TELEPHONES WITHOUT WIRES.

New Zealand Herald, Volume XLV, Issue 13583, 12 September 1908, Page 5 (Supplement)

TELEPHONES WITHOUT WIRES.

SUCCESSFUL EXPERIMENTS. - Would it surprise you if, on saying aloud that you wondered what a friend thousands of miles away was doing, he answered back and immediately 6et your curiosity at rest? This is not by any means an impossible happening of the future. Recent progress in wireless telephony lias been so rapid that already much may be done which quite (i short time ago was looked upon by scientific men as beyond the bounds of possibility. Ayrton, in discussing the future of wireless telephony, said: " The day will come when copper wires, gutta-percha covers, and iron bands are only to be found in museums ; when a person who wishes to speak to a- friend, but does not know where he is, will call with an electrical voice, which will bo heard only by him who lias a similarly tuned electrical ear. He will cry, Where are, you?' and the answer will sound in his ear, 'I am in the depth of a mine, on the summit of the Andes, or on the broad ocean.' Or perhaps no voice will reply, and he will know

that his friend is dead." That the wireless telephone is already in a state suitable for application to commercial work may be gathered from the success of the experiments carried out a few days ago on Barnes Common, when Dr. Manders and Mr. Shannon spoke distinctly and with the utmost facility over a distance of a third of a mile. Their system is based, like all modern systems, on the use of continuous electrical oscillations, and they employ a new and simplified form of arc lamp. ITS Sr-ECIAL USEFULNESS. The Zenal system, as it is termed, is not so complicated but that it could be utilised in a large factory, warehouse, or business house for purposes of speaking between different buildings, while for harbour work in shipping or military purposes its application could be immensely serviceable. An interesting point in connection with these and similar wireless telephone installations is that, although the receiver must be "tuned" to catch the sounds transmitted, it frequently intercepts wireless telegraphic messages in a perfectly guileless manner. The tappings of the Morse code are, in fact, audible through the effect of the electrical waves on the telephone coherer: telephonic reception of wireless telegraphic messages has indeed been very largely used in recent' times, as it is easier to catch the sounds which represent "dots and dashes" than to record the latter in the original way. The wireless telephone receiver, if provided with sufficient regulating arrangement for tuning, could thus be put to a double purpose, which might prove very useful in time of war. Hen- Wirth has just demonstrated at Nuernberg how one could, by his remarkable invention, accomplish the steering of dirigible balloons by wireless means. It ts equally within the bounds of possibility to equip military airships with wireless telephones ; day by day the weight of the apparatus— that vital factor— being diminished, and who can tell how Boon it will be made sufficiently light to render possible telephonic communication with those who navigate the sky? TESTS BETWEEN" BATTLESHIPS. One great value of wireless telephony lies in the fact that an inexperienced man can talk by telephone, while a trained operator is required for any form of telegraphic work. Only recently twentyeight sets of wireless telephone apparatus were ordered by the United States Government, and tests were carried out be-

tween the battleships Connecticut and Virginia, the distances varying between ten and twenty-five miles. Every word spoken was distinctly heard, and the trials were eminently satisfactory. The enterprise of the United States Government was thus as successful as it was legitimate. Practically the whole of the recent advance made has been founded on the discovery of a method of producing very rapid electrical oscillations. The electric arc

lamp is employed for the purpose, and it is interesting to note with what extraordinary properties this modern illuminant is endowed. Simon discovered that by having a microphone attached in a special way to the dynamo which generates the electricity for running an arc lamp it is possible to make the lamp, while burning, repeat every word or sound spoken into the telephone. An actual "arc lamp concert" was given at Frankfort, at which the arc was made to speak and sing almost like a human being. THE SCIENTIFIC EXPLANATION.

The simplest explanation of the method of transmitting speech is as follows: — These exceedingly rapid waves are generated at the sending station, and the sound waves formed in speaking are utilised so to modify them that they cany the sound impression with them. The waves are sent off by means of an aerial, or mast, and thus speech is transmitted in the form of electrical waves to anyone who is waiting to receive it. The receiving station is fitted with an aerial, which collects the waves, and these are made to actuate the earpiece of a telephone. Both' sending and receiving stations can be "tuned," in the manner already adopted hi wireless telegraphy, so that only the person to whom the message is addressed can receive it. This is, of course, a matter of vital importance in warfare, and at present the most likely applications of speech without wires will be to naval and army work and shipping.

The wireless telephony is to he used at some future time for special work by the London Post Office, though for the ordinary telephonic business it could never replace the present system, in which two wires are used, insulated from one another. But more than one portable wireless telephone is on the eve of introduction, which will prove invaluable in factories, hospitals, and large business houses, where speech can be transmitted with the utmost readiness over a distance of five hundred yards or more. Even in this compact little apparatus the speaker has the power to tune his electrical voice for any particular, person, so that while everyone is ready to receive a wireless order from the "head." ►he hitter individual will just speak with whom he pleases.