Bell Telephone Quarterly, April, 1934, pages 75-97:

Network  Broadcasting

1922 Republican Convention network
1925 Second National Defense Day network
1927 First Tunney-Dempsey fight network
1927 Chain network
1928 Election night network
EARLY in the development of radio telephony it became apparent that it was ideally suited for what might be called wholesale communication--that is, for the broadcasting of entertainment and of educational or informative matter. This type of communication was essentially new. Signal fires, columns of smoke, the beating of a drum or the blowing of a trumpet had been used, it is true, for the general dissemination of information, but with such exceptions as these practically all previous forms of communication--whether by sign, signal, written message, telegraph, wire telephony or otherwise were intended for use in what may be called person-to-person or point-to-point transmission of intelligence. The first extensive experimentation in radio telephony was along the lines of its development for this form of communication--that is, for the transmission of the spoken word across oceans, to ships at sea or to other inaccessible points to which it was not then practicable to provide wires, cables or other physical conductors. As early as 1915, engineers of the Bell System conducted a series of experiments in which radio telephone transmission was achieved from the United States to such distant points as Paris, France, and Honolulu, Hawaii. Out of these early experiments have grown the far-reaching systems of radio telephone channels which now provide regular telephone service between the United States and half a hundred other countries on six continents and the principal island groups.
    Poulsen, Marconi, Fessenden, DeForest and others had early experimented with the transmission of music by radio telephone, with results that, in those pioneer days, were considered satisfactory. The first of the broadcasting stations which have survived until the present was KDKA, Pittsburgh. This station presented its first regular program on Election Night, November 2, 1920, the broadcast consisting of a running account of returns announcing the election of President Harding.
    Other broadcasting stations were opened at various points throughout the country. Originally, their programs consisted entirely of music, talks or other forms of entertainment originating within the studio of the broadcasting station itself. Somewhat later, some of the stations began to go to more remote points to "pick-up" programs of one form or another--music by hotel orchestras, church services, football games and other sporting events, political conventions and similar public gatherings. For this purpose, wire circuits were employed from the point of origin to the radio broadcasting stations.
    It was at this point that the telephone companies first entered the field of radio broadcasting. It would have been technically possible, of course, for each broadcasting station to install its own circuits from the point where the program originated to its studio, but this would have proved unduly expensive. In many cases, however, local telephone companies already had circuits running to the points of origin, as well as to the broadcasting studios, and the necessary circuits could frequently be provided by connecting two such circuits to form a continuous link between point of origin and radio station.
    Meanwhile, it had become apparent to the executives and engineers of the American Telephone and Telegraph Company, the headquarters company of the Bell System, that the development of radio telephony, and its quite obvious usefulness for this new form of communication, imposed upon the Bell System what was nothing less than an obligation to apply to its development the accumulated experience of years of research in the field of wire telephony.
    Much that had been learned during the development of a telephone system which by this time was nation-wide in its reach would, obviously, be invaluable in the development of radio telephony, both for point-to-point transmission and for broadcasting. The Bell Systems intensive study of the characteristics of sound, and particularly of speech sounds its research directed toward ascertaining the best methods of transforming these sounds into electrical impulses and transmitting them clearly over greater and greater distances its development of apparatus for amplifying telephone currents which had lost strength, due to attenuation, while traveling over these long stretches of wire--this and a vast amount of other information had been accumulated during more than half a century of telephone development. In a peculiar and very true sense, the Bell System held this information as trustee, and was under the definite obligation of utilizing it in any field of communication in which it might prove valuable in advancing the interests of the public.
    It soon became obvious that radio broadcasting was such a field--that there was a public need for this type of service. But just how general this need was, or how pronounced or how permanent the demand for broadcasting service was to become, were questions as yet unanswered. If such a demand were to become widespread and if it were to give evidence of permanency, it was apparent that the Bell System would have not only an opportunity but an obligation to contribute what it could, in view of its long experience in the field of wire telephony, to the development of radio broadcasting. It was almost equally apparent that this contribution would lie not only in the direction of assisting in developing transmitting apparatus for the broadcasting stations and designing improved receiving apparatus, but in the equally important field of linking broadcasting stations with the points of origin of their programs and of connecting stations for simultaneous broadcasting--that is, for what later came to be known as chain or network radio service.
    But the participation of the Bell System in any of these phases of the development of radio broadcasting could be justified only by a study of the public need, as indicated by public demand, for this type of service. If this demand was to be limited in extent, or to give evidence of a public interest which would have no permanency the expenditure of effort or capital on radio broadcasting would be obviously unjustified.
    In order to continue its research in radio telephone transmission, begun in 1915, the Bell System established, late in 1921, an experimental station known as 2XB. This was located at 463 West Street, New York City, at what is now the Bell Telephone Laboratories. About the middle of 1922, Station WBAY was put into operation at 24 Walker Street, New York City, and shortly thereafter Station 2XB was given the call letters WEAF. Stations WBAY and WEAF were operated for some time, until WBAY was abandoned and WEAF became the Bell System's only broadcasting station in New York. These Bell System stations were used, not alone for the pur pose of continuing experimentation in radio telephone transmission, but for the not less important purpose of ascertaining the public reaction to radio broadcast programs of high quality. These stations became, in effect, laboratories in which were studied certain technical problems and the problem of public demand for radio broadcasting programs. After this experimental work had been completed, Station WEAF was sold to the Radio Corporation of America, ownership subsequently being transferred to the National Broadcasting Company.
    Meanwhile, Bell System engineers and scientists had done a considerable amount of work which was to have a direct hearing upon the development of radio broadcasting, and particularly on the use of telephone circuits for program transmission. Before the actual development of radio broadcasting, much broadcasting had been done with the so-called public address systems, in which loudspeakers were used to cover large audiences. In many instances, the speech and music thus broadcast was transmitted over long distance telephone circuits, a notable example being the transmission of the ceremonies attending the burial of the Unknown Soldier on Armistice Day, 1921, when large audiences in New York and San Francisco, as well as that at Arlington, Va., were enabled to listen to the impressive program.
    The apparatus and methods developed for use in connection with the public address systems were applied to the new field of radio broadcasting and proved to be invaluable contributions, since it also demanded high quality reproduction of speech and music.
    An early instance of the combination of the public address system, long distance telephone lines and radio broadcasting was afforded by the reporting of a football game played in Chicago in the fall of 1922. By means of high quality transmitters and amplifiers located at the football field, announcements of the plays and the applause of the spectators were delivered to a cable circuit extending to the toll office of the telephone company in Chicago. This circuit was connected there to a toll line to New York, where it delivered the telephonic currents to a radio broadcasting transmitter. In Park Row, New York, a truck was provided with a radio receiving set which was arranged to operate a public address system. In this experiment the factors involved were essentially those which characterize modern chain or network broadcasting: a source of the program; suitable apparatus for picking it up; a telephone circuit connecting this source with the radio broadcasting station; the transmitter at the latter station; and finally, the listener's receiving set.
    Early in the following year, station WEAF was to participate in experiments which more closely suggested the linking of two or more broadcasting stations for the transmission of the same program.
1931 network lines

