JULY, 1922 PRICE 25 CENTS

RADIO FOR EVERY PLACE AND PURPOSE

,o4r-.. .. An Evening with Dr. Alexander Graham Bell

Protection of the Receiving Antenna

A Church with a Mighty Congregation

A Simply Constructed C. W. Transmitter

Our Amateur Radio Reserve

DOUBLEDAY, PAGE & COMPANY, Garden City, N. Y. www.americanradiohistory.com -- --- . --c

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www.americanradiohistory.com Radio Broadcast ROY MASON, EDITOR ARTHUR H. LYNCH, TECHNICAL EDITOR

111) !hi Fr

CONTENTS FOR JULY, ,1922

Dr. Alexander Graham Bell Frontispiece THE MARCH OF RADIO 191 WHEN DE WOLF HOPPER BROADCASTED TO HIS BIGGEST AUDIENCE - 198 WHAT EVERYONE SHOULD KNOW ABOUT RADIO HISTORY PROF. J. H. MORECROFT 199 AN EVENING WITH DR. ALEXANDER GRAHAM' BELL - DONALD WILHELM 205 INCREASING THE SELECTION POWER OF A RADIO CIRCUIT JOHN V. L. HOGAN 211 PROTECTION OF THE RECEIVING ANTENNA G. Y. ALLEN 214 A CHURCH WITH A MIGHTY CONGREGATION - ARCHIE RICHARDSON 218 RANDOM OBSERVATIONS ON RUNNING A BROADCASTING STATION H. M. TAYLOR 223 RADIO PERSONALITIES 228 REGINALD AUBREY FESSENDEN LUCILLE JOYCE NEW RADIO NET FOR ROGUES DONALD WILHELM 231 HOW RADIO CAME TO INDEPENDENCE, KANSAS - THOMAS M. GALEY 234 HOW TO BEGIN TO ENJOY RADIO - - - CAPT. LEON H. RICHMOND, U. S. A. 236 A SIMPLY CONSTRUCTED AND OPERATED SHORT RANGE C. W. TRANS- MITTER ZEH BOUCK 24o OUR AMATEUR RADIO RESERVE - - - - MAJOR PAUL W. EVANS, U. S. A. 243 RADIO FOG SIGNALS AND THE RADIO COMPASS 247 THE AUDIO PILOTING CABLE IN THE AMBROSE CHANNEL DONALD WILHELM 249 PROGRESS OF RADIO IN FOREIGN LANDS 251 RADIO HELPING US ENJOY THE SUMMER ARTHUR H. LYNCH 255 RADIO IN REMOTE REGIONS 262 THE GRID -QUESTIONS AND ANSWERS 264 PRESENT RADIO BROADCASTING STATIONS IN/THE UNITED STATES - - 270

Copyright, 1922, by Doubleday, Page & Co. All rights reserved TERMS: $3.00 a year; single copies 25 cents F. N. DOUBLEDAY, Pres. ARTHUR W. PAGE, Vice -Pres. NELSON DOUBLEDAY, Vice -Pres. RUSSELL DOUBLEDAY, SeC'y. S. A. EVERITT, Treas. JOHN J. HESSIAN, Asst. Treas. DOUBLEDAY, PAGE & CO. THE WORLD'S WORK COUNTRY LIFE THE GARDEN MAGAZINE SHORT STORIES EDUCATIONAL REVIEW CHICAGO: People's Gas Bldg. GARDEN CITY, N. Y. NEW YORK: 120 W. 32nd Street BOSTON: Tremont Bldg. LOS ANGELES: Van Nuys Bldg.

www.americanradiohistory.com DR. ALEXANDER GRAHAM BELL Inventor of the Telephone

www.americanradiohistory.com JUL -7/922, Oci e,aaxcs ,} RADIO BROADCAST'

Vol. 1 No. 3 July, 1922

The March of Radio REPORT OF THE RADIO TELEPHONE COMMITTEE

AVERY important step was taken in public broadcasting, 40o miles or more from the progress of radio telephone de- the sea coast, exclusive, 65o -7oo; Marine radio velopment when the committee, telephony, non-exclusive, 525-650; Marine called by Secretary Hoover, handed telegraphy, exclusive, 525-650; Aircraft radio in their final report, containing re- telephony and telegraphy, exclusive, 500-525; commendations as to the proper allocation of Government and public broadcasting, exclu- wave lengths for the different radio telephone sive, 485-495; Private and toll broadcasting, services now existing, or anticipated. The 285-485 ; Restricted special amateur radio committee, under the leadership of Dr. S. telegraphy, non -exclusive, 3 to; City and State W. Stratton, the Director of the Bureau of public safety broadcasting, exclusive, 275-285; Standards, was made up of experts from all Technical and training schools (shared with branches of radio activity -the military and amateurs) 200 -275; Amateur telegraphy and civil services of the Government, commerical telephony, exclusive, 150 -200 meters (this radio engineers, college professors, and repre- makes the total wavelength range assigned to sentatives of the amateurs, all combined to amateurs 15o -275, part of it being shared with work out what seemed to be a reasonable di- the technical schools); Private and toll broad- vision of the frequencies available for radio casting, exclusive, too-15o; Reserved, all be- traffic. low too meters. The recommended assignment of wave Of course we are principally interested in the lengths was as follows- Transoceanic experi- wavelengths to be used for broadcasting. ments, non -exclusive, 5000 -6000 meters; Fix- Government broadcasting is defined as that ed service, 2850 -3300; Mobile service, non- done by departments of the Federal Govern- exclusive, 2500-2650; Government broadcast- ment; public broadcasting as that carried on ing, non -exclusive, 1850-2o5o; Fixed station, by public institutions, such as Universities; non -exclusive, 1550-165o; Aircraft radio tele- presumably church broadcasting will come phone and telegraph, exclusive, 1500 -1550; under this classification. Private broadcasting Government and public broadcasting, non- signifies that carried on, without charge, by exclusive, to5o -15oo; Radio beacons, exclusive, any communication company, newspaper, etc. 950-1050; Aircraft radio telephone and tele- Such broadcasting, if charge is made, comes graph, exclusive, 85o -95o; Radio compass ser- under the classification of toll broadcasting. vice, exclusive, 75o -85o; Government and In view of the interest of the public, as a public broadcasting, 200 miles or more from the whole, in broadcasting, it was strongly urged sea coast, exclusive, 700 -750; Government and that point -to -point radio communication be

www.americanradiohistory.com 192 Radio Broadcast discouraged; it is quite evident to any one that of the receiving set used and upon the skill of the use of one "channel" in the ether for con- the operator in adjusting it, but with the versation between two individuals is entirely average receiving set sold to-day it seems that out of the question unless such communication there may be ten or fifteen channels; if all the is impossible by any other means. Thus receivers in use were of the better types and in point -to -point communication by radio must the hands of skilled operators, probably twenty be allowed only for shore -to -ship, to light -ship, or thirty channels would be available, but of or to isolated islands, etc. The granting of course, such is not the case. Probably there licenses to companies organized for commercial will be not more than eight useful channels in radio traffic between cities should not be per- this range of frequencies. mitted. It is to be pointed out that if such The question must be indeterminate to a procedure had been followed during the last considerable degree because of the possibility few years, it would not have been necessary of large differences in the various signal to get out injunctions to prevent such inter- strengths. ]f, for example, two stations of ference as was caused by the operation of the equal power were transmitting from New York Intercity Radio station in New York City. and were being received fifty miles away, both Such unnecessary use of radio always impedes would be of equal strength, and it would be its progress for the financial benefit of a few possible to adjust the receiving sets for no in- men more interested in their own fortunes than terference with two wavelengths as close to- in that of the radio art. Wire telegraphy and gether perhaps as 300 and 310 meters. But telephony furnish ample means of communi- if one of the transmitting stations was within cation for commercial traffic, in fact, it seems a few miles of the receiving set, and the other likely that if inquiry were made 'it would be fifty miles away, then, in order to hear the dis- found that much of the " radio". traffic of such tant station without interference from the companies is sent over lines leased from the nearby station a wavelength difference of 30 wire companies. meters or more would be necessary. Private and toll broadcasting are also al- HOW MANY SIMULTANEOUS BROADCASTS ARE lowed another frequency band from 100 meters POSSIBLE? to 150 meters; although this is a comparatively IT WILL be seen that for private and public narrow band, there are several channels possible broadcasting the committee recommends because of the large difference in frequency of three bands of frequencies, rather widely the two limits, namely 1,000,00o cycles. It separated. Public broadcasting, such as might is quite likely that there are twenty more be done by a University carrying on extension channels available here for good receiving sets work or the free lectures sent out by city de- and five to ten with ordinary sets. lt must be partments, have wave lengths from 1050 meters pointed out, however, that practically none of to 1500 meters; this range should permit the the receiving sets which have been supplied to simultaneous transmission of about eight mes- the public so far will be much good for receiving sages without undue interference. In estimat- these low wavelength signals; most of them ing how many simultaneous messages are pos- cannot tune for a signal of such low wave- sible (or how many "channels" are available) length and those that can are very inefficient it is assumed that the receiving set is a good for such high frequencies. one of theConnection.using . vacuum tube and re- generative WHAT KIND OF BROADCASTING IS COMING? For private and toll broadcasting, the band IN THE range of wavelengths, 285 to 485 from 285 meters to 485 meters is assigned; it meters there will be about eight channels will be remembered that at present all private available. For what are these eight channels broadcasting is done on a wavelength of 360 going to be used? We do not need to consider meters. The frequency range permitted for the possibility of broadcasting lectures or other broadcasting of this kind in which we are especi- educational talks because for such work a ally interested is therefore from about 600,000 special frequency band has been allowed, to about 1,000,000 cycles per second, a range offering, for the present at least, plenty of of 400,00o cycles. How many separate chan- channels for such traffic. It appears then, nels are there available in this frequency range? that for entertainment and toll purposes there It must depend very largely upon the quality are eight channels available. This seems a lot;

www.americanradiohistory.com The March of Radio 193

at present we have only one channel, and lis- made, and of course that means advertising. teners in the vicinity of New York, for ex- Yet direct advertising is not to be allowed, if the ample, can hear nothing but WJZ when this recommendations of the committee are followed, station is in operation. KDKA and a few as they certainly should be, in this respect at others can be heard only if WJZ stops sending. least. The toll business will probably settle With eight channels open it seems as though we down into rather good entertainment, the only should have much better entertainment in the advertising the client receives directly being in the wording of the announcement of the selection. Much as we may frown on the idea of radio advertising, it must be appreciated that this is just the way WJZ's excellent programme is maintained to -day. The only pay the clients of the stations (in this case the artists) get is the advertising which the announcer gives them. Of course sometimes the performances of the artists also, are of advertising value to them, but if the tubes don't function properly, they are not. RADIO IN THE LONELY PLACES PROBABLY the million or more people who are listening every evening to the radio entertainment which various broadcasting sta- A progressive New Ygrk shoe salesman has installed a tions offer, are unanimous in their appreciation radio receiving set to entertain his customers. The large of this latest contribution of applied science; conical device is a loudspeaker made with a parchment dia- phragm which reproduces music with little or no distortion judged by the methods of the statistician it must indeed be a wonderful artwhich contributes future than we have had in the past. Just so much enjoyment to so many people. But what stations are going to furnish it is not yet there are much more important fields in which evident, but the public may rest assured that radio serves, fields in which the theatre, or the channels will all be spoken for soon after movie, or dance hall can contribute nothing they are available. because they are not available. Of course the Where does toll broadcasting come in? It real field of radio will ever be that in which is defined as broadcasting for which a charge is Jack Binns was the pioneer, the carrying of the

Even in Olongapo, P. I., the U. S. Navy carries on regular radio communication, and this little shack shelters the equipment

www.americanradiohistory.com 194 Radio Broadcast distress call of sinking vessels, or aeroplanes Not all of us have the vision and imagina- stalled in inaccessible places, or adventurous tion of a Faraday, so that there are still some explorers who have encountered difficulties details of radio theory which seem more or which make it imperative that they get help. less obscure. One of the developments of Besides these cases, in which the reception radio, which seems always to attract much of perhaps one millionth of a watt of power from attention, is the reception of radio signals by a the distressed operator means the difference be- set on a moving object, such as train, bus, tween life and death, there are other cases where aeroplane, etc. Now there is really nothing radio means the bringing to life of some people strange about this at all; in fact, it would be leading an existence so lonely that they are much more strange if signals were not received dead in so far as contact with other human be- on a moving car just as well as when it is sta- ings is concerned. To the dweller on a lonely tionary. isle, perhaps in connection with the rest of the Radio communication is carried on by means world only once a year, to the lonely watchers of disturbances -wave motions -in the ether; on the light- these waves houses and light- travel with the ships, for weeks speed of light and months at a (186,000 miles time abandoned per second) for to the wind and the very good waves, radio te- reason that they lephony offers are really the something of aI- same thing as most inestimable light. if we grant value. They can that a loo -meter now hear the radio wave is the voice of their fel- same kind of a low man perhaps thing as a 10,- every evening, 000 -meter wave, At the sea -shore or away in the m ountains it is now possible to be in and the music almost constant communication wit h the city. This portable radio set then radio and which travels to has a receiving range of several hun dred miles and a transmitting range light are the them so silently of four or five miles same thing; be- and swift1 ' must cause of the elec- put new life into their monotonous existences. tric and magnetic fields associated with There must be many islands on our coast where them, they are called electromagnetic waves. the installation of a radio outfit will bring lonely When an electromagnetic wave travels by an people into immediate touch with the rest of the antenna, it sets up alternating currents therein, human race. ln such places, and in the light- which, acting - on detector and telephones, houses and ships, radio broadcast entertainment give an audible signal. Now, will it make will bring cheer and enjoyment where nothing any difference whether the receiving station else avails. In a recent interview, George R. is moving or not? Radio waves being the Putnam, Commissioner of Lighthouses, re- same kind of disturbance as light waves, we ported that many of the lighthouses in Alaska may argue the question from the action of light. are being equipped with radio telephone ap- If a man in a passenger car, moving through a paratus. In some of these stations, he states, station, watches some one on the platform light the keepers have been without mail from the a match, will the color and intensity of the flame outside world for as much as ten months. be the same as if the car was not moving but In hospitals a receiving outfit should be a was stationary at the platform? The flame wonderful help in keeping patients interested corresponds to the transmitting station of a and comfortable. Furnished with a series of radio set and the observer's eye receiving the head sets, so that any patient may listen in or electromagnetic waves from the flame, cor- not, as he desires, a good receiving outfit would responds to detector and telephone. The an- prove a valuable adjunct to the cheerful nurse swer to the question is evidently -Yes, the in keeping a ward filled with smiles and content- motion of the observer does not in the least in- ment. terfere with the observer's eye perceiving the

www.americanradiohistory.com The March of Radio '95 flame. Of course, if the passenger was carried train was in a tunnel, a hundred feet under- past the station platform as fast, or faster, than ground. Not very strong, to be sure, but still the velocity of travel of the light wave he would strong enough to be read. It might be said never know whether the match was lighted or that the radio waves did not penetrate the not; the light wave which started from the ground so deeply but came in from the ends match when it was struck, would not be able of the tunnel. But we also know that a sub- to catch up with the observer, and so evi- merging submarine, even after it has gone 6o dently could not affect the nerves of his eye. feet below the surface still gets audible signals, But trains and buses do not travel with such and there are no tunnel ends for the signal to velocities, so we can eliminate that possibility come through in such a case. from our discussion. The ordinary theory of radio transmission In so far as motion of the receiver is con- shows that we can expect a certain amount of cerned, therefore, it is evident that there can penetration of the radio waves into the earth be no effect on the action of radio waves; re- or ocean; it can be predicted how far the waves ceiving a radio signal on a moving bus, or on a will penetrate sea water, and the experiments mile -a- minute train, is no more wonderful, with submarines check the theory. It's very from the standpoint of radio theory, than if the much the same as light going through water; bus or train were stationary. some will get through but most of it is absorbed I t is interesting to note that in some of the before the light has penetrated the water very experiments in getting radio signals to mov- far; just so is the radio wave absorbed in the ing trains, the signals were heard when the earth's surface.

Recent tests have proven that communication between moving trains and land stations along the route is now practical, and Edgar Sisson, Jr., is here shown operating the outfit on Lackawanna train Number 3

© Underwood & Underwood

www.americanradiohistory.com ¡96 Radio Broadcast

This absorption of radio waves gives rise to design and construction of communication ap- radio "shadows" such as are noticed if a high paratus. mountain intervenes between two stations. The vacuum tubes used have oxide coated fila- In such cases better communication is obtained ments, such as were employed in the detecting if the distance between the two stations is in- tubes used so extensively by the Signal Corps creased, because the shadow becomes less de- during the wàr. The larger tubes, of which finite, just as light shadows do in similar cir- there are four, are of 25o watt rating, using i600 cumstances. An interesting case of this sort volts in the plate circuit. An interesting de- is noticed near the island of Cuba; there is a tail in the construction of these tubes is the radio station on the south coast which cannot blackening of the plates to increase the radiation transmit reliably to ships on, the north coast, of heat; a black plate will radiate much more there being a mountain range intervening; if, heat, at a given temperature, than a shiny one. however, the vessel steams north for a hundred A special type of microphone is to be used, miles, thus getting out of the shadow, the com- the diaphragm of which is a tightly stretched, munication is much better although the dis- thin, steel membrane having a natural fre- tance from the transmitting station has been quency far above voice frequencies. It is more than doubled. designed to give better reproduction of the In a recent interview, Dr. Charles P. Stein- consonant sounds than does the ordinary metz, the chief consulting engineer of the Gen- microphone transmitter. It is anticipated that eral Electric Co., is reported to have said that only about 4o per cent. modulation will be em- "under certain conditions it will be easier for ployed, this comparatively weak modulation wireless waves to pass through the ground being used with the idea of keeping out the than through the air. Submarines already distortion of the voice sounds which occur if have sent radio messages successfully while complete modulation is attempted.' submerged, a primary substantiation of the The studio where the artists are to perform theory, which looks to the conquering of an- has been especially treated to reduce echoes other element in addition to the ether." If to a minimum. The ceiling has been deadened the noted engineer of Schenectady had ever by two inches of sound absorbing material; listened to the signals received by a submarine the floor is deadened with thick carpeting, and as she submerges, as has the writer, and had experiments are being made in padding the listened to them fall off rapidly in intensity until side walls with thick felt. It is the engineer's at only a few fathoms depth they are entirely idea that practically no echo should strike the gone, only to reappear as the depth of the sub- microphone; if it is actuated only by the ori- marine is decreased, he would be convinced ginal voice sounds, it seems that much clearer that it is much more difficult for the radio speech and music Will be sent out than if waves to travel through earth or water than echoes, from walls and ceiling, as well as the through air. In fact, going through a few feet original voice, are allowed to fall on the micro- of water the signal decreases in intensity as phone. much as it would in a hundred miles through The absence of echoes in the room give one a air; this difference in behavior of air and water strange feeling when talking; it seems as though increases as the wavelength is made smaller. one were talking into open space. It serves well to show how all of our senses combine to A BETTER BROADCASTING STATION give us a certain total impression; the exper- BY THE time this is in press a new broad- ience in this room convinces one at once that casting station will be in operation, a one's estimate of the size of the ordinary room station on the design of which probably more is fixed not only by what the eye reports but thought and talent has been expended than on also by the sound of one's voice, which, of any other in existence. It is on the top of one course, will depend largely upon the echoes of New York's skyscrapers and is operated by from walls and ceiling. the American Telephone and Telegraph Co.; AN EXPERIMENT IN BROADCASTING its call will be WBAY. The actual transmit- ting set was designed and constructed by the THIS A. T. and T. station is being con- engineers of the Western Electric Co., engineers structed, and is to be operated, purely as who know not only engineering, theory, and an experiment. It had its inception in re- practice, but who are especially trained in the peated demands upon the company for supply-

www.americanradiohistory.com The March of Radio 197 ing broadcasting transmitting sets, to be used tion, renting it to those firms and institutions by merchants, churches, philanthropic insti- which think they want such service; the station tutions, brokers, and what not. I n all there is to be a regular toll station where a merchant were more than sixty such requests for appara- rents the privilege of using the ether for calling tus, to be operated in New York City. And the his wares. Government restricts all broadcasting stations Is there a demand for such a service, and, still to 36o meters! more important, does the radio public want the Evidently it would have been short -sighted ether used for such purposes? The operation policy to sell these equipments -the purchasers of WBAY for a few months will probably fur- would soon find out they had white elephants nish an answer to these questions. Whether' on their hands. Such stations would evidently the answer be Yes or No the operation of this be installed for advertising, indirect, of course, station (which will have such a programme as but advertising nevertheless. And if a dozen to not interfere with WJZ) will be of benefit to of them were to operate at once they would the radio public because of the technical ex- so jam the air that none of them could be re- cellence of the station; the quality of trans- ceived. With the idea of avoiding this situa- mission will probably be better than any other tion and further to get first hand information station now operating, so will serve as a stimu- on the need and desirability of such broadcast lus to the others to improve the quality of their advertising the A. T. and T. Co. decided to transmission to equal that of this new station. erect and operate themselves a first class sta- H. M.

Submarine equipped by the Bureau of Standards, Department of Commerce, with special type of antenna for under -water radio reception and transmission

www.americanradiohistory.com When De Wolf Hopper Broadcasted to His Biggest Audience He Missed the Applause and Laughter and He Couldn't Gesti- culate, but He Heard Later How Much He was Appreciated

I X people had to do all the audible " I couldn't do this," he said mournfully, laughing for an audience optimisti- "when I came to the line'Str- r -r -ike out!' It tally estimated at three hundred was a peculiar thing, however, that I think thousand when De Wolf Hopper I never recited ' Casey' better. There I was broadcasted his famous voice from in that long narrow room, with no way to WJZ in Newark, tell whether I N. J., recently. But was pleasing my the laughter proved audience or not. a boon to the great There were only i comedian because six people in the he could judge by room, a gentleman its duration just and lady who had when the points of accompanied m e , his jokes had sunk my son, the soloist in, and it was time who was to follow for hi.n to resume me, and two opera- his moaologue. tors. But they all " I t was a pecu- laughed a lot, and liar and dramatic that helped me to sensation," he said, judge how long to "speaking to thou- pause toachievemy sands upon thou- effects. I would sands of people you wait until they couldn't see. I stopped laughing couldn't realize and then begin to that so many people 'talk again. were hearing me. "I told jokes, and My performance talked about 'Some lasted about twenty Party,' and greeted minutes, five and a some old friends, half of which I de- who had told me voted to reciting they would be 'lis- 'Casey at the Bat.' tening in,' but of That was the hard- course, I couldn't est thing of all be- tell how they liked cause I couldn't it. In the days Here is one of the famous gestures, the omission of which De gesticulate. I after my initial per- had Wolf Hopper lamented, when he recited "Casey at the Bat " by to keep my mouth radiophone formance, however, about six inches I got millions of from the little drum suspended in front of me." letters. I remember one in particular which ap- Mir. Hopper's mobile voice sank to a sorrow- pealed to me. It was from two baseball fans ful note as he spoke of the difficulty of de- telling me how much they appreciated ' Casey.' livering this famous baseball recitation with- They wrote that they had been baseball fans out the emphatic gesticulations which have all their lives, and that one of them was eighty - delighted his audiences for more than a quarter two and the other one was eighty -four. of a century. His fists involuntarily clenched " It was a strange experience at first," he themselves. concluded, " but of course I'm used to it now."

www.americanradiohistory.com What Everyone Should Know About Radio History By Prof. J. H. MORECROFT PART I

AT A recent dinner attended by the ment, they spelled all kinds of possibility and writer, the principal speakers of the opportunity; he didn't merely take them for evening both took as their theme granted, but inquired as to how and when and the complacence with which we where and why these speech- carrying wires Americans take for granted the came about, how they operated, and later how many conveniences and comforts surrounding their operation might be improved. The in- us, which the application of modern science has spiration he received started him on that career made possible. They were both foreign born, which brought him fame and reward and made both had come to America when young, and him finally the best known scientist in the field both had achieved remarkable success scienti- of telephone communication. fically and financially after adopting the United AFTER A CENTURY OF EFFORT States as their new home. Both of them are endowed with keen intellects and sound judg- An art or science is of importance to man- ment of men and events, which attributes no kind in direct proportion to the benefits men doubt contributed largely to their success, but derive therefrom; the appreciation of radio, both of them expressed the opinion later that and to a certain extent the pleasure arising they really saw and appreciated the advantages from it, will be greatly increased by a knowledge and opportunities of America so much more of its principles and development. The ac- than the average American that, in the race for complishments of the early workers, marking achievement, the native born was actually out the trail which was to lead to the present much handicapped because he took so much state of the art, make interesting reading and for granted, without inquiring how wonderful serve well to lay the background for discussing the things about him really were and how the work of the later scientists and inventors they came to be developed. whose contributions are directly incorporated in the radio receiving and transmitting equip- WHAT AN IMMIGRANT BOY SAW ments of to-day. Professor Pupin, one of our best known and Every one is now becoming more or less most successful scientists, is fond of relating familiar with radio communication, and it will his early impressions of America; the first walk soon be taken for granted as much as is the he took after landing at Castle Garden was telephone; to the average person the radio en- through the lower part of New York where the tertainment every evening will soon cause no streets were lined with poles carrying hundreds more wonder or interest than do the phono- of telephone and telegraph wires. Having graph or movies. Actually, the simple re- been told that signals and speech were being ceivingset of to-day, picking up music or speech conveyed over these wires from city to city, from a transmitting station many miles dis- scores of miles, he was filled with awe and tant, represents the result of nearly a century amazement; what an opportunity there must of effort and development by scores of scien- be, he thought, in a land where such things tists and inventors; before we become too were a part of the every day life of the people! complacent in the matter, and take the radio To the native New Yorker these wire-laden telephone in the same matter of fact way we poles meant nothing; he had seen them gradu- do the rest of our applied science miracles, it is ally installed around him, and they incited in worth while to review their labors and progress, him neither awe nor inspiration. But to young as a knowledge of their work will make the Pupin, fresh from a land of no scientific develop- evening's radio concert the more pleasurable

www.americanradiohistory.com 200 Radio Broadcast and appreciated. It is with this idea in mind eral idea as the foregoing, but the changes of that the following brief story of the wireless current were thousands of times as rapid as telegraph has been written. those formerly used; instead of using the ordin- The earlier name for communication between ary phenomena of induction, as explained by two stations without the use of connecting Faraday and Henry, a new concept of radiated wires was the wireless telegraph, but for rea- power was invoked and with this step taken, sons to be shortly pointed out the term radio success was assured. As long as the communi- telegraph or radio communication is now gener- cation between the two stations depended upon ally used and preferred. There are three the induction ideas of Faraday and Henry the closely allied developments in the growth of possible separation of the two stations was but the radio of to-day, all of which contributed a few times the dimensions of the coils used at their share toward our knowledge of the art. the stations; when high frequency radiated The first has to do with the early attempts to power was utilized, the possible distance of carry on ordinary telegraph communication communication was increased thousands of without wires, the earth's surface forming the times and made feasible the transmission of conducting medium between the two stations. signals between any two points located upon A great deal of work was done in this field by the surface of the earth. many Vorkers; the reward for a successful solution would have been great as it might have THE FIRST EXPERIMENTS BY STEINHEIL made unnecessary, to some extent, the very In 1837 Professor Steinheil, of Munich, while expensive cables being installed for trans- making some experiments with the telegraph oceanic telegraphy. This scheme of using the apparatus ordinarily using two wires, one for earth for conductor found application during the outgoing current and another for the re- the war just past for communication from the turn, found that it was possible to dispense with front line trenches and is well known to those one of the two wires hitherto thought necessary, acquainted with the work of the Signal Corps, and use only one wire. This one wire was con- where it goes by the abbreviation of its French nected, at the transmitting end through bat- name, T.P.S. (Telegraphie Par Sol). tery and key, to large plates buried in the earth and at the receiving end it was similarly con- OF WAS TRIED THEN THE IDEA INDUCTION nected to ground through whatever type of A second line of work used no conducting receiving apparatus was used. l-le thus showed medium whatsoever between the two stations; that the ordinary one wire telegraph system of comparatively slow change of current in one to -day, using the earth as the return was pos- coil was used to induce currents in another coil sible. This experience evidently aroused Stein - in the vicinity and these induced currents, by heil's imagination, as he suggested, in 1838, some prearranged code, were used to convey in- when discussing the results of his experiments, formation. This work was begun in England that it might be possible to carry on communi- and the United States at about the same time, cation with no connecting wires at all between by independent workers; it did not apparently the two stations! promise much success at the time, but with our PROFESSOR MORSE'S WIRELESS present knowledge of the art it seems that some of the experimenters missed the real solution In 1842, Professor Morse in America, ac- of the problem by a very narrow margin. tually did establish telegraphic communication This scheme has recently received much pub- between two stations on the opposite banks of lic notice because of its application to the a river, there being no wires at all crossing the guiding of vessels into a harbor during the night river. Along one bank of the river he laid or in a fog, when ordinary methods of navi- a wire in which were contained his sending bat- gation are not available. In this method of tery and key; this wire terminated in two metal navigation, a cable laid in the channel is tra- plates placed in the river itself. These plates versed by alternating current and coils placed were separated from each other by a distance on the sides of the vessel's hull receive induced greater than the width of the river. A similar currents from the cable and the navigator can wire and set of plates was used on the opposite maneuver his vessel by the relative strengths sideof the river, the plates on one bank being of the signals received on the two sides. opposite those on the other. The receiving The third line of work involved the same gen- galvanometer was inserted in series with this

