it is that he can on p. 454 of the July 8th issue.This article really ouly receive 600 metre signals on his single valveanswers all your questions. set. " A.B T." (Wolverhampton) asks for details. Your circuit diagram would indicate that yourand diagram for the construction of a telephone set is in order. We would suggest that you arrangetransformer for use with his crystal set.His telephones a variable condenser across the ends of the reactionhave a resistance of 100 ohms. coil.Are you receiving continuous wave signals, We do not recommend you to construct a step- and does your set oscillate ?If not, the reason why down transformer for use with your crystal receiver. you only receive 600 metre signals is that your setYou would be well advised to rewind your telephones will only pick up damped wave signals, the majorityto a higher resistance.This would probably be less of which are transmitted on this wavelength.expensive, and without doubt more efficient, and Your aerial, although inside the roof, is of goodvery little instruction on the method of doing it is length, and should give quite satisfactory results. needed.Use No. 49 S.S.C. for the purpose.If you We hardly recommend the addition of one H.F.are desirous of making a transformer, however, valve as a first step in obtaining increased signalturn to page 343 of the June 17th issue.You will strength. A low frequency amplifier would givefind there dimensional drawings of core and end much greater magnification. plates of the transformer.Wind the primary with " W.C.B.-G.' (Bradford)azika for a diagram No. 47 S.S.C. up to a diameter of i", over which wind of a five -valve receiver, together with details as toa secondary of four layers of No. 32 S.S.C.Insulate size of inductances, number of turns, etc. carefully between primary and secondary. See Fig. 4. Sizes of inductances and condensers " F.B."(Bayswater)submitstwo circuit according to wavelengths required. diagrams, one showing the principle on which his

C> Pm' C>

-I

Fig. 4. " R.M. " (Coventry) is constructing a two -valveapparatus is to be connected, and the other an actual receivingset.He has a number of components,drawing of an inside view of his instrument after and asks for advice on the selection and details of it is wired, and asks if the latter is correct. other parts required. We have carefully looked through the diagrams, Construct your own loose coupler or aerial and in particular that of the actual wiring, and as far reaction circuits.The windings depend upon theas we can tell this is quite in order.In this you wavelengths on which you require to receive, and for have arranged for a reaction coil in series with the a start construct an aerial on your inductances hav-primary of the H.F. transformer, whilst this is ing 4" of winding of No. 26 D.C.C. on a 5" former,not shown in the diagrammatic sketch, in which and the reaction coil sliding inside this consistingno provision is made for reaction.The set seems of 2" of winding of No. 30 D.C.C. on a 4" former,to be suitably wired and should function correctly. arranging tappings at increasing intervals on both aerial and reaction coils.For short wave telephony " R.V.T." (Westminster) asks (1) Whether a reception construct two coils as shown on pagesingle valve frame aerial set will give PCGG. "(2) 328, June 10th issue.The variable condenser should How tuning to various wavelengths is accomplished be of the air dielectric type, and have a maximumon the set.(3) For dimensions of a loose coupler, value between 0.0005 and 0.0015 mfds.The grid if necessary.(4) If the circuit shown in the issue of leak should have a resistance of about 2 megohms. June 10th will work with a frame aerial. " R.4B " valve would be found to give very satis- (1) Not PCGG, but itshould give London factory results.The panel for mounting the two broadcasting and local amateurs.(2) By adjusting valves might measure about 7" x 4i".You would the condenser in shunt across the frame.Not obtain a good deal of useful information by reading necessarily for the frame aerial set but in con- the arti les published in alternate issues on " Experi- junction with an outside aerial it will give much mental Station Design," and in particular the one betterresults.Suitabledimensions have been on the construction of a single valve panel, appearing repeatedly quoted.(4) We are unable to judge AUGUST 26.3% 1922 THE WIRELESS WORLD AND RADIO REVIEW xv with immediate delivery from stock MULLARD TELEPHONE HEAD SETS specially made for the reception of wireless broadcasting, are thoroughly well -made and fit securely and comfortably to the head. British Manufacture. The two high resistance ear pieces (4,000 ohms total) are flexibly attached to the fully adjustable, double head bands. The set is nicely finished in nickelplateandsupplied complete with standard flexible cords. A large stock is available at once butisbeingrapidly booked up.Send the coupon to secure immediate delivery to -day. These telephones are made by themakersofthefamoms ORA valve and Mullatd valve accessories.

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Visit our Stand No. 41.All British Wireless Exhibition, Horticulturar_Hall, September 30th to October 7th Dt avi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 THE " BROWN " MICROPHONE AMPLIFIER This Amplifier magnifies signals, or music, without distortion, and is ofconsiderable interest to amateurs and scientific investigators.The Magnification is much greater than that obtained from two valves, and thecurrent consumptionisabout 5o milliamps.In construction, this instrument is simple, and it is much more robust than other sensitive relays of this class.This instrument satisfies the urgent demand for a reliable, inexpensive amplifier, which the most inexperienced amateur can use, and which the most experienced requires.It is much cheaper, ultimately, than a multi -valve amplifier, and the operator is relieved from many of the varied causes of breakdown.It includes a transformer suitable for low resistance telephones or loud speakers. The price of the " Brown " Microphone Amplifier is £6 for low resistance (120 ohms) input and £6 2s. 6d. for high resistance (2,000 ohms) input. THE " BROWN " LOUD SPEAKER With an Amplifier signals or telephony may be so magnified as to cause discomfort to wearers of headphones, yet not be loud enough to be audible at any appreciable distance from the head.Every wireless experimenter sometimes wishes to let his friends hear, which would involve theuse of several pairs of telephones simultaneously with consequent loss of signal strength, as wellas considerable expense.The " Brown " Loud Speaker was designed to meet this need efficiently and economically, and is used inallup-to-date receiving stations. The soundisintensifiedby means ofahorn. The " Brown " Loud Speaker (120 ohms), Standard Pattern with Upright Funnel .. Wound to special high resistance .. £5 100 . . up to £5 150 THE "BROWN" SUPER -SENSITIVE TELEPHONES FOR WIRELESS,ETC. These Telephones are unquestionably the clearest and most sensitive made, and, consequently, increase the distanceover which the wireless can be heard. IN UNIVERSAL USE. As supplied to British, Allied and Foreign Governments. The " Brown " " A " Type Radio Headphones- s.d. Low resistance .. ..per pair 2 180 High resistance .. . perpair£32s.and 380 The " Brown " " D " Type Headphones (Improved flat diaphragm type)- Low resistance .. .. per pair 280 High resistance .. .. per pair 2 120 The abovetelephonepricesincludeCords. CATALOGUE POST FREE ON APPLICATION. SoleManufacturers:S.G. BROWN, LTD., SHOWROOMS wheremaytheaboinspectInstruments be edye 19, MORTIMER STREET, W.1 Works: Victoria Road, North Acton, London, W.3. Telegrams :" Sidbrownix, London.' Telephone :Chiswick, 1469. Sole Agent for the Argentine :Horatio D. Guerrero, Las Heras, 2480, Buenos Aires. Brown's Wireless Apparatus can be purchased from all Wireless Suppliers. EARLY DELIVERYof Telephones and Loud Speakers can now be given. our CaldNo.43. .A 1l Hitttai AA fireless Exhihit ion, I I (el icaltur tl Hull. S.q,teolher. :loth to October 7th

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CREED & CO., LTD.,Telegraph Engineers,Croydon, Surrey Telegrams : " Credo, Croydon." Telephone : Croydon 2120. AUGUST26, 1922 THE WIRELESS WORLD AND RADIO REVIEW 707 which of the circuits in the article quoted you are " D.J." (Tankerton) has submitted a circuit to referring to. the Post Office for approval, consisting of one valve " T.F.T." (N.W.1.) submits a circuit comprisingarrangedtogivehigh frequencyamplification, one detector oscillator valve followed by two notefollowed by a detector valve, the plate circuit of which magnifiers, and asks for criticism of circuit, particu-is coupled back to the aerial circuit, which has been larly as to its suitability for the reception of telephony.rejected, and asks for a suitable circuit, making use Your circuit is incorrect.When using a common of two valves, and arranged to give high frequency high tension battery for several valves, you must amplification. put all intervalve transformers on the plate side of See the diagram, Fig. 6. the battery.As connected at present, all the plates are fed through the firstintervalve transformer, which may give rise to howling.Also do not bridge both H.T. battery and transformer primary with one condenser, but bridge both with separate condensers.You should connect the aerial tuning condenser in series with the aerial tuning inductance, S and this will give you more inductance in circuit to tune to a given wavelength, and consequently a bigger potential will be stepped off for operating the detector valve.The reaction coil should be bridged with a tuning condenser having air dielectric and a maximum value of 0.0005 mfds. " C.B." (Ipswich) isdesirousof adding a single valve amplifying set to that shown in Fig. 1, and asks whether H. F. or L.F. would be recommended, and for a diagram showing how the amplifier should Fig. 6. be connected. " F.M." (N.4)isconstructing a long range single valve receiver onthe lines described in the issue of February 5th, 1921, and has submitted the circuit shown on page 781 to the Post Office for approval, in making application for a receizing permit.He has been informed thatthecircuit, which is the usual single valve reaction arrangement, cannot be approved, and asks for a suitable circuit diagram.

E Fig. 5.

