HOW TO DETECT SUBMARINES

Dominion, Volume 8, Issue 2461, 14 May 1915, Page 6

HOW TO DETECT SUBMARINES

FRENCH SCIENTIST'S THEORY. Writing in "Le Matin," Dr. Jousset-dc-Bellesme, a distinguished French scientist, makes an interesting contribution to the question, which has great importance at present, as to how an enemy submarine can be discovered and destroyed. The scientist declares it is possible to detect the presence of a submarine by the sound it makes under water.

_ It has been well known, for a long time, he says, that water is a liquid which is a perfect conductor of sound. More than a century ago a Geneva physician, Colladon, conducted a series of experiments in the Lake of Geneva to determine the rapidity with which sound can travel in water. It was discovered that water transmitted vibrations _ Tfhich were impressed on it with a quickness and an intensity superior to the air in. the proportion of 1 to 4. Sound travels in the air with a rapidity of 340 metres the second, while in water it attains to 1435 metres.

It will then be admitted that, if th# sound of a bell is perceptible in the air at a distance of one kilometre, it follows that an intense vibration in the water can be recognised within a circle of several kilometres if at the same time we have an ear to hear it. Now this ear exists. A screw which turns in the water at a rapid rate certainly produces in the water'vibrations sufficiently intense to be heard at considerable distanoes. One knows how far away ncise of the motor of an aeroplane can be heard. With even stronger reason one ought to hear in the water even farther away the noise caused by the screw of the submarine. If we arrive b.y this means to discover its neighbourhood at several kilometres of distance, it should be easy to evade it, and even to find out the direction in which it is, sailing, so as to give it chase and destroy it. As experiments have been made before this' tinie to perceive how sound travelled in water, there should oxist an instrument for its ascertainment, and if such does not exist the resources of physical science should be able to create one.

The English Channel appears to be a favourite hunting ground for submarines, becauso tliey need seldom be far from land, and can thus easily determine their position. Tin's portion of the sea having only a limited breadth, the acoustic research of these parasites of the seas could be made more easily in it than elsewhere.