www.americanradiohistory.com What Everyone Should Know About Radio History 201

second wire. When the sending switch was not feasible. The idea of a receiving coil closed it sent current through the river water weighing two hundred pounds is interesting from one plate on the sending bank to the other. when we consider that the coil of the galvano- The current spread throughout the river and meter actually used to-day weighs less than an some of it strayed to the opposite bank, flow- ounce. ing through the opposite plates and wire and In 1845 Wilkins, in England, suggested that thus through the receiving instrument. Al- Morse's scheme be used in establishing wireless though but a small part of the current reached communication with France, across the Eng- the opposite bank it was sufficient to actuate lish Channel, the same feat that was to make the galvanometer used for receiving, and thus Marconi famous fifty years later, using a differ- wireless telegraphy was an accomplished fact. ent and more effective form of transmission. It may be noted that quite long wires were Many more experimenters than the few necessary on the two banks of the stream so it mentioned here worked in this field, endeavor- could not logically be called wireless com- ing to eliminate the connecting wire between munication, but it the two stations, must be remembered among them Professor that such is always the Trowbridge, of Har- fact with our present vard. He reached the radio stations. In a conclusion that trans - modern radio trans - Atlantic communica- Atlantic station the tion by Morse's scheme sending antenna may might be possible if the contain 5o miles of two plates to be sub- wire in the overhead merged in the ocean net work and perhaps were as far apart as are even more buried un- Nova Scotia and Flor- derground. The es- ida. The wire thus re- sential point in wire- quired to connect the less communication is two plates would be as that there must be no long as the distance to wires connecting one be traversed, a state- station with the other. ment which gives the approximate range for BRITISH SCIENTISTS this type of wireless WHO CONTRIBUTED transmission. The In 1859, in Dundee, laws of the spreading Lindsay was working of current were better along the same lines MICHAEL 1. PUPIN known to Trowbridge that Morse had fol- than they were to Lind- lowed, apparently unacquainted with Morse's say when he first put out his project, and fur- experiments. He made many tests and en- thermore the telephone receiver had been in- deavored to find the laws of transmission vented in the mean time which gave to the distance in terms of the size of plates used, scheme a receiver much more sensitive than length of land wires, size of galvanometer coil, anticipated by Lindsay. etc. He came to the conclusion that if two Trowbridge also put forth the quite feasible plates were immersed in the ocean, one off scheme of fitting a ship with submerged plates the most northerly part of Scotland and the in bow and stern (or bow plate and a trailing other off the southern coast of England, if a insulated wire astern, carrying the second plate powerful set of batteries was used for sending, at its end) and sending out into the ocean an and if a galvanometer coil weighing two hun- interrupted current which would spread out dred pounds were used at the receiving station, all around the ship; another ship similarly it would be possible to send messages from equipped with plates and a telephone receiver England to America through the ocean water. for listening, would be able to detect the We know now that the laws he deduced were presence of the first ship, thus rendering colli- not quite correct and that such a scheme is sion in case of fog much less likely. if the

www.americanradiohistory.com 202 Radio Broadcast present scheme of radio communication had very small fraction of the transmitted power is not come into the field, it seems likely that actually received. In the modern radio scheme Trowbridge's scheme would have been uni- each station uses two points in a similar man- versally adopted. If the trailing wire should ner, but one of them is on the earth's surface be one quarter of a mile long, a second ship and the other is up in the air. The transmitting would be able to detect the presence of the and receiving antennae should both be vertical, first at a distance of about one half a mile and that is, parallel to each other as in the foregoing this would evidently give sufficient warning schemes. The essential difference of the two to prevent collision. schemes lies in the frequency of current used in the transmitting antenna, and the factor of ALEXANDER GRAHAM BELL'S EXPERIMENTS height of the two stations. In 1882 Alexander Graham Bell tried out the scheme of using two charged metal plates im- THE IDEA OF MUTUAL INDUCTION mersed in water for communication. Using A second possible method of wireless com- boats with a submerged plate at the bow and munication was opened up when the laws of the second plate at the end of a trailing wire electro- magnetic induction, discovered inde- one hundred feet long, using interrupted cur- pendently by Faraday in England and Henry rent in one boat and the telephone receiver in America, were made known. When a cur- for the detector in the other, he was able to get rent flows through a coil, a magnetic field is set signals when the boats were separated about up in the space surrounding the coil. When the one half a mile. This possible distance will current in the coil is varied, the magnetic field be much less when the boats are in salt water will correspondingly vary, and if another coil is than when in the fresh water of a river, however. placed in proximity to the first, and so situated In the T. P. S. scheme of the army, two iron in the magnetic field, the changing magnetic stakes are driven into the earth at a separation field will set up a voltage in the second coil and as great as feasible; a powerful buzzer, with if this is connected to some detecting device battery and key, is placed in series with the (such as a telephone or galvanometer) any wire which connects these two stakes. If two change of current in the first will be recorded other stakes are driven into the ground some in the second. In this method real wireless distance behind the front line trench where communication is possible, there being no the first pair of stakes is driven, and this second connection to the earth at either station. The pair of stakes is connected by a wire in series amount of current which can be set up in the with which is a sensitive telephone receiver, the second coil by the changing current in the first system forms a possible communication link decreases very rapidly with increasing dis- from a position where other types of communi- tance between the two coils, so much so that cation are impossible. the scheme is useful over only small distances. Thus if we have two coils say ten feet in dia- HOW MODERN RADIO DIFFERS meter, the possible distance of communication It is to be noticed that in the schemes of would be probably less than two hundred feet. communication so far described the sending and Remarkable as was the discovery of electro- receiving stations each connect two points on magnetic induction it contributed but little the earth's surface and the transmitting and re- directly to the problem of wireless transmission ceiving apparatus are connected between these of signals over appreciable distances; it is of two points; low frequency currents are caused course used throughout the transmitting and to traverse the earth's surface and a small receiving sets wherever two circuits are coupled part of the transmitted current reaches the together magnetically, but in so far as the surface where the receiving points are located. actual transmission of the power is concerned This is true wireless telegraphy, as much so it gave but little promise. In 1891, however; as the type used to-day for radio broadcasting, Trowbridge suggested an interesting use of this and the two methods have many points in principle, which, had it come about, would common. The line connecting the two contact have much resembled a modern radio installa- points at the receiving station should be es- tion. His idea involved the installation of sentially parallel to the similar line at the trans- large coils in the rigging of a ship, these coils mitting station; the transmitted power is sent to be as large as could be carried from the in all directions in both schemes so that but a ship's spars. If the current in the coil of one

www.americanradiohistory.com What Everyone Should Know About Radio History 203 ship should be interrupted many timesa second, was interrupted by scratching a contact on a file a telephone receiver connected to the coil of a and in the receiving coil a telephone receiver neighboring ship would receive a signal and s., was used for detecting the induced currents. the transmission of messages. Trow- permit WHY "WIRELESS" CHANGED TO "RADIO" bridge further pointed out that such coils would permit the determination of the relative direc- We have now come to the point in the tion of the two ships from each other, a rôle development of wireless communication where filled to-day by the radio compass. the really important work begins; it is worth while to review what had been done in the DOLBEAR, EDISON, AND STEVENSON rather more than half century which had In 1883 Dolbear described his scheme for elapsed since Steinheil had used the earth for wireless signaling in which he used at each sta- one of the conductors of his telegraph system tion an elevated wire, and had then put forth grounded on only one the proposition to do end; he was able to away completely with g e t communication any wire connecting over a distance of half the two stations com- a mile and some of his municating with each notes on the working other. A host of ex- of his scheme indicate perimenters had that he was very close worked on Steinheil's to a real solution of idea of using the earth the problem. or water as the only In 1885 Edison and connection between his associates devised the two stations, with a scheme for signaling some success, the most. to moving trains by promising being the induction from the tel- work of Bell; the feasi- egraph wires running ble distance of com- parallel to the railroad munication by t h i s tracks. The currents scheme, however, induced in the train seemed to be sharply receiving apparatus limited to a few miles were received with the at most. Electrostatic train at high speed and as well as electromag- the. system had the netic induction had advantage that the both had their adher- same wires could be ents, and considerable u sed simultaneously success had rewarded for regular telegraph their efforts as evi- traffic. In Edison's denced by Edison's apparatus the currents telegraphy with mov- had to "jump" from THOMAS A. EDISON ing trains and Steven - the telegraph wires to son's transmission the train, a distance of thirty to forty feet; it from mainland to island. The promise of much was evidently to this extent a system of wire- greater distance was rather slight with all of less telegraphy. these schemes, however, and the time was ripe The most remarkable achievement using the for the introduction of some new and radical principle of magnetic induction was accomp- step in the problem. lished by Stevenson in England in 1892; he This new step was rapidly forthcoming; was able to establish reliable communication the energy radiated by very high frequency from the mainland to an island half a mile alternating currents and some simple scheme distant, using at his two stations large horizon- for detecting the high frequency currents, tal coils two hundred yards in diameter. In the Were the new concepts 'which were to give the transmitting coil the current from a few cells development the wonderful progress which it

www.americanradiohistory.com 204 Radio Broadcast so soon showed. Incidentally, the new idea of the idea of carrying out this experiment when using radiated energy, as contrasted to the he noticed a peculiar event taking place in an- previous schemes, gives us the reason for the other experiment he was working on. He was change of name from wireless telegraphy, up to discharging a condenser through a spiral in- now a proper name for the art, to that of radio ductance coil, when he noticed that another communication, indicating that the power used coil in the vicinity produced small sparks every in carrying the message was not due to conduc- time the discharge took place in the first cir- tion through the earth's surface, or to magnetic cuit. This phenomenon is the same as takes induction, but to energy which was actually place every time a spark transmitter is operated shaken free from the transmitting station an- to -day; the current in the antenna of a spark tenna, and left to travel freely in all directions. set is excited by theoscillatory discharge in the so- called local circuit. MAXWELL'S THEORY OF RADIATED POWER STARTED The theoretical work of Clerk Maxwell AN ACCIDENT HERTZ carried out during the period from 186o to 1870 The sparks in the second coil took place with and published in complete form in 1873 showed such regularity that Hertz decided to in- that energy may be radiated from an electric vestigate their action. It will be noticed that circuit and that this energy shaken free from this beginning of Hertz's remarkable work the circuit follows the same laws as does ordi- was the result of accident; if the second coil nary light. In fact, Maxwell made light and had not been in the neighborhood of the first radiated electric energy exactly the same kind when the discharges were taking place, no of a disturbance in the universal ether, Maxwell spark would have been noticed in the second had, of course, no idea of the usefulness of this and probably nothing further on the problem startling concept; he was a scientist, of the would have been done by Hertz and some one pure kind as contrasted to the applied, and his else might have carried out his epoch -making -work was done in the spirit of pure science. work; in fact, Professor Oliver Lodge, in Eng- It was the truth regarding certain natural land, would have been almost sure to have phenomena as he saw it, and it is in the pursuit carried out the work if Hertz had not started of the truth about Nature's activities that men when he did. like Maxwell pass their lives. Their material Herti's own report of his brilliant and im- reward is generally nil, but that matters to portant experiments is available, as the ori- them not at all; the joy of finding out the se- ginal papers of Hertz have been translated crets of nature is the only reward required to into English and published under the title of keep them stimulated for further work. We " Electric Waves "; for the most part the book shall point out later the work of anothér pure is non -mathematical and makes very interesting scientist who predicted theoretically that the reading. As Hertz felt his way in this new field modern vacuum tube was possible; others his reports had all the fascination of those of the made the tubes and reaped the financial re- explorer of unknown lands. His various papers ward. To those buying the tubes to-day it followed one another so rapidly that in the undoubtedly seems that they are still reaping space of only two years, 1887 -1889, he had their reward. covered practically the whole field and had Maxwell's theory of radiated power was the established firmly the laws of electric wave subject of much scientific argument and dis- propagation as we know them to -day. He cussion; for many years this theory lacked showed that the waves sent off from an electric any experimental evidence, either for or against circuit carrying high frequency current travel- it. The English scientists in general adopted ed with the same velocity as does light, that the theory, but those of the continent were these waves could be reflected by mirrors and against it as being more complex and difficult refracted by prisms and lenses just the same as to understand than the older theories of light light. He measured the length of the waves and electricity. At the suggestion of von with which he was experimenting, and found Helmholtz, probably the best known of Ger- that his detecting circuit must be of the same man physicists, Heinrich Hertz was pursuaded natural frequency as the transmitter if the to take up the problem of connecting experi- response was to be appreciable. As one reads mentally the behavior of light and electro- the account of these experiments he feels that magnetic waves. Hertz had almost given up Hertz's laboratory was really the birthplace of

www.americanradiohistory.com An Evening with Dr. Alexander Graham Bell 205 the radio art and cannot help feeling regret Very shortly after the death of Hertz in 1894 that this keen experimenter could not live long the world began to hear of the modest successes enough to see the wonderful practical benefits of Marconi, whose optimism and aggressive- which mankind was to receive as the direct ness, combined with the wonderful foundation result of his work, carried out in the interest of knowledge which Hertz had given, soon of pure science. It is because of the results showed that the possible reliable distance of following from the work of such men as Hertz radio communication was probably limited that our most highly developed industries are only by the extent of the earth's surface. In to-day spending millions of dollars annually our next number will be taken up the work of in the support of purely scientific research; the later and better known inventors and the directors of these immense laboratories scientists, Marconi, Fleming, De Forest., Fes - know too well that no real scientific truth can senden, Armstrong and others, who, building be discovered without bringing with it some on the work of those earlier experimenters we application which will benefit the industry it- have mentioned in this number, have given us self. the modern radio telephone.

An Evening with Dr. Alexander Graham Bell By DONALD WILHELM

WE TELEPHONED to Dr. fectly steady hand. He wore neither glasses Bell shortly after dinner. nor spectacles. I glanced at his hands. There We, the managing editor of was not a tell -tale mark of age on them. Later, the World's Work and I, when he snatched a paper pad from a handy wished, if possible, to see him, table and with pipe dangling from his mouth his secretary was told, if he felt physically able and both hands and arms unsupported he drew to see us. a diagram, we could not discern the suggestion Back came the inquiry a bit later "What of a tremble. I confess that I wrote down in time would you like to come, to- night ?" my notebook then and there just this: "Think "To-night?" what this man has done for the world! The "O yes. Doctor Bell often receives callers hazards of Science are great enough, but where, at night. He says that he will be glad to see except in the world of Science, can a man give you at any time up until two or three o'clock his life for the millions yet conserve it still!" in the morning!" " Light up," he laughed, settling himself in At our end, we reckoned that there must be his chair. " Will you have a cigar or a cigarette something wrong with the line! We considered -O you prefer your own brands? That's that Doctor Bell was twenty-nine years of age fine! I like to pull on this old pipe." when he invented the telephone in 1876, must It was all like an idyl. Here was a man who, therefore be in his seventy -fifth year! Being, within the span of a lifetime, had seen his ourselves, in the thirties, we felt that 9:30 dreams come true; who had topped the moun- would be late enough for us. tain, held his ground, who says he never felt At 9:30 Doctor Bell arose from his family stronger intellectually. " My mind has a group, a figure as nearly majestic as the figure greater power of concentration," he observes of a man ever comes to be; a veritable oak of a when you ask him, "than it ever had. It man; a tall man finely put together, in a light seems to be quicker and it does not tire along gray suit, with a skin tanned by the out -of- the line in which I am interested. I sometimes doors, and eye as clear and blue and rested as work for eighteen hours at a stretch." And that of a young man. His white copious hair "by the by," to use his phrase, you are privi- was flung back. A curved pipe hung in a per- leged to go along hand -in -hand with him down

www.americanradiohistory.com 206 Radio Broadcast through his long life, in turning the pages of his ceiver, electromagnet, and its flattened piece Recorder. There are whole volumes -a score of steel clock spring, he met Thomas A. Watson, of them, each of 50o pages or so -with records and on June 2, 1875, after months of countless of his daily researches, experiments, specula- experiments, profited by an accident, one of tions, all packed with the bounty of an intel- those accidents that have contributed a vast lectual life in a variety that is incredible. In deal to Science. One of the transmitter springs these volumes, in fact, you find his tremendous stuck. The magnetized steel generated a energies devoted to the telephone, to kites and current that sent a faint sound over the electric aircraft and the scientific breeding of sheep, wire to his receiver. Then he knew that his to the utilization of waste heat, the need of a supreme dream of telephonic speech was within new acceptance of a metric system, experi- the realm of possibility. So, with his principles ments in preserving food, notes on eugenics and established, he went to work on his telephone. The Biologic History of a Cat; oral On March 1o, 1876, the birth -date teaching, a paper on the utility of of the telephone, he applied these action and gesture, observations on principles for the first time success- lip reading, on Hertzian waves, and, fully. In that attic room of his, among a hundred other subjects, not at the end of a hundred feet of wire, to mention many pages devoted to he put his mouth to his telephone glorfying Life in general, his descrip- and said, " Mr. Watson, come here, tion of his early experiments in I want you." Watson came rushing transmittingwireless signals through through the intervening door shout- the earth's crust and through the waters of the ing, "I heard you; I could hear what you said!" Potomac. Also, most interestingly, you find Doctor Bell likes to add, by the by, some of his papers on the first of all wireless telephones the singular incidents that followed. "The -the photophone, the light phone. Japanese language was the first language, after About this first wireless telephone, which of the English, used over the telephone," he said. course did not, like the modern radiophone, " I had two Japanese students. One of them use a tuned circuit, we wished Doctor Bell to asked me if the telephone would speak Jap- talk; also about his early experiments in detect- anese. I told them to try." ing and transmitting signals, and the first use On October 9, 1876, over a telegraph line of the telephone therefor, without the use of between Cambridge and Boston, Doctor Bell wires. And of course we yearned to have him and Mr. Watson held the first telephone con- discuss his invention of the original telephone, versation over a considerable distance. Soon and that momentous day, that birth -day of thereafter the Boston Globe transmitted the both wire and radio telephonic communication, first press report, from Salem, Massachusetts, March 1o, 1876. For, clearly, without the use to Boston, by telephone. Still, people were in- of some instrument as sensitive as the Bell credulous. Thus Mr. Bell was invited to dis- telephone, even Marconi could not have re- play his instrument at the Philadelphia vealed the enormous possibilities of the wire- Centennial. But there, in his remote corner, less. he attracted little attention until the Emperor The year 1871 found Doctor Bell, at the age of Brazil, Dom Pedro, took up the receiver to of twenty -four, teaching vocal physiology in listen, at the far end of a large room, to the Boston University. By the by he established voice of the inventor. He exclaimed, dropping his own school, applied his own system of the receiver suddenly, " My God, it speaks!" teaching the deaf, and went to live in the home That was an event which caught popular of five- year-old George Sanders, one of his fancy; still, it was not until sixteen months pupils, in Salem. In the Sanders cellar he set after Doctor Bell had filed his patent, he says, to work with tuning-forks, magnets, batteries. when there were already 778 telephones in use, For three years he worked. In 1874 he had that, in August, 1877, The Bell Telephone evolved what he called the harmonic telegraph Association, the first telephone company ever -a device for sending a number of Morse mes- established, was formed. It had no capital sages over a single wire at the same time by at the outset. It had four members only - utilizing the law of sympathetic vibration. Doctor Bell, Gardiner G. Hubbard, Mr. Wat- That is important because, in seeking to de- son, and Thomas Sanders, Georgie's father, who velop it, and to perfect its transmitter and re- furnished all the financial backing.

www.americanradiohistory.com An Evening with Dr. Alexander Graham Bell 207

But Doctor Bell was not interested in busi- Later he carried these experiments on in a ness. " It has always been that way," he told different direction. " First, in a vessel of me. "After I have made a discovery and water," he said, "1 placed a sheet of paper. got it under way my interest in it lessens." At two points of that paper were fastened two Hardly, in fact, had Theodore N. Vail and his ordinary sewing needles, which were also con- associates set about to make the telephone a nected with an interrupter that interrupted the universal servant when the inventor himself circuit about ioo times a second. Then I had struck off into new fields. two needles connected with a telephone: one It was, as accurately as the date can at pres- needle I fastened on the paper in the water, ent be fixed, toward the end of the year, 1876, and the moment 1 placed the other needle in in which he invented the telephone, that Mr. the water I heard a musical sound from the Bell, for the first time, used the phone, instead of telephone. By moving the needle around in a galvanometer, to experiment with and to trace the water, I would strike a place where there out the lines of the earth's potential. In these would be no sound heard. This would be experiments, where the elec- incidentally, he tric tension was used a steel -band the same as in the telephone, as it needle; and by ex- was then called, perimenting in to clasp the phone the water you to his ears, leav- could trace out ing his hands free with perfect ease -the first time an equipotential the helmet tele- line around one phone receiver of the poles in the was ever used. water." " Using two metal In July, 1877, exploring rods - Mr. Bell married they were really Miss Hubbard. stove pokers," he ^Q, Underwood 8 Underwood They went to Alexander Graham Bell, finding his own invention a source of annoyance, explained, " I set London on their had it removed from his room in favor of a radio receiver. Mr. Bell is to work on Mr. now 75 years old and an ardent radio enthusiast honeymoon. In Hubbard's place London he made on the outskirts of Cambridge. I drove the the classic speechon the telephone and explained rods into the ground. At the receiving rod and demonstrated the experiments described I found that upon listening with the tele- above to William Preece, the head of the British phone I could hear a clock ticking. 1 then Post Office system, who was vastly helpful to noted that at periodic intervals the clock would Marconi, and others. He also experimented miss a tick. By means of that irregularity I across the Thames. "On one side," he said, "1 was able to identify the clock as the time clock placed two metal plates at a distance from each of the Cambridge Observatory, a half mile other. and on the other two terminals connected away. There was, I knew, a telegraph line with the telephone. A current was established from the Observatory to Boston, to pass the in the telephone each time a current was estab- time. Using ground that was charged, with lished through the galvanic circuit on the op- the Observatory as the centre of an imaginary posite side, and if that current was rapidly in- circle, I was able to define concentric circles terrupted, you would get a musical tone." that indicated much more accurately than had On his return to America he discussed these been possible with a galvanometer, the lines of experiments before the American Academy of potential. In other words, if both of the rods Arts and Sciences in Boston, on December i 1, were in a part of the charged ground that was 1878. He described his experiments, which he to be designated as concentric circle 9, closest proceeded to develop on the Potomac. to the Observatory, both ends of my earth " In the experiments on the Potomac," he telephone circuit had the same potential, but said, " I had two boats. In one boat we had if one were in 9 and another in 8, there would a Leclanché battery of six elements and an be a residual effect and I would get a sound." interrupter for interrupting the current very

www.americanradiohistory.com 208 Radio Broadcast rapidly. Over the bow of the boat we made doubt the fact that electric currents actually water connection by a metallic plate, and be- traverse the earth's crust. The theory that hind the boat we trailed an insulated wire, with the earth acts as a great reservoir for electric- a float at the end carrying a metallic plate so ity may be placed in the physicist's waste- as to bring these two terminals about ioo feet basket. . . . Telephones have been fixed apart. I then took another boat and sailed upon a wire passing from the ground floor to off. I n this boat we had the same arrange- the top of a large building (the gas pipes being ment, but with a telephone in the circuit. In used in place of a return wire), and Morse the first boat, which was moored, I kept a man signals, sent from a telegraph office 25o yards making signals; and when my boat was near distant, have been distinctly read. There his I would hear those signals very well -a are several cases on record of telephone cir- musical tone, something of this kind: tum, cuits miles away from any telegraph wires, turn, turn. I then rowed my boat but in a line with the earth term- down the river and at a distance of inals, picking up telegraphic signals; a mile and a quarter, which was the and when an electric -light system furthest distance I tried, I could still uses the earth, it is stoppage to all distinguish those signals." telephonic communication in its He added, in our discussion, that neighborhood." Mr. Preece then one of the boats that he used was describes one of the first of all his ex- near Chain Bridgewhile his own boat periments, which was made, it is to was, at the conclusion of the experi- be noted, nearly five years after those ments, at the Washington Monu- described above of Doctor Bell. Sim- ment. And at the time of his experiments he ply, this experiment, in March, 1882, successfully pointed out the practicability, since " most of the linked up the Isle of Wight with Southampton passenger steamships have dynamo engines and when the cable between that island and South- are electrically lighted," of each vessel trailing ampton broke down. His complete circuit, a wire a mile or so long duly charged, and at- including the water, started from Southampton, tached to a telephone. "Then," he said, "your ran to Southsea Pier, 28 miles; across the sea, dynamo or telephone end would be positive 6 miles; Ryde through Newport to Sconce and the other end of the wire trailing behind Point, 20 miles; across the water again, 13 mile, would be negative. All of the water about the thence from Hurst Castle back to Southamp- ship will be positive within à circle whose radius ton, twenty -four miles. "With a buzzer, a is one -half the length of the wire. All of the Morse key, and 3o Leclanché cells at South- water about the trailing end will be negative ampton," he says, "it was quite possible to within a circle whose radius is the other half hear the Morse signals in a telephone at of the wire. . . . It will be impossible for Newport, and vice versa. Next day the cable any ship or object to approach within the was repaired, so that further experiment was water so charged in relation to your ship with- unnecessary. out the telephone telling the whole story to Since those early days, while on one hand it the listening ear. Now, if a ship coming in becomes more and more apparent that the radio this area also has a similar apparatus, the two art would have been infinitely harassed in its vessels can communicate with each other by origin and development without the telephone, their telephone. If they are enveloped in a it has also become apparent that the relation- fog, they can keep out of each other's way. ship of earth characteristics and those of the

