Sea Lions Helped to Detect U-Boats

1919

Design of Hydrophone Was Changed to Resemble Head of Acute Water Animal.

In the late months of the war some wild stories were published to the effect that the British naval authorities were training sea lions to catch German submarines. Of course this was ridiculous, but the story was based upon a fact, and that fact has only just been revealed.

It was at the recent meeting of the British Association for the Advancement of Science, when Sir Charles Parsons, the president, delivered an address on "Science in War and Peace." In it he described the development of the binaural hydroplane, with which submarines are located by the sound they make. Early in the game it was discovered that the first forms of these instruments were useless when the vessel bearing them was in motion or when the sea was rough, because the noises made by the vessel's motion and by the waves drowned the noise of the submarine. This is where the sea lions came in.

Hear at Six Knots an Hour.

Sir Richard Paget, the eminent biologist, made experiments to learn how far these interesting animals could hear under water and at what speed their directional hearing ceased. These proved that the directional hearing of the lions was good up to six knots an hour.

Dr. Arthur Keith informed the naval experimenters that whales' ears are too small to receive sound waves in the usual way, but that the animals heard under water by the transmission of sound waves thru the bones of the head.

Design Was Changed.

Now, the whale's organ of hearing resembles the hydrophone. So the design of this was changed, and those used in the last year of the war were hollow bodies in the form of fish or porpoises, made of celluloid, varnished canvas or thin metal, filled with water and towed by the ship. The hydrophone was fixed in the head, and the towing cable carried the insulated wire leads to the telephone receivers of the observer on board the vessel.

These were towed some distance behind the ship, thus losing most of the noises made by the swift motion of this, and it was found that they registered directional sounds when traveling thru the water at speeds of fourteen knots and at considerable distances.

—The Saturday Blade, Chicago, Jan. 3, 1920, p. 9.