“EARS FOR SHIPS"

Evening Star, Issue 22807, 16 November 1937, Page 3

“EARS FOR SHIPS"

A NEW INVENTION Hans Falk, representing the Viennese optical firm of C. P. Goerz, turned up in New York recently and invited newspaper men to see a hew invention which makes it easier for a ship to pick up the blasts of horns and sirens and the tolling of lightship bells in fogs and in the night, stated the ‘ New York Times.’ The inventor of this instrument, which suggests a battleship’s range finder, is Dr Max Maurer. One glance is enough to convince anyone who knows something about military equipment that Maurer has applied the principle developed during the World_ War to locate airplanes by tho inevitable noise that they make. In the war instruments, “ ears ” in the shape of horns were swung on a pivot in any direction. Two of these oh a has© line of known length were turned in the direction of the sound. When the ■humming of the aeroplane was at its loudest in both “ ears,” triangulation made it possible to locate the aeroplane. 1 A searchlight performed the task of revealing the prowler in the air. »

What the newspaper men saw in New York weretwo” ears ” swivelled on, a pedestal. The sound was caught in twp shell-like cups. Because of their paraboloid form they brought the sounds to a focus. At each focus were two horizontal, fattish tubes shaped somewhat like torpedoes. Asked about tbe peculiar shape, Falk said 1 : “They,are what the physicist calls ellipsoids. Just as a properly shaped concave mirror collects light and brings it to a focus, so these ellipsoid arms collect the sounds picked up by the cups and carry them to your ears.”

The officer on duty takes Ms stand in the middle between the ellipsoidal arms. Pneumatic rubber ear pads press tightly against Ms ears to keep out interfering sounds—shouts, grinding of gears on motors, and scores of drones and groans that are inseparable from the operation of a .ship at sea. He turns the range-finder this way and that. What’s that? The blast of a ship’s siren in the right ear. He swings the instrument until he hears the sound with equal intensity in both ears. An indicator plays on a scale with red and black figures (red for starboard, black for port), and so makes it possible for him to megaphone or telephone to the bridge tho exact direction from which the sound is coming. In addition a ■powerful binocular is swung with the instrument ns the bearings of the source of sound are taken, so that the officer is likely to see tho danger at the earliest possible moment. It is clear to anybody with even an elementary knowledge of mathematics that, given the course and speed of the ship on which the acoustic rangefinder is mounted, and given, too, the course and speed at which the sound is travelling (a siren on another ship), it is possible to plot both courses and to determine just where they will intersect, meaning in plain English just where there will he,a collision. With that knowledge it is easy to avert danger.

Most passenger steamers nowadays are equipped with underwater electric oscillators. By sending out notes and listening for the echo (from below) captains can determine the depth of water beneath, them. They also pick up the sounds of bells sent out from a lightship through the water. But they are useless when it comes to surface sounds from foghorns, buoy bells, and whistles. Moreover, sailing ships, tramps, andi the like have no underwater signalling apparatus. What is the range of the new apparatus? That depends on the size of the collecting cups. They may he as small as 16in or as large as 40in in diameter. With hig cups, sirens, and foghorns have been picked up at a distance of 12 to I's miles.