    The first of these experiments took place in January, 1923, when a special telephone talking circuit joined Station WEAF with Station WNAC, Boston. As radio receiving sets of that day were, for the most part, home-made devices with ear phones, and listeners were not critical of the quality of reception, the radio public as a whole was well satisfied with the success of the experiment.
    Not so the Bell System engineers who had conducted it. They knew that transmission over the wires linking the two radio stations could be bettered--and that it would have to be bettered if the future of network broadcasting was to be assured. They knew that there is a vast difference between the transmission of speech, as in the case of regular telephone service, and the transmission of music over the same wires. They knew that, for the latter purpose, specially designed circuits would have to be used. They designed such circuits and, in an experimental test in which Station WEAF was linked with Station WMAF, South Dartmouth, Mass., in the summer of 1923, they put such a specially designed circuit into operation. The special apparatus required for the test was removed after the completion of the experiment, but with this "hook-up" the history of modern chain or network broadcasting began.
    For it has been--in America, at least--the linking of broadcasting stations by a far-reaching web of telephone wires that has made radio broadcasting what it is today. Not otherwise could the hundreds of broadcasting stations which serve the nation--many of them in small cities, remote from the larger centers of population--have tapped the supply of artistic talent of which they are now giving their listeners the benefit. In no other way could football games and other sporting events, the proceedings of political conventions and other public gatherings, or the voice of a President, speaking from his study in the White House, be brought to the millions of American radio sets. Technical and economic limitations alike would have prevented the evolution of radio broadcasting into anything like the high degree of development it has reached in the United States, were it not for thousands of miles of telephone wire. Stretching from coast to coast and from Canada to Mexico, these telephone circuits have been utilized in binding radio stations together into groups and, as occasion demands, uniting these groups into a single network that is nation-wide in its extent.
    At important centers throughout the country, as at New York, Chicago, and San Francisco, so-called "control points" have been established and constitute the nerve centers of the 88,000 miles of wire regularly used by the eleven basic networks. Scores of other telephone buildings house the complex apparatus required for this form of service. These thousands of miles of wire are carefully watched over by specially trained employees totalling between 400 and 500 men.
1934 NBC red/orange network lines
1934 NBC blue network lines

