Torpedo

in naval warfare, a submarine projectile. It is essentially a powerful cartridge or shell designed to explode with destructive violence on touching the side of a ship. During the Civil War the Confederates invented what is known as the spar-torpedo. This torpedo was fixed to the end of a long pole or spar projecting from the prow of a steam launch about thirty feet. During the blockade of Charleston, these little boats crept out in the darkness several times and inflicted damage on the Federal gunboats. The point of the spar was lowered until the torpedo was under water. It exploded by percussion on touching the ship's side, or else it was pulled off by a wire running along the spar from the launch to a trigger. The Federal Housatonic was sunk and the historic Ironsides was injured by torpedoes. Lieutenant Cushing sank the Albemarle, the chief defense of Plymouth, North Carolina. Out of this experience grew the use of stationary torpedoes or submarine mines anchored in such a position that they are exploded when struck by a ship. Such contrivances are now a regular part of harbor defenses. The American battleship Maine was destroyed in the harbor of Havana, it is alleged by a submarine mine.

Since 1860 torpedoes have been used in every war. Torpedo boats--active steam launches fitted to discharge torpedoes--have formed a part of every navy. They have in turn given rise to a small, active, steel-protected boat up to 250 feet in length, known as the torpedo destroyer. These boats scour the waters to protect the men-of-war from the approach of torpedo boats. They carry swift-firing cannon and usually two torpedo tubes, so that they are themselves torpedo boats. The United Kingdom has added over three hundred of these destroyers to her navy. Other nations, including the United States, have added from fifty to two hundred, and the number is increasing. There were in 1905 about 1,500 torpedo boats.

The modern or Whitehead torpedo is not fastened to a spar, but is expelled like a cartridge from a torpedo tube. Only a small charge of powder is needed, merely enough to give the torpedo a start. The torpedo is as large as an ordinary skiff and has the general shape of a cigar. It is about 16 1/2 feet long, 18 inches in diameter, and weighs over half a ton. The front end is charged with from 100 to 200 pounds of a powerful explosive, known as guncotton. The nose terminates in a firing pin. At the rear is a small fan propeller. A chamber in the torpedo is filled with twelve cubic feet, about ninety pounds, of air compressed under a pressure of 1,500 pounds, 100 atmospheres to the square inch. Immediately the torpedo enters the water, this air begins to escape from the air flask through a turbine and to drive the fan propeller. Under this influence the torpedo propels itself and darts away like a fish. Taking advantage of the fact that sea water increases in density with increase of depth, a valve is set by a spring to withstand the pressure of sea water at the depth at which it is desired the torpedo shall travel. A steering apparatus that governs the torpedo like the tail of a crayfish is connected with this valve. If the torpedo be too near the surface and the sea pressure be light, the spring pushes the valve outward in such a direction that the steering blade causes the torpedo to descend slightly. If the torpedo be too deep, the pressure of the sea water forces the valve in against the resistance of the spring, the steering apparatus is turned up a trifle, and the torpedo changes its course slightly upward. So remarkable is the control effected by this ingenious device that an expert gunner knows within two feet how deep his torpedo will be half a mile away. In fact, a strip of a ship's side thirty feet long and two feet wide at any depth not greater than twenty feet is considered a fair mark half a mile away. In case the torpedo fails to strike, it rises to the surface and floats idly as soon as the compressed air has given out. It may then be picked up and recharged,--a very desirable quality as a single torpedo costs from $3,000 to $5,000. In case the torpedo strikes, there is a tremendous explosion. It was expected that the most powerful battleship, costing millions, would be sent to the bottom. A number of fine Russian ships were "torpedoed" by the Japanese off Port Arthur, but the use of water-tight compartments seems to confine the damage to one part of a warship, and does not put it out of the fighting.

In 1909 the invention of the Davis torpedo gun was announced. Instead of a charge of guncotton in its nose, the Davis torpedo carries a cannon which is designed to go off on striking and sends an eight-inch shell through the armor of the warship. This shell is provided with a time fuse and is charged with thirty-seven pounds of a high explosive. It is expected to explode within the hulk and to convert the finest warship into a mass of twisted junk. Target practice has demonstrated wonderful possibilities of the torpedo gun.

There seems to be a never-ceasing strife between the builders of warships and the inventors of means for destroying them. If the views of torpedo men are to be given weight it is useless to expend millions in building a navy.