With only one additional magnifier, we recom- Ci4 mend that it should be of the low frequency type, and the method of connecting is shown in Fig. 5. " BENCLAY " (Port-Madock) asks (1) For the wavelength of a certain loose coupler.(2) For information in regard to a certain transmitting set. (1) This coupler will be suitable for tuning to about 2,000 metres.(2) We regret we have no o information about this set. 7 " P.A." (Tottenham) asks(1) If a certain Fig. 7. crystalsetiscorrectlywired.(2) If telephones marked " 40 w " are suitable, and what the figures stand for.(3) If he should be able to get signals. There would seem to be some doubt at the (4) If any rearrangement should give him signals. moment as to the type of circuit that one is per- (1) We cannot say from the type of sketch youmitted to adopt.The circuit you refer to is very send.For instance, your potentiometer appearsextensively used and is the one usually recommended to have five terminals, but there is nothing to showto beginners, though, of course, it is liable to give us the relation each of these terminals bears to therise to serious interference as the number of users internal wiring.(2) The telephones are unsuitableincreases, and we appreciate the action of the Post for use except with a telephone transformer.The Office in now forbidding its use.Re -radiation can figures give the resistance of the windings, whichbe considerably reduced by using a two -valve in this case are low.(3) No signals are likely circ it as shown in Fig. 7, in which the plate circuit without change as in 2, but we cannot say whetherof the second valve is coupled back to the inter - results will then be obtained.(4) Arrangement asvalve high frequency transformer, and we have in Fig.1, page 404, June 24th issue, would giveno doubt that the Post Office will be prepared to satisfactory results. give you permission to use such a circuit. 708 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 " B.W.H.." (Widnes) 1) Submits a circuit of a changeable plug-in scheme.The primary circuit five -valve high frequency amplifier, giving values of these transformers should be tuned with small ofallcomponents, and asks forcriticism.(2) variablecondensers,which have a maximum Submits a circuit of a five -valve amplifier consisting value of about 0.0001 or 0.0002 mfds.As switches of two H.F. transformer coupled valves and three are being provided for various apparatus, it would note magnifiers, and asks for criticism.(3) How be a good idea to arrange one for connecting the to add three stage H. F. amplification to the Armstrongaerial tuning condenser either in series or parallel super -regenerative circuit.(4) Values of the com-with the aerial tuning inductance.The reaction ponents in building up the set. coil should be bridged with a tuning condenser (1) You do not say the wavelength on which ithaving a maximum value of 0.0005 mfds., and all is intended to obtain H.F. amplification, and pre- variable condensers should have airdielectric. sumably you have tested the use of 150 turns asSlightly better results would be obtained were an beingsuitablefor your purpose ;but we areindependent aerialcircuit adopted, to which a of opinion that 150 turns isonly suitable up secondary is coupled, and carried on to the terminals to wavelengths of 400 metres. Yourcircuitmarked B and G.You do not show the con- inprincipleisquite good forswitching from struction of the coils, but we would recommend you transformer coupling to resistance capacity coup- to adopt single layer coils for short wave, and multi - ling.You could simplify it, however, by leaving layer coils for long wave, and connected in circuit the grid condensers marked C2 in circuit all theby means of plugs.Your telephones are marked time without detrimental results, provided suit-low resistance, whilst by the action of the switches able valves are used.In amplifiers of this sort,you intend to connect them across the secondary it is essential that all H.F. valves are similar inof the intervalve transformers.These transformers characteristic and specially designed for the purpose. are of the step-up type, and have very high resistance We would suggest the use of " V24 " valves forsecondary windings, quite unsuitable for operating H.F. amplification, a " Q " as detector, and alow resistance telephones. An easy arrangement, " QX " as note magnifier. A condenser of 0.001 instead of using switches, is to use break jacks, mfds. should be bridged across the primary of theand terminate the telephones on a plug.The transformer T2.Resistances RI and R2 must beinsertion of the plug in the various jacks connects very carefully constructed, and must be of uniformor disconnects valves as required, or alternatively and constant value.The L.T. and H.T. voltagethe plate lead of the rectifier valve may be brought will depend upon the type of valve used.The to the arm of a three -stud switch.The contacts direction of winding of the transformers is im- of the three -stud switch are taps on to the primaries portant.If both primary and secondary are in theof the L.F. transformers.It is not necessary to same direction, the leads which pass from one end bridge the last two transformers with fixed con- are taken to grid and plate.You do not provide for densers.With regard to the actual design of the reaction, and this can easily be done if so desired apparatus, this appears to be rather neat but some- by winding a small coil 1" in diameter with No. 38 what complicated, and it does not permit of the S.S.C. wire, and connecting it in the grid circuit of fitting , ofall components to an ebonite panel the last oscillator valve and placing it near the endwhich canbe withdrawn complete fromthe of the first or second H.F. transformer. (2)This woodwork.It is not an advantage, as a rule, circuit is quite in order, but why not provide break to incorporate the accumulator inside the set, jacks at 3B, in order to disconnect the low frequency asits acid and acid fumes are liabletobe valves, and so obviate the necessity for turningdetrimental to the insulation.By sloping the off the filaments ?H.F. amplification can easily panel asshown, you considerablyreduce be added to the super -regenerative circuit by re-the amount of accommodation inside the box, placing the telephones and the condensers at thethough we presume this has been considered and primary of an oscillation transformer and workingample space provided.Special valves should be from common H.T. battery on similar lines to the used for the various purposes, and the detector method which you show in your circuit diagrams. valve should be one giving good rectification. (3) We do not think, however, that the circuitPotentiometer control might be arranged for the is particularly suited to H.F. amplification, as the two H.F. valves, and also for the detector valve. action of the separate oscillator is to produce con- " NOVO " (Ipswich) asks (1) If there is any siderable damping at rapid intervals.(4) By theadvantage in spacing the turns of wire for an inuse of the coils in the aerial circuit, the closed circuit ductance.(2) What capacity of variable condenser and reaction coil are such as will tune in the wave- isrequiredfog'acertaincoil.(3) How many length required, and as are used in a loose coupledfixed and moving vanes and what size.(4) If a reaction tuner.The coils, however, which arepotentiometer and battery is an advantage with a connected in the grid and plate circuits of the " Hertzite " crystal. oscillator valve are of a value that will produce (1) It may make a few per cent. difference in oscillationsjust above audible frequency. Weefficiency, but is not important.(2) It depends regret we cannot advise you more fully upon themore on the circuit than on the coil it is to be used operation of this circuit until more informationwith.If the aerial circuit 0.001 mfds. in series with comes to hand. the coil ;if for the closed circuit 0.0005 mfds. in " C.D." (W.1) submits a circuit diagram of a parallel.(3) 4" diameter plates, 1 mm. apart for five -valve receiving set, also a drawing of a proposed the 0.001 mfds., 15 fixed and 14 moving ;for the design of the instrument, and asks for criticism. 0.0005 mfds. half this quantity.(4) We have no The principle of the circuit is quite good, and theexperience of this crystal. method of switching in the various amplifiers should "11.M.W." (Kirton Lindsey) possesses one be satisfactory. We would suggest that the high single valve detector panel, one transformer marked frequency transformers be arranged on some inter- earthtovalves, twointervalvetransformers,one AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW xvii

vlARCON I GIVES UNRIVALLED WIRELESS SERVICE

gfie MARCON I INTERNATIONAL MARINE COMMUNICATION 03 LTD MARCON I HOUSE, STRAND, LONDON. xviii THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 "BRITWIRE " CONDENSERS. OWING to the demand for a good condenser, which at the same time is cheap, we are now manufacturing a Balanced Condenser for panel mounting, replacing the imported condensers hitherto sold.The plates are die-cast into the supporting columns, and are counterbalanced so that they will remain in any position when mounted on an upright panel. At present only two capacities are being manufactured, viz. :'0005 and '001, but other capacity condensers will be made in due course.Orders booked and executed in strict rotation. PRICE WITH EBONITE REVOLVING SCALE : '0005 17/6 '001 25/- Liberal'Discounts tothe`Grade. Send for Illustrated List, post free 3d.

POST ORDERS TO- BRITISH WIRELESS SUPPLY COMPANY 6 BLENHEIM TERRACE, LEEDS. Telephone : 26926 LTD. And at 11 Church St., West Hartlepool. Tel. 373.18 Eldon Sq., Newcastle -on -Tyne. Tel. Guy 36o. 33 High Street, Southampton. Telephone 403 Visit our Stand No. 42.All British Wireless Exhib,tion, Horticultural Hall. Sept. 30th to Oct. "Tth CS Exibeff BATTERIES FOR WIRELESS WE specialize in the manufacture of batteries for filament current supply to Valves and high-tensionbatteriesfor application of Anode Potential.We can supply these batteries in glass, ebonite or celluloid containers to any desired voltage. Exide batteries can be relied upon for wireless work and retain their charge over very long periods. Prices and Particulars on Application.

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Head Office : London Showrooms : Clifton Junction,219/1128 Shaftesbury Av. Dlr. Manchester. W.C.2 Visit our Stand No. 30.All British NVireless Exhibition Horticultural Hall. September 3oth to October 7th. 8 Volt 80 Amp. Hour Elide Battery. AUGUST26, 1922 THE WIRELESS WORLDAND RADIO REVIEW 709 telephone transformer, one grid leak and condenser, The apparatus is designed especially for short 4 Osram valves with holders and filament resistance, wave reception and the variometers in grid and one pair of 2,000 ohm telephone receivers, two variableplate circuits cannot be constructed to give condensers of 0.001 and 0.0005 mfds., and also llb. wavelength range from 100 to 1,000 metres, and for reception on the longer wavelengths we recommend you to adopt a different circuit.Alternatively you might bridge the plate -circuit variometer with av ariable condenser having a maximum capacity of 0.0004 mfds., and also arrange by means of a switch that will avoid dead end effect, to treble the number of turns connected in the secondary of the oscillationtransformer.This secondary, togetherwithitsvariometer,might thenbe bridgedbyavariablecondenser.Youwill probably find, when connected to your aerial, that the aerial tuning circuit will tune to over 1,000 metres when the aerial inductance is connected in parallel with an aerial tuning condenser.If it does not give the required range, a few more turns Fig. 8. might be connected in series externally.When tuning the grid and plate circuits to the longer of No. 36 D.C.O. wire, and asks for a suitable circuitwavelengths, you may find that insufficient reaction for reception of Hague concerts on a single wire aerialis provided for the reception of continuous wave, 85' in length. and should this be so, an additional variometer For circuit see diagram Fig. 8. will have to be constructed for the purpose of " W. D." (Blackheath) asks (1) The wavelengthcoupling together grid and plate circuits.I think range of his set, which consists of tuned aerial circuityou would findit much easier to construct an with coupled secondary and reaction coils. (2) Number independent receiver. of plates for variable condenser of 0.001 mfds., and " R.B.K.M." (Cirencester) asks re the American if there is a formula for working out the number ofshort wave receiver of the June 3rd issue (1) Whether plates for various capacities.(3) Area of tinfoil thecondensers need bevariable.(2) What their for making fixed condenser 0.001 mfd.(2) Dimen- capacity should be. sions forconstructing transformer forusewith (1) These condensers may be fixed if desired, crystal set for short wavelengths. although the variability of the grid condenser It is impossible to advise you on the wavelengthmight be a slight advantage.(2) Capacities may range of your set without knowing the dimensionsbe, grid condenser 0.0003 mfds. telephone con- of your aerial.However, the ratios of windingsdenser 0.001 mfds. of the various coils would appear to be satisfactory " W.J.L." (Sheffield) asks (1) (a) Maximum and it is quite easy to determine the wavelength and minimum wavelength of a set' described ;(b) range by identifying the stations which are tuned Size of reaction coil.(2) Sketch of dead-end switch. in.You should arrange to connect the aerial (3) If the terminals of a valve panel are correct tuning condenser either in series or parallel with the (4) Wavelength of a duolateral aerial inductance, and if this is done, the wavelength in sketch enclosed. range would probably be from 200 to 850 metres coil with a 0.001 condenser. when connected to a two -wire aerial of the maximum INSULATING. SLADE OF SWITCH dimensions specified by the P.M.G.(2)If the IIIIIIIII MOS moving plates have a diameter of 21" and are No. 20 S.W.G. in thickness, and the spacing washers 3/32", you will require approximately 25 movable STUD and 26 fixed plates to give a capacity of 0.001 mfd. Other capacities are directly proportional. (3) Three plates, being two in one direction and one in the other, ruby mica dielectric 0.002" in AXIS OF SWITCH thickness and with an overlap of 3.5 sqcm. ....ACN TYPE SWITCH SPEAFiNG (4) We presume you mean an oscillation trans- NEXT SECTION OF COIL former, and we cannot give precise dimensions Fig. 9. without knowing the size of aerial on which you propose to connect it.However, li" of winding (1) Maximum wavelength about 2,000 metres. with No. 24 D.C.C. and a 3i." former will tune the(b) As large a coil, wound with No. 36 single layer two -wire aerial from 180 to 600 metres with seriesas will swing inside the A.T.I.(2) See Fig.9. condenser of 0.001 mfds.The closed circuit which (3) The suggested arrangement will do fairly well, would slide inside should consist of lf" of windingbut why have A and E so far away from the A.T.I. of No. 28 S.S.C. on a 2+" former, and be bridged (4) If you use only 30 turns as suggested the wave- with a tuning condenser of 0.0005 mfds. length will be very small, perhaps 50 metres.If " T.R.K." (Pontypool)isconstructingthe you use 30 layers the wavelength will be of the American short wave receiver described on page 281 order of 10,000 metres. of the June 3rd issue, and wishes to know how to " H.W.E." (Halesworth) asks which isthe extend the wavelength range up to 1,050 metres, atvery best receiving set he can purchase, irrespective the same time permitting efficient reception on shortof price, for use on a single wire aerial of 100' long wavelengths. by 60' high.He intends to use a loud speaker, and 710 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 the apparatus is to cover the complete wavelengthdenser and the inductances.The condensers for range. tuning the closed circuit and the reaction circuit It is regretted that we cannot advise you on theshould have a maximum value between 0.0004 merits of the wireless apparatus at present on the and 0-0005.All condensers should be of the air market.If you make a point of arranging fordielectric type.At Gravesend you should certainly the demonstration of the apparatus you propose be able to receive most of the experimental London to purchase, it is quite easy to judge its merits.telephony, but the addition of one note -magnifying We would suggest that you adopt a tuning arrange-valve is to be recommended, as it would render the ment comprising aerialcoil,closed circuit coil,telephony much more comprehendable. and reaction coil, with variable tuning condensers, on e of 0.0015 and two of 0-0005.Inductances of " W.A.C." (Herne Hill)submits acircuit the plug-in type can be obtained to cover the fullconsisting of oscillator valve with tuned grid and wavelength range.The rest of the apparatus mightplate circuits, with crystal potentiometer and trans- be purchased in the form of units, which willformer connected across the ends of the reaction permit of making alterations as they may beinductance, and with the secondary of the transformer required from time to time.You might adopt twoconnected to a note magnifying valve, and asks if high frequency amplifyingvalveswithinter- it is correct, as he is unable to obtain results. changeable transformers for wavelengths up to The circuit would appear to be correct, excepting 2,500 metres, after which resistance -capacity ampli-perhaps that one lead from the secondary of the fication might be adopted.These two amplifierstransformer should be taken to the L.T. minus should be followed by an efficient detecting valve,instead of the L.T. plus, but this may be an error in the preparation of your diagram.Without more the grid of which may be provided with potentio- particulars it is impossible to suggest the cause meter control.After the detector, three note -of trouble. magnifying valves might be connectedGreat care The small condenser which you show should be taken in selecting thoroughly efficientbetween grid and plate for the purpose of producing intervalve transformers.You should be carefulelectrostatic reaction is hardly necessary when in the selection of a loud speaker, with a view to inductive reaction is provided.You should attempt obtaining one which gives a minimum of speech to obtain results with a single valve receiver only, distortion. omitting crystal and note magnifier.Try con- " J.E." (Blackburn) is constructing the appar-necting your telephones and telephone transformer atus shown on page 318 of the June 10th issue for in the lead between H.T. plus and reaction circuit. thecharging of accumulators from A.C. mains,When this functions correctly, you might add the and asks for details of step-down transformer for use crystal and then the note magnifier. on a 230 -volt supply. W.W.M." (Grimsby) asks(1) Ifcircuit It is presumed that the periodicity of the supplysketched is suitable for both " Q " and " V24 " is 50, in which case you can make a closed core valves.(2) If a grid leak and condenser is necessary, transformer in which the core, consisting of aand if so where it should be put.(3) What value number of flat plates, should have a cross sectional H.T. would he necessary. area of at least three square inches.The secondary (I) The circuit is quite O.K. except that the grid should be wound on first, and consist of three layerscircuit of the second valve should go to the negative of No. 18 D.C.C., whilst the primary should consistof the L.T. instead of the positive." V.24 " and " Q " may be used together off about 40 volts,if of 16 layers of No. 22 D.C.C., the length of windingthe " Q " is used for rectifying. in each case to be 5".It is advisable to connect Used in this way in series with this transformer a variable choke coil the circuit is best without a grid condenser and leak consisting of about eight layers of No. 20, on ato the rectifying valve.(2) It might be put in the bundle of iron wires 1" in diameter, by 5" long,grid circuitof the " V.24," but is not at all and tapped out at each layer.We do not recom- necessary.(3) For a resistance capacity coupling, mend the apparatus for giving long runs whenincrease the voltage to about 70. passing a current exceeding 2 amperes. -1" H.G.L." (Gravesend) wishes to make use of a 3 -coil holder, and submits two proposed circuits, and asks (1) If they are correct, and whether he may dispense with the tuning cnodensers across the reaction SHARE MARKET REPORT coil.(2) What make of valve would be advised for use in the circuit, and the best type of crystal. Prices as we go to press, August 18th, are :- (3) Values of condensers required for tuning inductances, and (4) Whether his apparatus is suitable Marconi Ordinary £2 80 for the reception of telephony. (1) Your circuit No. 2 is quite correct, though Preference .. '2 6 10i you will find tuning rather difficult after the use of Inter. Marine.. 1 107i the reaction tuning condenser, and particularly will you find it difficult to tune in telephony on short Canadian .. 106 wavelengths.(2) " R4B," perikon (copper pyrites and zincite) or synthetic galena. (3) For short wave Radio Corporation of America : - tuning, aerial tuning condenser should be connected in series with aerial tuning inductances, and have a Ordinary 1 09 maximum value of 0.001 mfds.For finer tuning, Preference 144i and for still further reducing the wavelength, a fixed condenser having a value of 0.001 mfds. might also be connected in series with the variable con- AtrousT 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW xis