The matter is so simple that I hope our ocean sea, must sooner or later have been given just steamships will experiment with it." such attention as Doctor Bell gave, and en- It is only to be added that these land and couraged others to give, -to them. There is water experiments of Doctor Bell without good ground for saying that these experiments question were factors in the success of Mr.- fathered many perfections in earth telegraphy, later Sir -William Preece in England. His first including the TPS work used in the main dur- experiment was made in 1882. In that year ing the war by both the Allies and the Germans in a public address, he said, "The discovery of for intercepting messages, notably telephone the telephone has made us acquainted with messages. But, it is also to be noted that many strange phenomena. It has enabled us, ground methods do not permit of the use of amongst other things, to establish beyond a high frequencies, do not employ tuned cir-

www.americanradiohistory.com An Evening with Dr. Alexander Graham Bell 209 cuits, and do not belong, in the view of many had progressed until we succeeded with them authorities, within the sphere of modern that Sunday when my daughter was born." radio. He smiled. " Looking back," he considered, Nevertheless -the proof is in of Mr. Bell's " I was very nearly not at home!" amazing ingenuity and resourcefulness -it may He related, then, how, when his experiments well be that his experiments with ground and had proven a success, he put all the records into water telegraphy and telephony might long ago a sealed envelope and deposited the envelope have given results that have not even now been in the Smithsonian Institution, where, un- attained if he had continued his experiments. opened, the envelope still remains. That fact But his fertile brain got to working in other leaked out. Shortly thereafter a gentleman directions, at aircraft, for instace. named H. E. Lix, of Bethlehem, Pennsylvania, We have seen how, on March io, 1876, he gave out the information that he had invented spoke the first words ever sent over a method of seeing by telegraph. a telephone line. The two ideas of an invention by Four years later, on Sunday, Feb- this unheard -of inventor and the ruary 15, 188o -he remembers the mystery of the sealed envelope be- date because on that day his daugh- came confounded in public prints ter, now Mrs. Fairchild, was born - with the remarkable result that two he received the first words ever English inventors assailed Doctor spoken over a wireless phone. The Bell for seizing upon their ideas con- words spoken and received were cerning an instrument by which one heralded by a flash of light through could see by telegraph! his laboratory window. Then he distinctly But Doctor Bell, himself, had nothing to heard, he told me: " Mr. Bell, Mr. Bell, if you say, for, by contract, all his inventions of that hear me, come to the window and wave your period automatically became the property of hat!" the American Bell Telephone Companies. The man who spoke these words was Charles Briefly, Mr. Bell had noted the remarkable Sumner Taintor. He was on the top of the characteristics of selenium, which, \Villoughby Franklin School, 13th and K Streets, N. \V., Smith in 1873 had demonstrated, would, if Washington. Mr. Bell was in his laboratory placed in an electric circuit, alter its resistance on L Street, between 13th and 14th, on the to the current under the influence of light of north side of the street. Curiously enough, it rapidly varying intensity. With this cue Mr. should also be added, though Maxwell and Bell developed a mirror in the shape of a tele- others abroad, in the years around 188o, were phone diaphragm -a mirror of minimum thick- suggesting and even assuming a medium ness. Fastened to this mirror was a mouth- through which electromagnetic action could be piece. When one spoke through this mouth- propagated, Hertz, who demonstrated con- piece the mirror vibrated. He then devised clusively the existence of that medium and re- means to throw a beam of light against this lated electromagnetic or " Hertzian" waves mirror and, by reflection, to direct this beam to and light waves, did not begin to produce his the receiving apparatus. Bit by bit he then tremendous series of papers until 1888. Yet developed improvements so that the mirror the instrument devised by Doctor Bell, by in its vibrations caused fluctuations (invisible which for the first time in history words were fluctuations, of course) in the light rays and transmitted beyond the power of the human corresponding variations in the degree of heat voice and without the use of wires, might have in the amount of light thrown upon the sub- been called a light -phone, was at both the stance designed to reproduce the sounds of the Louisiana Purchase Exposition and the World's voice. For instance, the word " Hello," which Fair displayed as the radiophone, and without makes changes in a modern electrical' circuit question projected speech on electromagnetic distinctly different, after being spoken into a waves, though not, of course, by means of high telephone, from those made by the word frequencies or a modern tuned circuit. "good -by ", caused certain vibrations in the " For some time," Mr. Bell told me, "we had mirror. These in turn caused fluctuations in been carrying on experiments between the top the rays of light, and the receiving apparatus, of the Franklin School and the Virginia Hills, under their influence, sent out sounds which re- a mile and a half away. These experiments produced the word, "Hello." For receiving, he

www.americanradiohistory.com 210 Radio Broadcast used selenium in an electric circuit with a tele- a thin layer of selenium and are attached to phone receiver, and, also vegetable fibre or the wires which connect with the telephone re- lampblack placed in a glass bulb from which ceiver. The glass bulb is then placed in a re- rubber tubes led to earpieces. On these sub- flector which concentrates the rays of the lamp stances (later it was demonstrated that many upon the selenium. others could be used, such as a bit of black At the sending end a searchlight such as is worsted cloth, of silk, or particles of rubber) used on vessels is used. From the telephone the action of the rapidly varying degree of heat transmitter, which is of special construction, in the light rays caused the substances in the wires lead to the lamp, and are attached to bulb to expel and absorb gases, alternately. the wires which carry the lighting current. These gases in turn produced vibrations in the When words are spoken into the transmitter, air in the tubes and these vibrations made the rays of the searchlight fluctuate. Standing themselves felt in the eardums of the person by the lamp, however, an observer sees no listening, causing an exact reproduction of the change, of course. At the receiving end, which words spoken at the transmitter. may be miles beyond visual distance The instrument worked, and stood by the naked eye, the selenium re- the test of many demonstrations. sponds to these fluctuations in the In the laboratories of the Bell Tele- light rays and the current in the phone Companies and later in those wires there increases and diminishes of the American Telephone & Tele- in thousands of infinitesimal changes graph Company, it was developed. which reproduce not only the spoken There arc lights came to be used words but the very tones of the along with many other variations voice of the speaker. in Mr. Bell's original device. Thus in April, The possibilities of the instrument, even 1897, Hammond B. Hayes, one of the en- though no results of its use with modern re- gineers of the American Telephone & Tele- generators are available, are greater than may graph Company, noticed that a humming be supposed. Thus it had been found that an sound, audible in the receiver of the "radio- electric arc lamp is of itself a telephone receiver. phone," corresponded in pitch with that pro- The big light that hangs from a pole on the duced by the generator supplying the current street corner may be made to talk! From the for the arc lamp used in the experiments. carbons in a lighted arc lamp there arises a Starting with this discovery Mr. Hayes con- column of vapor. If the lighting current is va- cluded that if the words spoken into a telephone ried by superimposing upon it a telephone cur- were made to act directly upon the lighting rent, the column of vapor around the carbons circuit, it would not be necessary to use the in the lamp will fluctuate and sound waves cor- mirror employed by Mr. Bell and the distance responding to the words spoken into the tele- which speech could be transmitted would be phone will be given out. Music can also be greatly increased. In other words, the tele- sent through the arc lamp-the notes of a phone current could be superimposed upon the bugle coming cleat and distinct from an ordin- lighting current. This was done by attaching ary electric light when no bugler is in sight the telephone wires to the wires in the arc light. afford a striking illustration of things already The principles remained the same, but with done. the improved device, which was patented in The application of the instrument to mari- June, 1897, the sound of the voice could be time use has also been developed, and it would heard with distinctness at points several miles be possible for one ship captain in his cabin to from the transmitter, and it was known that hear another in his cabin, or to hear from the good results might have been had at much shoreline, by means of this, the original radio- greater'distance. phone. The instrument, as it now stands, is simple in It can be used in the daytime as well as in appearance. The receiver used consists of a the night time, but fog is its enemy. selenium cell enclosed in a glass bulb no bigger It has been used by the German Government than that in which the homeopathic physician for lighthouse work, and by the U. S. Signal carries his pills. In making the cell, very fine Corps. brass wires are wound upon a bit of Indian It may yet be that the "talking arc," will pipe stone. The wires are then covered with come into its own, in spite of, or even in

www.americanradiohistory.com Increasing the Selection Power of a Radio Circuit 2 i conjunction with, the radio telegraph and the tion the world over long ago, those first words radio telephone. uttered on that eventful Sunday, February And, at any rate, it will be just as well for 15, 1 880: "Mr. Bell, Mr. Bell, if you hear Science, to add to its records of the original what I say come to the window and wave radio phone, which attracted scientific atten- your hat!"

Increasing the Selection Power of a Radio Circuit By JOHN V. L. HOGAN Consulting Engineer, New York; Fellow and Past President, Institute of Radio Engineers; Member, American Institute of Electrical Engineers

WE HAVE seen that by cor- But when we change the circuit frequency to rectly coördinating the a value different from the tuned or resonant amount of capacitance and value, at which it is in harmony with the re- inductance in a freely ceived wave, how much will our signal strength vibrating radio circuit, we be reduced? For example, how far must we are able to secure an agreement between the de-tune the circuit (or how great must be the most easily attained or natural vibration rate disagreement in frequency) before the current of the circuit and the received radio waves.* is reduced to one-half its maximum or resonant Each radio wave has a definite predominant value? This is the question whose answer ex- frequency of vibration; the standard broad- plains the matter of sharpness of tuning or the casting wave oscillates at the rate of 833,000 selective power of radio receiving instruments. cycles per second. By. adjusting the capaci- To understand why one resonant circuit will tance of an intercepting or receiving aerial and tune more sharply than another, we must con- the inductance of the tuning coil connected to sider a little more closely what happens while it, we may make the natural oscillating fre- such a circuit is oscillating. As we have seen, quency of the circuit from aerial wires to ground when a charged condenser is connected into a exactly the same as the frequency of the arriv- circuit including an inductance coil, the elec- ing wave; in this case there will be produced trical energy stored in the condenser will dis- the greatest possible amount of current in the charge as an electric current through the coil receiving aerial system, and consequently the and circuit. The current does not die away loudest possible signals will be heard in an and vanish unless the circuit is poorly conduc- associated receiving telephone. tive; it "overshoots" and recharges the con- denser in the opposite direction. Immediately SOME LOGICAL CONCLUSIONS thereafter, the condenser discharges backward ANATURAL conclusion to draw from the through the coil and circuit, the electrical fact that agreement of natural and received momentum or overshooting action of the coil wave frequencies results in maximum current is causing a third recharge of the condenser. that disagreement between these frequencies This time, however, the direction of the charge would cause a reduced flow of current. That is, is necessarily as it was when the current oscil- we would expect to hear weakened signals if we lations were started. lt is not hard to see that adjusted our antenna capacitance and tuning such successive reversing discharges of the con- coil inductance to correspond to a circuit fre- denser will generate an alternating current in quency differing from the received wave the system, and that the frequency of this al- frequency. That is exactly what does happen ternating current will depend upon the size of when the experiment is tried. the condenser and the coil. The larger the * "Tuning the Radio Aerial System" by John V. L. capacitance of the condenser (just as the greater Hogan. RADIO BROADCAST, June, 1922, p. 107 the flimsiness of the spring in a mechanical

www.americanradiohistory.com 212 Radio Broadcast

vibrating system) the less will be the force tend- the first discharge that no inertia or recharging ing to produce the electric oscillations, and effect will appear. consequently the slower their frequency will Now let us consider what this -natter of cir- be. The greater the inductance of the coil (just as the larger the mass of the vibrating weight in a spring pendulum) the greater will be the electric inertia of the circuit, and con- sequently the lower will be the natural alter- nating current frequency. Inductance Coll

REGARDING THE CONTINUITY OF OSCILLATIONS HOW long will such a circuit continue to oscillate, once the electric vibration has Fig. 1: A persistently oscillating simple resonant been started? Will the condenser continue to circuit discharge and recharge indefinitely, or will the cuit persistence, or the varying number of free electric energy originally stored all be used up oscillations, has to do with sharpness of tuning. after a certain number of oscillations have We have seen that as the natural frequency of taken place? The fact is that each successive a receiving antenna is varied, from a value re-charge is a little less than the one preceding it, because some of the electric energy is lost in Current heating the wire of the coil and circuit during each oscillation. The amount of energy thus lost is proportional to the electrical resistance Time of the circuit, which is simply a measure of the opposition which exists to current flow in any conductor. Clearly, the greater the resistance of the oscillating circuit, the more energy will Fig. 2: A persistent train of oscillations be lost at each swing, and consequently the such as would occur in the circuit of Fig. i. fewer electric vibrations that can take place before the current dies away to an immeasura- below the wave frequency of an arriving radio bly small value. signal, upward to and then beyond that fre- Fig. I shows a simple oscillating circuit in quency, the current flowing in the antenna which the resistance is small, being merely that circuit increases to a maximum and then de-

of the wires and coil. In such a circuit the Resistor oscillations will continue for a comparatively large number of swings, and hence it is called a persistent oscillator. Fig. 2 represents a gradually reducing or persistent train of oscil- lations such as would exist in a persistently oscillating (or, as it is often called, feebly Inductance Coll damped) circuit. On the other hand, we may increase the resistance of our circuit by insert- ing a resistor as in Fig. 3. This will make the circuit less persistent or more highly damped, and, since each condenser recharge will be con- Fig. 3: A simple resonant circuit including a siderably smaller than that which preceded it, resistance unit which decreases its persistence the number of cycles of oscillation before the current dies away to a useless value will be creases. The largest current value occurs at much reduced. Fig. 4 indicates such a highly resonance, or when the frequencies are in agree- damped train of oscillations, the reduced num- ment. The rapidity with which the current ber of vibrations resulting from an increase of increases as the resonant point is approached the circuit resistance. If the resistance is is what determines the sharpness of tuning of made too large, the circuit will not develop any the circuit. free electric oscillations whatever, for so much The antenna -to-ground circuit of Fig. 5 of the condenser energy will be used up in behaves almost exactly as does the closed res-

www.americanradiohistory.com Increasing the Selection Power of a Radio Circuit 213 onant circuit of Fig. i. If the antenna itself In other words, the higher the resistance effec- were charged, like a condenser, by virtue of its tive in a tuned radio circuit, the less sharp its capacitance, and allowed to discharge through tuning will be. Since the selection power, by the tuning coil to ground, it would vibrate means of which the circuit discriminates be-

Current Antenna (Capacitance) 100% + I& Loss during First Cycle A . A - Time

100% Tuning Coil (Inductance)

Fig. 4: A more highly damped oscillation train, char- acteristic of the non -persistent circuit of Fig. 3. electrically at its natural frequency. The number of oscillation cycles before the current died away to negligible values would, as before, depend on the effective resistence of the cir- cuit. Thus, if the switch were opened .só as to put into the circuit the resistor shown in Switch Fig. 5, the number of oscillations would be re- Resistor i duced just as in the case of the closed circuit. lf, now, we the aerial circuit (by Fig. 5: An aerial -to- adjust ground resonant changing the inductance of the tuning coil) .ircuit including a so that its resonant or natural frequency is switch which may he opened (to the 833,000 cycles per second, we will secure max- dotted position) for imum antenna current from any station sending decreasing the per- at that frequency. If the sending plant's wave sistence of oscilla- tion is altered to a value above or below 833,000 cycles, the current in the receiving antenna Earth will be reduced. We may plot, as in fig. 6, the amount of current which will be set up in tween waves of different for the antenna as a sending station is adjusted frequencies the purpose of to transmit successively all wave frequencies avoiding interference, depends di- from 800,000 cycles to 875,000 cycles, both with rectly upon the sharpness of tuning, it is obvi- and without the resistor in series. The amount of resonant maximum current which will build up in any such circuit depends upon the degree with which the free or natural Steep Rise of oscillations in that circuit coöperate with the Current in arriving impulses to magnify their effects. Persistent Circuit Slow Rise of Current Thus, the more persistent the natural oscilla- 50% when Circuit has Higher Resistance tions are in the antenna, the greater and the sharper will be the rise of current as the reson- ant frequency is approached and reached. This is quite clearly shown by the curves of Fig. 6; when is 0 the resistance of the circuit in- 800 810 820 830 840 850 860 870 creased and consequently the persistence of Thousands of Cycles per Second its natural oscillations reduced, the resonant Fig. 6. Curves showing how the addition of resistance rise of current is neither so sharp nor so great. to the antenna circuit reduces the sharpness of tuning

www.americanradiohistory.com 214 Radio Broadcast ous that for best selectivity we must keep. the c u i t , such as an antenna system, without un- wasteful resistances in our tuned radio circuits duly increasing its effective resistance. I n as small as possible. general, the less opposition to current flow The problem of building radio receivers in the receiving circuits the greater will be their which tune sharply and operate efficiently thus persistence, the sharper their selective adjust- reduces itself to the provision of a way to ab- ment to frequency, and the louder the received stract radio-frequency power from a tuned c i r - signals.

Protection of the Receiving Antenna Many Radio Enthusiasts Have Been Worried About Their Antenna as a Light- ning Hazard. The Following Description of Lightning Protection Includes the Much Desired Information Which Should Relieve This Apprehension. It In- cludes the Latest Recommendations of the National Board of Fire Underwriters By G. Y. ALLEN

S READERS of the June issue off comes in so loud that we can hear him in the " Radio Broadcast " will remember, next room." Jim Black's initial radio set con- " Fine work," said Mr. Gardiner. " You sisted of a small crystal receiver must have made a pretty good job of putting using a bed spring as an antenna. up that antenna. By the way, you didn't get a As was to be expected, however, Jim shortly lightning ground switch when you were here outgrew such elementary equipment with its last week. Thunder storms will be coming limited range, and experienced a desire to listen pretty frequently now and you'd better be pre- to stations farther away than was possible pared." . with a crystal detector. So one evening last "That's just what I wanted to ask you week he carried home a small tube regenerative about," Jim acknowledged. "The wife was a outfit. little scared last night during that shower, and In order to increase the possibilities of hear- I want to know what I must do to make the ing distant stations, he erected a single wire installation absolutely safe." antenna on the roof of the apartment house in "That's easy," said Mr. Gardiner. "Just which he lived. He hoped to hear Springfield attach one of these hundred ampere double and possibly Pittsburgh on this outdoor throw single pole switches outside of your antenna. house and run a number four copper wire down He had given no immediate thought to the to a piece of pipe driven into the ground." protection of his antenna until Mrs. Black " Do you mean to say that I have to attach raised the question one evening during an early that thing to the outside of the house and run summer thunder shower. No damage was a piece of that heavy wire down the front of the done that evening, but the possibility of his building ?" antenna being a fire hazard worried Jim and he "That is what the rules specify," said Mr. resolved to interview the dealer from whom he Gardiner. had purchased his set and find out what must "Well, I have a fine chance of getting away be done to safeguard the apartment from dam- with that in our neighborhood," said Jim. age. "Guess that little old antenna comes down if Accordingly, the following noon found Jim that's the way it has to be protected." at Gardiner's electrical store. Jim left the store in a very depressed state "Well, Mr. Black, how does the set work ?" of mind. He did not want to remove the an- asked Mr. Gardiner. tenna because Mrs. Black took so much "Slick as a whistle," said Jim. "We heard pleasure in listening to the concerts, and fur- Detroit night before last, and Schenectady thermore, he liked to fuss around with the set

www.americanradiohistory.com Protection of the Receiving Antenna 215 himself. Yet he knew that it was an impossi- tive device which he took home and installed bility to disfigure the apartment house with that night. a heavy switch and wire. It did not seem right The latest revision of the Fire Underwriters to require a fifty -foot span only a few feet above code applying to receiving antennas has made the roof of the apartment to be protected by possible the approval by fire insurance in- such a large switch when telephone wires of spectors of installations that could not possibly niuch greater length were protected only by be made acceptable under the old rulings. a small fuse and protector attached to the Manufacturers have been quick to recognize window sill in the basement. the value of the new requirements and there While thinking the matter over, Jim hap- are nowseveral protectivedevices on the market pened to remember an old friend who had re- which meet these requirements. cently become a fire insurance inspector and he The available types are divided into two decided to talk to him before removing the classes, namely, the enclosed atmospheric type antenna from the roof. and the type in which the discharge takes place The following day Jim called up his friend either in a vacuum or in some rare gas. This and went out to lunch with him. After the latter type is always sealed into a glass bulb. orders had been given Jim started immediately Fig. 2 illustrates one of the vacuum type of antennas. to question him on the protection Antenna He told how he had installed the set without giving much thought to protection of any kind Lead-In and of the information given him by Mr. To Antenna Gardiner. Post of Receiver "Now, Bill, you know there isn't one chance Gap that will break down in a thousand of my being able to put a heavy To Ground Post at 500 Volts switch outside of the house, and as for running of Receiver a heavy copper wire down the side of the house, T that is certainly out of the question." Bill looked at Jim's troubled face and Fig. 1. Illustrating in a very simple manner the scheme for protection from lightning. When an smiled. electrical charge strikes the antenna, it jumps " Your friend Gardiner is surely a back num- across the small gap and is carried to earth ber," he said. "The Fire Underwriters have. recently revised the rules applying to the pro- protectors and figure 3 shows its construction. tection of receiving antennas and when the new The distance between the spheres between simple specifications are followed, the antenna which the discharge takes place is not critical is a protection to the building on which it is and the adjustment for the proper voltage may erected instead of being a hazard. be controlled by the quality of the vacuum. " Instead of a heavy switch mounted outside Fig. 4 illustrates an enclosed atmospheric of a building, which by the way you may forget type of protector. It is similar to the light- to throw, you use a small gap permanently ning arrestors used for telephony with the ex- connected to a grounded wire. The gap is ad- ception that the blocks used are of special justed to operate at a voltage of five hundred or design. Telephone protection generally requires less. The protective device may be placed a permanent ground after the initial break- inside of the building and instead of a heavy and down of the gap whereas this property is highly unsightly copper wire, you will need only a undesirable in radio protection. In fact, static, number fourteen wire connected to the nearest which is of frequent occurrence during warm grounded water pipe or radiator." weather, may discharge across the protector As Bill talked he drew a sketch on the table- gap to ground many times a day and a satis- cloth similar to that shown in Fig. i . factory protector must be capable of with- " Well, now you are talking," said Jim. standing such service. " Where can I get one of these gaps ?" Fig. 5 illustrates the construction of a gap " You ought to be able to get one at any up- of this kind. As can be seen, the gap consists to -date dealer's," replied Bill. of carbon blocks made of a special grade of And so, the lunch being over, Jim arose in a carbon separated by a porcelain block. The much better frame of mind than when he sat quality of the carbon is such as to minimize clown, and immediately purchased a protec- the formation of carbon dust thus remov-

www.americanradiohistory.com 216 Radio Broadcast ing the possibility of short circuiting the gap. precaution the user of such a protector should The protector has the further feature of per- take is to be careful not to come in contact with mitting easy replacement of the carbon blocks the antenna wire on the outside end of the fuse should this be desirable. without having it first thoroughly inspected by The latest revision of the Underwriters code a representative of the power company. specifically rules against the exposure of a radio The construction of the protector is illus- trated in Fig. 7. It will be noted that the gap is formed by two punched brass pieces separated by a mica washer approximately two thousandths of an inch thick. This gives a gap that will break down at approximately five hundred volts and which will stand re- peated static discharges. The porcelain base provides excellent insulation. The new regulations permit installation of the protector within the house, and allow the use of number fourteen B. & S. gauge wire or its equivalent for connecting the ground ter- minal of the protector to a grounded structure. A single throw single pole switch of small capacity may be used in addition to the pro-

Fig. 2. One of the latest types of vacuum -gap lightning arresters is illustrated here. Its internal Sealing Compound construction is shown in the accompanying sketch receiving antenna to electric wires carrying vol- tages of six hundred or more. It can easily be appreciated, however, that installations initially free from such exposure may later be- come hazardous through no fault of the owner of the radio set. To protect the user fully under such conditions one of the manufacturers has designed the protector shown in Fig. 6. This protector is provided with a two -ampere fuse, and, should the antenna inadvertently become crossed with a power wire, the current to ground through the fuse will cause it to blow, protecting the radio apparatus and isolating the antenna. This makes all apparatus on the Fig. 3. The internal construction of receiving side of the protector safe. The only the protective device shown above

www.americanradiohistory.com Protection of the Receiving Antenna 217

efficient antenna can frequently be erected wholly within the house. In individual houses, three or four wires supported on the rafters in the attic make a very desirable antenna, par- ticularly in frame houses. In apartment houses good results can frequently be obtained by running one to four wires the length of the apartment just below the ceiling. If such a diminutive antenna produces sufficient signal

Fig. 4. Another type of protective device. The gap element may be replaced if necessary

Ga Porcelain Holder Carbon Block

arbon

Spring Holder A To Ground A`:` ¡ ; 111.1_111 INN '...:..... To Antenn;.

Fig. 5. The construction of the protective device shown above tective gap if desired. This is shown in figure 8 on the next page. The ground wire leading from the protector should be supported on porcelain knob insulat- ors and may be connected to a water pipe or to a hot water or steam heating system that is electrically connected to ground. The pipe should first be carefully scraped or cleaned with sandpaper and an approved ground clamp Fig. 6. A popular type of lightning placed around it. Installations in steel build- arrester fitted with a fuse to protect the antenna in the event of its coming ings may use the building frame as a ground. in contact with high voltage power lines If the installation is made in the suburbs where there is no city water supply, a piece of pipe seven or eight feet long may be driven into moist earth and the ground clamp attached to this. H Mica Ring Connected to 1 2/1000' Thick ,e5t,` m _ Antenna Terminal ANTENNAS NEEDING NO PROTECTION MI Brass r Connected to OM/ Punchings ¡ii Ground Terminal frr HE new regulations specify certain types of antennas which are exempt from any 17° protection requirements whatsoever. Among these are the indoor antenna and the loop Porcelain Base antenna. Fig. 7. The internal arrangement For covering moderate distances a very of the protector shown above

www.americanradiohistory.com 2I8 Radio Broadcast strength it has the advantage of reducing to a and also cuts out a large amount of interfer- large degree undesirable noises such as static, ence from spark telegraph stations. The loop antenna is another type re- Protective Device Insulating Entrance that Bushing Wall of House or quires no protection. The loop, however, does Window Casing not collect as much energy as does the indoor antenna and so will not cover as great distances

To Antenna without the use of more sensitive receiving ap- Post of Radio Receiver paratus than that generally used. But the To Ground Post of Radio Receiver loop antenna has many desirable qualifica- -`"i-Insulators tions and gives promise of development in the No. 14 Rubber covered Ground wire future. Gound Clamp In general, the latest revision of the Fire k Vater Pipe connected Underwriters rules will make the advantages of to Water Supply broadcasting receivers available in many cases Fig. 8. The method for employing the light- ning protective device installed within the in which installations would have been im- building and connected to a suitable ground possible under the old regulations.

A Church With a Mighty Congregation Pastor M. E. Dodd of the First Baptist Church, Shreveport, La., Who Installed a Radio Broadcasting Station so that His Aged Mother Four Hundred Miles Away Could Hear Him Preach, is Reaching Thousands of Radio Enthusiasts By ARCHIE RICHARDSON

WHEN the first radio services generator and operated by a licensed com- were held one Sunday in May mercial operator, was used. The station sends in the new half million out on a 36o meter wave length. The call dollar building of the First number has not yet been assigned. Baptist Church of Shreve- The station is located in the io -story tower port, Louisiana, but a small portion of the of the church. The antennas are suspended worshippers were found in the church audi- between the top of the tower and a 3o foot torium. skeleton steel tower built on an office building `l'he rest of the congregation were scattered across the street. They consist of four copper throughout the United States, in portions cf wires, 125 feet in length, too feet above the Mexico and upper South America, on the ground. islands of the Gulf of Mexico and in ships at sea. l t was planned to broadcast the dedicatory One of the country's most powerful radio services on Sunday, April 22, but part of the broadcasting stations carried the pastor's voice equipment failed to arrive in time to be in- through the hundreds of miles that lay between stalled before these services. him and his hearers. The normal radius of the station is 300 In hundreds of churches served by circuit miles, but under favorable conditions it can be riders, in hospital wards, in orphanages and old picked up from coast to coast, and is audible in people's homes and in residences of those portions of South America. affiliated with this church, receiving sets are The broadcasting feature of the new church being installed to take advantage of the oppor- plans was arranged primarily in order that the tunities offered by the first powerful radio aged and invalid mother of the pastor might broadcasting station in this part of the country. hear the sermons of her son. At her home in A 200 watt set, using a powerful motor Trenton, Tenn., nearly 40o miles away, a

www.americanradiohistory.com A Church With a Mighty Congregation 219 receiving set has been installed in her bedroom, in late years has caused her to lose touch with and daily it will bring to her the voice of her many of the world's developments. But her son. son reminded her that when telephones first Mrs. Lucy Williams Dodd, the mother of the came into general use, she had said she would pastor, Dr. M. E. Dodd, is nearly eighty years have none of them in her home. old, and for the last two years has grieved be- She consented to a trial, and a radio set was cause she could not hear his sermons. installed in her home. Now she is an enthusias-

The pastor's mother, Mrs. Lucy Williams Dodd, eighty years old and an invalid, listening by radiophone at her home in Trenton, Tenn., to her son in Shreveport, La. The broadcasting station was installed in the church primarily so that she could hear her son's sermons

While Doctor Dodd was visiting her recently, tic radio fan. Daily she listens to concerts and she expressed the fear that she would never hear lectures sent out from broadcasting stations, him preach again. That was the suggestion and enthusiastically declares that the new- that lead to the installation of the broadcasting fangled ideas aren't so bad after all, especially station. He made her a promise that arrange- for a woman of eighty who can scarcely leave ments would be made so that she would hear her bed. And now the completion of the every service he conducted as plainly as if she station in the Shreveport church has enabled were sitting in a pew before him. her to listen to the voice of her own son. For a long time Mrs. Dodd was skeptical. Hundreds of churches that have no pastor or The retired life her illness has forced her to lead that are able to have a preacher only once or

www.americanradiohistory.com 220 Radio Broadcast

First Baptist Church, Shreveport, La. twice a month have installed or are planning to in music and lectures, to receive market reports, install receiving sets. Now that this church to get the day's news, and to hear the many station has been completed, they will have other things offered by the country's broad- services twice every Sunday and throughout casting stations. the week as regularly as the city church. And But radio will not take the place of the pastor they will have the same sermons and the same of the small church, according to almost unani- music that the people of the biggest Baptist mous verdict of church leaders. They say the church in the world enjoy. personal touch of the individual minister can- It is stated that half of the Baptist churches not be supplanted by the radio service. They of Louisiana are without pastors. The same is regard it as supplementing his work, and offer- true of many other states. These churches are ing him opportunities for bigger work, rather in small towns and in neighborhood settle- than substituting for him. Many a church has ments, in many cases off the railroads. Bad fallen apart through lack of a pastor, because roads make many of them inaccessible through there was no reason for the congregation to a large portion of the year. assemble. The radio is expected to remove That the church radio will be a boon to the this condition of affairs. isolated congregation is agreed by all religious Aside from the religious services, many workers. Many preachers declare that radio features will be broadcasted by the Shreveport offers the church bigger opportunities than any- church station. The auditorium, the largest thing science has produced since the invention in the city, has been offered as a civic and edu- of the printing press. Some say that it ranks cational centre. The world's greatest singers above the printing press in importance. and lecturers will be heard here, and their The rural church, long a neighborhood concerts and lectures will be available to all gathering place, will take on greater importance who have receiving sets. On the ninth floor of as a civic, educational and cultural centre, as a the church tower is a 13 -bell chime, of which result of the installation of radio. People the largest bell weighs 3.000 pounds. Daily will gather at the church evenings throughout concerts are given by a trained chimer. A the week, as well as on Sunday, to hear the best chime connection makes the broadcasting of

www.americanradiohistory.com A Church With a Mighty Congregation 221 these concerts a simple matter. Recitals on There is only one fly in the ointment for the the four -manuel organ of the church, together pastor. He is much concerned over the fact with choir and congregational singing, will be that a bed spring makes a splendid aerial. features of the programme. A daily news ser- Much of his work, he says, is to get members of vice is being arranged for. his flock out of bed in time for Sunday school The pastor states that the performance of or even the morning preaching service. When marriage ceremonies will be one of the tasks of the people learn that they can listen to the his radio station. A marriage performed by services by attaching the receiving set to their radio is just as legal, and the ceremony can be bed springs, he fears there will be a growing as impressive as if the minister were present in tendency to lie abed Sunday mornings. person, he says. This, it is pointed out, will The matter of collections isn't worrying him, permit a couple to have their wedding solem- he says. While it is impossible to pass the nized by the minister of their choice who may collection plate around with his congregation be hundreds of miles away. The only thing in scattered over forty -eight states, he says that the way of a ceremony of this kind seen by just as effective means will be devised for Doctor Dodd is the tendency of the bridal financing the activities of the church. couple to arrive late, but he thinks a way can The broadcasting station is but one of the be found to get around this. unusual features found in this church, which The pastor expects to reach many of his is declared to be one of the most remarkable flock who are addicted to Sunday morning church plants in the world. automobile trips through his radio outfit. He A 10 -story tower, which furnishes quarters will insist that when they go out Sunday morn- for a Sunday School of 3,000 and many young ing they carry receiving sets in their cars. people's societies, has attracted much attention.

