SCIENCE NOTES.

Otago Witness, Issue 3574, 12 September 1922, Page 60

SCIENCE NOTES.

THE MAN WHO MADE BROADCASTING POSSIBLE. Every one -who has passed beyond the novice stage in radio lore has heard of the “feed-back” system which enables a local battery to contribute energy for ’the amplification of a signal received at a wireless station. But until very recently no one could be quite sure as to who was to be officially credited with the invention of the method, as the matter had been subject of legal controversies since 1914. Now, however, the courts have handed down a final decision in favour of iYLr Edwin H. Armstrong, whose popular sobriquet, “Feed-back Armstrong” thus receives substantial authentication. The New York Tribune, after remarking that the decisions of the courts would not only have a far-reaching effect upon all forms of radio communication, but also upon every industry to which an electrical oscillator may be used in the future, makes this explicitive comment: “Stripped of its legal and technical verbiage, the decision of the court, which is final, means that no transatlantic telephone conversation can be carried on without the Armstrong principle, nor can any of the big radiophone broadcasting stations now sending music nightly through the ether operate without using the Armstrong patent. Even the modern multiplex forms of wire telegraphy and telephony must use the Armstrong method. “The decision of the court is very broad. It confirms Armstrong in his patent, and recognises the fact that ho conceived the idea which revolutionised radio and made broadcasting possible as early as January 31, 1911!, and in this confirms the sweeping decision previously handed down by Federal Judge Julius M. Mayer.’’ The decision hinged on a simple diagram, clearly showing the feed-back principle, which young Armstrong drew and

had witnessed before a notary in January, 1913, at which time he was a student at Columbia. The few simple lines, which anyone versed in the art will readily understand, make record of an invention which Professor Michael I. Pupin, of Columbia University, characterises as “one of the most important inventions, if not the most important, in the wireless art-.”' As quoted in the Tribune, Professor Pupin, after referring to Armstrong’s invention on the feedback circuit, says : “The invention enabled him to make another most important step in wireless telegraphy, and that is the construction of a vacuum tube oscillator. When the feed-back circuit energised by the local source contributes more than a certain definite amount, then the system of circuits becomes an electrical oscillator, oscillating at the perfectly definite period which depends upon the inductance and the capacity ' of the controlling circuit. By varying either the inductance or the capacity, we can produce any period of oscillation between a few periods per second and many millions per second, and the oscillation once established maintains its pitch indefinitely.

“It is a generator of electrical oscillations, maintaining its pitch with a degree of accuracy never before obtained by any apparatus constructed by man. “The importance of the feed-back circuit in the reception of wireless signals and the importance of the electrical oscillator, not only in wireless telegraphy, but also in wire telegraphy and other departments of applied electricity, can not be over-estimated. “It is admitted by those skilled in the wireless art that the ordinary electromagnetic generator of high power will before long be superseded by the vacuum tube oscillator, which also will bring about more or less reconstruction of wireless transmitting stations. I am particularly pleased that this decision gives the credit for the invention to a man who is a former student of mine and a student of Columbia University, and who has made a deal of his work in the Marcellus Hartley Research Laboratory of Columbia University. It goes without saying that long-distance radio communication and radiophone broadcasting would be impossible without this invention.” In an interview published in the Evening Post (New Pork), the young inventor himself forecasts the future of the new art for which his own work is so largely responsible. What he has to say about prospective receiving outfits has interest for every amateur : “ ‘The time is not far off,’ said Armstrong, ‘when the raidophone receiver will be as common as the victrola now is. Not every home will have the radiophone, of course, but I can predict that every home now having a phonograph will be equipped with wireless.’ “This equipment will consist of none of the outside and unsighly wires, switchboards, and batteries now seen in every radio station, he maintains. The whole radiophone receiver, horn and a-11, will be no larger than the now ordinary music box, and the current to operate it will be supplied by an electric cord connected with the nearest wall pjug. “Instead of the aerial wires now used,' he said, “the radiophone receiver will have a small coil of wire, or a metal rod five

or six feet long, something no more conspicuous than the ordinary curtain rod. Outside wires will be unnecessary.” Armstrong can do this very thing now. At his home at 1032 Warburton Avenue, Yonkers, he has set iqy in his rooms a small receiver, employing no outside wires, which picks up music and other signals from the Westinghouse station at Newark with such strength that they may be heard for half a mile—if the window be opened. In every city he believes there will be one or more broadcasting stations, constantly sending out entertainment and information. The finest concerts can be provided by the city, and sent out free to every citizen who cares to turn on his receiver. There could be baseball reports, stock market quotations, weather predictions, the news of the day, educational j lectures, even political speehes, sermons on Sunday, grand opera at night—everything, iii short, for the complete recreation or edification of the people. That is to say, if political speeches may be said to do either of these things. Would anybody read newspapers then? Armstrong grinned in non-committal silence.

The original Armstrong circuit, as depicted in 1913, when the inventor was a student at Columbia University. This is the document that played an all-im-portant part in establishing Mr Armstrong’s clhim to priority of invention. Current from the plate battery B 2 is “fed back” inductively from the coil L 3 (“tickler”) through coil X. 2 to tire grid circuit, augmenting, or “regenerating,” the current from the aerial.