WITH the use of " REFTY" From " The Wireless World," April 22/22. Terminals loose contacts are A loose contact almost anywhere, but generally entirely a thing of the past. in the plate circuit.Test by striking the instrument Yet,theactofattachmentor table.'If this results in a particularly heavy peal, disconnection takes but a second, lookfor loose wires, tighten terminals, see that switch contacts are clean, and so on.This test, by and the wireisgripped with a the way, is quite a useful one, and can be applied perfectelectricalcontact. The so as to locate loose contacts in various parts of the terminals are made ofbest hard set.It is so popular with some experimenters that I am told that not merely do they wear their tables brass,thesprings areenamelled, into holes, but that this is the true source of the and the tops are ebonite. emphatic style of some wireless lecturers ! TYPE No. 4 TYPE No. 1 The particular advantage ofthis Single Sample, Terminal isthatwires of greatly 1 1post free. differing gauge can be used at the 126 doz. same time. Single Sample, 1 /4.1, post free, postfree. or 15 6 per doz., postfree. Takes up to State whether Plated Lacquer finish. No. 11 S.W.G. State whether Plate TRADE ENQUIRIES INVITED. orLacquerfinish Briti4h Prov. Pat. R. EFTY, 15594/22. F reign Patents Pending. 91, Osborne Rd., Romford,Essex JUST PUBLISHED NEW PRICE LIST AND WIRELESS GUIDE FOR AMATEURS Sent on receipt of 3d. (stamps). MANCHESTER ELECTRIC WAREHOUSE 1 & 5, LEVER STREET MANCHESTER

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111P e.X

VERNIER ADJUSTMENT FOR SLIDERS Complete with 13 in. bar. AERIAL WIRE Bar and Slider-4/6 Neat " ON " and 7/22 Enamelled Stranded. "OFF" Switches too ft. 6/- - --2.3 550 ft.- - --9/ - TELEPH 0 N E As illustrated TRANSFORMER% SINGLELAYER COILS

4i in.diam. 9 in.long. Wound with 24 Enamel. Unmounted (as illustration), CONDENSER SCALES Suitable for 120 w Phones. Engravel 0-180° - -- - - 15- Unmounted - - -3/9 Price - 6/6 In Box with Terminals --18 6 With Knob and Bush St. John Street, E.C.1 SON 395,9 'Phone - - 3173 CLERKENWELL. G. Z. AUCKLAND & Hall; Sopt. 30th to Oct 7th. Visit our Stand No.46. .111 British Wiieless Exhibition, Horticultural xxiv THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 THE WIRELESS WORLD EXCHANGE AND MART

TARIFF. Advertisements are acceptedfor FOR SALE. this Section at the rate of twopence per word, with a minimum charge of two shillings.The ELECTRADIX WIRES advertiser's name and address will be charged InductanceCoils. -Tuneto3,500III,' Highest Conductivity at, Lowest Prices. for, and single letters and single figures will bePolished mahogany ends and base.Best qu,,, gauge. D.C.C. S.S.C. D.S. counted as words. Compound wordswillbewire.22s.postfree.Stampforillustrat, 16 17.. -- counted as two words. pamphlet.-DAvis BROTHERS,ThorntonDale. 18 1 94 .. -- Yorks. 20 111 .. 4 0

MarconiScientificInstrumentCo.'sUnits, 22 2 5 .. 4 6 2 (Coils At, B, D),3 4, 6 for Sale. Just 24 3 0 .. 5 0 received from factory.Good reason for disposal. 26 3 6 .. 56 is Best offer gets them.-CARR, South View, forest 28 42 .. 5 9 1

Hall. Northumberland. 30 5 2 .. 68

FewOnly. -GenuineMarconi" Q "valve, 32 8 81 .. 8 2

EBONITE (tested), new condition, in boxes, bargains, 75. 6,1. 34 7 9 .. 9 6 1 RELIABLE GRADES ONLY each.Wanted Brown's High Resistance Tele- 36 2 .. 11 3 1 (See last week's Advt.) .. phones, ValvePanels, modem parts. -SERVICE 38 11910 .. 13 8 1 IN .. SHEET,ROD, TUBE, SALES, 8, Great Southsea, Southsea, Hants. 40 1624 .. 17 0 ..23

Seven Valve Amplifier. -Mark III Type Tuner, PANELS, MOULDINGS Prices at per lb.Postage Extra.Earth Cli s, 160-4,000 metres. Threevalvesresistance 8d. each.7/22 Aerial Wire, 7/- per 100 ft. Enquiries attended to promptly. amplifier, new.Bargains.Offersconsidered. Furtherparticularsfrom SYDNEY WRIGHT, EVERYTHING FOR WIRELESS IN STOCK - Albert Mills, Bingley, Yorks. RADIO EBONITE SUPPLIES. Two -Valve Telephony Receiver,for £11ros. LESLIE DIXON & CO., 4 Little College St., London, E.C.4 be seen working by appointment. -FRANKLIN, 9, Colonial Avenue, 511nories, E.I Central 4711. (Nr. Cannon St. Stalin.) Elmwood Road, Chiswick. Ivorine Tablets for Terminals, set of seven, Is. (near 41dgareStation. Telephosu Ave -Re 4/66. 1111 ME WMIvorine scales, 8d.Why Pay More ?--INDELIBLE PROCESS CO., 220. Albert Road, Peckham, London, Liberal terms to Agents. Small Parts Supplied from Stock. --Condenser RADIOPHONE TUNERS, plates,crystaldetectors,terminals,spacers, 200-1,400ms, 38/ - washers, nuts, contact studs and stops, valve Valve Panels for above 211 - legs.List free.-FRASER, Sentinel House, South- .. ampton Row, London. *0005 Variable Condensers..18/8 TRADEcirelco"" Read's2 -ValvePanel,WR1.80,costFive Above 3 make an Ideal Receiver. Guineas, as new. £3.Portable 2 -Valve receiver Broadcast Concert Coilspair 2/ - in case, coupled Hesketh tapped reactance unit allwavelengths, £4.Mk. III2 -way switches, Grid Leaks and Condensers 3/6 as. 6d.All New -two -slide cylindrical inductance Fixed Condensers .. 2/6 f,i, filament resistance 3s. 6(1., L.B.C. 4/40 accumu- 5 -Plate Condensers lator i5s.' Sullivan's 12o -'phones 125. 6d.Back 2 -Valve H.P. Amplifier Panels High numbers Wireless World -Particulars, JAMBLIN. 32/ - Small 82, York Road, Bury St. Edmunds. Neat Insulation Condenser Vanes, Aluminium, 20 G., fixed or Get our New Bargain List. movable, 7d. dozen, 6s. gross.Spacer washers, large Ofd. dozen, 4s. gross.Small aid. dozen, as. gross.Postage extra. -R. DOUGHTY & SON, AMATEUR SUPPLIES, Cooke Street, Wolverhampton. 184, COTEFORD STREET, Egg Insulators, Green Porcelain .. 6d. Inductance Coil, 12 x 4, mounted on mahogany TOOTING, LONDON, S.W. Reel Insulators, Best Quality .. 4d. base, £I. -2o, Sherfield Road, Grays. Telephones Rewound any Resistance.Inter - Aerial Wire, Stranded, 725 per 100' 3 6 valve Transformers suitable for panel mountin,, Aerial Wire, Stranded, 7 22 per 100' 5 - 15s.6d.Condenser plates, perdoz.,is.3d. We can quote you very keen prices for EboniteLead-in Insulators, with Condenser moving plate stems, 5d. each.Grid leak and condenser, 3s. 6d.q" x 6' Panel cases, SWITCH STUDS, VALVE LEGS. Terminals no soldering) . 2 - -ts 6d.Single valve panels, 25s. and 35s.\\e TERMINALS and OTHER BRASS Filament Resistance Panel Mounting, can supply all your wants.Trade enquiries. - Smooth Action .. .. 4 - WIRELESS COMPONENTS. HARRIS, 84, Ronald Park Avenue, Westcliff Special Terms for large Quantities. Knobs, fluted with 2 B.A. Brass Nut in Sea, Essex. Let us have your enquiries. centre (Best Finish) 4d. Valve Receiver with Crystal Rectification, with Valve Holders, with screwed legs and Valve and Telephones, 300-24,000 metres, f,15 155. Nicholls & Wallis, Braintree, Essex. nuts, ebonite Seen working ally H," 24,'Airedale .. Road, South Ealing, W. Hellesen, 36v. H.T. Batteries with Wander Brass Castings, -Every description. smallor Plug and tappings .. 8/6 large quantities. 14years'experience.Quota- Inductance Sliders with plunger and tions on request. NO WAITING.-GELDART & BROWN "A" TYPE PerikonDetectors, mounted on PARKER, Engineers and Brass Founders, 14IB, Ebonite complete .. 4/- Bartholomew Street, Newbury, Berks. Enam. Wire, 23 Gauge .. per flb. 1 - The Motor House Wireless Station Supply Depot. Radio Headphones. Telephone :Malvern 180. Malvern Link, Worcester- Intervalve Transformers 21/ - shire. Everything for Wireless.Valves, Bat- Guaranteed New and Unused Telephone Transformers .. 20/ - teries, Telephones, Condensers, AerialFittings, 8,000 Siemens Halske, and R.E.G. Valves, Insulators,FilamentResistances,GridLeaks, Sullivan 12)) Rectifying and Amplifying.. 10,8 one, two, three and four -Valve Receivers.All ohm 8,000 01,1D instruments highest efficiency. 48/6 41 6 Adapters for " A " Valve Hollers .. 3, - Two 24 H.P. Motor Generators, one 40' Mast 35/6 Call and Inspect. Postage Extra. DirectionFinders,DraftingInstruments,etc. Delivery from Stock at present. ex Admiralty surplus.Half prices. -THE LONDON ELECTRIC FIRM, Croydon. TERMS: Wireless Instrument Cases, Walnut or Mahogany, Cash with order. finest finish, If by 74" by 4' (outside), 8s. 6d. Postage 1/- extra. Grafton Electric Company Second quality,7s.6d.Any size proportion- Showrooms-54,GRAFTON STREET, ately, prompt delivery. Trade inquiries invited.- GOLLINGS & AYRES, TOTTENHAM COURT ROAD. HITCHCOCK, Colchester. 21 THE BROADWAY, AgateCylinders,etc., for loud speaking apparatus LONDON, W.L Telephone -Museum 241. from James R. Gregory & Co., Mineralogi,t,. BEDFORD. 139, Fulham Road, S.W.3. AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW XXV THE WIRELESS WORLD EXCHANGE AND MART