The upper portion of the 10 -story tower of the First Baptist Church of Shreveport, La., is shown in the fore- ground; the dome over the main auditorium in the background, and the roof garden to the right of the tower

www.americanradiohistory.com 222 Radio Broadcast

The four floors of the main building, together toys, sand piles, and children's furniture, under with the tower, have a total floor space of the supervision of a nurse, cares for children 51,50o square feet, and a combined seating of mothers attending services or working or capacity of 8,000 people. shopping down town during the week. The main auditorium will seat 3,000 people. The dining rooms furnish noon lunches daily It is equipped with a four-manuel organ, and to several hundred girls and women employed i

1

,. ISM.S ,. i; N- ' I R yryill 1 -1k 4i ---

J/ 7 ` ii ìn- Ir M*1 _ - nre -_!/ ._ iá '/ W;;;_ f .---a ad Drawing showing details of the radio installation a chime connection. The transmitter of the downtown. Several banquets are served every broadcasting outfit is inconspicuously located week. in the pulpit, and connected with the generator The banquet hall seats Soo people at two long by wires that run under the floor and up the tables. elevator shaft. A gymnasium is located in an upper room of Even the deaf will be provided for in this the tower. auditorium. An acousticon outfit has been The congregation of this church numbers installed with a transmitter in the pulpit, 2,200. Ten years ago its membership was 500. connecting by concealed wires with the pews. While the city has shown a growth of 43 per The roof garden provides accommodation for cent. the membership of the church has in- 1,000 people. During the summer, outdoor creased 400 per cent., while the contributions services, concerts, and socials will be held here. of the church to all causes has increased 3,000 The nursery in the basement, fitted up with per cent.

www.americanradiohistory.com Random Observations on Running a Broadcasting Station Success Demands a New Type of Impresario Who is a Sort of Combination Editor and Theatrical Manager By H. M. TAYLOR

UNNING a broadcasting station for nothing if the technical mechanism does is a novel, not to say fascinating not put them out so that the average person experience. There is no precedent can receive them clearly and fairly easily. to follow. There is no literature And perfect reproduction and transmission of on the subject (that is, no litera- programmes avails little if the operator in ture in the usual sense; I do not refer to let- charge does not possess a pleasing voice, speak ters from the correctly, put on radio audience his numbers advising how the without long broadcasting sta- waits and possess tion should be a certain inde- run). Each scribable mental broadcaster, gen- agilityof his own. erally speaking, Then the artists has to work out who entertain his own code of play an impor- rules, use his own tant part, of common sense, course, in the make his own success or failure formule, and of the broadcast. profit by his own To find an opera- mistakes. With- tor who under- out doubt a stands human broadcasting nature so that he technique w i 11 can be sympa- soon be worked thetic and at the out. It is being same time man- done now -rap- age temperamen- idly. But in the tal artists, suc- present state of cessful business the radio art, this men and others technique is in- who have attain- complet e- ed prominence in embryonic. world aff ai rs, who Miss Eunice L. Ran dall telling a bedtime There are two story in WGI, Me dford Hillside, Mass. can surmount the major problems internal friction to be encountered by those running a broadcast- 'ever present in all organizations, and who, in ing station. One is the mechanical or technical addition, thoroughly comprehends the scientific side. The other, for want of a more descriptive and mechanical operation of the broadcasting characterization, may be termed the human side. equipment, is difficult, to say the least. As the Both are of the utmost importance. The public, old farmer at the circus said, "There ain't no which is the ultimate judge of the success of a such animile." broadcasting station, can never be satisfied if Almost every large broadcasting station is one side is defective. Good programmes count operated by several men, with one man respons-

www.americanradiohistory.com 224 Radio Broadcast ible for its success. No one individual, at most acute form -but only for a moment. present at least, possesses all the qualifications The attack passed as quickly as it had come. necessary for running a broadcasting station. For I realized no one could see me, except the My own idea of the organization of a broad- artist and my everyday associates. casting department is to put a trained ad- To many, perhaps, this attack of radio stage vertising man at its head and surround him fright may seem a bit incomprehensible. Yet, with technical operators possessing as many artists who entertain large concert audiences of the so- called human virtues as possible. tell me they experience similar emotions, al- Tact, sincerity and unfailing good- nature are though very likely in much lesser degree. It just as valuable as the possession of a first -class is uncanny to sing one's best to a hundred commercial license. A ready use of proper thousand people-all unseen. Some artists phonetics is as essential as a knowledge of at- unfamiliar with the extent that radio broad- mospherics. The rise of radio broadcasting, casting has swept the country, frankly appear besides opening up limitless commercial pos- sceptical. Hardheaded business men often sibilities, and attendant problems, besides show by their expressions a certain doubt that furnishing a new source of entertainment and their messages were actually heard by thou- inspiration to the general public, has produced sands. They have been told there is a large a new type of impresario exemplified by him listening audience scattered over many states, who runs the broadcasting station, and a new but seeing is believing -except in radio. It kind of vocation for a corps of assistants as well. is because of this uncertain feeling, this natural It is not my intention in this article to air lack of complete faith on the part of the un- my own personal views and activities in running initiated, that broadcasting stations are contin- a broadcasting station. 1 do not wish to pose ually asking those hearing their programmes to as an expert, because I don't believe the expert write in and let them know it. One of the most has arrived. But I do believe the thousands helpful ways in which an individual can assist and thousands of people "listening in" to radio the broadcasting station, now maintained at programmes every night might be interested in large expense to the operating company únd the many difficulties, human as well as techni- giving programmes entirely free of charge, is cal, which are encountered at the transmitting to drop a card acknowledging receipt of the end. Moreover, an exchange of ideas among broadcast. those struggling to put over programmes for the Constructive criticism from those hearing the public interest, may help to improve those broadcasting is of course always welcome to all programmes for that same public. stations. Even destructive criticism may be I will never forget my first experience in helpful. As for anonymous, destructive crit- putting out a high -class programme. It was icism, perhaps the least said the better. I in the early days of radio broadcasting. The suppose every broadcasting station occasion- main feature was a piano recital by a promi- ally receives anonymous communications, just nent concert artist. The possible audience was as does every newspaper or magazine editor estimated at 25,000, an audience now tripled, and man in public life. As long as there is and then some, for any large broadcasting darkness, there will no doubt be people who station. I was to introduce the artist and prefer to cloak their movements in deepest had prepared a speech in carefully chosen shadow. words. Nonchalantly, I picked up the mi- The letters received in answer to requests for crophone to make the announcement on the them, as well as unsolicited letters (of which evening which was quite an event for us in the there is a great number, showing that the annals of broadcasting. With perfect sang- spirit of the American public is right, as has froid 1 removed a cigar and started to open always been maintained by those long in con- my mouth. All of a sudden, in such a rush, I tact with it) run the gamut of personal opinion. saw before me 25,000 people, strangers- before Some would have all jazz music, others nothing me to whom a speech before a score of friends but grand opera. Some like educational lec- was enough to start the cold sweat and the tures and talks, others would have only music. knocking knees. Who was I to talk to such a Subdividing, some would have violin repro- vast assemblage! -such a throng as witnesses duction predominant. others would eliminate inaugurations, baseball games, and bull fights! it entirely. (Any type of instrument may be For a moment I had radio stage fright in its substituted for " violin" in the above sentence.)

www.americanradiohistory.com Random Observations on Running a Broadcasting Station 225

There are those who are "bored to death" I believe the tendency in the radio programme with talks of interest to women, or market should be toward the classical, as people of and stock reports, or code practice and in- taste and education, who can afford to own struction, or bedtime stories, or popular music modern receiving apparatus, prefer this type or "highbrow" stuff. And then there are of music. The balance of the programme may those who like these things, or some of them. be filled with varied lectures, addresses by Just as among a group of ten thousand news- prominent men, readings, comedy sketches, paper readers there are comparatively few and useful information. In all this, emphasis who read with equal interest the same page is put on variety. If broadcasting is to con- or article, so tastes vary in radio broadcasting tinue in popular esteem after the first novelty programmes. The programmes are arranged has worn off, then it is necessary, I believe, for to meet these divergent tastes as far as possible. the programme to be instructiveand educational Experience seems to indicate just now that as well as interesting and entertaining. The musical features should predominate to a man responsible for broadcasting programmes greater or lesser extent. The musical pro- must have a rare sense of proportion, and be a gramme should be as varied as possible, giving fine judge of values. He must be a sort of the best, be it classical or popular in its nature. combination editor and theatrical manager.

The first radio recital from WGI, Medford Hillside, Mass., was played by Miss Dai Buell. The concert was transmitted from an office temporarily made into a studio. The walls were hung with blankets and then covered with wrapping paper. The sound was caught by the large megaphone which at the time of the concert was at the extreme end of the sounding board of the piano. Although the broadcasting was rather crudely arranged, this music was heard in Ohio and Maryland, and other places between 500 and 1,43oo miles

www.americanradiohistory.com 226 Radio Broadcast

Almost as wide in variety as the suggestions in awhile, after an unusually hectic day, I about programme. are the requests regarding wonder if the radio public doesn't think com- operating hours. A woman writes that her panies who operate broadcasting stations are husband is a night watchman and does not public philanthropists. A public servant is not wake up until 5 o'clock in the afternoon. He a public philanthropist. has a half hour to listen in at that time and Another thing. There is a great difference two hours when he cames home in the morning in the report of a broadcast. A man in one between 8 and io o'clock. Couldn't we broad- town will say he "got the concert clearly and cast then? Dealers and merchants want distinctly," while another man in the same broadcasting between 12 and one o'clock so town complains of a "hum," "a fuzzy rattle," that people can listen in on their noon hour, or a noise "like unloading a tip -cart of bricks." (a good idea). A young man wanted broad- Of course, reports regarding the concert itself casting after i 1 P. M. because he didn't get vary with the taste of the individual. home until that hour, as he attended night I have been asked about the future of radio

school three nights a week and worked evenings broadcasting. 1 am too busy with present de- the rest of the time. The idea that still persists tails to have time to think much about its among some people concerning radio broad- future. Then no one dares prophesy for fear casting is curious to say the least. The other of being reputed to-day a visionary and to- night I was listening to one of our programmes morrow exceedingly short -sighted. However, in the reception room of the factory which is one thing, in my opinion, is certain besides located a short distance from the broadcast- "death and taxes," and that is some new ing station. The night watchman came in method must be devised for financing radio wreathed in smiles and told me the following: broadcasting. Obviously, it is an enormous "A young lady just called me up," he said, expense to the operating companies for which "and said she would like to hear the radio. they are compensated by the sale of receiving She said she did not hear anything. I asked equipment. But other companies can sell her what kind of a set she was using and she receiving equipment which will receive broad- replied -`I am just in a pay- station over in casting programmes as well as those operating Boston. They told me to put a nickel in the broadcasting stations. Far be it from me to slot and call you on the telephone and I would mean by this statement that the sale of radio hear radio. ' equipment should be limited to those at pres- A woman who signed her name and address ent operating broadcasting stations, but on the wrote in and said -"We enjoy your perform- other hand the extra broadcasting expense, ance very much each evening and always have which benefits everyone in the business, can- six or seven people listening. To keep hus- not in fairness to all be borne by a few. Why bands home at night `Get a Radio,' says 1. can't there be a national broadcasting associa- Be it said, friend husband even comes home tion, under government supervision, to the in the middle of the afternoon now to hear support of which every manufacturer of radio your broadcasting." receiving equipment of a certain capitalization Sometimes people make really alarming re- contributes? This is one suggestion. Another quests and are greatly incensed when we are is that the government conduct and control unable to comply. A woman in New England broadcasting as it does the mails, or as cities wrote in recently that she wanted us to broad- do the water supply. These are merely sug- cast some dance music on Friday. "lt must gestions and of course only a few of many pos- be next Friday," she said, "because I have got sible ones. That radio broadcasting in some to be out both Wednesday and Thursday form will continue and improve and become evenings." As my secretary says, " You'd more widespread is, to those close to this new, almost think they were paying for it." Once epochal industry, as certain as sunrise.

www.americanradiohistory.com Radio Personalities IV REGINALD AUBREY FESSENDEN By LUCILLE JOYCE

LTHOUGH radio is but a side issue six inches in outside diameter, giving a quarter in the career of Reginald Aubrey horse power at 50,000 cycles and capable of be- Fessenden, inventor of the wire- ing used as an amplifier with a ratio of i-jo in less telephone and radio compass, current and 1-9oo in energy of amplification; the smoke cloud for tanks, the and a new type of radio telegraph receiver ca- electrically driven battleship, and the method pable of recording each individual radio wave, of locating enemy guns by sound, and, as en- thereby eliminating the troublesome static.

Professor Fessenden's radio frequency dynamo. The dyanamo is in the centre and the machines each side of it are merely employed to drive it. Although it is but six inches in outside diameter, it is capable of delivering ,'-, H. P. at 50,000 cycles. This machine is a forerunner of the present day high frequency alternators gineering commissioner for the Ontario Power Photograph A shows such a receiver, and Commission, responsible for the mammoth photograph B shows a record of dots made power distribution from Niagara Falls, he has at a frequency of 50,000 cycles per second. contributed to that science more perhaps than This photograph B is enlarged 2,000 times any other one man since the invention of wire- from the original record of the message, which less telegraphy. is micro -photographed on a strip of photo Among his newest inventions which will soon film, moving 2 inches per second developed be available to the average radio enthusiast, are continuously, or on an 8 in. by io in. plate a high frequency dynamo (Photograph D.), only developed hourly. Each plate holds one hour's

R. Record of dots made at a frequency of 50,000 cycles per second re- ceived by Professor Fessenden's new type of radio telegraph receiver

www.americanradiohistory.com Radio Broadcast

A. Professor Fessenden's new type of wireless receiver capable of recording each wireless wave, and used also in his radio camera record of messages which may be transmitted by four inches on a screen twelve inches away. at 50o words per minute or more. The film The coarse -grainness of the image at a distance is used for periods of heavy static, and the of twelve inches corresponds to the 5o dot plate for reference of the day's work. Two per inch process plate photo. records are made simultaneously, one of the A method of overcoming cross talk, though dots and dashes, and the other of the spaces, of infinite importance in the transmission of and with a highly damped aerial this gives speech, could not be published at the time reliable results. of its discovery, because the publication, filed A still more interesting development which in 1915, was forbidden by the Government on Professor Fessenden already has in working account of the war, and was only recently order, and which will be demonstrated in the released. The method consists of splitting near future, is the transmission of moving speech up into a spectrum band and trans- pictures of scenes in distant cities. With the mitting each element of the speech spectrum apparatus as he has developed it, it will be pos- separately, then reassembling the elements sible to point a radio camera, connected to a at the receiving end. When it has been gen- radio loop, at the steps of the Capitol in Wash- erally adopted, each subscriber will be given ington, and by so doing enable every radio a number, with probably six figures, in the wire- subscriber actually to see the President deliver less telephone directory, and on turning the his inaugural address and note every slight gest- indicator to the six figures of the call of the ure he makes, as well as to hear his words by person he wishes to talk to, and throwing means of the radio telephone. Photograph the switch, he will find himself in direct com- A shows the receiving end of this radio camera. munication with the person he called. The size of the picture, slightly limited at Not only is the brilliant professor interested present, as it is received, is four feet by four in developing means of adequate communica- feet on a screen twelve feet away, or four inches tion between individuals, but his inventions

www.americanradiohistory.com Reginald Aubrey Fessenden 229

be redeposited by the consumers at any time; and for the proposal in 1911 to make sun and wind provide all the power needed for mechani- cal use without dependence upon coal, is as remarkable in appearance and in personality as he is in intellect. He is a huge, bearded giant, well -built, genial, of stately bearing and im- pressive manners. In describing his dis- coveries he speaks without a great deal of enthusiasm, but with much precision and de- tail, in the manner of one describing the work of a third person. He rarely mentions him- self in connection with his most remarkable inventions, but discusses them in the passive. Perhaps this reticence about himself and the fact that he is always willing to give credit to his assistants are reasons that he is not more widely known in this country. In the combined study and laboratory of his beautiful home at Chestnut Hill, Brookline, overlooking the Reservoir, he spends many hours a day with his experiments, among his pieces of apparatus, his photographs, and his books. But he is not always working. He has two hobbies, golf and shooting. The wall REGINALD AUBREY FESSENDEN in a corner of the big room is covered with have been a remarkable boon to those who must trust their lives to the sea, especially the turbo-electric drive for battleships, and the iceberg detector. The oscillator shown in photograph C is now used on submarines for telegraphing under water, for detecting other submarines, and for telephoning between sub- marines submerged to a depth of ioo ft. at a distance apart of io miles, and for taking con- tinuous soundings while steaming at full speed. Professor Fessenden is at the present moment working not at some new radio improvement, but on a device by which one thousand pages of ordinary sized print can be reproduced in a space of a one inch square and read by means of projection on a 6" x 8" screen attached to the arm of a chair, the whole device is so small as to be carried about in an overcoat pocket. By photographing on and fusing into a kind of quartz by a method of his own invention, it is passible to preserve records in perpetuity upon a surface so minute as to be almost indiscerni- ble to the naked eyes. The man who is responsible for these re- markable inventions, as well as for a system of storing power at an annual cost of three cents C. Oscillator used on submarines for telegraphing under per kilowatt hour in banks from which water, and for telephoning between submarines submerged power can be withdrawn, and in which it may to a depth of ioo feet at a distance apart of io miles

www.americanradiohistory.com 23o Radio Broadcast action photographs of famous golfers, and near continuously. In 1899 he started four lines by stands a bag of golf clubs as though in of work for producing continuous waves, first readiness for a trip to the Country Club. Sev- by commutating a continuous current, second eral guns which he delights to clean as well as by a continuous arc, third by a high frequency shoot are a source of especial pride to him. In dynamo, and fourth by an unstable current. addition to out -of -door pursuits, he snatches He succeeded in 190o in first transmitting moments of relaxation now and then, and often articulate speech by wireless over a distance an upturned book shows that he has been in- of one mile at Cobb Point, Maryland, using a terrupted in reading "Curiosities of Litera- 10,000 cycle per second commutator. Though ture" by Disraeli, or other of his favorite understandable, the articulation was not per- authors. fectly clear. With the development of the con- i Although born in Bolton, Canada, in the tinuous arc generation method, he was able in year 1866, and a volunteer with the First 1902 to reach approximately 12 miles by using Canadian Contingent, and detailed to the War an arc frequency of 50,000 cycles per second, Office, London, by General Sam Hughes in producing much clearer articulation. In 1903 in 1914, he is proud to call himself a Yankee, Washington he demonstrated before a number and explains with pride that the first of his of prominent engineers an apparatus capable name to live in this country was John Fessen- of working 25 miles, which was put on the den, an original settler of Cambridge, Mass., market and and tendered to the United States a whose tan yard was somewhere on the site of Navy in 1905. the present Harvard College Yard. In the mean time he had proceeded with the At the age of nineteen he was appointed development of the high frequency alternator inspecting engineer of the General Electric and finally constructed three dynamos at the Company, and later was head chemist for Brant Rock, Mass., station, two of them oper- Edison, to whose instructions he attributes ating at 50,000 cycles, by using the fields of a whatever success he has had in inventing. previous dynamo failure, and a third operating He has been professor of physics and electrical at i oo,000 cycles. engineering at Purdue University, later at For a continuous receiver, in place of the old Pittsburgh, special agent for the United States coherer which had to be tapped back every Weather Bureau, and consulting engineer for the time a signal was received, he invented a num- Submarine Signal Company. Of recent years, ber of devices, the first of which was the ring however, he has felt it impossible to continue receiver mounted on a sensitive microphonic his more public work, and is devoting himself contact, followed by the hot -wire barretter and entirely to his inventions and experiments, all the liquid barretter. About this time he de- of which he realizes are of great practical vised an interesting type of receiver in which I value and of immense service to the world. a small hot -wire barretter mounted on a small His seemingly superhuman accomplishments rubber holder fitted inside the ear, invisible have been the result of a life -time of continu- wires ran to the hat -band and down the side ous and painstaking effort. As a child he was of the body, permitting wireless telephone interested in mathematics. The banking pro- messages to be received by a person walking fession, in which he was brought up, offered about in the fields several miles from a station. no incentive to his already inventive type of After building various types of amplifiers, mind, and science, with its unceasing appeals to he was able to maintain regular wireless tele- the imagination, excited him. phone communication between Brant Rock In 1892 he was giving a course in Hertzian and Jamaica, L. l., with articulation clearer waves at Purdue University, and from that than over the wire telephone lines between time to the present has added one marvellous the same places, using an apparatus in 1907 i device after another to the development of which permitted simultaneous talking and wireless communication. listening. In 1906 he had been able to demon- In endeavoring to transmit speech by wire- strate to a number of leading scientists the less, he found it impossible with the old spark transmission of speech by wireless between gap coherer system, because of the lack of Plymouth and Brant Rock, and the relaying two essential requirements, that the waves of conversation over the regular wire lines. should be generated continuously and that As the result of tests made by the Bell Tele- the receiver should be capable of utilizing them phone Company, contracts were drawn up by

www.americanradiohistory.com New Radio Net for Rogues 231

Mr. Fish in 1908 calling for the installation of which was accidentally accomplished in Nov. wireless communication links between Martha's 1906. Operators telephoning between Brant Vineyard and Boston, and for the construction Rock and Plymouth were overheard on several of wireless long distance lines between Boston, occasions by his operators at Machrihanish, New York, Buffalo, and Washington. The con- Scotland, who identified the voices of the men tracts were not carried out because the banking speaking and sent back several reports giving interests supplying money for the Bell Tele- the exact words of the conversations, which phone Co. decided that the company was ex- were subsequently verified by the log books panding too rapidly and revised their policy, in of the station. consequence of which wireless telephony for com- Since that time the inventor of the wireless mercial use was delayed for about a dozen years. telephone has been constantly improving upon Professor Fessenden describes the first trans- it, developing and simplifying it so that it may mission of articulate speech across the Atlantic, be adopted for more general use. New Radio Net for Rogues William J. Burns Tells Some of the Plans cf the Recently Established Bureau of Investigation of the Department of Justice. Radio to Play a Large Part By DONALD WILHELM

TO BE recorded upon the all -per- His Bureau is now setting up a kind of na- vading ether as a criminal, that," tional and international switchboard. It is says William J. Burns, detective to be called a bureau of identification. Its extraordinary and head of the De- handmaid will be radio. It will use radio, partment of Justice Bureau of In- Mr. Burns says, to broadcast even finger- vestigation, "will be as good as landing behind prints! the bars." "We will have registered in the Bureau cf The old -style rogues' gallery is now out of Identification," he explained, "the finger- date; we are, Mr. Burns says, on the threshold prints of any and every criminal, and of any of a system incomparably more thorough, in- other person who cares to put himself on record. comparably swifter, incomparably more dis- We will have their photos and descriptions. couraging to crime and criminals. We will be in touch with every police agency "The Department of Justice Bureau of In- in the United States." vestigation," he told me, " is soon to begin Many police departments are establishing using radio." the use of radio -they asked for, and were Radio, he explained, is to be used not only granted by the Radio Conference, the use for the detection of criminals but for the pre- use of a separate band of waves, for their vention of crime. "We are trying to prevent particular use, for city and state public crime," Mr. Burns said. "That will be our safety broadcasting. Chicago has found radio greater work." useful in detecting stolen automobiles and He added: "We are trying to make this automobile thieves. Philadelphia is coming institution function in the interests of the into line. Berkeley, California, whose Police people -for the first time." Chief, Vollmer, is matching science against He described how the Bureau of Investi- crime, has every policeman provided with an gation had been, in the main, a kind of service automobile and virtually every auto equipped bureau for the Government, whereas now, in with radio. And other city police depart- ways not heretofore revealed, its new aim is ments are equipping not only their motor to serve the entire American public in its un- boats, cycles and automobiles, and even in precedented battle against lawlessness-law - some instances their patrolmen, with radio lessness, he points out, that is aided and abetted but are using it to link up fire department by new and swifter means of transportation, apparatus. The writer's view is that this is especially the automobile. only the very beginning; war against common

www.americanradiohistory.com 232 Radio Broadcast

enemies of society radio beacons at every will not stop with this. Extract of a letter sent by William J. cross-roads. Even now With apartment Burns, Director, Bureau of Investigation, these could be pro- houses equipping their Department of Justice, to all chiefs of vided: if then a mur- suites with radio ex- police. derer-a John Wilkes a tensions from cen- One of the first observations which Mr. Booth, let us say- tral receiving set; with Daugherty made, after assuming the duties of were at large in Ohio thousands of city Attorney General, was to appreciate the need or Maryland, say, that dwellers hitching of establishing a Bureau of Investigation that man could be caught themselves to radio would function promptly and effectively and by radio. His descrip- waves; with virtually at the same time have the confidence and tion could be put upon every farmhouse coöperation of the forces of law and order in t he all -pervadingether equipped with radio each town, city, and state. It is the desire of without his knowl- to meet the farmer's the Attorney General and myself to bring edge. Every apart- business needs as well about this coöperation by a closer relationship ment, every farm- him diver- between the local police forces of the country house, every gathering as furnish and the Bureau of Investigation of this de- sion; with the Ameri- partment. In line with this desire, the At- point of human beings, can radio chain reach- torney General and myself have had several and mounted consta- ing round the world, conferences with the representative of the bulary as well (the and the Signal Corps, International Association of Chiefs of Police, Canadian Mounted Post Office, and other through the medium of the National Bureau Police are now experi- nets being developed of Criminal Identification, and have obtained menting with radio) to cover every inch of suggestions for the effective inaugurating and would have his de- American soil, the fu- carrying out of the plans for cooperation. scription. Even now, ture of crooks looks These conferences have been most productive with our present discouraging! and have led now to the crystallizing of the broadcasting system, plan for the establishment of a Central Bureau any fugitive could Still more intensive- in the Department of Justice be of Identification broadcasted ly, I believe, radio will in which will be placed the fingerprints, photo- pretty be employed for police graphs, and all detailed information available thoroughly. lf, in ad- purposes. At sea we concerning criminals in this country. This dition, by the use of know that when the it is hoped will not only be of material aid to multiplex telephony, SOS jams the air, the federal government but will be of inval- for instance, as Gene- every neighboring ship uable assistance to the law- enforcing depart- ral George O. Squier stands by. On land ment of the cities and states. suggests, along every when a similar SOS highway there were jams the air, in alarm boxes, ra- any emergency, dio would indéed every neighbor- be the handmaid ing individual of the police and will stand by. At of all communi- sea we have com- ties. pass stations, a We have seen wonderful chain so many cases of of them, brought fugitives over- into existence to taken bywireless combat subma- on the sea -the rines. Also we first was that of have radio bea- Dr. Crippen, cons continu- who was caught ously emitting by wireless en their warnings route to Canada by radio. And on under an as- shore there is no sumed name, ar- Motorcycle for police, equipped with the Thompson submachine gun and rested on land- reason why we a radio outfit. This is the most modern of all police equipment and is should not have rapidly being adopted by cities all over the country ing, returned to

www.americanradiohistory.com New Radio Net for Rogues 233

England and hung-that we accept such events " Radio," Mr. Burns went on, "will be in as a matter of course. finitely useful in crime work. Using it, we can Again, it was only the other day that a add greatly to the strength of a central agency banker in Dallas, Texas, who wasn't up on like ours. Criminals can be reported in the radio, walked out of the back door of his bank, various ways heretofore used and also by radio. a defaulter. He was reported by radio by the We can broadcast them. We can use radio Dallas police to Post Field of the Army Air to detect mere thieves " -the cry "Stop Thief!" Service. At Lawton, Oklahoma, an amateur must now have a far wider meaning -"for caught the word. notifying people This amateur to look out for spotted his man,. forgers, so that reported him. merchants can be Before the end on their guàrd, of the day the and ágainst of er defaulter was kind's, of public lodged in the enemies. We are Lawton jail. going to be able Mr. Burns, to broadcast de- himself, told me scriptions of fin- of a case even gerprints wit h more sensa- sufficient accura- tional. cy to wa rrant the Into the West- detention of any inghouse plant suspect until his at Pittsburg identity is finally came a young, established." well -dressed in - lt will be re- dividual. He membered that, represented him- abroad, the Be- self as a com- 1 i n ograph -a mittee of one Frenchman's in- sent by a com- vention by m unity organi- means of which zation to borrow photographs,sig - a receiving set. natures, and the He was loaned like have been one of the very transmitted best and did not across the At- return it. The lantic -has been situation was re- developed to ported to the transmit finger local Burns de- ® Harris & Ewing exactly. William J. Burns, Di rector of the Bureau prints tective agency of Investigation, De partment of Justice Mr. Burns' plan After an inves- does not look tigation this young man was broadcasted: to using the Belinograph. Instead he is de- Twenty-four years of age or so, about five feet vising a new code that can be used more eight inches tall, blue eyes, a scar on his left handily and will yet serve the main purpose. cheek, etc. That evening, it so happened, this With the coöperation of such organizations as fugitive was entertaining his mother and some the International Society for Personal Identi- of his friends with his new receiving set. They fication, he is devising a code that classifies were sitting by when out of the ether came a the varying whorls, arches, ridges, and loops flash of the whole situation. The next morning in such ways that anyone familiar with the his mother saved her son from arrest by appear- peculiar markings of each individual can tell ing at the Westinghouse offices with saved -up at a glance whether a suspect belongs within earnings with which to buy the receiving set. a certain category.

www.americanradiohistory.com How Radio Came to Independence Kansas By THOMAS M. GALEY

This is a typical story of how the rage for radio is spreading, community by community, through - ,out the United States: THE EDITORS.