    The part which the telephone plays in making possible the far-reaching radio broadcasting networks which serve America's millions of listeners has been summarized by an officer of one of the large broadcasting companies as follows ("Broadcasting: a New Industry," Harvard Alumni Bulletin, December 18, 1930.):
    It is to the telephone, not to radio, that we owe the development of the equipment whereby speech and music are made available for broadcasting.
    More than this, it is the telephone wire, not radio, which carries programs the length and breadth of the country. John Smith, in San Francisco, listens of a Sunday afternoon to the New York Philharmonic Orchestra playing in Carnegie Hall. For 3200 miles the telephone wire carries the program so faithfully that scarcely an overtone is lost; for perhaps fifteen miles it travels by radio to enter John Smith's house. And then he wonders at the marvels of radio!
    But what about programs from overseas? Here, indeed, wireless telephony steps in, but not broadcasting in the ordinary sense. The program from London is telephoned across the Atlantic by radio, but on frequencies entirely outside of the broadcast band.
    Broadcasting, then, is the child of the telephone; in America it is certainly the child of the American Telephone and Telegraph Company. The whole structure of commercial chain broadcasting as we know it today has grown out of the pioneer work done prior to 1926. Telephony has largely created the mechanism of broadcasting.
    It is quite possible that the hypothetical John Smith, to whom this writer refers, may be aware that the program to which he is listening in San Francisco has not been carried across the continent by radio. But it is also quite possible that his information on the point does not extend far beyond the vague notion that in some way that he does not understand, "it is done by telephone wires." And to John Smith, and millions like him, a telephone wire is a telephone wire, and that is the end of the matter.
1934 CBS purple network lines

    But it is not the end of the matter for the engineers of the American Telephone and Telegraph Company. They have learned from long experience that the technical problems involved in the provision of circuits for the broadcasting networks are quite different from those confronted in the provision of commercial telephone service, with which the Bell System organization has long been thoroughly familiar and for which its plant and equipment have been designed.
    From the days when Alexander Graham Bell conducted the first of the experiments which led to his invention of the telephone, he and his successors of the organization which bears his name have been students of sound and of its electrical transmission. When confronted with the problem of providing circuits for network radio broadcasting, they knew, from more than half a century of experience that this problem involved factors not encountered in the provision of regular, commercial telephone service.
    Telephone wires had, it is true, been used as early as 1877, the year following the invention of the telephone, for the transmission of music. In order to arouse public interest in the telephone, Bell gave demonstrations or lectures in various cities of the East, and one of the features of these was the transmission of songs, cornet solos, cabinet organ and similar musical selections from some outside point to the auditorium in which the lecture was held. In the light of present knowledge of the telephone art, however, it is perhaps safe to assume that these demonstrations though they amazed the audiences which heard them, were reminiscent of Dr. Samuel Johnson's comment on the performance of a dog which he had seen dancing on its hind legs. The good doctor remarked, it will be remembered, that the spectacle was extraordinary--"not because the dog danced particularly well, but because it danced at all"
1934 Don Lee network lines
1934 Father Coughlin (yellow) network lines

