THE TALKING BEACON

Hauraki Plains Gazette, Volume XXXXII, Issue 2768, 28 August 1931, Page 6

THE TALKING BEACON

A NEW FORM OF LIGHTHOUSE. A lighthouse which actually talks to passing ships is one which would have appealed to Robert Louis Stevenson, not only because of the romantic aspect of the invention, but because he came of a family of light-house-builders and himself began to train for a place in the family business. Mr Charles Stevenson, who, with with his son, Mr Allan Stevenson, has finally perfected the “ talking bea;con,” is a cousin of R.L.S., and is at the head of the firm which just 140 years ago erected the Little Cumbrae Lighthouse, where the talking apparatus has recently been installed. The invention, which is designed to provide greater safety for ships in [fog, is based upon the fact that, whereas sound waves move comparatively slowly, namely, at 1090 feet per second, wireless waves move so quickly that transmission and reception of sound by' their agency are almost simultaneous. Gramophone records are used in the instrument, which state cables and knots at a speed measured so as to agree with the sound-speed of the lighthouse foghorn. The mariner will hear the counting by means of an ordinary radio receiver, and will note the number of knots and . chains reached by the time the sound of the foghorn arrives. That will give him, within a few yards, his distance from the lighthouse. The counting is prefaced by three foghorn'blasts sent by wireless and the name of. the lighthouse, and the whole warning is repeated every 70 seconds.