MAR WI BLE brought it. At constructed with his own hands, the receiving least it was Omar who opened set with which he heard Pittsburgh, using the gates to it when, on the jelly glasses, "Quaker Oats" cylinders, some fifth of last December, he heard wire, and an electric light bulb; at least, that over his wireless telephone, the is how the installation looked to a young busi- services at the Calvary Church in Pittsburgh, ness man who promptly called to see what sort Pa., and the local newspaper printed an ac- of an apparatus could enable a man to hear count of his experience. The curiosity of the church services 863 miles away. public was instantly aroused, and many local Omar Wible, whose chief trouble at that time telephone inquiries kept Omar Wible busy was that he had to make a living beating the vindicating the veracity of the local press. drum in a moving picture show every evening For about a dozen years before that, to be during the very time when broadcasting fairly sure, Hubert Devore had been reading the big fills the air, went on and built himself a trans- spark stations, and one evening about a year mitter, using a generator from a junked auto- ago he was startled by the sound of a human mobile, so that the whole apparatus cost only voice in his receivers. It was the operator at about forty dollars. Then he broadcasted a the station on Catalina Island in California concert by the Girls' Glee Club of Emporia Col- whom he heard talking, but that startling ex- lege. Some of the members of the club perience didn't get into the newspapers. So slipped away to homes where friends, gathered it was Omar Wible's hearing of the church ser- around receiving sets, were eagerly awaiting vices which gave the craze its first impetus. the concert. The songs were pretty much Independence is a prosperous town in south- garbled and the college cheer sounded like a eastern Kansas. Its twelve thousand inhabi- dog fight, but everybody was delighted. tants are of average intelligence and education, Omar Wible's aerial was tied to the top of a but only half a dozen boys who owned little twenty -foot post, and stretched its crooked home -made sparkers had ever heard, until length from the front curb to the alley. In- then, that telephoning without wires was a dependence has seen many aerials since, but practical reality. But soon, the word "broad- it hasn't been able to get rid of that feeling of cast" began to be heard, and then the fact the supernatural, the impossible, which Omar's became public property that the East was al- aerial caused in those who gazed upon it. ready started on a rampage of radio. Kansas Even the detector tube, which, after all, only is generally about two months behind the translates the faint impulses caught by the East in experiencing a business boom or de- aerial cannot exceed the wonder of it. pression. This seems to be equally the case About a dozen individuals promptly planned with radio, but by the middle of last February to put in transmitting sets, so they could keep it appeared that everyone wanted to "listen in touch with relatives in Los Angeles or Cape in," and by the end of that month the myste- Cod, but that wave of enthusiasm diminished rious functions of a variometer or a grid -leak as local knowledge progressed. I t finally sim- were becoming rather ordinary talk about mered down to the establishment of a real radio town, especially where there was a small boy store and a rather costly I K\\' transmitter. in the family. To be sure, there is not much genius to trans- Omar Wible had played with electrical ap- mit, but all the same it is planned to carry paratus ever since he had attended school in church services to every farmhouse within a Chanute, Kansas, a dozen years ago. He had reasonable radius and occasionally Schumann- I

www.americanradiohistory.com How Radio Came to Independence, Kansas 235

Station. The service from this station came regularly with startling perfection. There were now three big stations which could be depended upon. Then Dallas came in, and, night after night, new ones appeared; notably Schenectady, Indianapolis, and Atlanta. So many attempted to use the narrow band, about 360 meters, that KDKA was crowded out. For weather, market reports, and good music, the big cities are depended upon. Several fans even sent contributions to the Detroit News to help finance the Symphony Orchestra con- certs so marvelously broadcasted. The dramatic effect of the radiophone is far more profound in the rural districts of the West than in New York City, and the time will arrive with startling speed when every farmhouse will have a set. Already one hears grumbling in the Eastern cities about the character of the programmes of certain of the big stations, so exacting and critical is the public mind in a big, conven- tional city. But our Western listeners are less critical of the programmes from the East, and the anticipation of marvelous broadcasting developments next winter is creating a rapidly Omar Wib le, who heard on his home -made receiving growing interest. A sound that becomes each set the services at Calvary Church in Pittsburgh, day more familiar in the Central West is: "Say, Pa., 863 miles away, and thus started the craze where can I get some bulbs ?" The sewing machine peddler who "sells" Heink or Al. G. Fields may provide the touch of the farming districts in his little "whoopie" genius. It is thought the local ministers must will be crowded off the road by the radio brace up to com- peddler with pete with the most any sort of beautiful services a set from a dol- from Pittsburgh lar up. I t is on and Detroit. the farm where By the last of the best receiving January it was success will pre- possible to get vail, being far KDKA in Pitts- from high ten- burgh and Fitz- sion lines, dirty simmons Hos- street car com- pital in Denver mutators and every night, at power houses. least when Bob It is to the Flint was not lonely farms of sending crashes the Central of energy to West that the Chester Pendar- Home of Omar Wible whence he broadcasted the first concert and first radiophone will vis at Elk City sermon in Southeastern Kansas on a transmitting set that cost him bring a new eighteen miles only forty dollars interest, an distant. interest which A month later, "listeners -in" heard a new may hold the ambitious farm boys, and the farm call and a voice announcing the Detroit News girls as well, from flocking to the city.

www.americanradiohistory.com How to Begin to Enjoy Radio By CAPTAIN LEON H. RICHMOND, SIGNAL CORPS. U. S. A. Editor. Technical Training Literature, Office Chief Signal Officer

Captain Richmond, who was Professor of Physics at Western Maryland College before the war, was commissioned in the Signal Corps at the outbreak of the war. After passing through various instruction camps, he was assigned to the Royal Navy (British) Flying Field at Cranwall, England, where he worked with Lt. Commander J. M. Robinson (British Navy) in developing a radio direction finder and other radio apparatus for airplanes. Upon the completion of this duty, and after a short time at an American flying field, he was assigned to duty at the Army Signal School, Langres, France, where he was in charge of the Radio Department at the signing of the Armistice. For the last year and a half, Captain Rich- mond has been on duty in the Office of the Chief Signal Officer at Washington. -THE EDITOR.

II

WHENEVER it is desired to on a spring balance. If set in motion, the receive a certain transmitting weight will move up and down, that is, it moves station, the radio receiving alternately in one direction and then in the set must be tuned to that other, without any outside aid. A little station. This is done by turn- thought about it will show that there are two ing the knob or knobs on the receiving set. It factors which cause this up and down motion. is the purpose of this article to tell just what is The weight is one factor, the spring is the other. done when these knobs are turned, i. e. why When started in downward motion, the weight turning the knobs tunes the set. keeps moving beyond the position where the two will finally come to rest. but as soon as it OSCILLATING CURRENTS gets beyond the point of rest, the spring begins ARADIO wave is produced by an electric pulling back. The further the motion from current which moves first in one direction the point of rest, the more the spring pulls until i along a wire, then moves in the opposite di- finally the weight stops moving down and starts rection. Such a current is called an alternating moving up, being pulled back by the spring. current, the word alternating describing the We can get the same effect in another way. change in direction of the current. When the It would be well to do this experiment to fix i alternations of current (changes of direction) the idea firmly in your mind. Take the blade take place thousands of times per second, the of a hack saw or some similar object and fasten term oscillating current is used to describe it. it in a vice allowing some of it to project. By Radio waves used in present day radio com- some means fasten a weight to the projecting munication are produced by electric currents end. Pull the end to one side and let it go. It which oscillate with a frequency of between will vibrate back and forth. Again the weight 10,000 and 6,00o,000 times per second. This keeps it moving beyond the point of rest and oscillating current sets up radio waves of the the springiness of the hack saw blade pulls it same frequency. (See first article of this ser- back toward the point of rest. Try this ex- ies for relation between frequency and wave- periment with a hack saw blade, a kitchen length.) The radio wave, coming to your re- steel knife, or a spatula. ceiving set, sets up in it oscillating currents, The condition under which any system will IF THE RECEIVING SET IS TUNED to that fre- oscillate is clearly set forth in the above ex- quency (wavelength). periment. To state it again, it is that there must be present something which will keep the CONDITIONS FOR OSCILLATIONS (FREE) system moving beyond the point of rest, and ABETTER understanding of tuning can there must also be present something that will be had if we compare it with something pull the system back toward the point of rest, with which we are all familiar. Let us first the pull becoming stronger the farther the consider what happens when a weight is put displacement from the point of rest. When

www.americanradiohistory.com How to Begin to Enjoy Radio 237 these two factors are present in a system, it is RENT FROM DYING AWAY, hence causing all the seen from the experiment that the system, electrons on A to move over to B. The con- when once set in motion, will vibrate or oscil- ditions are exactly the same as they were at late of its own accord. first and exactly the same events take place It is evident then that if we wish an electric with the exception that it is now capacity B current to flow of its own accord to and fro which is charged and which gets rid of its (oscillate) in a circuit, there must be intro- electrons. This to and fro movement will duced into the circuit, each of these two factors. continue until the energy dies away by wast-

One of these factors is called inductance; the age. The . to and fro movement of the elec- other factor is called capacity (sometimes called trons is an oscillating current. capacitance). The fundamental idea that l Thus it happens that if a circuit contains in- desire you to get now about inductance is this: ductance and capacity, an electric current will When inductance is present in a circuit it tends oscillate in the circuit when energy has been to prevent any change in an electric current. supplied. This is the exact counterpart of a Thus when a current tries to die away the in- mechanical system represented by the hack saw ductance of a circuit will try to prevent it from blade and weight which has elasticity (springi- dying away. Inductance acts like a weight in ness) and mass (weight). The reader should this respect. The fundamental idea l desire compare step by step the action that takes you to get about capacity is this: When capac- place in the mechanical and the electrical ity is present in a circuit it will store up elec- systems. He will find that the action of one tricity, but as soon as it begins to store some it is similar to that of the other. rid of it. The more electricity that tries to get NATURAL FREQUENCY AND RESONANCE it stores, the harder it tries to get rid of it. Thus it is seen that capacity of a circuit corresponds NOW let us go back to the hack saw blade to the springiness of the hack saw blade. and weight experiment and notice an- Let us represent, as in Fig. 1, a circuit hav- other fact about it. Start it vibrating and ing inductance and capacity and study it. notice the number of vibrations per second. Capacities A and B are equal to each other. Change the amount of weight on it and cause it to vibrate again. The number of vibrations per second is different from what it was. Change the stiffness of the blade (make it U longer or shorter). Again the number of vi- brations per second have been changed. What U we have learned is this: that this mechanical system has a NATURAL FREQUENCY OF VIBRA-

Fig. i TION which may be changed by changing either the stiffness of the blade or the weight attached By some means let us put a charge upon the or both. capacity represented by A in the figure. This Electrical oscillations are exactly the same. charge is shown by the minus signs, which re- In Fig. I the number of to and fro motions of present the small particles of electricity called the electrons (oscillations) depends upon the electrons. As has been noted, the capacity value of the inductance and capacity in the TRIES TO GET RID of its charge and is able to do circuit. Changing either one or both of these so, as there is a circuit leading to the other will change the number of oscillations per se- capacity. The electrons pass along the wire cond. This may be summed up by saying that to the capacity B thus making a current an ELECTRICAL CIRCUIT CONTAINING AN IN- through the inductance. if it were not for the DUCTANCE AND CAPACITY HAS A NATURAL PE- inductance, when the capacity B had received RIOD OF OSCILLATION, DEPENDING ON THE VALUES half of the electrons that were on capacity A, OF THE INDUCTANCE AND CAPACITY. Every re- the electrons would stop moving, for capaci- çeiving set has inductance and capacity. ties A and B would each be trying to get rid What you do when you turn the knobs on the of their electrons with equal force. But the receiving set is to change either the amount electrons are moving from A to B and hence of inductance or capacity in the circuit. (On there is a current flowing. The inductance some sets there are also knobs used to control now comes into play and PREVENTS THE CUR- the current supplied the vacuum tube or tubes.)

www.americanradiohistory.com a 38 Radio Broadcast

Thus the circuit can be adjusted so that its Now we are ready to get a better understand- natural frequency is any value desired (with- ing as to why we can have more than one radio in the limits of the set.) message in the ether at the same time without TUNING then means that you adjust the interference. Suppose one station is trans- natural frequency of your receiving circuit so mitting on a wavelength of 30o meters and an- that it is equal to the frequency of the radio other on a wavelength of 600 meters. Their waves you desire to receive. frequencies are then I,000,000 and 500,000. Why must this be done? Because the Now if you adjust the natural frequency of amount of energy in the received radio wave your cirruit to be 500,000, it will be in reson- is so small that, if the receiving circuits were ance with the 600 meter wave and out of re- not tuned, there would be no effect produced sonance with the 30o meter wave. The 600 by the waves. lt is a case of resonance. We meter wave will affect your receiving appara- are all familiar with resonance effects though tus; the 30o meter wave will not unless the we may not call them by that name. When latter is very close by. You are tuned to 600 you swung your playmate you used the princi- meters. You did it by adjusting the values of ple of resonance. You timed your pushes so the capacity or inductance in your receiving that they would come just at the right instant. set. By doing this you were able to make the swing From the above explanation it might be go very high, using only slight pushes. The thought that your receiving set will respond to swing had a natural period of oscillation; by one frequency (wavelength) only. Unfor- timing your pushes (tuning them, so to speak) tunately this is not the case. There is a band you got a large effect from a small amount of of wavelengths to which your receiving set will energy. respond. The width of this band depends up- Examples of resonance are numerous. The on the receiving set. It may be that if you fool who rocked the boat knew about reson- tune to 600 meters your set will respond al- ance. He timed the swaying of his body to the most equally well to any radio wave whose natural frequency of oscillation of the boat, length is between 510 and 690 meters. This is thus overturning it. He secured a large effect a variation of 15 per cent. on either side of the from a small amount of energy. Have you 600 meters. This is not very selective tuning. noticed, very often when a piano is being It is to be noted that any station transmitting played that, as a certain note is struck, the on a wavelength between 5 I o and 690 meters glass in a picture frame or some other object would cause interference if the waves had will rattle. This is because the object has a nearly the same amount of energy as the waves natural period of vibration equal to that of the you were trying to receive. Some receiving note. The two are "in tune" and thus the sets are capable of better selection -sharper small amount of energy in the sound wave tuning. A set that will respond to wave- produces a large effect. lengths between 570 and 63o meters (5 per cent) Thus, then, when any system which has a when tuned to 600 meters is a fairly sharply natural period of oscillation or vibration of its tuned set. Such a set diminishes the possi- own is acted upon by a very feeble force that bility of interference. has the same frequency, the effect produced by This then is a limitation on the number of the feeble force is large. The radio wave from ether waves that can be utilized without inter- a distant station has only a feeble energy when ference. Another limitation lies in the fact it reaches your station. It has a certain de- that a transmitting station radiates an impure finite frequency. If you desire that your re- wave. That is, instead of radiating its energy ceiving set be affected by the feeble energy in at one wavelength, it radiates a band of wave- the radio wave, you must adjust your circuit lengths on either side of its main wavelength. or circuits so that their natural frequency is Thus we have the transmitting station radiat- equal to that of the radio wave. The receiving ing a band of wavelengths and a receiving circuit and the radio wave are then in reson- station responding to a band of wavelengths. ance, hence the latter produces a compara- This limitation upon a limitation greatly re- tively large amount of energy in the receiver. duces the number of messages that can be in This process of adjusting the natural frequency the ether without producing interference at the of the receiving set to equal that of the desired receiving station. Rapid progress is now be- radio wave is called tuning. ing made in the reduction of the width of both

www.americanradiohistory.com How to Begin to Enjoy Radio 239 of these bands, thus increasing the number of contains an inductance and a capacity. It is wavelengths available for simultaneous com- only a tuner that is shown; the detector and munication. phones not being included in the diagram. In the receiving set the band can be greatly Note that there are five variable quantities re- narrowed by the use of two selective circuits presented in this tuner; that means that there and this is a common arrangement. The first are five knobs or handles to adjust. Your circuit selects a band of frequencies (wave- tuner may not be like this one, it may have lengths) from all the radio waves present in the fewer variables, but it will certainly have some ether. The second circuit selects a very nar- of the features of this typical tuner. For in- row band of frequencies from those present in stance, your tuner may have only one selective the first selective circuit. This double se- circuit and it may have only one variable lection is very effective as the effect is cumu- quantity in this circuit. Again your tuner may lative. have two selective circuits with only one vari- able in each and no means of adjusting the A TYPICAL RECEIV1NC, CIRCUIT effect of the one circuit or the other. Other ATYPICAL receiving circuit is shown in combinations are possible also. Fig. 2. All the symbols used are those customarily employed. The reader should INDUCTANCE AND CAPACITY fix them firmly in mind, for they are not usually ET us conclude this article by describing labeled in diagrams. Wherever an arrow ap- how an inductance and capacity are made pears it signifies that the quantity represented and how they are made variable. We will by the symbol through which it passes or to first consider capacity. which it points is variable. Thus a coil re- Capacity may be likened to a tire. Compare presents an inductance; the arrow, A, pointing a bicycle tire and an automobile tire. Sup- to the coil means that it is variable. Two pose we take 4 cubic feet of the air in a room straight lines of equal length near and parallel and pump it into an automobile tire and also to each other represent a condenser, which is pump another 4 cubic feet into a bicycle tire. the name of the instrument that furnishes a The same amount of air has been put into each capacity. An arrow through the lines means tire but the results are different. The pressure that the capacity is variable. The long arrow in the bicycle tire is, say, loo pounds per square through the two inductances, one in either cir- inch. This means that the air inside the tire cuit, means that the strength with which the is trying to escape with a force of loo pounds. It also means that, in order to blow up the Antenna tire, a force just greater than wo pounds per square inch must be applied. But the same amount of air in the automobile tire causes a pressure of only, say, 20 pounds per square Inductance ---, inch. The air inside is trying to escape with To Detector a force of only 20 pounds, and it required a force of only a little more than 20 pounds to it in So in Condenser put the tire. electrical capacity, (Capacity) the amount of capacity determines the force (electromotive) with which a certain quantity of electricity will try to escape and also the

Ground - force needed to put that amount of electricity PRIMARY SECONDARY (First Selective (Second Selective into the capacity. Using the same amount of Circuit) Circuit) electricity, the larger capacity requires less Fig. 2 force to be charged and exerts less force trying to discharge itself. primary circuit affects the secondary circuit may In Fig. 3 -A there are shown two conducting be varied at will. The method of doing this plates placed close together but separated will be explained in a later article. by a nonconductor. The dashed lines are not a part of the circuit The plates may be of any metal and for the but simply indicate its division into two se- sake of compactness they are usually a number lective circuits, each of which, you must notice of small plates all joined together as shown in

www.americanradiohistory.com 240 Radio Broadcast

A made semi -circular in shape. A shaft passing + ++ + + ++ through the movable plates enables them to be rotated so that all or any part of the plates can be brought between the plates of the stationary set, thus varying the capacity. Such an ar- B C rangement is represented in Fig. 3 -C. An inductance is made by winding wire in a coil. The more turns of wire in the coil, the

Inductance E D

Fig. 3 To Remainder of Circuit Switch with 7 Fig. 3 -B. This is equivalent to one large plate. Contact Points The material between the plates may be any Fig. 4 nonconductor, but the most common materials used are oil, air, mica and paraffined paper. greater the inductance. A variable inductance The whole apparatus is called a condenser. is made by winding a coil and connecting leads Fig. 3 -B shows how a condenser may be made to it at every few turns. These leads or taps variable. The figure shows only a small por- are run to studs, any of which may be used. tion of one set of plates opposite to the other In this way a variable number of turns and set. This gives a small capacity. If the plates hence a variable inductance may be included are moved toward each other, larger areas of in the circuit. Fig. 4 clearly shows the ar- the plates are opposite, thus increasing the rangement. A further discussion of induc- capacity. In ordinary use each set of plates is tance will be given in a later article.

A Simply Constructed and Operated Short Range L. W. Transmitter By ZEH BOUCK

THE majority of battery phone sets It was altogether by accident that 1 hit upon are theoretically inefficient. The the following circuit which employs the difficulty generally lies in dissipating antenna as an integral part of the oscillating a proportionately large amount of system, and which radiates exceptional power energy from the antenna without in proportion to a low input. stopping oscillations. For this reason the The circuit is fundamentally that employed Colpitts, a rather critical circuit at any time, is by the British Government during the war, and almost altogether inoperative from a low one that 1 have very successfully used in a five - voltage supply except with an aerial of certain watt set with an oscillator and modulator. definite inductance and capacity. Many B While experimenting with the effect of differ- battery phones employ an inductively coupled ent positive and negative grid potentials on the system to govern the transference of energy space current of the modulating tube, I from what is often the split filament circuit. accidentally clipped eighty volts in B battery But here again if a relatively large antenna (working blindly in the rear of the panel) to current be momentarily indicated the compar- the plate of the oscillator. The current was atively feeble oscillations will be smothered. choked through the modulation transformer,

www.americanradiohistory.com A Simply Constructed and Operated Short Range C. W. Transmitter 241

and as I turned up the filaments, preparatory strips were used and bent as indicated, i.e., so to throwing in the generator, 1 was surprised to that the separation between them was about see the radiation meter jump to slightly under one eighth inch and the machine screws passing one tenth of an ampere. A little investigation through the ends would support and connect and experimenting resulted in the set I shall the grid condenser on the other side of the describe. panel or base. A piece of very fine sandpaper,

While 1 intend giving details of the electrical scraped so that it will take pencil lines without construction of the apparatus, the purely powdering, makes an excellent marking surface mechanical end, such as panel design and and is slipped under the blades. For the mounting, will be left to the taste and ingenuity original adjustment the paper should be fairly of the experimenter. The set is in no way well blackened. critical, and the builder need only approximate The reactance or choke, X, may take almost my directions with the single exception of any consistent form, from an L2oo honeycomb tapping the grid coil. coil to the bobbins of a telephone receiver. If CI is a variable condenser of a capacity no desired it may be wound with two hundred less than .00t and preferably a .0015. With turns of number thirty single cotton -covered some antennas and tubes it is possible to wire on any convenient spool. As it is merely eliminate the grid condenser C2 and the leak a high frequency choke, designed to prevent Ri, merely shorting over; but in the majority the high voltage battery from shorting the of cases better results are obtained with them condenser Ci, the core indicated in the dia- in the circuit. C2 is a standard grid con- gram is not necessary. denser, without leak, of the type sold by most Li, the main antenna inductance (Fig. 2), is dealers for thirty-five cents. I found the wound on a four and a half inch (outside diame- customary receiving grid leak of one or two ter) tube. Number twenty single or double megohms too high a resistance for transmitting cotton -covered wire may be used for all wind- purposes and I substituted a variable one ings. The forty turns are tapped every fifth of my own design that gave very satisfactory turn from the inside, and brought down to results. (Fig. 1.) binding or clip posts on the lower periphery of l t is of the pencil mark type but the wide the tube. The upper half of the winding is contacts and their proximity make very low insulated with two layers of empire cloth or resistances possible. Three -quarter inch brass tape over which the grid inductance, L2, of twenty turns is wound. The taps, which are Brass Strip brought out directly in short lugs, begin at the Paper with turn from the top and continue from Pencil Marks tenth there on with every alternate turn. In operation the upper end of the main inductance is connected to condenser C1 so that the grid winding is always over the active part of Li. The modu- IV Condenser (CO lating coil, L3 of one, two, or three turns shunted by a microphone, is wound over the grid inductance, its ends twisted or taped Pencil Marks together. The number of turns in this last inductance varies with power and transmitters, but generally a single turn will suffice, giving the best modulation without blocking the tube. Any amplifying bulb of sufficient hardness may be used as an oscillator; a state of hard- ness being evidenced by a total absence of blue or purple haze when the filament is lighted and the plate potential applied. For the most consistent work the excellent results obtained Fig. i illustrates the method used for making a variable from the Western Electric V. T. t, commonly grid -leak. By sliding the pencil- marked sandpaper under known as a " J " tube, will more than compen- the brass clips different resistance values may be obtained. The upper illustration merely shows the location of the sate for the expense and trouble of securing one. grid condenser The microphone is of the conventional type,

www.americanradiohistory.com 242 Radio Broadcast

(coincidentally the magnetic field) and the whole operation is repeated, in the case of a two- hundred meter wave, one and one half million times a second. But this rise and fall of flux also cuts Li itself, inducing therein a high-frequency current which radiates energy from the antenna in the form Insulation of electro- magnetic and static fields. For preliminary tuning the microphone is disconnected and a hot wire or thermo-couple meter (preferably the latter) reading from zero to two hundred and fifty milli- amperes is placed in series with the antenna. The aerial and plate should be connected to Taps on Ll brought down the thirty -turn tap, and sixteen turns clipped Inside of Tube in the grid circuit. If no radiation is indicated Fig. 2. The method of winding inductances is clearly with filament burning normal illustrated here the slightly above brilliancy (this is usually necessary when using generally, with the exception of nine points of amplifying tubes for transmitting) L2 should the law, the property of the Bell Telephone be reversed. The plate and grid taps and Company. Trial will often show superior condenser Ci are then varied until the greatest modulation with different transmitters of the radiation is secured. (From 5o to 200 milli- same make. amperes.) The wave length may be altered The B battery is most conveniently built up by varying either the antenna tap or condenser of from five to ten twenty -two volt blocks, and Ci without any alteration being made in the it is a commendable precaution to disconnect other adjustments, a wave meter being used them when not in use, thus preventing any at this stage of operations. With some tubes possible short through condenser Ci. the grid potential as determined by the leak The system is principally a tickler one and a Ri will be found critical. theoretical explanation of its functioning will Connections for buzzer modulation are be conducive to more intelligent operation. shown in Fig. 3, and straight C. W. (continuous As the A and B batteries are thrown in, the wave) may be employed by inserting a key in plate current rises (not instantly, as it is re- the positive or negative lead of the high -volt- tarded by the reactance in Li through which it age battery. When transmitting with one of flows) from zero to maximum, and with it a these two systems, the microphone circuit, magnetic field about Li, which, due to its proximity, cuts L2. if L2 is connected in the correct direction (determined by experimen- tation) the current induced in it through the cutting of its turns by the lines of force from Li, will place a negative potential on the grid of the tube. This negative grid voltage repels the electrons (electrons being minus charges, and like charges repel each other) permitting fewer of them to complete their journey from the filament to plate. As the plate current (that current traveling through Li and which originally set up the magnetic field) is directly dependent on the intensity of the electron stream, it will decrease, with a corresponding fall of the magnetic flux. As the lines of force withdraw, L2 is now cut in the opposite direction with a reversal of its current and the Fig. 3 is a schematic wiring diagram of the complete short charge on the grid. The electrons are again range wireless telephone transmitter employing a receiving permitted to pass, the plate current rises vacuum tube and B batteries

www.americanradiohistory.com Our Amateur Radio Reserve 243 which absorbs considerable energy, should be cost more than thirty -five dollars. The range, opened at the switch S. is, of course, dependent on many factors, not With the exception of the radiation meter the least of which is antenna and geographical and the microphone, the set is completely location. But with two hundred volts on the constructed of receiving parts and, including plate, consistent communication of twenty high- voltage batteries and tube, should not miles on C. W. is not phenomenal.

