Radio broadcast .. (1922-30)

A Biography of Emile Berliner, Inventor of the Microphone —What the Radioman Should Know; about Isobars, "Highs," "Lows," etc. The Microphone in the Making EMILE BERLINER — MAKER OF THE MICRO- PHONE. By Frederick William Wile. Preface by Herbert Hoover. Published by the Bobbs-Merrill Company, Indianapolis, Indiana. 355 pages, jo illustrations. Price, $4.00. ''HEN Herbert Hoover writes the pre- face and Frederick W. Wile the text, a book is produced worthy of your notice. That the subject is Emile Berliner, one of the picturesque personalities of the past fifty years, assures interest to the reader—and profit, also, if one would learn from history in its most at- tractive form of biography. Emile Berliner aided two arts with important inventions at strategic moments in their early days, the art of the tele- phone in 1877, and that of the phonograph ten years later. Inventions, whether of means or methods are, broadly speaking, products of evolution; they arise like brachiopods, Java men, or four-toed horses from antecedent conditions. Given a suit- able and general state of scientific knowledge, the induction motor and the telephone, insulin and permalloy, the quantum theory and relativity, are inevitable, although the name of the inventor will depend on accidents of native ability, per- sonal interest, and background of experience. Individual credit is not thereby lessened; genius is enhanced, not diminished, by a timely setting. For the genius of Emile Berliner, the early days of telephony and of the phonograph pro- vided the timely environment. These arts had been created, respectively, by Alexander Graham Bell and Thomas A. Edison. For both arts, the stage was set by the existing knowledge of elec- tricity, although both had resisted previous ef- forts of other inventors. To Bell had come the accomplishment of the telephone through a happy combination of clear thought and labora- tory discovery—the latter arising from the trans- mission of the twang of a vibrating-reed armature and the former a recognition, which would be expressed in our modern terms by saying that a carrier current must be modulated in exact con- formity to the speech significance which is to be transmitted. The only carrier current of those days was that of zero frequency, being the direct current conveniently derived from batteries. Its modula- tion, as we now recognize, is possible whenever through speech there is correspondingly varied, in a circuit containing a battery, either induc- tance, resistance, or capacity. Capacity variation is relatively inefficient; and the development of a condenser-transmitter therefore awaited the more timely setting of the present days of vac- uum tube amplifiers. Inductance variation is not nearly so inefficient, and with it no battery is re- quired, provided what is varied is the reluctance of the magnetic path of a permanent magnet which links with the transmission circuit. This method—that of the electromagnetic transmitter —was Bell's earliest system; although insensi- tive, it was peculiarly adapted to his discovery, tor the same mechanism may be used inter- changeably to convert current variations into a relative motion of the magnet and its armature, that is, to act as an electromagnetic receiver. Historically, modulation by varying the re- sistance of a circuit came last. In one form, how- ever, it came promptly; for Bell's first complete sentence was effected by an electrolytic trans- mitter in which a plunger, actuated by the dia- phragm of the transmitter, vibrated more or less deeply into an electrolyte. Such was the art when it aroused young Berliner to intensive experi- ment and eager study, who already had his time well filled with earning his living and with efforts to learn the manners, customs, and language of America. And he won through, with a variable- contact resistance and a conception of possible multiple contacts, which proved a patent of value because other and famous inventors were follow- ing similar lines. Edison, for example, he beat in filing date by thirteen days; but the story of his invention and its later litigation is too excit- ing and too well told to be abstracted. A coincident contribution which Berliner made to the telephone may best be described in its modern terms as "carrier suppression in direct- current carrier circuits." Working for two-way transmission, and curiously enough, attempting to use his variable-contact resistance device both as a transmitter and as a receiver, he found it necessary to employ local batteries and to couple the local circuits through transformers to his main transmission line. The modulated direct current of the local transmitter circuit, therefore, induced in the main circuit an