SUNBEAM TELEPHONY

Dominion, Volume 12, Issue 274, 15 August 1919, Page 7

SUNBEAM TELEPHONY

'■ REMARKABLE INVENTION. Dr. A. 0. Rankine, of' University College, London, has succeeded in harness, ing the sun's rays and using them as a means of voice transmission. He lias completed a. remarkable -.-Tvention which, makes it possible to talk along a beam of light, natural or artificial, using it as a substitute'-for tho; telephone wira with a transmitter at one end and a receiver at the other.

The invention has been approved by the Adihiralfy, and has tho advantage over wireless telegraphy or tebphony in Tendering a conversation • absolutely secret. Boforo the cessation of hostilities, the Admiralty were in great need of a means of secret signalline. Dr. Rankine set to work in his laboratory, and after a long series of experiments in perfecting this invention, which would have been actually in u*e lad not hostilities ceased.

In ono of the laboratories at University College, Dr. Rankine gave a demonstration of this new method of voice transmission 'to a "Daily News" representative. Two electrical instruments wero placed some distance apart'and a. beam of electric light was projected from ono to the other.

Dr. Rankine spoko into the voice receiver, which resembles a Email phonographic sound-box. The beam of light wos first of all reflected on to a small mirror about the size of a pea, tho mirror, taking the place of 1 tho needle of a' phonograph. By means of an electrical apparatus and tho application of the wonderful element selenium, tho vibrations of the voice caused corresponding vibrations of the beam of light which were reproduced at the receiving end. Dr. Pan leine's voice was reproduced as clearly and as loudly as if he were standing at the receiving end of tho beam. "I have already had several talks with friends over, a distance of a mile, and a half, using tho suns' rays as the means of transmission, explained Dr.. Pjonkinc, "and there would be not tho slightest difficulty in holding a conversation over a distance of seven or eight miles, that, of course, being about the extent to which a beam of light could be thrown to tho horizon. By increasing the size of the-mirrors and the- electrical -power"'greater 'distances • could be traversed were it possible to throw a beam of light farther. "The invention would provo highly use- • ful in tho caso of .ships coming to anchor ' outside a port, and anxious to get into communication with tho shore authori- I lies immediately. As. a rule, the laying i of telegraphic or telephonic cables from i the shore bus resulted in great delay, i But this invention would enablo a ship I to begin verbal communication immo- ' diatcly with the shore simply by focus- ! in" tno su!.s rays or using the search- | light. And it would- be absolutely im- j possible for anyone.to rap the conversa!- i tion. Nothing but the destruction or j the partial destruction of the beam of j li>h-' would stop the conversation."

"Endless possibilities arc opened -up by this invention. Secret verbal communication with aircraft is not impossible. Although it would require a. skilful manipulator to keep the beam of light fixed on the receiving mirror. With a slowly moving airship it would he comparatively easy to talk' to tlio pilot, so lons as tho airship remained in-sight. .There are a thousand uses to which it could be put in the army and navv and mercantile marine, and it would entirely displace the use of tho heliograph anil other devices for signalling in Morso cudo. In sunny climates it would bo of great service to surveyors. Dr. TCankino has not lost of these possibilities, and has been in communication with the authorities on the subject with the view to further submitting his invention to uovernmont or private enterprise.