WINNING THE WAR.

Sun (Christchurch), Volume VII, Issue 2143, 28 December 1920, Page 2

WINNING THE WAR.

PART PLAYED BY EDISON. HOW HE TRACKED U-BOATS. Thomas Alva Edison devised no marvellous electric machine to annihilate, at one stroke, the armies of our enemies, as eredulous persons expected, at the outset of the War, that he would do. "What Edison did do, however, is set forth by a contributor to '' Engineering and Contracting" (Chicago), and, after perusing the account, the reader may not be blamed for adding the name of Edison to those of the numerous persons and organisations who are credited with •'winning the War." Some of Edison's contributions were: The device for detecting submarines, \>y sound, from a moving vessel. That for turning a ship quickly at right angles. Collision mats for minimising loss from torpedo attack. Methods of camouflaging vessels. Obstruction of torpedoes with nets. The under-water searchlight. Oleum cloud-shells. High-speed signalling with searchlights. " Water-penetrating projectiles. Researches on the zigzagging of ships. Production of nitrogen gas from the air. A hv.drogen-deteetor for submarines. Protection of observers from smokestack gas. Device for use in watching for periscopes. Putting out coal-bunker fires. Direction-finder for hostile airplanes. Locating hidden guns by "soundranging." The preservation of submarine guns from rust. Detecting "Subs." by Sound. When submarine activity began to play havoc with shipping, the problem of detecting the location of submarines by sound was considered one of the foremost problems of the day, and In a very short time it was recognised as being, perhaps, the most difficult one. Mr Edison gave this problem a large part of his attention, and in the summer and fall of 1917 had reached a fair degree of success in detecting sounds of torpedoes as far as 5000 yards distant. He became convinced that if he could install on a ship a device that should be arranged so that it would always be from 10ft to 20ft ahead of the bow of the vessel, and if this device should carry a vibrating diaphragm, it would not have to contend with the noises of the ship itself. The device succeeded, and boats moving 1700 yards away could be readily heard while the vessel was going full speed. A submarine bell five and a-half miles away could also be heard by the operator while a big storm was in progress. With this device there would be no difficulty whatever in hearing a torpedo more than 4000 yards away, and this is far beyond the effective distance at which a torpedo can be launched from a submarine. The noise by a torpedo is very piercing and peculiarly distinctive. Quick Turnings.

Mr Edison desired to provide cargo-! ■boats with a means of turning the ship ■very quickly to a right-angle course on hearing the launching of a torpedo by his listening-device. Mr Edison's plan included the use of four sea-anehoTs, each about 9ft in diameter at the mouth and each attached to a 4in rope. Thespian was to fasten the ends of these rojfes securely in the bow of the ship and to have the sea-anchors placed at the end of the ropes and midway of the ship. If the observer at the listening-deviee reported a torpedo launched by a submarine at a distance, the signal w'as given and the four seaanchors were to be immediately released and thrown overboard, and the helm thrown hard over, bringing the ship-al-most to a standstill, rapidly turning her at right angles in her original course. In a test a loaded vessel 325 ft in length was turned 90deg. from her course in 2min lOsec, with an advance of only 200 ft. Mr Edison experimented on a plan to enable merchant ships to escape torpedoes by the use of a gun, similar to a trench-mortar, from which should be fired an obstruction netting. The plan was that a large number of these nets should tie thrown in its path, giving sufficient retardation that it would be stopped or be bo delayed as to miss tie ship. One of the problems placed before Mr Edison was to provide a searchlight to be used under water by submarines. After making a great number of experiments he found that the green line of barium in

the arc (light) penetrated salt -water farther than any other he had observed. His last experiments were wjth a 60-foot tube filled with sea-water, at the end of which sufficient light was transmitted to read print. During the height of enemy submarine activity, Mr Edison also devised a type of projectile which would enter the water direct without ricochet, and would continue its course without deflection and make a penetrative hit. A simple little device for use by lookout men in watching for periscopes in bright sunlight was suggested by Mr Edison. It consisted of a tapering metallic box, open at both ends, fitted with a light-excluding eyepiece, and having diaphragms placed at intervals along its inside length. The device was painted a dead-black inside and out, and its construction was very cheap. With itobjects could be discerned in the full light of day that were otherwise invisible. Locating Hidden Guns. The determination of the location of hidden guns by. observing the time intervals between which the sound of their discharge reached several known points was early undertaken by Mr Edison. Actual tests made with modern guns showed that under varying weather conditions the position of an unknown sound could be located within 2 per cent., plus or minus, of the measured distance, with a base-line not exceeding one-sixth of the range distance. Under favourable conditions some remarkable close results were obtained. ' With a base-line 1800 ft long (the longest base-line used) the gun'has been located over two and a-half miles away, within a foot or two of the actual position. . One of the problems submitted to Mr Edison was to find some method of preserving submarine guns from rust. He made a large number of experiments and finally found that if extra fine zinc-dust is mixed with vaseline and smeared over the gun no rust whatever formed, either in air, or sprayed with seawater, or wholly immersed in fresh or sea-water. If only plain vaseline was used the polished steel" became badly rusted.