alternating cur- rent corresponding to the modulations; the trans- former action eliminated the direct current. All this before the real days of alternating-current technique, at a time when transformers were induction coils used only as spark coils in giving shocks, setting off explosives, or demonstrating luminous effects of electricity. Ever since, the name "induction coil" has been used in tele- phone parlance for the transformer which passes the modulation of a transmitter out into the line. After a time, Berliner left telephony and turned toward the phonograph art which Edison had initiated. In the latter's instrument, sound was recorded by a groove the depth of which was supposed to be proportional to the sound inten- sity. In other words, a narrow trench was dug into the wax by a cutting needle and the contour of the bottom of the trench was a succession of ups and downs, hills and valleys, the levels of which corresponded to the volume of the re- corded sound, and the frequency, to its pitch. The graving tool was driven by a diaphragm upon which the sound waves impinged. Obvi- ously, the mechanism of the system was faulty. As the diaphragm approached the end of its vi- bration it was required to dig most deeply into the wax; but that was impossible, because the force which it could exert grew less as the turning point of its vibration was approached. Berliner solved the difficulty by causing the graver to trace a wavy line—in effect, an oscillo- graph of the sound. There was then a lateral cut of uniform depth, instead of a vertical cut of varying depth. Simultaneously, he solved the problem of the reproduction of phonograph re- cords; for his graver cut its trace in a %hin film of wax on a metal disc and thus permitted the etching of the exposed line of metal. For years, until superseded by electroplating methods, Ber- liner's photo-engraving process of making ma- trices for records was successfully employed; and that, with further developments, made the gram- ophone of "the gay 'nineties"—the precursor of the talking machine, which, by a cumulated series of developments, has become the Ortho-, phonic of to-day. JOHN MILLS. Radio Prognostication THE WEATHER FOR RADIO LISTENERS, BROAD- CASTERS, AND OTHERS: By Eugene Van Clecj. Published by the Taylor Instrument Companies, Rochester, New York. 34 pages. 7 illustration!.. (See booklet listed as No. 67, page 5/2.) THE conversation of two gentlemen of some literary attainments brought together at a party for the special benefit of their follow- ers may serve to introduce a little booklet of more than passing interest on a subject of more than passing importance: "Nice weather we're having," opened the con- versation between the two. " I never talk about the weather," was the stiff rejoinder. "It's the only thing I ever talk about," replied the first, thereby closing the conversation perma- nently. "The Weather for Radio Listeners, Broad- casters, and Others" is the booklet, and the author is Eugene Van Cleef, who needs no intro- duction to the readers of RADIO BROADCAST. The booklet is published by the Taylor Instru- ment Companies of Rochester, New York. The weather, Mr. Van Cleef points out, as a topic of conversation should not be relegated to those who have nothing else to talk about, but should be considered as worthy of our best fa- vored conversationalists. It is the common topic for talk among all peoples of the earth, and al- though most people have something to say about it, after reading Mr. Van Cleef's book, one need not be in the class mentioned by Mark Twain as those who talk a lot about the weather, but do not seem to do anything about it. Weather affects radio reception as everyone knows, and a lot of us know that isobars, "lows", and "highs" have something to do with the matter too, but it remains for the Taylor Instru- ment Companies to try to explain, with Mr. Van Cleef's aid, what it is all about. This he does with considerable ability, not only stating the apparent relation between long distance recep- tion and the barometric pressures existing over the country, but explaining something of the nature of static as well. As a matter of fact, the burden of the little booklet is to interest listeners in the study of weather and its effect on radio, and it may be pointed out, for those who don't know, that the Taylor Instrument Companies have organized a vast group of widely distributed listeners who desire to have their share in undermining the secrets of good reception. Even if one does not care to take an active part in collecting data on weather and radio, the booklet gives a good picture of how one can study weather maps with the object of prognosticating for himself the probabilities for good "DX". KEITH HENNEY.