KNOCK-OUT BLOW TO U BOATS.

Taranaki Daily News, 30 August 1919, Page 10

KNOCK-OUT BLOW TO U BOATS.

STORY OP A WAR-TIME SECRET. THE SUBMARINE DETECTOR.

Naval experts state with conviction that if the conflict had continued thiough another summer, the submarine ■would literally have been driven from the ocean. The "Journal of Electricity" 'San Francisco, June 1), describes the operation of the wonderful electric "listening device," which was, perhaps, the most important of America's efforts toward the termination of the submarine menace. This device, kept secret, of course, during the war, was the composite work of several large electrical constructing firms, assisted and advised by many eminent scientists, engineers, and research men, under the auspices of the National Research Council. From these sources grew finally the American submarine detector —a development ot the old principles of sound-wave transmission in water in an altogether new r-nd startling manner.

SCHEME AT WORK. "The apparatus was first designed to hang overhead from naval craft, aniid."hip below the water-line, and it depended for its direction-getting qualities on the peculiar and heretofore little understood faculty of the human ear to detect the direction of sound by the shifting of that sound from one ear to the other. To overcome the obstacle of interference of sounds made by the listening ship's own motors another device was developed which could be trailed oil' the stern a hundred or so fret away, where the engine noises of the ship were out of range, and the sound was then brought in to the operator in the ship's hold A third adaptation of the listening principle was an instrument which protruded through the hull and was a stationary part of the vessel's equipment. '

While demonstrating the device to the LVitish Admiralty Hie engineers were •isked to study the question of fitting submarine detection units to aeroplanes, balloons, and dirigibles. After some experimentation, followed by more practical tests nnd conferences with the Lan'•aehire group of scientists at, Harwich, apparatus was developed which met these needs, and many aircraft were reuipped with sound-detectors which rendered it possible for them to follow the course of the enemy after they had seen her submerge, a valuable faculty which such craft did not possess nniil the introduction of the American detector.

'•When the device* had proved themselves eminently satisfactory sifter exhaustive experimentation here, the Navy Department organised a special service party under Captain 11. H. Leigh, of the C::reau of Steam Engineering, to demonstrate the detectors to the British Admiralty. Shortly after .the arrival of this party abroad, (he American snbmarne detectors were universally adopted by all the Allied navies, "tinder idea! conditions, with extraneous noises reduced to a minimum or entirely eliminated, the device was effective at a raii'ie of fifteen to twentyfive miles and under average circumstmces at a range of between three and oiaht miles. Trained operators could clearly distinguish between the sounds made by approaching surface-craft and roulcnvater vessels (submarines). Within five miles the engine characteristics of different vessels were clearly marked, even to the point of identifying by name certain unseen vessels after they had been observed previously for more than one time. The direction of sound could usually be computed within a very few degrees of its actual location, and a good judgment of the distance could generally be made. It was found practical to tell when a submarine changed from her oil engines to electrical drive, which wrb necessary every time she submerged. The addition of these listening devices to submarines ndded the heretofore lacking sense of hearing to all the underwater craft, and made them at once a much more effective weapon of offence.

A GRIM CHASE. "An Allied submarine on one occasion chased a German U-boat for four hours, while both craft were submerged, without once losing sound-contact with the enemy. The engagement occurred one morning in the English Channel. A ismall squadron of chasers discovered an enemy craft moving slowly up the channel submerged. Forming for the attack, they rushed over the spot where their listeners indicated the U-boat to be, dropped a pattern of depth bombs, and then withdrew to take observations. "Feverish activity and the sound of hummers ringing against the ship's ride was heard. The submarine engires would then start up and stop, start, and stop Again.

'Further attacks were delivered, and more noise came to the listeners from the hold of the submarine Evidently the first depth charge had taken good effect, and the enemy's crew were m«K--iiiß a last desperate effort to reach the surface. Then there was a dead silence, broken at last 'by twenty-five sharp reports like revolver-shots. The Crew, giving up in despair, had committed suicide. The loss of this submarine •yas later substantiated by the British fr.tclligeuce Department."

OTHER INCIDENTS. Another time, on New Year's Day, 1918, Captain Leigh went out in the Channel with three trawlers, equipped with the detecting apparatus. A wireIces message from an airship pave the position of a submarine which had just been seen to submerge. The Channel had been laid out in squares to facilitate the location of craft, and the squad•on steamed over, got their devices out, and picked up the submarine's course. To quote further: "When believing themselves about jovor the enemy they discharged depth bombs, and later a trawling instrument wits used to indicate that the submarine Ir.id been destroyed. Great quantities of ;'il rising to the surface also substantiated the success of the attack.

"After some months another squadron was equipped and sent into the Mediterranean and Adriatic, where at this time submarine activity was at its height.

"Three of the chasers patrolling in '"■ i'""tion abreast one dark night heard '«, KiihTiiarine approaching. The bearings i" .amed by the two beam vessels point- '■'! directly toward the centre boat. The middle boat now heard the submarine approaching from a position dead astern. The enemy came nearer and nearer, and finally passed right under the chaser, so close to the surface that those on board felt a wave of water along the keel of their ship. "When the German had passed on and out in front, the attack was made in unison, a pattern of bombs was 'let go,' Lfuul the little fleet halted for further

observations. Pretty soon, the whirl of the submarine electric motors was heard, evidently in an effort to reach the suriace.

"Then camp a crunching noise, not unlike the popping in of a blown-up papering It whs apparent that the submarine had been damaged and put out oi control and that, she had collapsed from the tremendous water-pressure at these depths. "Many incidents of this kind occuriPtl during the subsequent operations in foreign waters, and several submarines were accounted for through the direct aid of tlie American listening devices. In fad', naval experts state with conviction that if the conflict had continued through another glimmer the submarine ivf.uld literally have been driven from the ocean."