Our Amateur Radio Reserve MAJOR PAUL W. EVANS, Signal Corps Chief of Training, Office Chief Signal Officer, U. S. Army

THE Signal Corps is that part of the economy have retained in service many older United States Army whose duty it is type spark stations and also due to the fact to handle communications. It is that different sized camps, posts, or organi- a small corps, being only about two zations each require their own particular type percent. of the whole Army. Several of station which is adapted to their needs. books have already been written about the work Thus, a long established army post may be of the Signal Corps during the war, but it is the found operating the same old spark set which object of this article to tell about the work of has given good service for the last ten years, the Signal Corps in time of peace, and only while a mounted organization in the field may that part of the work which deals with Radio. be found equipped with the latest type of por- One job of the corps is to keep up the com- table continuous wave set. munications for the Army,and another is to pre- In preparation for war, the Signal Corps is pare for war. Keeping up the communications of course constantly engaged in training its of the Army is no small task. Aside from the own men, sending them to the famous training telephone service at all camps and posts, the school at Camp Alfred Vail, New Jersey, and Alaska cable between Seattle and Valdez, and fitting them in general to become better oper- the various telegraph lines, there is the radio ators, better electricians, and better radio communication between the various head- engineers. It also supervises the instruction quarters. The Army in the United States is of the Signal Corps Units of the National grouped geographically into nine corps areas. Guard and the Organized Reserve. These Each corps area has a headquarters, and each organizations go into camp every summer, one of these headquarters is under the direct where they receive special instructions in the control of the War Department in Washington. field with the latest types of army signaling Hence the Signal Corps has a large station in devices, demonstrated by picked troops from Washington which communicates with a station the Regular Army. at each corps area headquarters. These lat- At eleven selected electrical engineering ter stations are at or near Boston, New York, colleges in the United States, there is in ex- Baltimore, Atlanta, Indianapolis, Chicago, istence what is known as a Signal Corps Unit Omaha, San Antonio, and San Francisco. of the Reserve Officers' Training Corps. Here They form what is known as the Army Net. electrical engineering students are given special All stations are continuous wave stations and training in army signal work, and when they operate on wave lengths between i000 and 3000 are graduated by the university they are given meters. Each corps area headquarters has su- commissions as second lieutenants in the Signal pervision over the various stations which are Officers' Reserve Corps. Each one of these located at posts and camps within the corps Signal Corps Units is under the direct command area. This forms what is known as a Corps of a selected Signal Corps officer from the Area Net, of which there are nine. The sta- Regular Army. tions, within the corps area nets are not all The Great War served to bring home to the alike, due to the fact that the demands of people of the United States an important bit

www.americanradiohistory.com 244 Radio Broadcast of knowledge that has been known to military saying goes. A large percentage of amateur men for many years, namely, that success in a operators would become impatient at the de- great war is dependent not only on training, lays attendant to recruiting specialists and military knowledge, and wealth, but on the would rush off and enlist to carry a rifle or Man Power of the nation. ln a great war of swing a pick. In realization of this, the Chief Signal Officer, General George O. Squier, has directed that effort be made to bring the radio amateurs of the country into some sort of an organization so that their names and relative abilities may be known. The organization is known as the Amateur Radio Reserve, and the work is being carried out by the Signal Officer in each one of the corps areas. When an amateur joins this organization he does not enlist in the Army. His allegiance is taken for granted, and he is under no obligation to the United States other than that of the average citizen. He sends his name in to the Signal Officer of his corps area, signifying his interest in radio ©.Underwood &Underwood work and his desire to ally himself with the Young America is learning to make its own radio equip- Signal Corps. The Signal Officer writes to ment. School boys form a great percentage of the radio him, informing him of the schedule and wave fans. The growth of this tendency means more and better Reservists -eventually, better citizens length of the broadcasting station at corps headquarters. In many corps areas the Ama- to -day, the nation who is victorious must teur Radio Reserve have held regular meetings exert the last ounce of energy and must utilize and have formed a permanent organization the last available man. under their own elected officers. At each If the United States were to go to war to- corps headquarters there is a radio expert morrow, then what would be the work of the who is able to answer questions, give instruc- Signal Corps, and what part would Radio play in that work? In the first place, there would be needed many thousands of radio operators. The number of trained Signal Corps operators now enlisted in the Regular Army, National Guard, and the Organized Reserve would not be nearly enough. The number of operators now holding commercial licenses and jobs on commercial stations would not by any means make up the deficit. The country would have to depend upon the amateurs to fill the breach. Every available amateur would have to be considered as a potential operator for the Army of the United States or some other combatant force. Thus we see what Man Power means from the By means of this clock -work arrangement, a buzzer, key, standpoint of radio work. a dry cell or two, and a pair of telephone receivers the To try to select these men after the nation youth of to -day learns the International (Continental Code). He not only fits himself for a place in the " Re- had been called to arms would result in con- serve" or a position in radio, but actually secures much siderable confusion and loss. The thousands enjoyment which others miss of local draft boards would be so busily en- gaged in picking out experts of various trades tion, and assist the amateur operators in many for each of the various arms of the Service that ways. Sometimes these instructions are sent many men, well qualified as radio operators, out by radio and sometimes by mail. Although would become "lost in the shuffle," as the this organization is only a few months old, it

www.americanradiohistory.com Our Amateur Radio Reserve 245 has become surprisingly popular, and in one Radio Communication Pamphlet No. t, entitled corps area alone, that around New York, the "Elementary Principles of Radio Telegraphy number of member stations has reached al- and Telephony "; most a hundred. Radio Communication Pamphlet No. 2, entitled "Antenna Systems "; Many amateurs have written in to the Radio Communication Pamphlet No. 20, entitled Office of the Chief Signal Officer in Washington, "Airplane Radio Telephone Sets "; or to their congressman, requesting that they Radio Communication Pamphlet No. 28, entitled be sent pamphlets on signal work. The "Wavemeters and Decremeters "; economy of public money has forced the Signal Training Pamphlet No. i, entitled "Elementary Corps to curtail its printing bill, and no Electricity" (i5 cents). general distribution of these pamphlets can be A larger book, Radio Communication Pamphlet made. They can be obtained by purchase, No. 4o, entitled "The Principles Underlying however, from the Superintendent of Docu- Radio Communication", came off the press ments, Government Printing Office, Washing- about April t. and is sold for $1.00 by the Government Printing Office. ton, D. C., at a very small cost, usually about ten cents for each pamphlet. Among the Since there are many amateurs who may pamphlets which will be of special interest to desire to join the Amateur Radio Reserve, beginners are: there is given below a list of the Signal Officers

GOOD MATERIAL FOR OUR "RADIO RESERVE" Seventeen -year -old R. E. Leppert, Jr., of Harrison, N. Y. and his eleven - year -old sister, Vera, in a car that he designed, with a complete radio outfit designed and built with his own hands. He found the wreck of an old Ford in a ditch by the road- side and persuaded his father to buy it for the parts. Then he got new wheels and designed the body, which he had a tinsmith make. He began with radiotelephony three years ago, trying a simple crystal outfit first. Since then he has made many outfits, each an improvement over the previous one

©. Ewing Galloway

www.americanradiohistory.com 246 Radio Broadcast

By means of this portable transmitting and receiving set, Radio reservists are able to communicate with each other and with headquarters while en route of the various corps areas, with the states in- Signal Officer, 5th Corps Area, Fort Benjamin cluded in each area: Harrison, Indiana. States of Ohio, West Virginia, Indiana, and Kentucky. Signal Officer, Ist Corps Area, Army Base, Boston Signal Officer, 6th Corps Area, 1819 West Pershing 9, Massachusetts. States of Maine, New Road, Chicago, Illinois. States of Illinois, Hampshire, Vermont, Massachusetts, Rhode Michigan, and Wisconsin. Island, and Connecticut. Signal Officer, 7th Corps Area, Fort Crook, Ne- Signal Officer, 2nd Corps Area, 39 Whitehall St., braska. States of Arkansas, Missouri, Kan- New York City. States of New York, New sas, Iowa, Nebraska, Minnesota, North Dakota, Jersey, and Delaware. and South Dakota. Signal Officer, 3rd Corps Area, Fort Howard, Mary- Signal Officer, 8th Corps Area, Fort Sam Houston, land. States of Pennsylvania, Maryland, Vir- Texas. States of Texas, Oklahoma, Colorado, ginia, and the District of Columbia. New Mexico, and Arizona. Signal Officer, 4th Corps Area, Fort McPherson, Signal Officer, 9th Corps Area, Presidio of San Fran- Georgia. States of North Carolina, South cisco, California. States of Washington, Ore- Carolina, Georgia, Florida, Alabama, Tennes- gon, Idaho, Montana, Wyoming, Utah, Nevada, see, Mississippi, and Louisiana. and California.

www.americanradiohistory.com Radio Fog Signals and the Radio Compass

IN THE radio fog signal station and its The radio compass on shipboard responds to complement, the radio compass, the mar- these signals and indicates the direction from iner has found a new and powerful weapon which they come. to use against his ancient enemies -fog The navigator locates his position by the and thick weather. process of triangulation or cross bearings and On May 1, 1921, the Bureau of Lighthouses steams through the fog free from fear of shoals placed in commission in the vicinity of the port or reefs. He may get his position from the of New York the first three radio fog signal signals of a single station, either by taking re- stations installed in the United States. After peated bearings and logging the distance travel- observing their operation the lighthouse service led between bearings or by a single bearing and pr9poses, as means are available and needs dead reckoning. The method of cross bearings are developed, to establish similar stations is, naturally, more convenient and more ac- near important ports on the seaboard, on the curate. Great Lakes, and on some of the principal When the system is more widely developed, capes and lightships. when all ships are equipped with the radio This newest ally of the seafarer enables him compass as well as the customary radio ap- to guide his ship or determine its location, al- paratus, the danger of collison between ships though sea and sky may be blotted out by fog will be greatly lessened and the rescue of dis- at the time. The method is not at all complex. abled craft will be greatly facilitated. Two One or more lighthouses or light vessels are incidents will illustrate this point. equipped with apparatus for sending radio The Norwegian steamer Onataneda was in signals of simple and definite characteristics. distress in a fog off Newfoundland, and gave

The Lighthouses are Miniature Transmitting Stations. Signals from them are picked up by the square coil in the fore- ground when it is pointed in their direction. The coil is mounted above a magnetic compass which always points north. The direction taken by the square coil when signals are heard loudest indicates the bearing of the lighthouse. Where two such bearings cross is the position of the ship

J:gn,r:enyc,.?rn o,t JcSco :0eYliGDtJ c:..

t "l

www.americanradiohistory.com 248 Radio Broadcast

three dashes. The particular station is thereby as definitely located in a fog as a lighthouse in clear weather. The signals are operated con- tinuously during foggy weather. To avoid interference the signals are sent on different L r is AcWR AMBROSE CNRN.-: A time schedules, thus: Ambrose Channel sends LIGHT VESSEL ON TE RenuNSin- FIRE ISLAND LIGHT VESSEL for twenty seconds, silent twenty seconds; Id W Fire Island sends 25 seconds, silent twenty -five Q .. seconds; Sea Girt sends sixty seconds, silent SEA .IRT. LIGHT STATION sixty seconds. W A special automatic, motor-driven timing °f`l switch produces the desired signal at regular Ffr° . intervals. A wave length of l,000 metres is used and the range varies from thirty to one hundred miles, depending upon the sensitivity of the receiving apparatus. The radio compass is a simple mechanism consisting of about ten turns of insulated cop- per wire upon a rotating wooden frame about four feet square. The frame or aerial is 39-0 mounted on a spindle provided with a pointer. The aerial is usually mounted on the roof of

73 30 73 72 30- the pilot house and the spindle terminates directly above the centre of a standard ship's Chart, showing location of three radio fog s'gnals in the binnacle. vicinity of New York, with example illustrating the use of The pointer on the spindle, there- radio signal as leading mark for which a vessel may steer in fore, enables the navigator to read the direc- approaching New York; also example of the obtaining of tion of the fog signals directly upon the corn- the position of a vessel by cross bearings on three radio stations. The distinctive characteristics of the signals pass card. from these three stations are indicated by dots on the cir- The principle upon which the radio compass cles; the larger circles are at the approximate useful limits works, then, is this: When the plane of the of these signals coil on the pilot house is parallel to the direction from which the radio signal comes the signal her position by dead reckoning ninety miles reaches its maximum distinctness. As the in error. The only ship able to discover her coil is revolved the sound diminishes until it correct position and help her was the Fanad reaches a minimum, either side of the maxi- Head, equipped with a radio direction finder. mum point. Halving the difference between The steamer Wahkeena was within fourteen the two minimum points indicates the direc- miles of the steamer Alaska, lost off Cape tion more accurately than the point of maxi- Mendocino, Cal., when the latter was sending mum intensity. As the coil rotates the pointer out distress signals. But the Wahkeena had no on the spindle accompanies it around the com- means of determining the direction of the sig- pass, so that the navigator can get the magnetic nals and she steamed around in the fog for bearing of the radio signal station at a glance ten hours before she reached the scene of the when the minimum point is reached. wreck. Long before that time the Alaska had During the war considerable use was made gone down. abroad of radio compass stations located on The three stations established near the port shore. After the war the Navy Department of New York are the Ambrose Channel light established similar stations on the coast of the ship, the Fire Island light ship, and the Sea United States and a number of these stations Girt light station. A glance at the accom- are now in active operation and furnishing panying chart will show the reason for these bearings to ships asking for them. The sys- designations; that is to say, they form a natural tem is the reverse of that adopted by the triangle. Bureau of Lighthouses, since the bureau sys- Characteristic signals identify each station. tem enables the navigator, if his ship is equip- Ambrose Channel sends one dash; Fire Island ped with a radio compass, to take his own a group of two dashes; Sea Girt a group of bearings.

www.americanradiohistory.com The Audio Piloting Cable in the Ambrose Channel By DONALD WILHELM

THERE are times when seamen yearn ped,if he can but hear, can steer a ship accur- for a peep of the Ambrose lightship ately along such a cable. -times when fog hangs over them, The proof is in. Pilots, blindfolded, with the old man of the sea. There are only a bit of instruction, have publicly demon- times when, just short of New York strated just that. With only the first run Harbor, and hundreds of other harbors as well, of experimental coils, amplifiers, condensers, they have to lay to and wait for hours or days. and switching devices, all of which the Navy is perfecting at the New York Navy Yard, novi- ces, or old seafaring men new at the radio game, and other mere landlubbers, took the helm, and though blindfolded or with the 4.6/Ani _ bridge of the experimental ships closed in with canvas, followed the first major audio cable part or all the way from Fort Lafayette to hailing distance of the Ambrose Light or from fir the Light back the other way. MtGAMBLE Clearly, such a device has a future in these The manner in which a ship is guided by the "Audio days when some sailors have come to trust Piloting Cable" is shown in this illustration. The collector coils on either side of the vessel are affected equally by the more and more to radio and when they have current in the cable when the vessel is directly above it. become accustomed, as many have, to the use This results in the production of sounds of equal intensity in the telephones used by the pilot

It's depressing to passengers, to crews, to everyone on shipboard to be brought up short like that with their journey's end in view. And it's expensive -when a great liner has to wait on the weather the hourly maintenance cost per vessel ranges all the way from $500 to $4,000, the authoritative figures. But for $50,000 initial cost, and as little as fifty cents an hour operating cost, an audio piloting cable has been laid and been operated through the Ambrose Channel, and can be laid at relative cost, and be operated through almost any When a vessel leaves the direct path of the "Audio Piloting channel in the world. Cable" the collector coil nearest the cable is affected to a The Navy has demonstrated that. Figuring greater extent than the farther coil. This results in the production of unequal sounds in the pilot's telephones, and the cost of receiving equipment on each vessel he then alters his course in the direction of the stronger at $t,000, it has shown that the typical vessel signal until the strength of each is the same might pay for its equipment with less than the cost of a few hours' delay off a typical port. of the radio compass to get them within auto- And the cost of the cable itself, incidentally, is matic steering distance of the cable. Thus, no more than any one of a number of individual it has been recommended to the Navy that the buoys in and about New York or almost any Ambrose audio cable be extended past the large and typical harbor. Light a mile or so, at which point it will divide What's more, a blind man, properly equip-. and run northeasterly and southerly for five

www.americanradiohistory.com 250 Radio Broadcast

miles or so. Then New York Harbor will lose of the ship. The experiments conducted on its terrors even in the worst weather, to ships the G -1 demonstrated that its commander properly equipped with radio. lt will, we can could tell on which side of his vessel the cable assume, be as safe for navigation during bad lay. The strongest signal was always picked weather as the open sea. In other words, up by the coil nearest the cable while the liners or other vessels properly equipped -and minimum signal was received by the coil once the audio system is in vogue, legislation farther from the cable. And when the end of can be employed to make them carry equip- the cable was reached both signals eased off. ment, exactly as legislation has required all At once, then, the Navy proceeded to larger vessels with more than fifty souls on board to experiments in the Ambrose Channel. But carry distress there was trouble wireless equip- when the longer ment -can race cable laid there in toward the was tested out Lightship, pick and investiga- up their bearings tion proved that by radio corn- the cable had pass, edge in and parted, probably make contact in the laying, at with the audio precisely fifty - cable, and make two places! So the harbor. the New York lt was in Octo- Navy Yard went i ber, 1919, when at the business Commander of developing Stanford C. and testing out Hooper, in a decidedly bet- charge of the ter cable, which, radio division, when duly laid Bureau of En- and anchored, gineering of the did all that was Navy, ordered U. S. S. "A LGORMA" expected of it. i A. Crossley, an For the U. S. S. expert radio aid, to proceed to New London Algorma, a large Navy sea -going tug, fitted and undertake the Navy's first major experi- with receiving equipment, steamed at her ments with the audio cable, the promise of master's whim, almost exactly over the which has already been indicated by a long "audio." range of theoretical conclusions, along with The amplifier and switching device used on the development of the equipment necessary, her were installed in the pilot house and the plus a few actual experiments, notably those of collector coils were rigged out from the oppo- Expert Radio Aid R. H. Marriott, who made site sides of the vessel on a level with the upper some experiments in Puget Sound and sug- deck, about amidships, and about fifteen feet gested their development to Commander above the water -line. Steaming at right Hooper. angles to the cable, she could pick up the sig- At New London, first a wooden ship was used, nals ioo yards from it, and to follow it was a launch. And when it was discovered that like following a hand in the daylight. During there was no shielding effect from the launch's the return trip to the city, in fact, the pilot hull, it was found to be practicable to keep the house was blanked off with shutters so that launch within ten feet of the invisible cable, the navigating officer could not see daylight horizontally, and to steer it, of course, either yet he brought the Algorma through the Chan- way, to pick it up here or there and to use the nel without aid of any sort, with the ship at no device handily. time more than fifty yards from the cable and Then a metal ship, a submarine, was used, most of the time squarely on top of it -this, and the shielding effect of the metal hull was though the navigating officer had received only noted, on the action of the coils at either side three hours of training. And when the de-

www.americanradiohistory.com Progress of Radio in Foreign Lands 25 I stroyer, Semmes, was used later in public 1,000 yards on either side of the cable, " which," demonstrations, one of those who took charge, he adds, "further increases the possibilities of Captain Battle of the Cunard liner, Virgilia, the system for deep -water work." He re- though a total stranger to the system, by re- marks that very little difference was noted in lying on a certain constant signal strength the received signal strength when the coil from the port coil, steered the Semmes along was submerged or placed above the surface of the twenty miles of the cable always within the water, and that the use of the loudspeaker fifty yards of it, and always on the correct side was found to be impracticable as the minute of the channel. energy received from the cable at a distance The power used was supplied by commercial will not actuate the diaphragm of a loud speaker sources via Fort Lafayette. It was demon- -only when the vessel was within forty yards strated that a current flow of three amperes of the cable would the loud speaker operate. was sufficient for all needs in water up to 200 There are practicable refinements in the cable feet. Other conclusions reached by the expert used and in the receiving equipment, which the radio aid in charge, A. Crossley, pointed out Navy is developing. that a collector coil having 800 turns of wire And there is a future for the audio cable, gave twice the audibility of the 400 -turn coil; the Navy officials are agreed. Its fullest use- that the coils obviously must have identical fulness at American ports and elsewhere,waits, electrical constants; that the use of tuned however, on that larger appreciation of radio resonant receiving circuits increased the ef- devices for sea as well as air navigation which ficiency of the system 1,000 per cent., under pilots, both on the sea and in the air, expect, which condition the cable can be picked up at but do not as yet demand.

Progress of Radio in Foreign bands

vvORD has been received that Northern France on April 7th, among other the three daily newspapers in resolutions the following were passed: That Vancouver, British Colum- all commercial airplanes must be equipped bia, have each installed with radio telephones; that additional ground high -power radio sending radio and weather reporting stations should be equipment, by means of which isolated camps established at Poix and Noailles on the French and farms are being brought into touch section of the London -Paris airway; that the with the happenings of the outside world. terminal air stations of Croyden and Le Bour- Statistics recently published in the United get should now be in constant communication States show that, whereas six months ago there with each other by radio telephone as well as were less than 50,000 receiving outfits in the by ordinary radio; that the question of inter- whole of the country, and 40,000 of these within ference with radio telephony by the powerful loo miles of New York, to-day there are at Eiffel Tower radio station should now be in- least 800,000 of them, and the demand con- vestigated; that the ground radio station at tinues to be so great that the factories cannot St. Inglevert, on the French coast, which was cope with it. There are well over 200 radio- destroyed by fire recently should now be re- phone broadcasting stations now in operation placed. in the United States, and we can be certain that our neighbor to the north is becoming RADIO ON FISHING BOATS quite as enthusiastic about radio telephony as ACCORDING to an article in a recent we are. In a short time we shall be listening Bulletin of the Oceanographical Society in to Canadian broadcasting stations along of France, it appears that despite the interrup- with our own home stations. tion due to the war, considerable progress has At a conference recently held in France by evidently been made in the extension of radio the airway managers and pilots in order communication to the French fishing fleet. to draw up rules to prevent a recurrence of such In the space of ten years radio apparatus has an air collision as that which took place over been installed on some 200 vessels. In order

www.americanradiohistory.com 252 Radio Broadcast to have the messages from the fishing vessels do. For instance, it is reported that a loud - transmitted as rapidly as possible, the French speaking radio telephone receiving set has just postal authorities, who are in control of com- been completed at Lausanne, in Switzerland, munication systems in France, have them which gives the radiophone concert sent out telephoned direct from the coast radio stations by the Eiffel Tower in Paris, a good 50o miles to the owners. La Rochelle is the.only fishing distant, as well as the stations in London and port of importance which is not yet provided Berlin. The high -power radio telegraph sta- with a radio station, although some forty tions of the United States are also being picked trawlers of that port are equipped with radio. up by this receiving set and made audible At St. Pierre and Miquelon there is not as yet throughout a large room. a sufficiently powerful coast station, but an PORT up- to-date equipment with a radius of 600 EXPEDITING BUSINESS WITH RADIO miles is expected to be installed during the next Pr HE radio telegraph stations which have season. been installed in the port office of the French inland city of Rouen and on certain WHAT IS A RADIO OPERATOR? pilot boats by the Rouen Chamber of Com- FROM the London Electrician we learn of a merce have been officially put into service. dispute that has arisen between the These installations will be used exclusively for Association of Wireless and Cable Telegraphists transmitting messages relative to maritime which has a membership of between 5,000 and affairs, promotion of the port, and services for 6,000 (95 per cent. of the total of British wire - and of the port. The pilot boats equipped lesss operators), and the London District with radio will keep the port office informed Association of Engineering Employers, repre- of the arrival of vessels coming up the Seine senting the shipowners and the wireless com- River on every tide and will be instructed by the panies. The men's secretary states that, in port office in regard thereto. Merchant ves- addition to a reduction of wages, the tele- sels not equipped with radio and having urgent graphists were to be called upon to perform dispatches to transmit to local ship brokers "other duties" besides telegraphic work. They before docking can do so through the port had attempted to get a definition and a con- office, via the pilot boats. Other radio mes- ference, but only a vague reply was given which sages or dispatches not relating to navigation would leave them entirely at the mercy of or the port of Rouen and its services must be the shipowners and the captains. The ques- sent through the public radio station at Ble- tion of wages alone could no doubt be satis- ville. factorily settled. The men had been instructed THE TELEPHONE RECEIVER MORE SEN- to refuse to sign on any ships, and already 300 MAKING to 40o men were out. No doubt by the time SITIVE this is read the trouble will be over, but the NO LESSER authority than G. Seibt of Ger- fact remains that a radio operator is often many has found it possible to increase the called upon to do work quite foreign to his sound intensity of a telephone receiver by duties as a radio operator. So the question: laminating or subdividing the pole pieces above What is a radio operator? the poles of the permanent magnet and by in- troducing a magnetic shunt or by -pass for the THE INTERNATIONAL LOUD -SPEAKER magnetic flux, just below the coils, according to WH EN our loud -speaker enables us to hear Elektrotechnische Zeitschrift. The pole -piece radiophone broadcasting stations sev- divisions or laminations are made of 4 per cent. veral hundred miles distant, we believe we are silicon steel. The magnetic shunt air gap was doing very nicely, do we not? Well, in found to be most effective when set to about Europe they are doing still better, and taking it 2 millimeters. The diaphragm is made of more or less as a matter of course. While we the same steel as the pole -piece laminations have made remarkable progress in the trans- instead of the previously used American ferro- mitting end and in the introduction and work- type steel. Tests made with such receivers ing out of the radiophone broadcasting idea, it showed an increase of sound intensity of from appears that the Europeans know a little more two to two and four -tenths times that of the about radio -frequency amplification than we old model. The new receiver is already being do-at least they make more use of it than we made on a large scale.

www.americanradiohistory.com Progress of Radio in Foreign Lands 253

IN RADIO, at least, Great Britain has much the best results over this distance can be ob- to learn from us, even if we are a much tained by the use of relatively short waves younger country. Until the present the Brit- during the night and of a long wavelength ish radio amateur has been operating under the during the day time. It is recommended that most adverse and discouraging circumstances, the masts be of steel, Boo feet high, insulated and if his numbers have increased despite all not only at the base but at intermediate points. the obstacles placed in his path, it is due to the Counterpoises are recommended instead of attraction which radio holds for so many of us. ground connections. With regard to duplex The problem of licenses in Great Britain has working, it is recommended that each receiving become very acute. Just so long as the ama- station should have a separate antenna and teur was satisfied to receive and perhaps to receiving apparatus for each distant station send with extremely limited power, there was with which it may have to communicate, so no objection to his activities. But now that as to allow of simultaneous reception from all. the amateur is getting more ambitious, the As a temporary expedient, it is suggested that problem is getting serious. Another thing is the lack of public broadcasting in Great Britain. The British amateur, as well as the clockmaker, receives his time signals from Paris, Moscow, and other centers -second -hand Greenwich time, to be sure; but since his coun- try does not broadcast its own official time, he must get it from abroad. The British ether is filled with dots and dashes, but practically no radiophone broadcasting. The amateurs are now clamoring for a central broadcasting sta- tion like those operating in the Hague and in Paris, and it appears that their demands will be granted in the very near future.