T0 MP SON'S SURPLUS DEPOT KEYSTONE WIRELESS SUPPLIES ELECTRADIX RADIOS have for SALEI aKnockout WHOLESALE ONLY. Hundreds of Head Prices thefollowing goods :- Sets in Stock.All Ebonite, cabinet work, engraving, expert I2 only Portable Field Telephone Sets, complete with cords.Sterl- designers inamplifiers.Slab inductances, Magneto ringing, unused, in teak cases, 15/- each. ing Brown Phones, basket coils, etc.Switch arms, contacts, Below. Marconi Standard Terminals. Scales. Direct Coupled 31 K.W. lighting sets, comprising 2,000 ohms, 51/ - Low Prices High Finish. 8 H.P. Douglas water cooled engine, Ito volts pair ;4,000 ohms, Offices : 32 amp. G.E.C. dynamo with radiator, etc., 52/- pair ; Brown's 33, Trinity Road, TOOTING, S.W. self-contained,price, complete with switchboard A 120 ohm L.R. andshuntregulator,guaranteedperfect, head 'phones, 40/ - £45 each.Below. pair, Sullivan's Condensers, Variable, all high class material, same L.R.ditto,with CONNOLLY, BROTHERS quality, double elsewhere.o00075, 16/- each; 6 ft. cord, plug and WIRELESS APPARATUS MANUFACTURERS, 0'0005, 12/- each ;wool, 20/- each.Post 1/-. jack, 22/, LOSTOCK RD., URMSTON, MANCHESTER. Below. HighRes.Head Spares & Complete Components at Trade Prices. 200 Pairs High Resistance 'Phones, 4,000 ohms. Sets, 1,500 ohms, High Class French instruments as sold elsewhere 26/-; 4,000 Examples :5o' x 6' Double Wire Aerial, 4o' at 45/- we are selling in three grades, price 30/-, 80/ - complete. Lead in, ready for fixing, 17/6.7/22 Stranded 34/ -,and 85/-, all new and guaranteed perfect, Second-hand 8o - Wire, Id. per foot.z' Reel Insulators, 43d. cash returned if not satisfied.Post 1/-.Below. ohm head - sets each.4' x re Wound Inductance Coil, 4/9. too Single Valve Panels. For receiving speeches, guaranteed, 15/-.Single L.R. Receivers,4/8. 28's Enamelled Wire, *lb., 2/-, Ali., 3/6. concerts,Paris, Dutch concerts,etc., minus Cords for double 'phone new, 2/6 and 3/9. CARRIAGE PAID ON ORDERS OVER £2. Valve and 'Phones.Offer cannot be repeated, Used. 1 6.4 -Way Plugs, 2/-. price 27/- each.Post 1/ -,all new.Below. Microphone Transmitters, breast plate, 12/8; Wireless Sterling Sparkoils, Ebonite Panels, Hand, 2,8.Insets, 9d. all guaranteed tested perfect, cost £4 each, Aerials.-Wire and every accessory in stock. PURCHASE YOUR WIRELESS our price 10/8 each.Post 1/6.Below. Condensers.-Fixed and variable in all sizes. REQUIREMENTS THROUGH 4 only Wireless Generators 4o volts 5amps., Relays, G.P.O., 21/-; Weston M.C., £210x. 25/- each.Below. MorseInkers,45/-.Soundersetsfor The Viper Re -Covering Co., Ltd. too Thompson Bennett Single H.T. Magnetos, making rectifiers, 12/6 each. new, less contact breakers, 17/- each. Post 1/8. Panel Switch FlushFitting,D.P.,3/8. 7 8, POULTRY, E.C.2. Plugs and Jacks, 1/6 pair.6o volt Battery, (r minute from Bank) Tele. : City 1897 Below. too Dixie Single Magnetos, complete and perfect, 41v. units, in polished mahogany case, six 17/6 each.Post 1/6.Below. sockets, two plugs, 17/6.Finest set ever Marconiphones, Sterling and R.F.H. Sets, etc., 5o Bosch Starter H.T. Magnetos, perfect 18/- each. offered. can be supplied. Place your orders NOW. Post 118.Below. Receivers, all new.Marconi Trench, 5oD.C. A.V.I.A. singles Magneto-,, in new condition, 25/-. Cost £40.Complete, £5 19g. Post 1/6.Below. Amplifier Receiver, Mark II, z -valve, with 4 Cyl., 6 Cyl. and 8 Cyl. Magnetos, incomplete, variable condenser, £7 10s. Single valve 10/- each.Below. panel, 35/6.3 -valve Amplifier, Mark IV, £8. Potentiometers for crystal receiving sets, High H.T. Motor Generators to t,000 volts, £15. Instrument Wires Class, 8/6 each.Post 9d.Below. kW 220 to 25 volts, £80. FROM STOCK CondenserVanes,HighClass,Polished,1/6 EVERYTHING FOR WIRELESS. dozen, in gross quantities, 12,- per gross.Below. Call at our El,trical Showrooms and inspect. g Stud Tuning Switches, best instrument finish LESLIE DIXON & CO. S.W.G. S.C.C. D.C.C. S.S.C.D.S.C. En. on ebonite, 8/- each.Post fld.Same quality Near Aldgate Station, Met. Ry.First Turning 47 - 110/- 120 41/- 101- elsewhere.Below. on left in Minories. 46 97/- 28/- Complete Crystal Receiving Sets. Guaranteed 84/- 80/-20/- sets for receiving telephony, etc., from 25/ - 45 - up to £2 10g.'Phones extra.Below. 44 50/- 68/-16/- 4 H.P. Gardner Petrol Engines, Magneto ignition Your Case Work 43 40/- 52/-13/- solix carburettors, as new, £12 each. quote you for your wireless 42 31/- 33/- 9/- 2 0111k, 440 Volt, 1 H.P.Direct current motor, Let us - £5 each.Below. casework. We are specialists in this 41 30,- 32/- 8/- All above material is the best to be obtained. class of work and feel sure our work- 40 14- 17- 18 - 22/- 6/6 For other numerous instruments and fittings manship and prices will interestyou. send for lists, price 2d.Lowest discounts to Phone: L.W. 272o. 39 12/6 151- 17 - 21/3 8/- trade. We have everything in the wireless 38 11'- 14 - 16/- 19/- 5/8 line. CARRINGTON & NEWBERY LTD., 18/20, Normans Buildings,Old Street, E.C. 37 10,- 121- 14/6 17/8 4/11 T. W. THOMPSON & CO., 36 8/6 10/- 18/9 15/- 4/8 Government Surplus Depot, 35 7/9 9/8 12/9 14/- 4/6 39, London Street, Greenwich, S.E.10. 34 6/10 8/- 11/3 13/9 4/4 HEATH & Co., Ltd. 33 62 7/6 10/6 13/- 4/3 Instrument Works, New Eltham, S.E.9 32 5 10 7/2 9/1 12/104/2 are prepared to undertake in their fully 31 5 6 6/10 8/9 11/6 4/- equipped works-Wireless Apparatus 30 5 - 5,4 7/9 9/103/10 Our Speciality : and Parts for the trade. Quotations given 29 4 9 5'- 7/8 9/6 3/8 toBlue Prints.Immediate attention. 28 4;3 4/6 7/2 9/- 8/8 Phone-Let Green 301. Wire-'Polaris, 27 42 4/5 7/- 8/6 3/5 WIRELESS Prices per lb. Bobbins free. Electrical Supply Stores Orders of £2 or over, Carriage Paid, G.B. Strawboard Inductance Tubes Terms-Cash with Order. 5, Albert Terrace, King Cross, Halifax, Eng. 2' to 6' dia., for Crystal Sets, etc. Attractive Prices - Quick Delivery FINE WIRE SUPPLIES, Our Motto : (A. E. DAVIS) Enquiries attended to promptly. 41, Arlingford Road, A. EATON LEE & CO., PROMPT SERVICE 4,Little College Street, LONDON,E.C.4 Brixton, S.W.2 LISTS - - TWO STAMPS Central 4711. (Nr, CannonSt.Station.) xxvi THE WIRELESS WORLD AND RADIO REVIEW Auousr 26, 1922 THE WIRELESS WORLD EXCHANGE AND MART

FOR SALE-continued THE UNIQUE N.M.C.(WirelessPatents) Two -valve Receiving Unit, combining Filament Resistance, B.A. Screws, Nuts and Washers, assorted gross Aerial, Tuning In- 2S.,lists 2d.-J. H. BENNETT, Station Road, Contracts Wanted ! duotance, Aerial Tuning Condenser, Grid Willesden Junction. Toning Inductance and Oscillating Condenser, complete in polished case, 12' x x 0', Wireless Masts.-Improved Girder Type. Light The 26 Os. less Valves. and strong, 30 to 50 ft. at IS. ft. 50 to I00 ft. The Set to obtain maximum efficiency. atxs.6d.ft.Cash with order, carriagefor- WellingtonEngineeringWorks, N.M.C. 4,000 W., Double Head Gear, 35/ - ward.-F. ARMSTRONG, Weybridge. ALDERSHOT. Inductance Tubes. Several Wireless one -valve Experimental Receiv- All Experimenters' Supplies in Stock. ingSets,perfect,complete,cheap,-RAD101 INVITE ENQUIRIESFROM FACTORS, N. M. CO., 145, Northeote Road, COMPONENTS, 7, Jamaica Row, Birmingham. MERCHANTS, SHIPPERS AND AGENTS Trade Supplied. London, S.W.11. FOR THE MANUFACTURE OF WIRELESS APPARATUS. TRADE ENQUIRIES. 1,2,3or4 VALVE RECEIVING SETS. VALVE PANELS ON THE UNIT SYSTEM, Northern Wireless Buyers get ToManufacturers.-Wanted.All kindsof L.F. ANDH.F.INTERVALVE TRANS- yourrequirementsfrom The Grand wireless fittings and accessories.Instruct agents FORMERS, VARIABLE CONDENSERS, AND Electric Wireless Supplies Depot, Ocean to Call.-LAWRENCE BROS.,102,CityRoad, FILAMENT RESISTANCES. Cardiff. COMPLETE CRYSTAL RECEIVING SETS. Road, South Shields. The Wireless Sup- SUPERIOR FINISH.PROMPT DELIVERY. plies Depot, 2, Market Place, Morpeth. South Wales Electrical Firm, 15 years standing, KEEN QUOTATIONS. want agenciesforallkindswireless.-Apply Large stocks for amateurs making own Box R2, BERTRAM DAY'S ADVERTISING OFFICES, sets.Burndept 3 -valve, Burndept Ultra g/to, Charing Cross, S.W.x. IV, Tingey 5 -valve sets, on view.Free Designs of Receiving Sets, Motors, etc., supplied. demonstrations. Pay us a visit or send Sound advice given.Enquiries invited-O. S. CONDENSERS your enquiries. PUCKLE, Buckhurst Hill, Essex. VANES WASHERS " Danwill Wireless Supplies." Cheapest on market.List on application. -47, Old Dover SCREWED RODS. SCALES Road, Blackheath, S.E.3. CONTACT STUDS New Firm of Factors require Manufacturers, TO THE TRADE Lists, Samples, and keenest prices all Wireless INDUCTANCE TUBES Most of the big Manufacturers of Receiving Supplies.-Gaurni,8o,Newington Causeway, ROD AND SLIDERS Sets, are using OUR Skeleton Condensers for CRYSTAL CUPS & CRYSTALS Panel Mounting. Verb Sap. Write for terms. Quotations Wanted for all Wireless Components The W. S. Fallon and materials.Trade only.-RIDGwAY RADIO, EBONITE. TERMINALS Wimbledon. Condenser Manufacturing Company WIRES, &c.&c. AdvertisersRequest Quotations manu- 230a, Hermitage Road, London, N.4 facturers forall parts used in construction of wireless instruments, also condenser scales, knobs Sendfor keenestprices to rheostats, switches, etc.-TEX ALO MANUFACTURING CO., South Shore, Blackpool. GROVE R. & A. WORKS Aluminium Wireless.-Our stocks are complete, and we can give prompt deliveries. Send stamp for lists.- Short Rd., Leytonstone London El 1 ELECTRICAL SUPPLY STORES, 5, Albert Terrace, Condenser Vanes King Cross, Halifax. We are open to quote low prices for the above tothe trade.Wholesale only. MISCELLANEOUS. STAR DELTA WIRELESS G. BROWN & Co.Berkley Street East Ham, Wanstead, Ilford, Manor Park and SUPPLY COMPANY STAMPERS & PIERCERS Birmingham Forest Gate.Amateurs should not fail to come INSTRUMENTS TESTED FREE. to the RADIORENDEZVOUS.log, Manor Park Broadway (over Liptons).Club open till xo p.m. The House ForAllWirelessAccessories nightly. FOR SALE Nave You Called ? If Not, Why Not 1 BOOKS. Tubular Steel Masts with finial, rope cleat, 888a, Oxford Road, MANCHESTER. guy clips and baseplate.Painted, light and TechnicalBooks.-Second-hand and New durable. Books on every conceivable subject.Catalogue 12', 25 - (2 Sections), 40 -. free.State wants.Books sent on approval. The Proprietor of the Patent No. 9.4931, of 1914, 40'(3Sections), 80 -. Books bought.-FoyLE, 121, 125, Charing Crossfor improved receiving system for continuorn 100' 7/22 copper wire, 6 insulators, halyard, Road, London. electric waves, is desirous of entering into arrange- pulley and lead intube,10 6.Carriage forward. RadioMagazines,allthelatest," Radioments by way of licence and otherwise on reason- World,"mid.; " PopularRadio," able terms for the purpose of exploiting the same Trade Supplied. roid. ;and ensuring its full development and practical Works, 5, Kramer Mews, Earl's Court. " Radio Broadcast," is.6d.;" Radio News," is.6d. ; "Science and Invention,"is.gd. ;working inthis country.All communications L. S. COMPTON, 17, Femshaw Road, S.W.10. " ScientificAmerican,"as,fid. PostFree. should be addressed in the first instance to- INTERNATIONAL NEWS COMPANY, LTD., 15, Bream'sHASELTINE, LAKE & CO.,CharteredPatent Buildings, London, E.C.4. Agents,28, Southampton Buildings, Chancery Lane, London. W.0 2. HEADPHONES. New and Unused.Not reconditioned.Cash refunded if not perfectly satisfied. EBONITE "A" TYPE 4 PRONG Brown's A -Type.120ohms,Usualprice, R E S 1J ifs.Our Price, 35 -. Whether as a source of practical informationT S Brown's A -Type, 8,000 ohms, £36s.Our VALVE HOLDERS for the Amateur or as a valuable medium for price 39/9. every Advertiser, the bestresultsare Sullivan's 8,000 ohms. Usual price c255. 1/6 each, post free. Invariably o Our Price, 29.9. throughbtthaeined " wireless World" Post and packing, 1 - extra. For /id!! narhcuiar,anti ad;7 .ffly to Write or call for our Wireless Price List. WILKINSON BERTRAM DAY & CO., LTD. THE MASCO PATENTS MANIJF'NG COY., LONSDALE RD., KILBURN, N.W.6 Complete Advertising Service, 79 Rosebery Crescent. NEWCASTLE -ON -TYNE TRADE SUPPLIED. Established 1900 9and 10 CHARING CROSS. S.W.1 AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxvii

DISTORTIONLESS AUDIO FREQUENCY INTERVALVE TRANSFORMER 16/9 post free. CHAS. BAKER Wound with 20,000 turns of wire with the layers spaced and insulated. The wire used is of heavy gauge thus eliminating the risk of AND CO.'S STORES, LTD burning out.The core is of special design and built up from LARGEST OUTFITTERS IN LONDON best quality Stalloy iron laminas. Insulation resistance between primary and secondary windings and between both windings and core is guaranteed to be not less than 100 megohms. Thistransformerisfree from distortion giving perfect reproduction of speech and music. Each one is fully guaranteed.Delivery immediately from stock. Also H.F. plug in transformers from 3/6 each. A. WOOD, Manufacturer of Wireless Apparatus, 44, BRACEBRIDGE STREET, NUNEATON.

THE PARAGON RUBBER MANUFACTURING CO. SCULCOATES, HULL. EBONITE WIRELESS Sheet, Rod & Tube KNOBS ELECTRICAL V ALVES MOULDINGS SLIDERS, Etc. Wholesale only. London Oft ce : PERCY W. C. TRICK, 20, LITTLE PORTLAND STREET, W.1 rei,hone MUSEUM 2041 " DIOPLION " INTERVALVE TRANSFORMS

+ \ 111%-allt.- F- - 21r-21r- 4 Nir -Mr----1'21r

Are the result of 18 months careful research, and will be found equal to any.They are sold on High-class Tailoring the " money back " principle, and we areconfident that once you AT MODERATE PRICES have made atest,your future supplies will all be " DIOPLION " INDIAN COLONIAL & types. FOREIGN OUTFITS IMMEDIATE DELIVERY cat, be given to EARLY APPLICANTS and the trade should take advantage without delay. egulation Uniforms ,,,tfuir Stand 21.AllBritish Wireless Exhibition. Idn. ,ittur d II.11 s. ins alb, I toOctober7th.

MITCHELL'S :',EillirsALLt: Head Depot 271-274 HIGH HOLBORN McDermott Road, Peckham, S.E.15 City Branch 41, 43 LUDGATE HILL (Retail Store, 188, Rye Lane, S.E.15) 37-140 Tottenham Court Rd., 256 Edgware Rd., &c. 1 E 2 xxviii THE WIRELESS WORLD AND RADIO REVIEW Al'ClUST26, 1922 IMPORTANT NOTICE- Specially designed A. C. COSSOR, Limited, hereby give notice that the order of Mr. Justice Russell of the for 1st March, 1922, continually advertised by the Marconi Co., was an order ARRIVED Broadcasting AT BY CONSENT. Being engaged at the time in the production of an improved and different type of valve, A. C. COSSOR, Limited, didnot consider thepatentsin question of sufficient importance to warrant the expense of litigation. A. C. COSSOR, Limited, respectfully leave the public and the Trade to judge whether the constant repetition of the notification of the judgment referredtois necessary or HEADGEAR expedient in the circumstances. .orStandNo. 29.Allliritish Exhihiti,,, RECEIVERS Ion ,iltural Hail Stag, slur 3,411 t.1 (111,bcr ;th,. Designed and manufactured by A. C. COSSOR, LIMITED leadingTelephone Manufacturers Aberdeen Works, Aberdeen Lane, Backed by many years' experience. Highbury Grove, N.5 Highestefficiency, concentrated magneticfield,instantaneously adjusted to the ears, comfortable WARNING. in wear, either receiver detachable MARCONI'S WIRELESS TELEGRAPH CO., LTD., from headband, protectedterm- v. inals, lightweight, twin series cord. A. C. COSSOR, LTD. Marooni's WirelessTelegraph Company, Limited, GIVE NOTICE that an ORDER was made A.T.M. LOUD A.T.M. Crystal m the High Court of Justice, Chancery Division, SPEAKING DetectorSets by Mr. Justice Russell on the 1st March, 1922, RECEIVERS Highest Grade. restrainingMessrs. A. C. Cossor, Ltd., from Three typesof infringing the Marconi Company's Letters Patent Maximum Efficiency. Nos. 28413 of 1913 and 126658, except so far as amplifyinghorn, ModerateCost. Messrs. A. C. Cossor, Ltd. manufacture for

H.M. Government. Messrs. A. C. Cossor, Ltd., were further Ask yourdealerfor ORDERED upon oath to DESTROY allarticles and apparatus (other than those constructed to A.T.M. the order of H.M. Government) made or used by them in INFRINGEMENT of these patents, Broadcasting Apparatus and TO PAY THE MARCONI COMPANY DAMAGES Visit our StandNo. 52.AllHi itish 1, less ,hibition. 11311, AND COSTS. horticultural Suptuniber 3oth 1 Oi haier 7th The M -O Valve Company, Limited, of Osram Automatic TelephoneManufacturingWorks, Brook Green, Hammersmith, London, Co., Ltd. W.6, is the only firm in this country licensed to manufacturethermionicvalvesunderthe Head Office & Works : London Office : patents belonging to the Marconi Company. Any valve similar to those generally known Milton Rd., Edge Lane, 6o Lincoln's Inn Fieldsas the " French type " constitutes an infringe- Liverpool. W.C. z. ment of the above patents whether manufactured in this country or imported from abroad. Marconi House, Strand, London, W.C. 2. AuousT 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxix WE PUBLISH WINNERS.AUGUST 5th ISSUE Best Answer:Crystal (Palace). Qaestion :At what station does the train of Oscillations stop? Sent by :-S. W. Bastowe, 18, Moyser Road, Streatham, S.W.x6, who has been presented with a parcelof goods chosen by himself.

EFFICIENT. SENSITIVE. Head Receivers and Loud Speakers OUR AIM Maximum efficiency with low p:ndection costs enabling us to sell boil receivers and loud speakers at most attractive p:ices. All are tested before leaving works and any not meeting the test are rejected. PHONES

1.ro ohm. .. 80'- Complete 4000 ..82/- with cord 8000 33' - LOUD SPEAKERS 70OhL0 0 complete 2000'22 10with cord 4000, Delivery 1st week in September. Extracts from our price list. 4d. (post free). Condenser Vanes.1/- doz.Postage 2d. doz. Valve Holders.Best moulded ebonite.Corn- plete with nuts. 1,4 each. Postage 3d. each. Diam. Knobs. 7d. each. Postage 3d. each. LIGHT. Aerial Pulleys.1/- eachPostage 3d. each. OF SUBSTANTIAL CONSTRUCTION. LIBERAL DISCOUNTS TO THE TRADE. J. L CARTWRIGHT & CO., Manufacturing Electrical and Radio Engineers, DEPT. W. Phone-Cent. 4209 130;132, LONDON ROAD. MANCHESTER. Grams-Pladuram, Manchester. WORKS :BERRY STREET. LONDON ROAD.

PROVIDENCE PLACE, WEST END LANE, KILBURN, N.W.6 1, 8.M. 25. 31 all p -asWest-E,c1 Lart Telephone: HAMPSTEAD1261 Nearest Tube Station: KILBURN PARK ( BAKERLOO) New, Unused, Ex -Government All -AluminiumDiaphragms BROWNS' Reconditioned and Guaranteed by Mfs., S. G. BROWN. Ltd. HIGH RESISTANCE LOW RESISTANCE PHONES 55/-Pe Pi50/- We also have a LARGE stock of unused ex -Govern- 120 ohms 4000 ohms ment BROWNS' PHONES, which have not been37/643/6 reconditioned by Mfs. S. G. BROWNS.' PER PAIR These we purchased direct from the Government. (Prices include Cords)

VISIT OUR STAND-No. 38 A SPLENDID ALL -BRITISH WIRELESS EXHIBITION TWO -VALVE 5 0 HORTICULTURAL HALL See our further ad- September 30th -to- October7th SET . . . vert.inthis issue,

Send for our ILLUSTRATED CATALOGUE. 16 Pages. 100 Illustrations. Postfree.Sixpence x xx THE WIRELESS WORLD AND RADIO REVIEW AtrausT 26, 1922 111111111111111111! WIRELESS I Large or Small Contact Studs .. .. dos. 10 Valve Legs, complete with nut and washer .. each 3 Bart Accumulators, 4 -volt, 24 amp. hour ..each 149 Postage and Packing extra ..each 1 3 STILL THE CHEAPEST I FIRM FOR WIRES. S.W.G. S.C.C. D.C.0 Single Silk Dbl. SilkEmd. 12 1/10 1/11 4/. 5/4 1/8 Important Announcement to the Trade 14 1/11 2/- 4/- 5/4 1/9 I 16 2/- 2/1 4/2 5/6 1/1 LIVE AGENTS WANTED IMMEDIAT ELY IN 18 2/1 2/2 4/4 5/8 1/110 ALL PARTS OF THE COUNTRY TO STOCK 20 2/2 2/8 4/8 8/3 26 22 2/8 2/U 6/- 6/8 2/8 FULLER BLOCK ACCUMULATORS 24 8/- 8/6 6/6 7/4 2/8 FOR WIRELESS PURPOSES. I 28 8/7 4/1 6/8 8/2 3/2 28 4/4 4/7 7/2 9/- 8/8 There is an unprecedented opportunity for the retailer to 80 build up a wide connection amongst wireless enthusiasts 5/- 6/6 8/- 10/- 8/10 82 6/- 7/8 9/2 18/- 4/2 by supplying a really efficient Accumulator, one that is 84 fool -proof, an important factor when the same is to Le 7/- 8/8 11/8 14/- 4/4 Iused by the Amateur. I 88 8/8 10/2 14/- 15/8 88 11/8 13/2 16/- 19/- 68 Don't run the risk of making adissatisfied customer by 40 15/- 18- 18/6 22/8 6/8 supplying a plate -type battery, which will not hold its 42 17/3 21/- 81'6 84/ - 9/- charge when not in use.The E.M.P. of the " Block " cell At per lb. Iwill not fall below a volts even if left unattended forI All orders of 1 lb. or over wound on reelsfree.For less than a period of 12 to x8 months. 1 lb. reel 3d. extra. We are about to establish reliable Further Lists on application.Trade Supplied.Postage! extra. ACCUMULATOR CHARGING STATIONS Visit our Stand No.19.All British Wireless Exhibition, Ithroughoutthe country inreadiness for the rash ofI Horticultural Hall,September 3othtoOctober 7th. business which is sure to follow as soon as the broadcasting scheme is launched. If interested, please write to " AGENCY " I J. B. Bower & Co., Ltd. THE CITY ACCUMULATOR CO,Dept. 88)I Wireless Manufacturers, 79, MARK LANE. E C.3 Phone Avenue 91 (3 Lines) Telegrams : Tyche, Fen. London 15, Kingston Road, WIMBLEDON, S.W.19 I I 'Phone : Wimbledon 1080. Works : Merton.