    Imaginative writers--and artists, for that matter--of the early days of the telephone, delighted in predicting the time when entire audiences, as well as individual telephone subscribers, would be entertained by opera and orchestra programs transmitted over the wires. The truth is that music carried by wire, in the pioneer days of telephony, was hardly more than sufficiently faithful in its reproduction to be recognizable as music. As an entertainment feature, its attraction lay in novelty rather than in esthetic beauty.
    Since these early days, telephone instruments and circuits have been much improved. The telephone today is quite adequate for transmitting speech which can be clearly and easily understood. Even today, however, regular telephone circuits are not adequate for transmitting musical selections or other entertainment programs. There are sound technical reasons for this. For every-day telephony, the prime requirement is ability to transmit messages easily and accurately and at reasonable cost. The transmission of music and other sounds for entertainment purposes, however, involves much more severe technical requirements than the satisfactory transmission of speech for message telephone service, in order to maintain, for example, the aesthetic values involved in the reproduction of high grade music. In order to meet the qualities demanded for program transmission, it has been necessary for Bell System engineers to develop and provide special circuits quite different in their characteristics from ordinary telephone circuits. Their inherently higher cost is justifiable because of the fact that, in broadcasting, a single circuit is shared by many listeners.
    Take the matter of frequency range, for example. For every-day telephony, circuits which will transmit a frequency range of somewhat more than three octaves, starting with middle C, give a high degree of intelligibility so that ideas can be easily and accurately interchanged. Circuits for entertainment purposes, however, require that a range of frequencies more than twice as wide as this be transmitted. The higher frequencies transmitted over these circuits add to the "brilliancy" of music, since more of the high-pitched notes and important overtones are transmitted. The lower frequencies give body to the reproduction. Transmitting these higher and lower frequencies, in other words, reproduces the programs much more naturally, so that nice distinctions between sounds of various musical instruments are preserved.
    Circuits used for radio program transmission must also be so designed as to take care of a considerable variation in volume or loudness. In an ordinary telephone conversation, the range of variation in volume is relatively small. When, however, a musical selection, as, for example, a concert by a symphony orchestra, is to be transmitted, the circuit must be arranged so that the weaker passages will reach the radio listener dearly and without "cross-talk" or other undesirable noise. The circuit must also be specially arranged so that when the higher volumes are transmitted, the apparatus in the circuit will not overload and thus distort the musical tones. For these higher volumes it is also necessary to take special care to avoid the possibility of "crosstalk" from the program circuit into paralleling circuits which may be carrying other programs or regular telephone messages.
    Provision must also be made for still another factor which, although also encountered in the transmission of speech, is of particular importance in the transmission of music, by reason of the wide range of frequencies transmitted in the latter case. This is technically known as delay distortion. Although the electrical currents on a telephone line travel very rapidly--from 10,000 to about 130,000 miles per second, depending on the type of circuit--there is, on a long circuit, a measurable period of time--though often only a small fraction of a second--during which the electrical impulses are traveling from the transmitting end to the receiving end of the circuit. The different tones or frequencies may travel at varying speeds and arrive at the receiving end of a long circuit at different times, thus overlapping each other and causing a blurring or distortion. Special means of avoiding or correcting this distortion must be employed when long circuits are to be used for high quality program transmission.
    The provision of the high grade program transmission circuits now in service has been a gradual development. In the early days of network broadcasting, open-wire circuits were largely used, as they could more readily be made suitable than the cable circuits then available. Later, it became the practice of the Bell System, when installing cable required for its regular long distance telephone business, to include a number of 16 gauge pairs specially located in the cables which were reserved for use in providing radio network facilities.
    In addition to providing these special conductors, it is necessary to provide special forms of amplifying equipment or repeaters, capable of taking care of the wide range of frequencies to be transmitted. Various other forms of supplemental apparatus, including special loading coils, are also required.
1933 People's Pulpit network lines
1934 Roosevelt's Birthday network lines

    Whenever a circuit is removed from regular service and transformed into a program circuit, the change involves the loss, not only of the two physical wires which make up the circuit, but of other circuits which might otherwise be operated simultaneously with the regular telephone circuit on this same pair of wires. Thus, on open wires, a change from program service means giving up the use of the same conductors for telegraph messages which would ordinarily be transmitted simultaneously with the telephone messages and often the surrender of two or three message telephone circuits in
    order to obtain one program circuit. Where cable construction is used, special pairs devoted wholly to program are generally provided, but where, for shorter distances, pairs normally intended for message service are employed, a similar sacrifice is necessary.
    It should be borne in mind that, as the efficiency of radio broadcasting equipment and radio receiving sets has been improved, there has been a growing demand for better quality of transmission over the program circuits provided by the Bell System to the broadcasting companies. Circuits which might have been acceptable a few years ago would now prove quite inadequate to meet the requirements of the broadcasting companies today, or those of their millions of radio listeners.
    The provision of physical circuits and the supplementary apparatus required to make them adequate to the requirements of radio network transmission has necessitated the investment of large amounts of money on the part of the Bell System. To this must be added still other investment in apparatus required to switch from one station to another as the "layouts" for the various programs change from period to period throughout the day. To this must be added the cost of various forms of control and monitoring apparatus and of circuits set aside for telegraph or teletypewriter communication required in the operation of the networks.
    But the provision of this service requires more than the investment of money in machinery--it necessitates the employment of man-power on a nationwide front. At various points along the thousands of miles of wire which constitute the broadcasting network, specially trained telephone employees are stationed, charged with the important responsibility of watching over the circuits, seeing that the quality of transmission is at all times up to the required standard, making the innumerable switches that are required in the routine of changing from program to program--and standing by, ready to change, at a moment's notice from a regular program circuit to a "spare" or alternative circuit if trouble develops in an emergency.
    As has been said, the past development of the program circuit service furnished by the Bell System to the broadcasting companies has been a gradual development, an evolution. As radio transmitting and receiving apparatus has been improved, the circuits linking broadcasting stations have had to be improved correspondingly. The Bell System has endeavored in the case of this service--as it always has in the case of its regular message service--to keep in advance of the requirements of the public it serves. To maintain this advance, it must look into the future anticipate, in so far as this is possible, the radio broadcasting requirements which this future will bring; and plan to meet these requirements. A part of the service which it is providing to meet the needs of the present consists of preparing for the needs of the future and of making a reasonable investment to this end.
    Money, mechanisms, men--these are the elements which lie behind the provision of the telephone circuits required to make possible radio broadcasting as America knows it today. They are the fundamentals upon which has been built, in response to a public need, a far-reaching public service.