GREAT BRITAIN'S WORLD -WIDE RADIO PLANS THE publication of the report of the com- mission appointed to study the problem CWide World Photos of world -wide radio communication for the The English Marconi Company has produced this broad- British Empire discloses a number of interest- cast receiver for home use. I t may be installed and ing facts bearing on present -day radio. To operated by the layman begin with, the commission suggests that the communication should be effected in steps of arc generators be used. However, these are to about 2,000 miles, which is considerably less be replaced as soon as possible with tube os- than the more ambitious jumps of a few years cillators. It is interesting to note that no ago. Then the suggestion is made that va- reference is made to high- frequency alterna- cuum tubes be employed to generate the tors. radio energy used in transmitting. The ex- cellent results obtained with a set of 48 va- FRENCH GOVERNMENT COMMUNICATION cuum tube oscillators used in the Carnarvon PERIODICAL station with an input of too kilowatts, which AMERICAN radio men will find much of was pushed up to 15o during the trial, are re- interest in a French Government period- ferred to. Messages were successfully trans- ical called Annales des Postes, Telegraphes, et mitted to the United States, India, and Aus- Telephones. This periodical is issued bi- tralia with this arrangement. It is stated that monthly by the French Ministry of Posts and valve or tube renewals will be from 5o to 6o Telegraphs and each issue usually contains per cent heavier if alternating current is from loo to 200 pages. It has been published used instead of direct current, presumably due for the last ten years. Telegraphy, telephony, to the use of thermionic rectifiers. With radio communications, and the machines used regard to wavelength, it has been found by in post offices are included in its field. In wire actual tests between Horsea and Egypt that telegraphy, automatic high -speed systems, as

www.americanradiohistory.com 254 Radio Broadcast well as older systems, are covered. Com- pick up the radiophone concerts and enjoy munication by submarine cable also receives them, high in the air. attention. In telephony, attention is given to the ordinary systems, and to automatic A UNIVERSAL RADIO SIGN LANGUAGE systems, repeating devices, traffic and operat- FROM various sources these days we hear ing problems, and the use of radio -frequency requests to the effect that all radio dia- currents. In radio communication, attention grams be made in a uniform style. Since dia- is given to the principles, construction, and grams, as a rule, require no explanatory text, operation of a wide variety of devices and it is evident that they are one and the same methods for transmission and reception. Re- for all languages. They are a universal lan- sults of researches conducted by the Ministry guage, to be sure. But due to the use of many of Posts and Telegraphs are published in this different styles of symbols to mean one and the periodical. Notices and abstracts are pub- same thing, much confusion is encountered in lished of articles pertinent to the field of the using radio diagrams. It is now proposed that Annales which appear in other French period- all diagrams be made with the same kind of icals, and in foreign periodicals. The editorial symbols, which could be standardized with staff of the Annales includes a number of little trouble. 1 n Germany the radio symbols prominent engineers, including Messrs. Den- have been practically standardized, so that all nery, Blondel, Ferrie, Milon, Abraham, and radio diagrams are more or less of the same Gutton. The annual subscription price is 27 general appearance. francs, and orders may be addressed to the THAT GERMAN INVASION Annales at 3 Rue Thénard, Paris, France. FROM time to time someone starts a rumor RADIOPHONE BROADCASTING IN PARIS going the rounds of the radio fraternity, NOT slow to appreciate what broadcasting to the effect that Germany is soon to invade has meant to the American public, the this country and flood it with wonderful radio French have gone in for the same thing. Just apparatus. We have heard such rumors, one now the broadcasting centre of France is the and all of us. We have heard of the remarkable Eiffel Tower station, operated by the French vacuum tubes that are to be sold so cheaply Army Signal Corps. The station has a radio- that they will be virtually given away. We phone range of 1500 miles and is transmitting have heard of the remarkable receiving sets, radiophone programmes on a regular pro- costing so little that it will no longer pay to gramme basis. In connection with their broad- bother making a set, and so on without end. casting activities, it appears that the French However, several months have gone by, and Army Signal Corps have been experimenting the German flood or invasion, whichever you with the radio link idea -the insertion of a wish to call it, has not materialized. And it is radio telephone section in regular telephonic our firm belief that it is not likely to mate- communication. It is believed that at an early rialize in the near future. The patent situation, date it will be possible for a subscriber in Paris with regard to many features of radio equip- to speak, via his own telephone instrument, to ment, is such that German products, many of a friend in London, using his own telephone in- which are not licensed or patented in this coun- strument, the Eiffel Tower station being used try, are not likely to find their way to our mar- for one end of the radio link. But for the time kets because of the danger of their being being the radiophone broadcasting is of prime infringements of American patents and en- importance and is pleasing the French public gendering expensive lawsuits. Especially is quite as much as our broadcasting activities this true so far as tubes are concerned. All in all, have pleased us. lt is also reported that the the American radio industry has little to fear from airplanes traveling over France and to England German competition for a long time to come.

www.americanradiohistory.com Radio Helping Us Enjoy the Summery Our Vacations may be Better Spent if Radio is Taken with Us. In this Article Various Means are Suggested for Eliminating the Difficulty of Erecting the Summertime Antenna By ARTHUR H. LYNCH

UCH rapid strides have been made and less operators, who took it upon themselves so much good has come of boys and to establish a reliable communication service young men operating amateur wireless and thus let the rest of the country know the stations, that the U. S. Government needs of those who were suffering. has gone so far as to encourage its use, That was before the Government had taken and Uncle Sam has not been satisfied merely to such active part in the promotion of amateur say, "That's a very instructive and helpful hob- wireless affairs, and there were many other simi- by you have taken up, my boy, keep at it and it lar instances of like importance which went to will do you a lot of good." No, indeed; he has prove that the hobby was valuable, not only to done much more than simply express his the boy who enjoyed it himself, but to his pleasure and give some verbal encouragement. fellows. It is interesting to observe a few He has actually instructed various government things which have gone on since that time and wireless stations to give the amateur a helping see what effect they have had upon the country hand. And who is in a better position to help at large. in that regard than our benevolent uncle? One of the most striking examples of the For some time past, there have been men in value of radio to the country is seen in the the employ of the Government, who, either for Great War. There are but few who will even selfish reasons or because they did not have attempt to claim that this country was in vision enough to see that one day wireless would be of vast importance to our country, have endeavored to introduce and put into effect laws which would materially reduce the scope of amateur radio endeavor, if not prohibit it entirely. Such narrowness is to be regretted, and we must feel grateful to those who have overcome such attempts at legislation and have brought about a condition in which the ama- teur radio worker is not only encouraged but materially aided. Perhaps it will be of value to consider some of the reasons which would make such laws harmful not only to the worker himself but to the entire nation and possibly the world. It sometimes takes a war, or kindred upheaval, to make some men realize the value of things which seem useless or even an impedi- ment to progress, and that is precisely the case with amateur radio. But a few short years ago there was a flood in this country and the railroads were put out of business in the section which was flooded. The telegraph lines were also torn down, as were the telephone lines. The people within the stricken region would have been This is an ex- service, man -carrying kite now used to carry without communication with the rest of the an antenna. Some idea of its size may be had ty com- country had paring it to the men who are holding it. A suitable kite - it not been for the amateur wire- string may be made from a stout clothes line

www.americanradiohistory.com 256 Radio Broadcast a state of preparedness, even though we should the workings of the enemy, and would not have have learned a lesson about preparedness been able to have military or naval maneu- from our Mexican Border experience when vers regulated with the precision which was the supplies for the National Guard were so found to be so necessary. But that is a long insufficient as to hold up the movement of story, and we will not discuss it more. The our troops in nearly every state of the Union for point in mind is this; when the war broke out long periods'. Even at the end of the Border there were nearly 5,000 amateur radio operators Expedition, we could hardly claim to be pre- in this country, who with little or no instruc- pared for any great emergency. But we went tion were capable of entering upon a military into the war with Germany unprepared, and the career which was of great value and impor- result of our unpreparedness is reflected in our tance to the nation. Those fellows who had having resorted to the floating of five loans, learned to send and receive rapidly, to build amounting to many billions of dollars, for the their own apparatus, to take reasonably good production of military supplies, to say nothing care of storage batteries, and especially those of food and ships. Unfortunately the ships, who had done any work with the latest forms at least a very considerable part of them, were of apparatus could step right into the breach built at too great a cost and in a manner which and prove their worth by doing in a very short would prevent them from being kept in service time what it would have taken them months for any considerable period. and to-day the to learn if they had not been allowed to carry waste resulting from our unpreparedness may be on their pet hobby in times of peace. indicated by the fleets of war time ships which There are instances without number which have been lashed together and placed in har- would go to prove these statements, but as bors from which they will never again sail. interesting as they are, we can not consider They are a total loss, except for the purpose everything at the same time, and they may they served, which, though it was important furnish the fruit for interesting discussion was also extremely costly and would not have later on. But we must say in passing that been necessary if we had been prepared. such instances as have been mentioned have And then there was the matter of training gone far to establish a place in Uncle Sam's many thousands of men to take up various heart for the amateur radio fan and have helped forms of military duty, and it is here that we to bring about some of these very encouraging may pause a moment and consider again how conditions. amateurs were able to help the Government. It is needless to mention that Uncle Sam has In any form of military training a certain endorsed the activities of the Boy Scouts in this amount of time must be spent in learning the country and that he wants to do everything in ways of the army and the navyand the air forces his power to assist them. One of the greatest in war time. There were but very few of our subjects in the Scout's course of study is military units which could be filled by ordinary signalling, and we must pause for a moment to citizens and there were but few of our citizens consider it and how much Uncle Sam thinks of capable of stepping into the stride of military it -more, perhaps, than any other branch of affairs by reason of their experience in civilian Scout work. And there are many boys through- life. In some instances, especially the pro- out the country who do not know how far our fessional branches of the service, which were good uncle is going in his effort to help them capable of carrying on their work with little to help themselves and help him, if he again or no military training, we see just the opposite, needs their help, in this matter of signalling. for instance the Medical Corps, composed as it was of doctors and druggists and nurses, who A FEW OF THE MORE IMPORTANT AIDS did not have to be put through a long course of FOR many years the U. S. Naval Radio training before they were<.iu \a position to do Station at Arlington has sent out time good work. And this is exactly the case with signals and weather reports for the guidance of radio. mariners. and this is also true of many of the Radio, in the war, was as necessary to our other naval and other government stations winning it as were our battleships, our troop throughout this country and its dominions. ships, our guns or our men, for the reason that The value of these signals is very great, as it is without its aid our army and navy would not through them that it is possible to keep ships' have been able to keep such accurate check on chronometers -which in plain American,

www.americanradiohistory.com Radio Helping Us to Enjoy the Summer 257

to progress to a point where he will be able to receive the regular press and commercial messages without difficulty. The general plan followed is to have several of the stations, gen- erally Navy stations, send out these amateur broadcasts each evening at a scheduled time. Where there are radio clubs, the value of these broadcasts is increased because the fellows can get together and compare the results of their receiving and locate their errors. Another and just as important step has been taken by the Bureau of Markets, of the De- partment of Agriculture. In order to keep the farmers advised of market conditions as well as the weather, this department has undertaken to establish a wireless telephone service, which embodies several stations which send out the above information on certain schedules in such a way as to enable them to be received over distances of approximately two hundred miles without requiring any particular skill on the part of the operator. All that is needed to secure the information which is thus sent out is a simple receiving set, such as may be found in many amateur sta- tions. The value to the boys and the farmers of this information is very great. In towns When the kite is near the ground it sometimes behaves where this information has not previously been badly and requires considerable attention, but once it has reached a height of Soo ft. or more, little difficulty is received with regularity, it will be possible for experienced with it. the boys to rig up an outfit and invite their merely means " clocks "- checked up and thereby navigate with more certainty. The weather reports are of similar importance and need no further mention. These signals,_sent as they are on regular schedules, give the stu- dent of radio an opportunity to practice ad- justing his apparatus as well as practice in receiving by the International, or as it is better known, the Continental Code. In addition to this time and weather reporting service, there are many stations throughout the country which send the news of the day to all stations which may desire to copy it, and the amateurs may well avail themselves of this opportu- nity. In addition to these signals and those of the regular commercial and amateur stations, Uncle Sam has decided that every opportunity will be given the amateur to become proficient in receiving the code and has accordingly in- structed certain of his naval and other stations to transmit certain amateur information upon well -regulated schedules Ashore, the kite -supported antenna materially increases and at a slow speed, the distance over which radio broadcasting may be re- so that the beginner will have an opportunity ceived. The kite in this illustration is 7 ft. high

www.americanradiohistory.com 258 Radio Broadcast friends in to hear a representative of the U. S. wire for the making of several aerials, and it is Government talking to them over the wire- also advisable to have several well -designed less telephone. They will not even have to kites along, to be used as described later on. know the code. The value of the information The first and most simple aerial is made in a few may not be understood by the boys themselves minutes and requires but one boy to get it in the for a time, but go and get the president of the air. If the troop is supplied with some stout chamber of commerce in your town and tell twine and a few porcelain insulators, which him that you can supply him with information may be had for a few cents, it is merely neces- about the weather and food market conditions, sary to attach one insulator to the end of received right from Washington and you won't the string and then cast it, sling-fashion, over have to do any more worrying about where the top of any tree suitable for the purpose. the money is coming from to buy new wireless When the insulator reaches the ground, apparatus. The information will be worth on the opposite side of the tree, it is merely enough to the community for it to buy your necessary to fasten a wire to it and pull in apparatus for you. if you don't think so, take enough of the twine to raise the wire to a posi- this with you and ask your local Chamber of tion about fifteen feet from the branches of the Commerce or Board of Trade what they think tree. The twine may then be fastened, and of the plan. So that is what Uncle Sam is the wire may then be used for an aerial. doing, and from now on we will consider the Another very satisfactory method for raising least expensive method for obtaining satisfac- an aerial is to fly a kite or several kites and run tory results in availing ourselves of these very a wire up on the string. By using a suitable great aids to the study of wireless telegraphy. kite, such as the one described, it is possible to substitute copper wire for the kite string and SOME OF THE DIFFICULTIES OVERCOMING fly the kite directly on wire, as is shown in the ONE of the greatest difficulties in connec- accompanying photographs. The kite string tion with a wireless station, especially (wire) should be brought to an insulator before where it is not to be a permanent installation, is being connected to the set and the insulator the arranging of the overhead wires, generally should be fastened to the ground by means of known as "aerial" or "antenna." Now, for a piece of cord or another piece of wire. use in connection with communication in sta- tions which are to be permanent, it is very MAKING THE KITE desirable to refer to some good authority on DURING the writer's boyhood, he was such matters and not go into the thing in a J fortunate enough to have made the ac- haphazard fashion.* quaintance of a man who was an expert on But, where there is no possiblity of planning kites and kite flying, and a few tips upon the the station beforehand, which is generally the selection of the proper sort of kite for use in case when it is desired to communicate between conjunction with a radio set as well as further two Troops of Boy Scouts in different parts tips concerning the making of such a kite from of some woods, it is necessary to do whatever the figures of the kite expert himself will prove is possible and more or less trust to luck. For helpful. The kite shown in the illustrations this reason we will consider two methods which was made according to the directions here given have been tried with very great success, es- and proved entirely satisfactory. . pecially with portable sets. It is best to be sure that the wood used for Of great importance is the erection of the the ticks is spruce. That both the upright aerial, so we will now consider it. The most and cross sticks are of the same length. That suitable aerial for amateur portable field sets is, the cross stick crosses the upright stick at the single wire; that is, merely one wire in the a point one -seventh the distance from top to air. There must also be a ground connection, bottom. That no nails be driven through or but that is readily taken care of by driving a into either stick. That the proper method of metal rod three or four feet into the ground or, holding the sticks in place is to wrap them better still, dropping it into water and attaching securely together, so that they may be readily a wire to it, so we will confine ourselves to the taken apart again and folded up for carrying aerial. On camping trips, it is generally ad- purposes. That the vertical or upright stick visable to be provided with plenty of copper be placed so as not to bend, but with its flat *See page 214, also RADIO BROADCAST for May and June. side at right angles to the kite cover. That

www.americanradiohistory.com Radio Helping Us Enjoy the Summer 259 several sets of sticks should be provided for each good,- strong, light, and in every way suitable cover so that it may be used for flying in dif- cover may be made from percaline, and if you ferent winds, the light sticks being used for the are not very handy with the sewing machine light wind and the heavier sticks for heavier it will be a good idea to get some female mem- winds. That the cross stick, in order to have ber of your family to make the cover for you. the kite fly with- The bridle out a tail, must should be at- be bowed, and tached to the that the amount front of the kite of bowing should with a single be measured piece of cord ex- from the bow- tending from the string to the bottom of the point where the upright stick to sticks cross and the point where should be equal the two sticks to one -sevent h cross and this the length of the string should be stick. That the just long enough bowing on each to extend to side of the centre either tip of the should be equal. With a portable radio outfit and a kite these two radio enthusiasts are kite. The kite This may be about to step into their canoe from the pier of the Bayside Yacht Club string should readily deter- be attached to mined by bowing the stick, placing it upon a the bridle at a point found by bringing the flat board and following along the inside of the bridle to the tip of the kite, for ordinary flying. stick with a pencil, then reversing the position If it is desired to make the kite fly on a greater of the stick and comparing the second position angle, that is "higher," it may be done by mov- of it with the lead pencil mark; wherever there ing the kite string further up the bridle. In is a variation it most cases this may be corrected has been found by carefully to be bad prac- sandpapering the tice because the stick until the kite does not fly desired result is steadily but obtained. This rises to a high is very impor- point and then tant. falls back. In making the Several kites, kite cover it is a constructed very good idea to along these lines, use four brass may be taken rings at the cor- apart and packed ners, connected in a small space together by pic- and weigh very ture wire, so that In the canoe the antenna is held in place by two small insulators and the little, so it will kite is somewhere above. The "ground" connection is made by merely the cover may be dropping a brass rod attached to the ground wire over the side of the be seen that they removed easily, canoe form a very satis- and it is also a factory means for good idea to use similar rings on each end of a making the aerial, where there are no trees piece of picture wire to form the desired bow- available, such as is the case in the canoe, string, which, by the way, is always at the rear of shown in one of the illustrations. the kite. It is not advisable to use paper for the From these few facts about making kites very kite covering because it will tear too readily satisfactory results may be secured without and will not withstand water for very long. A much difficulty and for all around purposes

www.americanradiohistory.com 260 Radio Broadcast where a single kite is to be used the two sticks hundred feet and then tie the end of the string should measure five feet and their thickness to the end of the wire. depends upon the condition of the wind, though There are so many varying conditions which they never should measure less than one -half by govern the amount of money a fellow may nine-sixteenths inches. Where smaller kites are spend and the best type of set he can get for his used it is advisable to fly two or more on the particular purpose for that amount, that it is same string which they will carry without quite impossibile to attempt a description of much sag. Box kites may be used, but it the most suitable radio equipment, here. If should be remembered that they do not fly on a you are in doubt, go to your radio dealer, and if very great angle and they require considerably there is none in your town it will be well for more wind than the kites described. It you to write to some responsible manufacturer, should be further remembered that kites do not who will be pleased to direct-you in the matter always behave as we would have them do, and of your purchase. Do not be afraid that he will it is not safe to fly them with wire for a kite rob you, because he is as anxious to satisfy you string where they will be at all likely to drop as you are to be satisfied; that is good business. over high tension wires and possibly cause Once you become interested in radio you trouble. It is well to be some distance from will find it very entertaining, especially if trolley or other exposed carriers of heavy you are near some of the large cities, where current. If you use a kite in a canoe, as manufacturers of radio telephone apparatus shown in the photos, be sure that there are send out wireless telephone concerts. With a couple of paddles aboard, because the kite a set, such as illustrated here it would be may pull you some disance unless you drop possible to receive music from such a station an anchor. many miles distant, and by amplifying the received music it would be possible to have INTERCOMMUNICATION the entire summer colony hear the concert. Where two stations are equipped with the By coöperating with the editor of a country same kind of sets, it is a good idea to use the newspaper it would be possible to issue daily same length of antennae or aerials, and in order the market reports previously described and to prevent confliction with the law, which re- last, to the author the use which appears of quires that amateurs work on a wavelength not the greatest value is in connection with your to exceed 200 meters, it should be remembered Scout activities. Troops may well be several that a single wire t oo feet long will have a wave- miles apart and communicate with each other length of approximately 15o meters; 200 feet by erecting radio stations which may be carried will produce a wave of 270 meters and 30o feet, by a single Scout, or strapped to the baggage 375 meters. As kites do not fly very well upon carrier of a motorcycle or bike, which may such short strings, it is a good idea to fly the be set working within less time than it takes kite on string till it reaches a height of several to tell it.

Here are two types of kites employed by the author in experimenting with the portable receiver. For all around use the left hand one is more suitable, but the right hand kite is better for an extremely high wind

www.americanradiohistory.com RADIO BROADCAST ADVERTISER púneis and Radio Parts START right. The panel is the very foundation of your set. High volume and surface resistance are essential factors. Make sure that you get them in both the panels and parts that you purchase. To make doubly certain look for the dealer displaying this sign ELORÖN Radio Panel Service Condensite Celoron Grade 10- approved by the Navy Department Bureau of Engineering -is a strong, handsome, waterproof material, high in resistivity and dielectric strength. It machines easily, en- graves without feathering and is particularly desirable for panels. It is also widely used for making many other important radio parts such as tube bases, platform mountings, variable condenser ends, tubes for coil winding, bases, dials, knobs, bushings, etc. We are prepared to make these various parts to your own specifications. Where economy is a factor we can supply panels of Vulcanized Fibre Veneer made of hard grey fibre veneered, both sides with a waterproof, phenolic condensation product. This material has a hard, smooth, jet black surface, machines and engraves readily and will give excellent service where very high voltages at radio frequencies are not involved. Shielded plates (patent applied for) are made with a concealed wire shield. This shield, when properly grounded, effectively neutralizes all howl and detuning effects caused by body capacities. Send to -day for our Radio Panel Guide Are you an enthusiast? This Guide describes our panels in detail -gives tests -and tells just how much the panel you want will cost. Are you a Radio Dealer? Let us tell you how easily and profitably Celoron Radio Panel Service enables you to supply your custom- ers with panels machined and engraved to their specifications. Write to -day for our Dealer's Proposition covering panels, dials, knobs and tubes. Diamond State Fibre Company Bridgeport (near Philadelphia) Pa. BRANCH FACTORY AND WAREHOUSE, CHICAGO Offices in principal cities In Canada: Diamond State Fibre Co. of Canada, Ltd., Toronto.

www.americanradiohistory.com Radio in Remote Regions

This department is devoted to stories of the use and benefits of radio communication in regions devoid of telephone and telegraph wires, and which are not reached by cable. Radio is proving a great boon, not only to explorers in the Arctic, the Tropics, and other distant places of the earth, but to mariners and lighthouse tenders on solitary islands, to distant army and trading posts, to hunters in the woods and ships at sea, to station agents at lonely junctions, and even to farmers dwelling in the midst of our country but separated by many days or hours from the news of the rest of mankind. RADIO BROADCAST Will welcome any and all incidents which illustrate the value of radio in remote regions, and pay for those accepted at its regular rates. -THE EDITORS. First Ship to Reach Island in a Year Gave Inhabitants News Three Minutes Old

T WAS early in the summer of 1921 that the received at sea, and presented it to them when U.S.S. Hannibal, doing survey duty in and we reached port again." around Mosquito Cays, Nicaragua, Cen- The enthusiasm of the inhabitants of George- tral America, steamed into the port of town, Grand Cayman, can be understood when Georgetown, Grand Cayman, in the Brit- it is realized that this little island, twenty miles ish West Indies south of Cuba. This was the long by five wide, has absolutely no means of first ship that had entered the harbor in a year, communication with the outside world. No and, says Radioman W. D. Ross, U. S. N. telephone, cable, or wireless connects it even "they sure were glad to see us." to near -by Cuba. There is a small local tele- This gladness changed to something akin phone there, running from the Commissioner's

U. S. S. "HANNIBAL" to rapture when they discovered that Ross could office to the post -office, a distance of one mile, and would put them into almost instantaneous but Radioman Ross was informed that his touch with the news of the outside world. radiograms to the United States interrupted Even stale news was more than welcome. local telephone conversation. The mile of "They enjoyed the press that I gave them wire must have acted as a sort of antenna. that was months old," says Ross, "and made It takes months for a letter from the United special trips to the ship to get it. During the States or England to reach this island. From Dempsey -Carpentier fight we received the re- the former it leaves Kev West for Havana, sults three minutes after the knockout, pick- Cuba, whence it proceeds to the Isle of Pines. ing up the high power station at Marion, Then it must go by steamer to Kingston, Mass., which was sending to London. They Jamaica, and from there by schooner to George- were well pleased with the news. We always town, Grand Cayman. "And schooners," kept additional copies of our daily radio press says Radioman Ross, "are scarce."

www.americanradiohistory.com RADIO BROADCAST ADVERTISER

The end of a perfect howl

squalls of a two year old are as music to the THEear beside the howling demonstration put up by a fractious radio set. And how a set can howl unless one offers the soothing influence of the proper ampli- fying transformer. Most any transformer can amplify sound, but it will also amp- lify the stray fields which produce howling and distortion. It takes the Acme Amplifying Transformer with its specially con- structed iron core and coil to put an end to the howls and yowls. Only when you add the Acme do you get the realistic tone and volume so markedly absent in the ordinary radio re- ceiving set. The Acme Radio Frequency Transformer greatly increases the range of any receiving set, either vacuum tube or crystal de- tector type. The Acme Audio Frequency Transformer produces not only volume, but reality of tone. It is indispensable to the satisfactory operation of loud speaking devices. The combina- tion of one or more stages of Acme Radio and Audio Frequency Transformers assures the maximum of range, of volume and of reality in tone. The Acme Apparatus Company, pioneer radio engineers and manufacturers have perfected not only Radio and Audio Fre- quency Transformers as well as other receiver units and sets, Type A -2 Acme but are recognized as the foremost manufacturers of Transmit- Amplifying ting Apparatus for amateur purposes. Sold only at the best Transformer radio stores. The Acme Apparatus Company, Cambridge, Price $5 (East of Rocky Mts.) Mass., U. S. A., New York Sales Office, 1270 Broadway.

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www.americanradiohistory.com The Grid QUESTIONS AND ANSWERS

The Grid is a Question and Answer Department maintained espeçially for the radio amateurs. Full answers will be given wherever possible. In answering questions, those of a like nature will be grouped to- gether and answered by one article. Every effort will be made to keep the answers simple and direct, yet fully self- explanatory. Questions should be addressed to Editor, "The Grid," Radio Broadcast, Garden City, N. Y. The letter containing the questions should have the full name and address of the writer and also his station call letter, if he has one. Names, however, will not be published. The questions and answers appearing in this issue are chosen from among many asked the editor in other capacities.