A 220,000 DEAL IN WHICH EVERY The Universal Tuner WIRELESS AMATEUR MAY PARTICIPATE The Universal Concert Tuner is the small- est, cheapest and most efficient tuner on the market for the reception of the Dutch "BROWN" "A" TYPE Concert and Marconi Broadcasting. RADIO HEADPHONES Guaranteed new and unused. NOT re -conditioned.

120 8,000 ohms. ohms 42/6 49/6 Maker's Maker's Price Price 58/- 66/-

SULLIVAN 8,000 ohms,...36/6 Why pay the full price and wait weeks for delivery when Its light polished wood case, fitted highly we can supply from stock at lacquered brass terminals and fastening PRICE less than trade price ? catch, with 2 coils as illustrated. Size Teems cash with order. Postage1/- extra.Approval' for 7 days 4" x 4fixII" Trade enquiries for quantities solicited. Complete with full instructions. Secure one of these Tuners 7s. 6d. FULLER" BLOCK" TYPE AC- today. You willbe perfectly POST FREE delighted. CUMULATORS 4 volts, 4 amp., 32 6 the only practical battery for wireless. Electrical and J. LIPOWSKYWirelessEngineer THE CITY ACCUMULATOR CO. 614, OLD FORD ROAD, BOW. LONDON, E.3 79, MARK LANE, E.C.3. Telephone :East 3345 Phone :Avenue qr. Telegrams :Tvelle, Fen, London.' xxxi AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW

WE SPECIALISE 1.100 IN CLIV g

E'') EBONITE -"t:3 7 503 ,t1 a3 0 el au 0 0 n %7Z. x 9 EQUIPMENT U U14 Ai 4 V FOR cry > §0 rr'Oixn `ci rs".

'" ." -6 ri_LA d 0 WIRELESS SETS cTit.,c§t C.) C4

? SHEETS: TUBES : PANELS 814ax":1.41 u E KNOBS, CONDENSER COVERS Lr. ale) 2#1.% >,"0c k WHOLESALE ONLY csi . op ,y, al WI C 1m1.I

FROM STOCK EFEL1 E o -0gor if, 1:).o ..2i7/1 c ELz zT4 gu E HIGHTENSITE LTD. u 1-4 -cJ o to- Normandy St., Custom House, E.16 -.0L. o.E? :Cg fag (-9) 'Phone :EAST 3153. r.L.> :I-5 4. i- c..)2u

THE opportunity you cannot GENTS' MAKE afford to miss in FITMENTS WIRELESS ACCESSORIES Accumulators, BestMake.- 4v. 20a, 18 64v 40a, 22;6: SEND FOR OUR 6v 20a, 276 : 6v 40a, 35 - Aerial Wire 7/22 ...... per 100 ft. 5/8 SUNDRIES Batteries, 15 V.H.T. Best Make . each 313 PAMPHLET Condenser Grid, mtd. Ebonite each 2/6 Condenser Vanes, Alum... per pair 3d. Condenser Washers, Large .. per doz. 8d. Condenser Washers, Small .. . per doz. 4d. Contact Studs, with nut and washer .. per doz. 1/6 Crystals, Best ...... per piece 6d. MAKE USE Coils mounted with ebonite push fittings. --175-400, 4/- each : 250-550, 4/6 each: 325-750 4/9 each :450-1200, 5/9 each : OF OUR 550-1500, 6/6 each: 850-2000, 7/- each: 1350-3000, 7/6 each : STOCKS 1500-1000, 8/- each : 2000-6500, 8/6 each : 3000-9500, 9/- each Ebonite Knobs ...... each 6d. Headphones, complete, 4,000 ohms. Headphones, complete, 8,000 ohms. Valve Sockets, nut and washer,.. ..Bet on ?.td.. Valve Holders, ebonite ...... each 2;- Filament Switch, ebonite...... each 8/9 ASK US Switch Arms, laminated.. . each 1/6 TO QUOTE Terminals, nut and washer. .. per doz. W- FOR YOUR Ebonite, best i in... .. per lb. 4,6 CASH WITH ORDER GOODS BY RETURN. WHOLESALE REQUIREMENTS CARRIAGE PAID £2 and over

GENT & Co. LTD.FAR DAYK;S LEICESTER Angell's Wireless Supply Stores LONDON: 25, Victoria Street, S W.1 95, HIGHBURY NEW PARK. LONDON, N.5 NEWCASTLE -ON -TYNE: Tangent House, 52, Blackett Street THE WIRELESS WORLD AND RADIOREVIEW AuGusT 26, 1922 NV I It LESS CRYSTAL RECEIVING SET. Specification. -Solenoidtypeinductancewithtappings, erulle-Ocor -0005 variable condenser, perikon detector or galena, thewhole being assembled on 1" ebonite, and mounted ina highly polished cabinet.This receiver is ideal for the reception of telephony Wavelength, 180/1,800 metres approx.Price, complete with phones (4,000) 15 12 6 COWL INSULATORS CRYSTAL RECEIVING SET. 100% PROTECTION Specification. -Doubleslidetuning inductance, galena detector with dustproof case, blocking condenser, thewhole AGAINST SURFACE LEAKAGE being assembled on a highly polished mahogany base, beingan ideal receiver for the reception of telephony. Price, complete with phones (4,000) . £4 10 0 Filament Switches, under panel type, ebonite .. . 31 Aerial Insulators .. 3d. Valve Legs with two nuts . ..per set of 4 lOfd. Ex -Govt. 2 -valve Receiver (less valves etc.) .. £75 0 Variable Condensers (21 plate) .. .. H.T. Units, 15v. 17,- .. . AERIAL INSULATOR . .. 3 3 & 3'9 Length 3i " H.T. Battery Boxes, complete with switch and fuses, etc. 6 6 Diam. Condenser Spindles with knob 1- Per Set of Grid Condensers .. Price 2i6Four 10 26 Valve Holders each 1/- Fuller Inert Cells. llv. 9d Ali Condenser Plates The Crystor Cowl Insulators are abso- per doz. 143 lutely essential Crystals per piece to every wireless aerial, Zincite 8d. and by providing completeprotection per piece 9d. against surface leakage due to rain, hail, Valve Pins with nut per doz. 1 9 snow, or fog, will immediately increase Single -valve and 2 -valve panels efficiency OF YOUR SET. Accumulators for Valves.. ..from 16 6 Dutch Concert Coils per pair 48 Send for full particulars without delay. Inductances wound on formers .. 49 Aerial Wire, 7.22 . . per 100 ft. 5.9 Microphones with rep lacable insets k)Holizontal or Wall Vertical Roof H.T. Leads (red and black) 26 LEAD-IN LEAD-IN .. each 4d. Phones, new (4,000 m.), double .. 30 - Post Ebonite Knobs each 6d. Price 10/6 Price 10!- Free Switch Arms, laminated with bush .. 2 - Carriage Free on £1 and over. C. S. SWAN, 191 Bishopsgate, TWE (NEXT TO BRANDON'S). and 65 Windsor Road, Leyton, E.10 E.C.2

Coil -Holder. Wireless THE SIMPLEST AND MOST The Fraser Patent Coil -holder (Concentric variation).Adaptable for two or three coils.Very compact, and suitable for EFFICIENT RECEIVER independent or panel mounting.Price101-.Extra coil blocks, 2'9. SLAB COIL ADAPTER. -Invaluable for use with slab,or basket coils.Standard plug pitch.Fits any coil -holder. 2,6 each. Condensers (assembled), 0.001. 21 parts 18 -. TheCrystophone type Condensers (assembled), 0.0005, 1313, parts 11-. 20 T.T. as illustrated, has Condensers (assembled), 0-0002,9 -, parts 7!-. a wavelength of 180 to Condenser Spindles, 9d., 10d. 1/2, 1 '4. 3500 metres. No extra Condenser Spacers, Large, 9d. ;Small, 3d. doz. coilsrequired Desired Intervalve L.F. Transformers, 16,6. range can be obtained by Ebonite, 31' x 21" x 3 16ths, trimmed suitable for condenser merely operating fine," tops, 7d. coarse,"or - long range" Detector Panel, parts, 18/9. With Dulled Ebonite Top. controls. High Frequency Panel, parts, 23/6. ditto Low Frequency Panel, parts, 23/8. ditto Switch Arms, 2/3. Contact Studs, per doz. 1/6. Ebonite Knobs, 8d. Price Complete : Valve Legs, 2 nuts, washer, 3d. Condenser Vanes, per pair, 2.d. £5 10 0 Marconi Phones, B.R., 15 -. Terminals, wt. 3d. Ebonite Panels, Trimmed, V x 45" x 3 16ths, 2 -. All other parts at standard prices.Orders of £1, carriage paid. Complete Sets, including Aerials, Re-ased Price List A. Gratis. Receivers and Phones, from £7126 JAMES FRASER & CO. Sendforfullparticulars AT ONCE lin collaboration with Electrical Training College, address below. SCHOOL INSTRUCTION. WIRELESS SUPPLIES CO. Day, Evening and Pcstal Courses in Wireless, Valves, etc., P.M.G. Exam.) and Amateur Classes.Also Cable and Tele- 64, MortimerStreet, London, W.1 graphy. 'Phone, North 1036. Prospectus Free. 'Phone : Museum 2872. ' Grams : Adragonax, Wesdo, London. PRINCIPAL : Visit our Stand No. 1. AllBritishWirelessExhibition, HorticulturalHall, September3oth toOctober7th. ELECTRICAL TRAINING COLLEGE, Radio House, Manor Gardens, Holloway,N.7 AtGusT 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxxiii PHONES (PaitrzaLotiLieleeZ. 30/- CRYSTAL SET 37/6 Special Wireless Telephones, 4,000 ohms,30/-post free. Receiving Set on Mahogany base, single slide Tuning Inductance, Fixed Condenser, Crystal Detector, Terminals,40/-postfree. Valveholdersin Ebonite,firstquality only,1/-. Parisisreceived quite easilyon thisset. I. K. STEVENS & Co. Wireless Section, 32a, Chester St., Grosvenor Place, S.W.1 Trade Inquiries Invited. Phone-Victoria 5837

THE AMERICAN MONTHLY JOURNAL OF THE WIRELESS AGE WIRELESS TELEGRAPHY AND TELEPHONY A " Go -a -head " Magazine for Operators and Amateurs.

Sole European Agents : THE WIRELESS PRESS LTD., 12-13 Henrietta St., Strand, London,W.C.2

SUPPLIESWIIZELESS ACCESSORIES AND PARTS for Making Single, Two,ThreeandFourValve RECEIVING SETS, CRYSTAL SETS VALVE PANELS TUNING PANELS. Transformers,Inductances, Potentio- meters, Condensers, Filament Rheostats, VariableCondensers,Grid Leaks and Condensers, Telephones, Amplifiers and Loud Speakers, HoneycombCoils and Holders,Basketand Slab Inductances, CrystalDetectors,CupsandCrystals, Valves and Valve Sockets, Aerial Wires and Insulators, H.T. and L.T. Batteries, Instrument Wires, Etc., Etc. TRADE ONLY Catalogue A/23 onrequest

tralA UONSIOtie PLND1.1 -`,:g4;"1111,..lvlANCHISIII2

Questions and Answers THE " W.P. " COUPON Morse Practice Key To accompany Questions First -slam Finish. Thoroughly Itallable sent induring the week 7/6 Post Free commencing Aug. 26th, 1922. VOL. X, NO. 22. THE WIRELESS PRESS, LTD. See Conditions on Page 703. 12-13 HENRIETTA STREET, LONDON, W C. 2 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 A NEW THERMIONIC TRIODE!

