RADIO TELEPHONY.

Star (Christchurch), Issue 12646, 2 June 1919, Page 2

RADIO TELEPHONY.

$ TS I,™ AN EPOCH-MAKING APPARATUS. (“ Now York Sum”) Iho wireless telejlhono 1 1 ;vs been promised oil' and ou for a number of years, and, strictly speaking, wo have had this means' of vocal intercourse in a laboratory way, potentially practicable, lor some time, but there were stumbling blocks m the goal to robustness of apparatus, reliability of performance and reciprocal effectiveness between transmitting and receiving stations that halted commercial recognition. One by one (hose technical obstacles have been dodged or surmounted, and to-day, instead of being able to talk without wires for only a, few miles, wo are actually spanning an atmospheric gap measured by the bosom of the broad Atlantic. LIGHTING THE WAY TO SUCCESS. And what has really constituted the foundation stone of this amazing achievement? What particular effort of American enterprise opened the vista, of this possibility? It was nothing more pretentious to the casual eyo than a glowing incandescent lamp of a size akin to those which barn become a commonplace in the household. And this particular electric light was the product of Dr Lee do Forest. Wo nulst tell something of the story of this littlel appaaitus in order that the layman can again grasp the fact that astonishingly big things often grow out of strangely small ouet. In January of 1913 transcontinental telephoning by wire was inaugurated. The exports of the American Telephone and Telegraph Company thus brought to a. climax their varied labours and showed how tho exiromoly feeble vocal waves starting at tho.distant transmitter could he roinvigorated from time, to time ami .reproduce the initial speech after travelling tho long wire route of quite 3COO miles. Numerous electrical features contributed to this realisation, but probably none of thorn played ai more vital part in that success in the long distance, transmission of speech than the. Do Forest audion amplifier. For tho bettor part of two decades previously telephone engineers had striven- to find an apparatus, which would pick up surely arriving speech waves, and then, with now strength, ■send them forward ou their next lap toward the remote goal. The problem was a sorb of vocal relay race, and to be or real service it waa necessary that tho incoming message should he faithfully caught and sent forward without distortion. A small army of inventors and telephono engineers contended with this baffling puzzle. Curiously well nigh all those men sought to modify or to adapt well-known features of tho telephone— Professor M. I. Pupin being the, one conspicuous exception. Professor Pupin gave' the world his inductance coils, but these could not bo used commercially for transcontinental telephony simply because of their staggering cost. DR DE FOREST’S AUDI ON. Work in the field of wireless telegraphy, strange as it may seem, actually blazed the way for the wire telephone which brought Now York and San Francisco within vocal range of each other. In 1902 Dr Loo do Forest, then starting his pioneer experiments with wireless defectors, apparatus which would pick up the faintest of arriving Hertzian waves, discovered that a heated gas was affected by such waves and would constitute a new detective agent for use in radio telegraphy- Here was a medium that prove.d to be exquisitely sensitive to oncoming impulses, and because the gas was imponderable it Faithfully reproduced the character of each wave. Indeed ft was infinitely more responsive to these electrical disturbances than any previously known wireless receiver. Dr do Forest called his little apparatus “andion” because the incandescent lamp which he employed nude audible tho action of the ions of heated gas which surrounded tho incandescent mentWorking tirelessly to improve his andion, Dr de Forest discovered that the gas ions responded perfectly to telephonic currents, in fact _ quite as well as to those of tho far higher frequencies used in wireless. But this was not all that was revealed to this investigator: he learned that’the andion had twofold powers—it received puny impulses sympathetically and was able, also to amplify those voice currents so that the transmitted speech was reproduced perfectly and with increased strength. In 1913 the American Telephone and Telegraph Gompnny purchased an exclusive license under all the De Forest andion patents for wire telephone purposes. What is the nature, of this epochmaking instrumentality? Dr de Forest thus describes his invention;— “The andion amplifier consists of asmall incandescent lamp bulb exhausted of air, containing in, addition to the usual filament two thin plates of nickel about ■ one-eighth of an inch from the filament, on either aide. Between the. filament and. the plates are two pieces of nickel wire bent grid-shaped. That is all. Can yon imagine anything more simple—more utterly unlikely to operate as a repealer of the telephone currents?” In the four years that have intervened this electrical wizard has forged steadily ahead to his climax: and by pursuing developments along the line of his andion he has actually given ns a transmitter, guided by _ the. voice, which can rend broadcast wireless waves of far-reaching capacity. INVALUABLE TO WAR CRAFT. We had Wn at war with the Central Bowers but a short while when it was made evident that it was necessary to efficient service that, nur submarine chasers be able to maintain touch with one another by vocal means even when separated a number of miles. Flag or flash signals would not answer,’for the boats, if trailing a submarine, would he expected to act in perfect concert. The chances of misunderstanding had to_ be reduced, to a minimum, and wireless telegraphy, apart from requiring skilful operators on every craft, admitted of too many slip ups. Nothing would satisfy hut word of mouth contact. Here, is where, the wireless telephone came into its own. Before the wireless telephone was available, small craft groping for Üboats, especially during periods of fog, were woefully handicapped, and it was next to impossible for them to do their hunting in groups with anything like co-ordinated efforts. They were moveapt to collide with one another as they sped along than to hem about and to run down the elusive submarine. Wireless telephones with-which we equipped our chasers functioned beautifully. GREAT AID TO AIRMEN. We were just beginning to feel our own strength aloft when the armistice was signed, but even so the Germans were amazed by the accuracy of our battery live and the uncanny precision with which our field guns fell, out quickly tbe prime positions or vital spots along the foe’s linos. Previously well nigh all tho airmen of the Allied forces relied upon wireless telegraphy to signal hack to tho batteries how to alter their elevations and points of attack. Wireless intercourse from ground todying machines was but seldom satisfactory, because the man up iu the air

Tv ns all too apt to road the Morse code incorrectly. The advent of the wirgless telephone transformed the situation, and our experts made, it possible for a flight commander to direct bis squadron vocally and to exchange speech with Ilia friends on the ground and miles away. There was no guesswork about what was then expected of the fliers aloft or of the battery commanders behind the lines. Comimuiicniinn was positive, full and explicit. An airplane transmitter of the do Forest type, the onlire equipment weighing a. little, over eighty pounds, was developed capable' of having a vocal range of twenty-jive miles or of brine used as a radio telegraph over a distance of 100 miles. SPANNING THE OCEAN. Transoceanic wireless talks should not now be cause for wonderment. As a matter of fact, Dr do' Forest showed that this was possible, as far backas 1915, when the naval wireless station at Arlington, Va., spoke to the radio station of the Eiffel Tower in Paris. At that time 300 bulbs were used for Iho purpose of effecting transmission. In September of the same year wireless speech was sent from "Washington to Honolulu—<a total distance of 4600 miles, 2500 of which were over this continent. Put intercommunication was not achieved simple- because both terminal stations were not similarly equipped. Since then, many difficulties in the art from a commercial point of view have been mastered, and it cannot bo long now before wo shall think no more of calling up London, Paris, Rome, etc., than a New Yorker would in having speech with a friend or business associate in San Francisco. Many men and many mods have been engaged latterly, in breaking down Nature's barriers of distance. It must be clear that w© have nowreached a. stage in radio telegraphy wnere the range of radiated speech through the air will be limited only by the power of the sending station and the acuteness or sensitiveness of the receiving apparatus. American genius is also battling successfully with the bugaboo of “static,” and thus clearing the way for the unimpeded spread of speech bearing waves to .shores thou-I sands of miles removed, i