ON THE SEA.

Taranaki Daily News, 25 September 1917, Page 5

ON THE SEA.

BRITISH DESTROYER SUNK. BY GERMAN SUBMARINE. Received Sept. 2,1., 7.35 p.nS. London, Sept, 23. The Admiralty reports that a German submarine torpedoed and sank a British destroyer hear the approaches to the Channel. There were fifty survivors. UNSINKABLE SHIPS. THE PROBLEM SOLVED. London, Sept. 23. It is authoritatively stated that the problem of building uusinkable ships has been practically mastered, but naval circles are of the opinion that the ships will not solve the submarine menace owing I to the difficulties of construction and the small cargo space. Rome, Sept. 23. An Italian marine commission states that it has solved the question of making merchant ships unsinkable, and believes that within half a year the Italian mercantile fleet will be safe ftom submarines. STORM RELEASES MINES. DRIFT AMONG SHIPPING, Received Sept. 24, 10 p.m. Copenhagen, Sept. 23. A storm released hundreds of mines in the North Sea. Many are ashore at Jutland. Some drifted into harbors among the shipping. SHIPS FITTED WITH MICROPHONES. Rome, Sept. 23. A high naval authority states that ships are being fitted wttfc microphone's so perfect that they can detect a submarine, and tell its distance and the direction in which it is proceeding.

THE TORPEDO. HOW THE WEAPON WORKS. ITS POWERS AND LIMITATIONS.

In consequence of many requests for information, the Scientific American recently published the following description of the torpedo:— The speed of a torpedo will' vary according to the conditions. The largest has a range of 10,000 yards with a speed of nearly 40 knots. To secure this result means great size and weight. The warhead of this torpedo contains over 300 pound 9 of high explosive, and the weight of the air in the air flask (used for driving the engine) will be over 200 pounds. The diameter is 21 inches and the length about 20 feet. The Germans are using a torpedo of about the same size and presumably of about the same range and speed for their warship?; but in designing a torpedo for their submarine work they realised that a range of 10,(KW yards at 40 knots was unnecessary, for the reason that the submarine can draw up quite close to its target before letting fly. Hence they reduced the power of the engine and the size of the air flask, and increased the warhead charge to 425 pounds These torpedoes have a range of probably not over 2000 or 3000 yards, with a probable speed of about 30 knots. This is the typo of torpedo that was used in the early days of the submarine piracy against merchant ships. But when the ships began to arm themselves and a submarine could no longer sink them hy gunfire, it became necessary to increase the number of torpedoes carried. This we have learned on good authority is being accomplished t>y making use of an early type of tho 14-inch Schwartzhopf, and sacrificing speed and range by doubling the warhead charge. These torpedoes will probably have a range of not over 1500 to 2000 yards. The distance of a submarine from a vessel when it fires its torpedo depends upon the conditions during the attack. It is difficult to make the correct calcu-

lations for hitting & ship many thousand yards distance, and hence the submarine commander trits to edge up to within 1000 to between .100 and 600 yards—before firing. It is doubt-

ful if he would think it worth while to risk a torpedo at over 1500 to 1800 yards, unless, indeed, the ship attacked was steaming at on 'unusually slow speed. The depth below the water at which

the torpedo travels is determined by the torpedo officer on the submarine. This depth is controlled 'by a diving rudder at the tail, which is operated by the movements of a diaphragm which is subject to water pressure—the deeper the torpedo goes the greater is this pressure and thus the greater the movement of the diaphragm. The diaphragm is regulated by a spring, the tension of I which is set to correspond with fhe depth at which the torpedo is to run. So

well does this depth-control function operate that after the torpedo has been fired it seeks at once the pre-determined level, and continues to ran on that level, which is usually somewhere between 8 and 15 feet, until it strikes the ship. In case the attack is on a vessel of shallow draft, such as a destroyer, the depth mechanism is set so aa to cause the torpedo to run only a few feet below the surface. It should he understood that it is cot necessary for the submarine to be at the depth at which the torpedo is to travel; for whether the torpedo is fired when the submarine is travelling at the surface or 20 or 30 feet below the surface makes no difference to the which under the guidance of its dhing rudder will descend or rise as the case may be, until it reaches the depth of 21 or 15 feet at which it is set to run. If the torpedo is fired when the top of the periscope is above the surface for observation, the torpedo tubes will be from 20 to 25 feet below the surface of the water, the depth, of course, varying according to the size of the submarine.

It might he mentioned here that the course ot the torpedo follows a slightly wavy line, the action of the hydrostatic valve and the diving rudders causing torpedo to run slightly above and then slightly below its mean line of flight. The amplitude of this curved line is greatest at the start of the flight, and diminishes to practically nothing aa the ; torpedo gets well under way. i Tho detonation of the high explosive i striker of which is a small metal rod I projecting through the noee, which when contact is made with the ship is driven 'in. flrina tin share*