THE THE "E E C " XTRAUDION XTRAUDION PRICE PRICE 151- 151-

A CM A L s /F.

FILAMENT CURRENT -0.5 amperes at 4 volts. ANODE CU R R E N T-Anode grid potential 50 volts, + 12 volts, 2'4 milliamperes, 0 volts 0'5 milliamperes, - 12 volts 0 milliamperes. V A C U U M TEST -Anode 150 volts, Grid -2 volts grid current less than 1milli- ampere. THE " E E C " " EXTRAUDION " Rectifies, Oscillates and Amplifies. Equals any other Triode as a Rectifier or Oscillator, and surpasses all as an Amplifier.Has exceptional mechanical Strength and Rigidity of Electrodes.Is silent working. Has a specially Coloured Glass Container to screen the light rays. Visit our Stand No. 51.All British Wireless Exhibition, Horticultural Hall, Sept. 30th to Oct. 7th TRADE ENQUIRIES SOLICITED FROM THE PATENTEES- ECONOMIC ELECTRIC, LIMITED, 10, FITZROY SQUARE, LONDON, W.1 OR FROM THE SOLE AGENT- Mr. H.S. TYLER, 23b, Balham Hill, London, S.W.12 Am: usT 26, 1922 THE WIRELESS WORLD AND RADIO REV] EW WIRELESS TRAINING COLLEGE LTD. ST. MARY ST., CARDIFF, & NEPTUNE CHAMBERS, VICTORIA ST., BRISTOL. The above Colleges are amongst the most successful in Great Britain for quickly qualifying Students for the Wireless Service. We have, since the outbreak of War, passed over 1,000 Students to Wireless Appointments. Two Systems are taught, the Marconi and Siemens Quench Spark System. We make a speciality in training ex -service men who have some knowledge of Wireless. q Ex -service men can have a free test to ascertain the time it would take to qualify them if they will call at the College. For Terms apply to- LI BUT -COMDR. J.R. SCHOFIELD, M. B. E.,R.N.V.R.(C),Principal. P.S.Every student who qualified at our Colleges was placed in a permanent situation. DON'T PAY FOR YOUR SETS AT TOP PRICES. BUY FROM THE MAKERS & SAVE MONEY TELEPHONY RECEIVERS FIXED CONDENSER, 1/6.GRID LEAK, 21. TWO -VALVE RESISTANCE AMPLIFIER.-Will receive all TERMINALS, POLISHED AND LACQUERED, 2/6 doz. wavelengths from 180 metres to 30,090 metres.Perfect for INDUCTANCE FORMERS,ror x 31". READY FOR telephony.Mounted in French polished mahogany cabinet WINDING, 10d. with ebonite top.Perfectly simple, and can be operated by EBONITE SWITCH KNOBS,POLISHED & KNURLED, did. anyone.Finest workmanship and finish. VALVE HOLDERS, EBONITEBASE, LACQUERED LEGS, 2/-. Every instrument tested and guaranteed to give perfect results. LAMINATED SWITCH ARMS, WITH BUSH & NUTS, 2/9. CRYSTAL DETECTOR, 5/-.CRYSTAL RECEIVER, £2. PRICE 2 -valve£5,3 -valve£6. L.F. INTERVALVE TRANSFORMER (SILENT), 19/8. One -valve panel.A very superior instrument. Price 28/, INDUCTANCE SWITCHES, 5 STUD, 7/6 ;10 STUD, 9/- Illustrated Catalogue, 3d., post free 19 STUD, 12/6. AGATE CYLINDER FOR JONSEN-RABECK LOUD SPEAKER, 22/6. LEWIS POLLARD, Mail Order Office - MANUFACTURER OF WIRELESS INSTRUMENTS, 126, FOREST ROAD, EVLINSDALSTON, LONDON, E.8 209,CunliffeRoad, BLACKPOOL. Price List Post Free on application. TRADE SUPPLIED.

C62, Crownhill Rd., Harlesden, SOMETHING NEW e LONDON, N.W. COLOURED HIGH FREQUENCY TRANSFORMERS Phone: 3370 Willesden Interchangeable type tofltstandardvalveholders. WIRELESS These transformers are manufactured from a new insulating material, with equal insulation properties to ebonite, and are SPECIALISTS supplied in various colours to quickly distinguish the wavelengths. FROM The various coloured transformers will improve the appearance of your receiver and relieve the dull monotony of an ebonite panel.Supplied in white, green, red, amber, and blue. OCK Unwound formers fitted with split pins, 4/'-to 5/6 EACH, postage extra. POST EE. Thetradesupplied. LEWIS POLLARD, 21/ - Manufacturer of Wireless Instruments, L.F. INTERVALVE #120W TELEPHONE 21 /- 209, CUNLIFFE ROAD, BLACKPOOL. I HAVE IN STOCK 5000 BROWN'S PAIRS(120 ohms) " A " PHONES Three Valve ReceivingPanel NEW AND UNISSUED POST Am. PER First-class Workmanship FREE-al-IF I PAIR Price (minus valves) £5 5 0 CASH WITH ORDER

HENRY J. BREWSTER & CO., WILKINSON, Lonsdale Rd., Kilburn, 11, QUEEN VICTORIA STREET, E.C.4 TRADE SUPPLIED (Same address since 1900)N.W.11 xxxvi THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922

Silk and Cotton Covered H.C.Copper Wire, Resistance P. ORMISTON & SONS Wires, Fuse Wire, Binding Wires, Charcoal Iron Core (P. H. ORMISTON) ::ESTABLISHED 1793 Wire, Asbestos Covered Wire, Braided and Twisted 79 Clerkenwell Rd., London, E.C. Wires, Bare Copper Strand and Flexibles of any Con- struction, Wire Ropes, and Cords(finesizes)in "Ormiston, London." tt 13259Central. Galvanized Steel, Phosphor Bronze, £3c.

THE TINGEY UNIT SYSTEM Established rpm HAS PROVED ITS EFFICIENCY "t"' Write for ILLUSTRATED CATALOGUE (3d. post free) which contains an article on Wireless Made Easy and a Complete List of all Wire- help you? less Goods in Stook Can I Visit our Stand No. 26.All I WILL GIVE YOU £50 British Wireless Exhibition, if I fail to produce over 7,000 testimonials from others I have HorticulturalHall,September helped to a successful 3oth to October 7th. career. 92, Queen Street, Yours to success, W. R. II. TINGEY Hammersmith, London,W.S. duery man is the Architect of his own Fortune ! ARE YOU QUALIFIED 9 FOR THE JOB YOU SEEK MRELEs WETEACH ADVICE Flit Et'. LEARN A TRADE Mon moderate charges OR BY POST Payable monthly. PROFESSION. Write for one of our FREE BOOKLETSonanyof the RECEIVERS, following subjects : CAN BE Architectural Drawing 1 Matriculation Building Construction Metallurgy Clerk of Works' Duties Mining REWOUND Aviation Mine Surveying Boiler Engineering Motor Engineering TO Boiler Making Naval Architecture Chemistry Pattern Making 4000 Ohms Civil Engineering Salesmanship Concrete and Steel Sanitation PER1 21ow SET Draughtsmanship Shipbuilding Electricity Structural Engineering TURNOCK, 41 High St. Aston, Bham Engineering Surveying and Levelling G. Foundry Work Telegraphy & Telephony Internal Comb. Engines Wireless Telegraphy SENSATIONAL REDUCTIONS. Marine Engineering Special Course for Valve Holders, 2 nuts on each leg. 1,- Post 3d. Mathematics Apprentices Condenser Plates. Fixed or moving. 1/- per doz. Post 3d. What proof do you carry? Your word to an employer is not Washers for fixed plates 3d. per doz. For moving 53. per doz. proof that you are efficient, but a College Qualifying Diploma or Post 2d. Certificate, signed by the Professional Staff, is a proof of efficiency, and a Threaded Rod for Spindles, etc.5d. per foot.Nuts for same valuable asset in seeking a remunerative position. 3d. per doz. We specialise iu all ennuis. connected with technical subjects. If you are preparing for any exam. ask our advice.All 3" Semi -Circular Scales o-ifio degrees.8d. each.Post 23. Particulars FREE OF CHARGE. Parents should seek our advice for ly Ebonite Knobs with threaded centre, ed. post 2d. Pointers 2d, their sons. If you are interested in any of the subjects mentioned above Stop -pins 1/- doz. Bush and Lock Nut 5d. Extension Handle 4d. write, naming the subject, and we will send you our FREE BOOKLET Valve Lege or Sockets 1/10 per doz. Post 3d.(complete with Please screw or nuts.) state Mark HI Terminals with nuts 2/3 per doz. Post 4d. your age. Vernier Condensers, 3 -plate 6f- ; 5 -plate, 7/-. Post 9d. Courses 7 -Strand Silicon Bronze Aerial Wire, per too ft. 4/-; per 15o ft. specially 5/9.Post 9d. com- Filament Resistances for panel mounting 3/9. Post 3d, bined to These are only a few of the numerous items contained in our meet all Catalogue which will be sent free with order. require - SCLEHTIVIC SUPPLY STORES, 8, Newington Causeway, merits. 'Phone-Hoi, 4177. LONDON, S.E.1 North Wales Wireless College & Amateur Supplies COLWYN BAY. 'Phone 407. Most Complete Stock of all Wireless Students prepared under ideal conditions as and Accessories. Wireless and Cable Operators Instruments POSTAL AND RESIDENTIAL TUITION. PROMPT DELIVERIES. SPECIAL POSTAL COURSE FOR AMATEURS. LIST BY RETURN. STAMP. PROSPECTUS POST FREE. AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW xxxvii

- WAR ON CHINA! Carriag1°IeIBRASS ROD !el./- alr'rtit dg Paid Each Parcel contains: INSULATORS. 2feetI inch square 2 feet inch round

Better INSULATION of your AERIAL 2 round

2 5/32 2 to7/16 means LOUDER MUSIC from your * 2 2

2 ,5/x6 2 x/r6 RECEIVER. 20 S.W.G. Alum. Condenser Vanes.1/- doz.Fixed or movable. Spacers.Small 3d. per dozen.Large 6d. per dozen. We are offering at a remarkably low price 20,000 MX. II (Above are guaranteed to oor either way.) EBONITE double -hook INSULATORS asillustration) and Valve Legs with Nuts and Washers. 2d. each. Copper Foil for Condensers. oo2 thick. ed. foot. 6 inches wide. we can recommend these for RECEPTION or TRANSMISSION Hexagon Brass Nuts.4.BA. 4d. dozen.2.BA. ea. dozen. as the best of their kind extant. Screwed Brass Rod.4.BA. 4d. foot.2.BA. ed. foot. They are unbreakable in wear, will last a likUme, and have Trade Enquiries Invited.(Actual Manufacturer). been tested to 5.000 Volts. 34, Queen Ames Grove, Bush SYDNEY S. BIRD Hill Park, Eafleld, London, N. AS USED BY BROADCASTING STATIONS AND Telephone:EN1,1 ILI 67.2 MANY HIGH POWER TRANSMUTING STATIONS. Size :Length overall, 8k".Diameter, SKINDERVIKEN BUTTON. A Supersensitive Microphone. Known all over the world and patented in every civilised country.Over 60,000 sold.ENGLISH Manufacture. Make up your own Loud Speaker. Transmit your GRAMOPHONE music PRICE: 2/- each. Set of Four 7/6 to any room in your house. Special Trade Terms. Post free. The only practicalPrice Microphone Si- for useeach in Detectiphone Sets. Special Lnw Resistance Receivers (for use with S. GOODE, the Skinderviken Buttons) 10/- each Read what Lieutenant C. Special Gramophone Attachments.. famous Wireless Expert, says of these insulators. Write for 16 page BOOKLET fully illustrated and containing muchusefulinformationforallinterested inElectrical Messrs. W. Ward & Son. LONDON, W. Sound Transmission. M. Post free. HINCKLEY. Sole Proprietors: DEAR SIRS, MIKRO LTD., 274/6, Pento tville Rd., London, N. I have used the type Mk. II ebonite insulators, precisely as Opp.Hine'.Cross lifeti lily Station). those submitted to me by you, on Transmitting and Receiving Aerials in many different countries under all climatic conditions.Through the intense cold of the Arctic Regions and OOJAH the heavy rains of the South, I have proved these insulators to be superior to any other kind I have handled.I can strongly HIGH FREQUENCY TRANSFORMERS. recommend everyone using aerials, whether for Transmission or Reception to fix these insulators in preference to any yet available at such a mcderate price. C. S. GOODE, Lieutenant (Tech.) M.W.S.Ldn.

