Tasting and Seeing Radio

Radio Record, Volume IV, Issue 25, 2 January 1931, Page 15

Tasting and Seeing Radio

Novel ‘Method of Communication [HS use of ‘visible. indicators for reading incoming signals. dates back to the early. days of ordinary telegraphy when Morse impulses sent over a line were first recorded by a vibrating needle, The change-over from sight to sound came with the introduction of the telephone and its greater sensitivity. In wireless signalling, owing to the relatively small amount of energy picked up by the receiving aerial, there

would at first sight seem to be no possible alternative to the use of headphones. In these days of broadcasting, the valve amplifier and the loudspeaker, the term "listener" has, in fact, stuck fast. At the same time there are certain circumstances in: which the ear cannot function efficiently, so that the use of headphones becomes unsatisfactory. Yor instance, in.an aeroplane the noise of the engines is sufficient to deaden any wireless signal. ‘ ._ In practice this difficulty is overcome by wearing a sound-proof helmet with the earphones snugly encased inside, Although effective in allowing wireless signals to be réceived, the use of a sound-proof helmet has certain decided drawbacks. For one thing it cuts out all other external sounds, a fact which is not altogether desirable when the helmet is worn by a pilot who is in sole charge of the machine. Also the headgear is cumbrous and cannot easily be discarded in case of sudden emergency. As an alternative, it has been suggested that, for aircraft work, wireless messages should be received by taste instead of by ear. This may at first sight appear rather far-fetched, but the proposal has been thoroughly tried out, and as the result of a series of tests was favourably reported on by Professor Goldsmith, of the Radio Cor-

poration of America, He found that it was perfectly feasible to substitute the ‘tongue for the ear, and to detect incoming signals by taste. The sensitivity was. considerably less, but this could be made good by suitable amplification. en ee sets It is a well-known that: a-pecu-liar and characteristic taste is experienced if two wires at slightky different potentials are. applied. to the tongue. To a-minor extent the sensation is felt when strips of two different metals, such as copper and zine, or a copper and silver coin, are placed, together and applied lightly to the tip of the tongue. The combination, when moistened, forms a miniature voltaic cell, and the resulting B.M.F. is "tasted." a This effect was utilised in the aeroplane tests mentioned above,. The incoming signals are fed to two electrodes,. preferably made of strips of silver so as to prevent the formation of injurious salts, The electrodesseparated by a thin sheet of insulating material and fastened together--are held lightly in the mouth, with the tip of the tongue pressing gently on the end, so as to bridge over the insulating strip between one silver electrode and the other, . The incoming signals could not only be definitely detected by their taste, but they also gave rise to a curious effect on the sight, At first the operator thought that a lamp nearby "flickered" each time a signal was received.

-- ~~ — It was subsequently found that a definite "flash" accompanied each signal, which could be "seen" even whe the eyes were tightly closed.