Care of Vacuum Tubes -Use of Rheostat With ordinary care tubes shoud last a long time. Speaking only of tubes used in receivers or amplifiers, My vacuum tube lasted only two weeks. Can you tell me practically the only wear that takes place is in the fila- the reason for this? ment. As is well known, the filament, when heated, emits Will a rheostat improve the action of an audion? electrons. Although new electrons take their place, the I wish to make a rheostat to use in the filament circuit of my filament undergoes slow disintegration. Thus with per- detector tube. What resistance should I use? fect mechanical care a tube will in time become useless. How can I make a rheostat for my audion? However, much can be done to prolong the life of a tube. The brighter the filament burns, the more rapidly it AVACUUM tube is a delicate piece of apparatus and disintegrates and hence the filament should be lighted up must be handled with proper care. The designers just enough to give the desired result in the signals. The have carefully planned the size, shape, and relative dimmer the filament is lighted the longer the tube will positions of its three elements (filament, grid, and plate) last. A curve showing how the current passing through a and have provided, in most cases, the strongest possible tube varies with the temperature of the filament is shown supports for these elements. However these supports are in Fig. t. The curve gives a good indication of how a necessarily frail and the tube must not be roughly handled because one or more of the elements will break away from its support and thus the tube will be made useless. BO Sometimes jarring a tube will simply loosen an element from its support and the tube will apparently be in perfect condition. Such a tube when used in a receiving set will cause it to "howl" whenever the set is subject to the slightest vibration, such as that caused by a person walk- ing in the room, or a truck or trolley passing in the street. The howling is caused by the to and fro movement of the loose element, which, in turn, causes a variation in the current passing through the tube. This variation of cur- rent produces a noise in the telephone receivers which drowns out the desired signals. As the name implies, the air has been exhausted from the 85 Volts on Plate inside of the vacuum tube. Extra special precautions have been taken to get a high vacuum -that is, to get out all the air. The tube is then sealed to its base. Hence no strain should ever be put between the tube and its base as this would be apt to loosen it and allow air to leak in. To sum up, then, a vacuum tube should be handled very carefully. It is as easy to damage as an egg is to break. 1800 1900 2000 2100 2200 Many tubes are burned out by applying too high a Filament Temperature voltage to the filament. Never use a voltage higher than that for which the tube is rated. A frequent cause of Fig. I. Curve illustrating electronic flow for various filament temperatures burning out a tube lies in faulty connections of the plate (B) battery. This battery, which always has a compara- tively high potential, has its negative terminal connected change in filament temperature changes the number of to one side of the filament. It often happens that the electrons which it emits. As it is the current passing insulation on the positive lead of the plate battery becomes through the filament which makes it hot, a method of worn out. Any movement of the receiving set is likely to controlling the current will also control the temperature cause the uninsulated part to come into contact with an of the filament. Control of the current is secured by the uninsulated part of the filament lead. This throws a high use of a rheostat. A rheostat is a resistance which may potential across the filament and it immediately burns out. be varied at will. It is well to check over the wiring when a tube burns out A rheostat in addition to giving control over the bright- to see that there is no fault or short circuit in it. ness of the filament permits it to be heated up and cooled

www.americanradiohistory.com RADIO BROADCAST ADVERTISER

Glhe Book that brings Radio into the home

What the Book Contains

Section 1. HOW RADIO ENTERS THE HOME. Con- tains just the information sought by the man who wants to buy a set. What set shall I buy? How much does it cost? What will it do? This section answers a hundred such ques- tions. All types of sets are de- scribed from the least to the most expensive. Full installing and operating instructions.

Section 2. HOW TO RE- CEIVE MOST EFFICIENTLY. Important receiving accesso- ries are described in language that the layman can under- stand. For the benefit of the amateur, technical data are given on audio and radio fre- Price quency amplification, erection of antennae, battery charging, regeneration, etc. Valuable re- 35c ceiving- circuit diagrams are published for the first time. FOR the first time a book is published at a small Section 3. VACUUM TUBE TRANSMISSION FOR price which gives the public all that it should know THE AMATEUR AND EX- about radio. It is called "Radio Enters the Home," PERIMENTER. Everything and it is written by experts. It tells how to enjoy from A toZ about transmission with new, completely revised popular radio broadcasting, and it gives complete de- transmitting -diagram, incor- scriptions of apparatus and installation instructions. porating radiotron transmis- No book so richly illustrated, so accurate, and yet so sion and kenotron rectifica- understandable has thus far been published. tion. Valuable operating in- structions are given, and the The book is divided into sections. Over 200 illus- use of mica condensers for trations, 112 pages, size 8" x 11 ". The technically un- transmission is emphasized. informed man will find in sections written especially for him the simply presented facts that he seeks; in Section 4. GENERAL other sections are data and diagrams that appeal to INFORMATION -A VERI- the trained amateur. TABLE GUIDE BOOK TO RADIO. Government laws, 35 National Electric Code Radio PRICE, AT YOUR DEALER . . . cents Rules,vacuum -tube "Don'ts," list of broadcasting stations, If your dealer has exhausted his supply, send 35 cents to radio glossary, specifications for a scientifically constructcd amateur station, complete price list of all R C A equip- ment. Ldiçj Corporation of _merica Sales Division, Suite 1807 233 Broadway, New York City

www.americanradiohistory.com 266 Radio Broadcast down gradually for it provides a means of gradually turn- can be made to touch only one turn when it is centred. ing on,and off the current. This gradual change of temper- In winding the resistance wire leave enough space beyond ature of the filament reduces to a minimum the danger of its free end so that the sliding contact can be pushed be- the filament breaking due to the expansion and contraction yond the wire thus breaking the circuit. occurring when a change of temperature takes place. Figure 3 shows how to make a panel rheostat. The Still other advantages of a rheostat lie in the facts that it studs and the sliding contact are mounted on the face of gives some control over a noisy amplifier; that it some- the panel. The resistance wire, which is soldered to the times aids in eliminating interference; and that, by its studs as shown, is in the rear of the panel. Two small use, any fluctuation in the filament battery potential may stops (Off and Maximum) prevent the contact from being he equalized. moved too far. The sliding contact must be broad enough Many detectors and amplifiers are provided with a to touch both studs as it passes from one to the other and rheostat, hut, in case yours is not, one can be easily made. yet narrow enough to touch only one stud when it is cen- Three different types are shown in figures 2, 3, and 4. tred over it. The leads should be made of wire of low The total amount of resistance should he about one ohm. resistance. Less than this may be used if the receiving set has been A very easily made rheostat is shown in Fig. 4. Re- carefully designed. Bare resistance wire should be used. sistance wire is wound spirally on a small cylinder (4 to In figure 2 the resistance wire is wrapped spirally around Sliding Contact Sliding Contact

Résistance Wire Resistance Wire Slide Bar

Fig. 4. This is a very popular form of rheostat. The shaft to which the sliding contact is connected is generally made long enough to carry the usual control knob as well as to permit either front or rear of panel mounting. A rheostat of this type permits accurate adjust- ment of the filament temperature

inch). It is then slipped off and put on the outside of a circular block of insulating material as shown in the figure. A groove must be made on the edge of the block to prevent Fig. 2. A typical cylindrical rheostat provided with a slider for altering the number of turns of resistance wire in use the wire from slipping out of place. The spiral is stretched just enough to prevent adjacent turns of the wire from a form made of some insulating material. To one end of touching. As in the other rheostats the wire used for leads the resistance wire and also to the slide bar are spliced wires must be of low resistance. of negligible resistance to form the leads. The other end of the resistance wire is fastened to the form, but not con- The Three -Slide Tuner nected electrically to any other wire. The slide bar is a conductor made of stiff material. The sliding contact Will you please inform me as to the advantage of the three should be wide enough to touch two turns of wire as it slide type of tuning coil for radio receiving set over the two passes from one to another and narrow enough so that it slide type? -H. H., Chicago, Ill. Resistance Wire THE question asked will be answered by showing first the necessity of having a flexible coupling between Sliding Contact the primary and secondary circuits in the receiving set and then by showing the advantage of the 3 -slide tuner Stud over the 2 -slide tuner in this respect. In the receiving set the antenna (primary) circuit is tuned to the frequency of the signals which it is desired to receive. The current in the antenna circuit from these signals becomes large while the current from signals of other frequencies remains small. This is due to the reson- ance effect obtained by tuning in. It is thus seen that the antenna circuit makes a selection from the radio waves that may be present at the antenna. The secondary, which is also tuned to the desired signals, is another resonant cir- cuit and further eliminates any currents that may arise in the primary from signals which it is not desired to receivé. One of the important factors that necessitates two selec- tive circuits in the receiving set lies in the fact that most of the detectors or rectifiers in use have a high resistance Off Maximium Leads and, if included in the antenna circuit, will give that cir- (Stop) (Stop) cuit a high resistance. This is fatal to good selectivity as a study of Fig. i will show. This figure shows the current Fig. 3. One method of making a rheostat for front -of-panel established in a circuit tuned to 40o meters by radio waves mounting. The studs are mounted on the panel and are connected to the resistance coils in the rear of different wavelengths. Three different curves are shown.

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www.americanradiohistory.com 268 Radio Broadcast

Curve A shows the response of a circuit of moderate re- Another fact about coupled circuits that should be known sistance; Curve B shows the response of a circuit of very is that when two circuits are coupled, each circuit has two low resistance; and Curve C shows the response of a circuit frequencies at which it will resonate. If the coupling is made loose these frequencies approach each other and may be considered to coincide. Fig. 3 shows the effect on a tuned circtiit of coupling to it another circuit tuned to the same frequency. The effect of a tight coupling is shown by curve E. Note that there are two wavelengths to which the tuned circuit will respond well; i.e. there are two humps in the curve. Evidently such a coupling ought not to be used when it is desired to tune out all but one wavelength. The effect of a very loose coupling is shown by curve F. Here the two frequencies have been brought to coincide but the current produced is very small. Curve D illus- trates the use of á correct coupling. There is practically

350 400 450 500 WAVE LENGTH

Fig. i 370 400 430 460 of high resistance. The last -named circuit is not very se- WAVE _LENGTH lective for it responds almost equally well to many wave- lengths. Such would be the response of an antenna circuit Fig. 3 having in it a detector of high resistance. The primary circuit picks up energy and transfers it to only one wavelength at which resonance occurs and the the secondary circuit. When two circuits are so arranged current is comparatively large. Coupling adjustment is that there is a transfer of energy from one to another, the an important factor in clear reception as can be seen from circuits are said to be coupled. Coupling may vary in de- the above discussion. The correct coupling for any signal gree, being "tight" if the effect of one circuit on the other is found by trial. In other words, the coupling is varied is large; being "loose" if the effect is small. In Fig. 2 until the desired result in the signal is obtained. is shown how the current in one circuit varied with a change There are various ways of coupling one circuit to another. in coupling. The circuits were tuned to each other. No- The 3 -slide tuner uses direct coupling. Part of the tice that there is a hump in the curve. This means that coil i (Fig. 4) is common to the primary circuit, A -1 -G, and there is a certain degree for which the current generated in also to the secondary circuit, C2- K -I -N. The connection is the secondary is greatest. thus a direct one. This coil is often called an auto- transformer because the coil transfers the oscillations of one circuit to another and is a part of each circuit. The degree of coupling between the two circuits depends upon the amount of inductance common to both circuits as com- pared to the amount of inductance in each of the two cir- cuits. It is seen that the amount of inductance in the antenna circuit is governed by the position of the slider, S. The positions of the two sliders, K and N, govern the amount of inductance in the secondary circuit and also the amount of inductance common to both circuits. In general, the advantage of the 3 -slide tuner over the 2- slide tuner lies in the fact that the former is more flexible than the latter. (A 2 -slide tuner would be one in which either one of the contacts, K or N, was immovably connected to its end of the coil.) This greater flexibility, gained by having the third contact movable, allows better tuning and coupler adjustments. 0 DEGREE OF COUPLING One particular advantage of the 3 -slide over the 2 -slide Fig. 2 tuner lies in the fact that for any given degree of coupling,

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www.americanradiohistory.com 270 Radio Broadcast

To detector To detector

Fig. 4 Fig. 5 there is allowed a wider range in the amount of inductance This control over the amount of inductance in the second- that may be used and hence a greater tuning range for the ary allows a wide variation in the relative values of the in- secondary circuit. A comparison of Fig. 4 and Fig. 5 will ductance and capacity in the secondary. Thus it permits make this clear. The amount of inductance in the second- their adjustment for the best efficiency of the detector. ary circuit is greatly different yet the coupling is practically It makes possible the use of a "stiff" circuit, that is, one the same. In Fig. 4 the inductance common to both having a comparatively large inductance. It often happens circuits (this is the greatest factor in determining degree of that the relative resistances, due to faulty construction, coupling) is that between K and N. I n Figure 5 it is that etc., of the inductance and capacity vary greatly for between K and S. The latter is slightly larger than the their different values. The flexibility gained by the use former in order to compensate for the increase of inductance of the 3 -slide tuner enables a greater choice in the in the secondary circuit. This slight increase is necessary values of the capacity and inductance used in tuning in in order to keep the coupling the same. Of course the in- and thus permits one to get an adjustment at which the ductances between K and N and between K and S could resistance is the minimum obtainable with that particular have been made equal if desired. circuit.

Present Radio Broadcasting Stations in the United States List of stations broadcasting market or weather reports (485 meters) and music, concerts, lectures, etc. (j6o meters).

WAVE CALL OWNER OF STATION LOCATION OF STATION LENGTHS SIGNAL

Alabama Power Co. Birmingham, Ala. . 360 WSY Aldrich Marble & Granite Co C F Colorado Springs, Colo 485 KHD Allen, Preston D Oakland, Calif. 360 KZM Altadena Radio Laboratory Altadena, Calif. . 360 KGO American Radio & Research Corporation Medford Hillside, Mass. 360 WG I Anthony, Earl C. Los Angeles, Calif. 360 KFI Arrow Radio Laboratories Anderson, Ind 360 WMA Atlanta Constitution Atlanta, Ga.. 360,485 WGM Atlanta Journal Atlanta, Ga. 360,485 WSB Atlantic -Pacific Radio Supplies Co Oakland, Calif 360 KZY Auburn Electrical Co Auburn, Me. 360 WM B Bamberger & Co. L., Newark, N. J 360 WOR Beacon Light Co Los Angeles, Calif. 360 KN R Benwood Co. St. Louts, Mo 360 WEB Bible Institute of Los Angeles Los Angeles, Calif. 360 KJS Blue Diamond Electric Co. Hood River, Ore. 360 KQP Bradley Polytechnic Institute Peoria Ill 360 W BA E Braun Corporation Los Angeles, Calif. 360 I<\S

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Stop Buzzing and Sizzling

FORMICA insulation for Radio use is perfect insulation ! It pre - vents buzzing, sizzling and noise that makes it hard to hear over your radio telephone. There are no weak places in Formica panels. They are not affected by moisture and weather conditions and do not deteriorate. They will give perfect service for years. Formica is the most widely used radio insulation. It is approved by the Navy and the Signal Corps. It is a thoroughly high quality pro- duct -the finest possible insulating material all the way through! It contains no absorbent matter that will take up water and lose its insulating strength through humidity and moisture. Formica panels have a handsome gloss or satin finish -black and natural brown. Dealers: We have now in operation an addition to our plant which doubles our previous capacity. Back orders for Formica are being shipped rapidly. We always do our utmost to serve you promptly. The Formica Insulation Company 4628 Spring Grove Avenue, Cincinnati, Ohio Sales Offices 50 Church Street, New York, N. Y. 422 First Ave., Pittsburgh, Pa. 9 South Clinton Street, Chicago, Ill. Sheldon Building, San Francisco, Cal. 414 Finance Building, Cleveland, Ohio 932 Real Estate Trust Bldg., Philadelphia, Pa. 1042 Granite Building, Rochester, N. Y. 321 Title Building, Baltimore, Md. 415 Ohio Bldg., Toledo, Ohio

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www.americanradiohistory.com 272 Radio Broadcast

PRESENT RADIO BROADCASTING STATIONS IN THE UNITED STATES -Continued

WAVE CALL OWNER OF STATION LOCATION OF STATION LENGTHS SIGNAL Buckeye Radio Service Co. Akron, Ohio. 360 WOE Bullock's Los Angeles, Calif. 360 KNN Bush, James L Tuscola, Ill. 360 WDZ Central Radio Co Kansas City, Mo. 36o WPE Church of the Covenant Washington, D. C. 36o WDM Chicago, City of Chicago, Ill. 36o WBU Cino Radio Mfg Co Cincinnati, O 360 WIZ City Dye Works & Laundry Co Los Angeles, Calif. 360 KUS Clark University Worcester, Mass. 360,485 WCN Coast Radio Company El Monte, Calif. 360 KUY Columbia Radio Co. Youngstown, O. 360 WMC Commonwealth Electric Co St. Paul, Minn. 36o WAAH Continental Electric Supply Co Washington, D. C. 360 WIL Cooper, Irving S. Los Angeles, Calif. 360 KZI Cosradio Co. Wichita, Kansas.. 360,485 WEY Cox, Warren R. Cleveland, O. 360 WHK Crosley Manufacturing Co. Cincinnati, O. 360 WLW Daily News Printing Co Canton, O 360 WWB Dallas, City of Dallas, Tex. 36o,05 WRR Dayton Co Minneapolis, Minn. 36o WBAH DeForest Radio Telephone & Telegraph Co. New York, N. Y. 360 WJX Deseret News Salt Lake City, Utah. 360 KZN Detroit News Detroit, Michigan . 360,485 WWJ Detroit Police Dept. Detroit, Michigan . 360 KOP Diamond State Fibre Co Bridgeport, Pa. 360 WBAG Doerr -Mitchell Electrical Co. Spokane, Wash. . . 36o . KFZ Doran Brothers Electrical Co. Hamilton, O. 36o WRK Doubleday-Hill Electrical Co. Pittsburgh, Pa. 360 KQV Doubleday -Hill Electrical Co. Washington, D. C. 360 WMU Duck Co., William B Toledo, Ohio 360 WHU Dunn & Co, J J. Pasadena, Calif. . . 360 KLB Eastern Radio Institute Boston, Mass 360 WAAJ Electric Equipment Co. Erie, Pa. 36o WJT Electric Lighting Supply Co Hollywood, Calif. . 360 KGC Electric Power & Appliance Co Yakima, Wash. . . 36o KQT Electric Supply Co. Clearfield, Pa 360 WPI Elliott Electric Co. Shreveport, La.. 360 WAAG Emporium, The San Francisco, Calif. 360 KSL Erie Radio Co Erie, Pa. 360 WSX Examiner Printing Co., San Francisco, Calif. 36o KUO Fair, The Chicago, Ill. 36o WGU Federal Institute of Radio Telegraphy Camden, N. J 360 WRP Federal Telephone & Telegraph Co Buffalo, N Y 360,485 WGR Fergus Electric Co. . . Zanesville, O. 36o WPL Findley Electric Co. Minneapolis, Minn. 360 WCE First Presbyterian Church Seattle, Wash 360 KTW Ford Motor Co. Dearborn, Mich. 360 WWI Fort Worth Record Fort Worth, Tex. 360 WPA Foster -Bradbury Radio Store Yakima, Wash. 360 KFV General Electric Co. Schenectady, N. Y. 360 WGY Gilbert Co., A. C New Haven, Conn. 360 WCJ Gimbel Brothers Milwaukee, Wisc. 360 WAAK Gimbel Brothers Philadelphia, Pa. 360 WIP Gould, C. O. Stockton, Calif. . . 360 KJQ Groves -Thornton Hardware Co Huntington, W. Va. 360 WAAR Hale & Co San Jose, Calif. 360 KSC Hallock & Watson Radio Service Portland, Ore. 360 KGG Hamilton Manufacturing Co. Indianapolis, Ind. . 360 WLK Hatfield Electric Co. Indianapolis, Ind. . 360 WOH Hawley, Willard P Jr Portland, Ore. 360 KYG Herald Publishing Co 'Modesto, Calif. 360 KXD Herrold, Charles D. San Jose, Calif. 360 KQW Hobrecht, J. C. Sacramento, Calif. 360 KVQ Hollister -Miller Motor Co. Emporia, Kansas 36o WAAZ Holzwasser Inc. San Diego, Calif.. . 360 KON Howe, Richard H Granville, Ohio. 360 WJD Howlett, Thomas. F. J. Philidelphia, Pa. 36 WGL Hunter, L. M. & G. L. Carrington Little Rock, Ark. 36o WSV Hurlburt -Still Electrical Co Houston, Tex 360,485 WEV Interstate Electric Co...... New Orleans, La. 360 WGV Iowa Radio Corporation Des Moines, Iowa. 360 WHX

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www.americanradiohistory.com 274 Radio Broadcast

PRESENT RADIO BROADCASTING STATIONS IN THE UNITED STATES- Continued

WAVE CALL OWNER OF STATION LOCATION OF STATION LENGTHS SIGNAL

J. &. M. Electric Co . Utica, N. Y. 36o WSL K. & L. Electric Co. McKeesport, Pa. . . 360 WIK Kansas State Agricultural College Manhattan, Kansas 485 WTG Karlowa Radio Co. Rock Island, Ill.. 360,485 WOC Kennedy Co., Colin B. Los Altos, Calif. 360 KLP Kierulff & Co., C. R Los Angeles, Calif. . 360 KHJ Kluge, Arno A Los Angeles, Calif. 360 KQL Kraft, Vincent I. Seattle, Wash 360,485 KJR Lindsay, Weatherill & Co. Reedley, Calif 360 KMC Los Angeles Examiner Los Angeles, Calif. . . 360 KWH Love Electric Co. Tacoma, Wash. . . 360 KMO Loyola University New Orleans, La. . 360 WWL Marshall -Gerkin Co. Toledo, Ohio. 360 WBA Maxwell Electric Co. Berkeley, Calif. . . 360 KRE May (Inc ) D W Newark, N. J. 36o WBS McBridge, George M Bay City, Mich.. . . . 360 WTP McCarthy Bros. & Ford Buffalo, N Y 360 WWT Metropolitan Utilities District Omaha, Nebraska 360,485 WOU Meyberg Co., Leo J. Los Angeles, Calif. . 360,445 KYJ Meyberg Co., Leo J. San Francisco, Calif. 360,485 KDN Middleton, Fred M. Morestown, N. J. . 360 WBAFG Midland Refining Co El Dorado, Kansas . 485 WAH Midland Refining Co Tulsa, Okla. 485 WEH Millikin University James, Decatur, Ill. 360 WBAO Minnesota Tribune Co. & Anderson Beamish Co. . Minneapolis, Minn.. . 360 WAAL Missouri State Marketing Bureau. Jefferson City, Mo. . 485 WOS Modesto Evening News Modesto, Calif. . 360 KOQ Montgomery Light & Power Co Montgomery, Ala. . 360,485 WGH Mullins, Electric Co., Wm. A. Tacoma, Wash. . . 360 KGB Mulrony, Marion A. Honolulu, Hawaii . 360 KGU Nelson Co. I. R. Newark, N. J 360 WAAM New England Motor Sales Co.. . . Greenwich, Conn. . 360 WAAQ New Mexico College of Agriculture and Mechanical Arts. . State College, N. Mex. 360.485 KOB Newspaper Printing Co. Pittsburgh, Pa. . . . 360 WPB Noggle Electric Works Monterey, Calif. . . . 360 KLN North Coast Products Co. Aberdeen, Wash, . . . 360 KNT Northern Radio & Electric Co. Seattle, Wash 360 KFC Northwestern Radio Manufacturing Co. Portland, Ore 360 KGN Nushawg Poultry Farm New Lebanon, Ohio. . . 360 WPG Oklahoma Radio Shop Oklahoma City, Okla. . 360,485 W KY Oregonian Publishing Co Portland, Ore 360 KGW Palladium Printing Co. Richmond, Ind. . 360,485 WOZ Paris Radio Electric Co... Paris, Tex 360 WTK Pennsylvania State Police Harrisburg, Pa. . . . 360 WBAX Pine Bluff Co. Pine Bluff, Ark. . . . 360 WOK Pomona Fixture & Wiring Co. Pomona, Calif 360 KGF Portable Wireless Telephone Co Stockton, Calif. . . 360 KWG Post Dispatch St. Louis, Mo 360 KSD Precision Equipment Co Cincinnati, Ohio.. . 360,485 WMH Precision Shop, The Gridley, Calif 360 KFU Prest & Dean Radio Research Laboratory Long Beach, Calif. . 360 KSS Public Market & Department Stores Co. Seattle, Wash 360 KZC Purdue University West Lafayette, Ind. 360 WBAA Radio Construction & Electric Co. Washington, D. C. . 360 WDW Radio Service Co. Charleston, W. Va. 360 WAAO Radio Shop, The Sunnyvale, Calif. 360 KJJ Radio Telephone Shop, The San Francisco, Calif. . 360 KYY Radio Supply Co Los Angeles, Calif. . . 360 KNV Register & Tribune, The Des Moines, Iowa. 360 WGF Rennysen, I. B. New Orleans, La 360 WBAM Reynolds Radio Co...... Denver, Colorado 360,485 KLZ Ridgewood Times Printing & Publishing Co. . . . . Ridgewood, N Y 360 WHN Riechman- Crosby Co Memphis, Tenn. . 360,485 W KN Rike - Kumler Co. Dayton Ohio 360,485 WFO Rochester Times Union Rochester, N. Y. . 360,485 WHQ Roswell Public Service Co. Roswell, N. Mex. 360 KNJ St. Joseph's College Philadelphia, Pa.. . . 360 WPJ St. Louis Chamber of Commerce St. Louis, Mo 360 WAAE St. Louis University, St. Louis, Mo 485 WEW St. Martins College (Rev. S. Ruth) Lacey, Wash. 360 KGY San Joaquin Light & Power Corporation. Fresno, Calif. 3(ío KMJ

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` ` jjlll,,,, ! N-, . ,, =.; L , . `ti .--s, ` \ '. For uniform filament current To meet the requirements of radio service, the Exide Radio Battery was specially designed for the maintenance of a uniform voltage during a long period of discharge. You will take great satisfaction in a battery whose voltage does not drop quickly to a point where frequent adjustment of the apparatus is necessary. Plates, separators, jars, terminals, every part and each detail of this battery is the result of the ex- perience of the makers of Exide in building batteries for every purpose since the beginning of the storage battery industry. Exide Batteries are used by governments and great industries all over the world. They propel mine locomotives and submerged submarines; they operate the fire alarm system and send your voice over the Bell telephone. Most of the government and Radio Corporation wireless plants are equipped with Exide Batteries. You can get Exide Radio Batteries at every place where radio equipment is sold and also at all Exide Service Stations. THE ELECTRIC STORAGE BATTERY CO. Philadelphia Oldest and largest manufacturers in the world of storage batteries for every purpose

www.americanradiohistory.com 276 Radio Broadcast

PRESENT RADIO BROADCASTING STATIONS IN THE UNITED STATES -Continued

WAVE CALL OWNER OF STATION LOCATION OF STATION LENGTHS SIGNAL Seeley, Stuart, W East Lansing, Mich. 485 WHW Service Radio Equipment Co. Toledo, Ohio. . 360 WJK Ship Owners Radio Service New York N Y 360 WDT Snip Owners Radio Service Norfolk, Va. 360 WSN Shotton Radio Manufacturing Co. klbany, N Y 366 WNJ Southern Electrical Co. San Diego, Calif.. . 360 KDPT Southern Radio Corporation Charlotte, N. C. . . 360 WBT Spokane Chronicle Spokane, Wash, . . 360 KOE Standard Radio Co. Los Angeles, Calif. . 360 KJC Sterling Electric Co. & Journal Printing Co. Minneapolis, Minn. 360 WBAD Stix -Baer -Fuller St. Louis, Mo 360 WCK Strawbridge & Clothier Philadelphia, Pa.. . 360 WFI Stubbs Electric Co. Portland, Ore 360 KQY T. &. H. Radio Co. Anthony, Kansas 36o WBL Tarrytown Radio Research Laboratory Tarrytown, N Y 360 WRW Taylor, Otto W. Wichita, Kansas.. . 360 WARP Thearle Music Co San Diego, Calif.. . 360 KYF Tulane University of Louisiana New Orleans, La. . 360 WAAC Union College Schenectady, N. Y. . 36o WRL Union Stock Yards & Transit Co. Chicago, Illinois . 360.485 WAAF United Equipment Co. Memphis, Tenn. . . 360 WPO University of Illinois Urbana, Illinois . . 360 WRM University of Minnesota Minneapolis, Minn. 360,485 WLB University of Missouri Columbia, Mo. 360 WAAN University of Texas Austin, Texas . 360,485 WCM University of Wisconsin Madison, Wisconsin 360,485 WHA Wanamaker, John Philadelphia, Pa.. . 360 WOO Wanamaker, John New York, N Y 360 WWZ Warner Brothers Oakland, Calif. . . 360 KLS Wasmer, Louis Seattle, Wash 360 KHQ West Virginia University Morgantown, W Va 360 WHD Western Radio Co. Kansas City, Mo. . 360,485 WOO Western Radio Electric Co. Los Angeles, Calif. . 360 KOG Westinghouse Electric & Manufacturing Co. . East Pittsburgh, Pa.. 360 KDKA Westinghouse Electric & Manufacturing Co. . Chicago, Ill. 360,485 KYW Westinghouse Electric & Manufacturing Co. . Newark, N. J 360 WJZ Westinghouse Electric & Manufacturing Co. . Springfield, Mass. . 360 WBZ White & Boyer Co. Washington, D C 360 WJH Williams, Thomas J. Washington, D C 360 WPM Wireless Phone Corporation Paterson, N. J 360 WBAN Wireless Telephone Co. of Hudson County, N. J. Jersey City N J 360 WNO Yeiser, John O Jr Omaha, Nebraska . 360 WDV Young Men's Christian Association Denver, Colo. 485 KOA Zamoiski Co.. Joseph M Baltimore. Md. 36o WKC

Radio Broadcasting has been perfected to a degree where the ap- pearance of the Critic has become necessary. The public demands the highest class of en- tertainment, and large radio broadcasting stations check up their own work in this manner

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