Fit these in place of your present insulators and note the INCREASED EFFICIENCY.

MAR CKOENI TRANSMITTERS MA Good range using only 6 -volt Acc. >6 FIG. I. FIG 2. ," Patent pending Rd. No. 685488. SPARK B.MK. II. ..,.,6;" These H.F. Transformers have been designed to meet the grow- ing demand of the Wireless Experimenter for a cheap and it 100-180 Metres on Aerial.tze efficient H.F. Transformer. They were used Successfully in the recent Transatlantic Tests. NEW AND PERFECT is All Transformers are wound with D.S.C. paraffin -waxed copper wire (affording the highest degree of insulation) of a gauge Size 9 X 6!" x 614" 1.,,e''' o:.". far thicker than transformers now upon the market ;the H.F. resistance being extremely low. Complete ,e,9co.1 No. 3 is recommended for the reception of the Dutch Concert with Tools and Spares. 47o S)

GREENSLADE & BROWN ... LANSDOWNE ROAD. CLAPHAM, S.W. 9. 4t"" t..... , .. 639. Telephonesritoon ...i'`). ....P .... THE WIRELESS WORLD AN I) RADIO REVIEW Ai:(;tsT 26, 1922 We areexhibitingat thefirst ALL-BRITISH WIRELESS EXHIBITION AND CONVENTION HORTICULTURAL HALL 1922 SPECIAL TRADE DAY Vincent Square, Westminster ADMISSION OCT. 2nd : 1/3 (including tax) SEPT. 30th to OCT. 7th SPECIAL PUBLIC DAY (Saturday) (Saturday) 113 OCT. 3rd : 5/- (including tax) 10 a.m. to 10 p.m. daily INCLUDING TAX Public admitted on both days after 6 p.m. The only Exhibitionwhose Conventionwill be held under theauspicesofthe WirelessSocietyofLondon. Auckland, G. Z., & Son. " K. B." Radio Equipment Co. Automatic Telephone Manfg. Co., Ltd. Marconi Wireless Telegraph Co.,Ltd. Bertram Day & Co., Ltd. Marconi Scientific Instrument Co., Ltd. Bower, J. B., & Co., Ltd. McMichael, L., Ltd. British Thomson -Houston Co., Ltd. British Wireless Supply Co. Metropolitan -Vickers Electrical Co., Ltd. Brown, S. G., Ltd. Mitchell's Electrical & Wireless Ltd. Burndept, Ltd. Mullard Radio Valve Co., Ltd. Chloride Electrical StorageCo.,Ltd. Osram G. E. C. Lamp Works. Cossor, A. C., Ltd. Coomes & Co. Pettigrew & Merriman, Ltd. Peto Scott Co. Dubilier Condenser Co. (1921), Ltd. Radio Communication Co., Ltd. Elwell, C. F., Ltd. Radio Instruments, Ltd. Econ. Manfg. Co., Ltd. Radio Service, Ltd. Economic Electric, Ltd. Radio Press, Ltd. Ever Ready Co. (Great Britain), Ltd. Rogers, Foster & Howell, Ltd. Fellowes Magneto Co., Ltd. Siemens Bros. & Co., Ltd. Gamblen & Partners, L. A. Sullivan, H. W., Esq. Gambrell Bros., Ltd. Sterling Telephone & Electric Co., Ltd. Gamage, A. W., Ltd. General Radio Co. Tingey, W. R. H., Esq. Graham, A., & Co. Telephone Manfg.Co., Ltd. Harwell, Ltd. Wates Bros. Hart Accumulator Co., Ltd. Western Electric Co., Ltd. Hambling Clapp & Co. Wireless Supplies Co. H. P. R. Wireless, Ltd. Wireless Equipment, Ltd. Wireless Press, Ltd. Igranic Electric Co., Ltd. Isted, T. H., Esq. Zenith Manfg. Co., Ltd. ORGANISERS : BERTRAM DAY & CO LTD. WIRELESS PUBLICITY SPECIALISTS 9 and 10, Charing Cross, London, S.W.1 Gerrard 8063/4 AUGUST 26, 1922 THE WIRELESS WORLD AND RADIO REVIEW IF YOU WANT A PETO -UNITS GOOD P BOOK ON RADIOTELEPHONY Copied but Never Equalled GET PETO THE MANOF PARTS stilloffers his originalproductions. TELEPHONY UNIT No, 8.

WITHOUT WIRES i :- H.F. BY , ea,. ..t. ',111 p - t. 'o

1 AMPLIFYING PHILIPR.COURSEY,B.Sc. (ENG.),A.M.I.E.E. °P.. 111 - PETO.SCOTI UNIT. , . ..,z. Nett 1 .... Price 15/. 13-1 Set of Parts 13/8 ( Postage 9d.) - 13 Cabinet to fit3/6 It contains a complete collection of information on the ''-(Te various schemes, proposed and tried, relativeto the ,-, electrical transmission of the sound of voices through --fir-ft space without wires. s'aee" An excellentlistof references to UNIT No. 4. papers and articles, forms aomplete bibliography ofthe whole subject.

,! ,c lb. .0 THE WIRELESS PRESS, LTD. ea''' DETECTING -o Dept. W.W. 8/4 .1 UNIT.

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Get our illustrated catalogue post free 8d., with 108 99 22/6 1/3 Fully Illustrated List containing over 100 illustrations, post free 4d listof transmitting stations and wavelengths. Visitour Stand No. 18.All British Wireless Exhibition, H. D. BUTLER & CO., LTD. HorticulturalHall.September 3othto October 7th. Office :Bank Buildings, 222,GreatDover Street, BOROUGH, S.E. I (OppositeBoreTube Station) PETOSCOTT, condenser King Works :Canonbury. London. N.7 64, HIGH HOLBORN, LONDON, W.C. I. TelephoneHop 3029.Telegrams :Ingenuity. Phone. London. Also at x7, Frome Road, Wood Green, xl THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26, 1922 WIRELESS EXHIBITION

under the auspices of The South London Wireless and Scientific Club will be held On 24th, 25th and 26th August At ST. JOHN'S INSTITUTE LARCOM STREET, WALWORTH, S.E. 17 2 minutes' Southwark Town Hall 5 minutes'Elephant & Castle Open from 2 o'clock to 10.30 Thursday & Friday. 12 o'clock to 10 Saturday. SPECIAL ATTRACTIONS Wireless Controlled Airship in operation by the inventor, CAPT. DE. VILLIERS. Wireless Controlled Torpedo Boat. Broadcast Receptions, Numerous Trade and Amateur Exhibits. Frame Aerial Transmission and Reception. " Come and .Hear Your Own Voice by Radio." Magnavox and Other Loud Speakers.

LightRefreshmentat " Light "Prices.

Sec.: W. G. ANSELL, Admission 1'- 69, Larcom Street, S.E.17 includingtax. AuGuar 26. 1922 THE WIRELESS WORLD AND RADIO REVIEW

The London Telegraph Training College, Ltd. Telephone ESTABLISHED WESTERN 2696. Morse House, Earl's Court, S.W. 25 YEARS. OFFICIALLY RECOGNISED BY THE WAR OFFICE AND POSTOFFICEAUTHORITIES CABLE AND WIRELESS TELEGRAPHY. pARENTS desirous of placing their sons in either of the above Services and of affording them the best training facilities should apply for particulars of Courses and the methods of instruction which place this Institution in the first rank.Cable Telegraphy offers at the present t -me excellent prospects to youths from 15 years of age and upwards, and the College has exclusive facilities for obtaining posts for qualified students in the leading Cable Companies at commencing salariesof£150 to£300 per annum, with yearly increments of £12 to £25, and ultimate possibilities of obtaining positions as Supervisors, Assistant Superintendents, Managers, etc. In the Wireless Telegraph Service the commencing remuneration at the present time is approximately £150 per annum, and Operators, when qualified by obtaining the Postmasser- General's Certificate of Proficiency, are nominated by the College for appointments. NoCorrespondenceClassesorBranches. DAY AND EVENING CLASSES. Prospectus containing all information will be forwarded on application to THE SECRETARY (Dept. H.), 262, Earl's Court Road, Earl's Court, London, S.W.5 Sole Proprietors of the "Scott" Training Disc, which contains useful formulae and other information for Wireless Telegraph Operators and is invaluable to Army Signalling Officers for range finding, ate. Price, complete with instructions for use, lb..Postage 2d. The YEAR BOOK of WIRELESS Telegraphy and Telephony 1922 476 Pages. Price 15/- Nett. Demy 8vo. Postage 11, Abroad 1 /4.

CONTENTS Record of the Development of Wireless Telegraphy-sNational and International Wireless Laws and Regu- lations-Directory of the World's Land and. Ship Wireless Stations-International Allocation of Call Letters-Alphabetical List of Call Letters-Meteorological Section-International Time and Weather Signals-National Resumés of Progress in Wireless Telegraphy-Particulars of Wireless Telegraph Patents, 1921-Aviation Section-Tabular List of Aviation Stations-Useful Data Section-Wireless Terminology-Conventional Signs used in Wireless Diagrams --Companies Engaged in the Commercial Development of Wireless Telegraphy-Biographical Section-Literature on Wireless Telegraphy and Telephony-Directory of the World's Wireless Societies-Directory of Wireless Colleges and Schools-List of Licensed Amateur Transmitting Stations-Code Section-Special Articles on " The Earthing Resistance of Antenrue," by Dr. Miessner-" The Recording_ of Wireless Signals," by Dr. Abraham-" The Birth and History of Long Distance Wireless Telegraphy "-" The Beatification Effect in its Reaction to the Composition and Structure of Crystals." d valuable feature of the present issue is the specially drawn map, which gives, for the first time, a simple means of finding the distance and true direction of Wireless Stations in all parts of the World, from London as the centre.

DEPT. W.W.. 12-13 HE THE WIRELESS PRESS, LIMITED, ST., STRAND. LONDON.NRIETTAW.C.2 THE WIRELESS WORLD AND RADIO REVIEW AUGUST 26,192!'

I BROADCASTING Sullivan Patent TelephoneReceivers for Radio Telephonyand Telegraphy Of High and Uniform sensitivity andDISTORTION -LESS being thus specially adapted for receiving speeches, news and concerts fromBROADCASTING and other stations. WINDINGS highly insulated, durable and reliable in all climates and under all conditions of service.This was strikingly evidenced during the Great War when a vessel carrying "SULLIVAN" phones shipped to the order of an Allied Government was sunk through misadventure, but at a later date was successfullyraised and the cargo salvaged.The Telephones themselves were found to have sustained much damage through the action ofseawater,butthecoilsprovedtobeperfectelectrically and mechanically notwithstanding their long immersion, and all were again brought into requisition. IMPORTANT NOTICE These Telephone Receivers mu.)t not be confused with the old and comparatively insensitive " SULLIVAN " phones, sold by the Disposals Board and still being retailed by certain dealers, nor with those new but comparatively insensitive Radio Telephone Receivers of Continental and other origin bearing a misleadingresemblanceto my own pattern.

While aCeial Headbands supplied if desired. Visit our Stand No. 49. All -British Wireless Fxhinition, Horticultural Hall, September 30th to October 7th D EMONSTRATION Without Public advertisement olany AND SHOWROOMS: kind, over one quarter ofa million Liverpool House, Middlesex Street. sets of " SULLIVAN" phones have London, E.1 been made and sold /Or" Wireless" (Two minutes' walk from Liverpool Street and Broad Street Stations). alone. Trade Terms onApplication.

Works. 0 /I e . "LIVERPOOL HOUSE"HW. SULLIVANWINCHESTER 1-10USL. MIDDLESEX ST.,LONDON.E.1 LONDON,EC.2., ENGLAND Phone. Avenue4871 Tait OR "DCDISC/Vr, STOCK,1.01.400.:" PhoneyLondon Well3518

IN IN Printed by Sanders Phillips & Co., Ltd., Chryssell Road, London, SAV.9, for the Proprietors and Publishers, The Wireless Press, Ltd., 12-13, Henrietta Street, London, #.4.7-:11W.0.2 ;Sydney, N.S.W., 97, Clarence Street ;Melbourne, 422-24, Little Collins Street :New York, 326, Broadway.