TORPEDO. During the war between Great Britain and the United States in 1812-14, this name was applied to certain mysterious boats invented by Fulton and other Ameri cans for the purpose of navigating beneath the surface of the water, and injuring the bottoms of hostile vessel's. In those days of hand-to-hand naval war, these designs (which, by the way, were failures) were looked upon as little less than diabolical. The progress of destructive weapons during half a c. has removed this aversion. The modern torpedo is of two kinds—first, the locomotive torpedo, which is in various ways projected against the side of a hostile vessel; secondly, the fixed torpedo, a kind of sta tionary bomb-shell intended to explode under the bottom of the enemy's ship. To these fixed torpedos it is now more usual to give the appropriate name of submarine mines.
The weapon was first used by the Russians in the Baltic in 1854; but in the Ameri can war of secession of 1861-65 it was extensively and often successfully employed. The damage effected by a torpedo exploding beneath a ship is very great, but the fail ures are very frequent by the explosion happening at a wrong moment. In the Franco German war of 1870-71; the French fleet was effectually scared from the Prussian ports by the dread of torpedos. Torpedos were much employed in the Russo-Turkish war of 1877.
Of fixed submarine mines there are two classes—those which are self-explosive on a ship touching them, and those which are dependent on an electric current supplied from the shore. A torpedo of the self-acting class is shown in fig. 1: abe is a hollow iron cone, water-tight, with a ring at b by which to anchor it. The upper part, B, is left empty, for the sake of buoyancy, while the lower end, A, is filled with gunpowder, the charge varying from 100 to 300 lbs. At the top of the powder is an iron case, C, filled with lime, and in it a tube of thin glass, D, containing sulphuric acid. The upper part of the glass tube is enveloped by the ringed end of the iron rod, E, which passes through the top of the torpedo, and some distance above it; and has horizontal rods, G, called feelers, attached rigidly to its upper extremity. When a ship impinges on the feelers, the rod is deflected from the perpendicular; the ring at its lower end breaks the glass tube; the acid acting on the lime, generates great heat, and explodes the powder.
In the tivetric torpedo a wire insulated in a small cable is laid from a battery on shore to the sub-marine mine. It enters it by an insulated joint, and is then soldered to a small piece of platinum wire placed in the middle of the priming of the torpedo; from the other end of the platinum a second wire municates with the metal sides of the torpedo case. On closing circuit at the battery, the current passes by the cable into the torpedo, heating the platinum to incandesceuce,and exploding the mine. There is thus no need of a second cable; the water and the earth take its place. Submarine mines are usually charged with gun-cotton, which has the great advantage of being explosive by means of a fulminating fuse, even when wet through leakage of the torpedo case.
bubmarine mines are usually moored or laid on the bottom in several lines, the mines of the second line being opposite the intervals of the first, so that it is diflienit for a hostile ship to pass np a defended channel without coming within reach of one or more of them. As a ship approaches, her course is carefully watched so as to fire a mine at
the right moment. In order to explain how this is done, let us take the case of the channel AB.
Two or more lines of mines are laid down across its mouth. For the sake of clearness we show only a few of those of the first line in the diagram. At C and D two stations are selected, commanding a view of the defended waters. At C is the voltaic battery, and the wires from the mines connect them with D, while a second series of wires, each corresponding with one of the first series, connects D and C. There are thus two breaks in the circuit of every mine, one at C, where a number of "firing keys" are arranged so as to place at will the battery in connection with any of the wires; the second break is at D, where similar firing-keys connect at will each wire of one series with the corre sponding wire of the other. A ship is seen approaching on the course AB. When she is at a the observer at C. notices that her bearing is the same as that of mine No. 1. He therefore closes the break in the first circuit by means of the firing-key, but no current passes, for the observer at D sees her well to the left of the bearing of mine No. 1, and therefore leaves his break open. Not until she is actually over No. 2 will both observers at the same moment see that her bearing corresponds to that of No. 2. and both breaks in the circuit, fire the mine. By means of a telescope combined with the firing key, these bearings can be taken with great accuracy. In some cases the ship herself is made to close the circuit in striking a rather complicated apparatus called a circuit closer, which floats above each of the mines arranged on this system.
Of locomotive torpedoes there are three classes: (1.) The Whitehead fish torpedo, which has a fish-shaped case, and is propelled in a straight line under water by means of a small screw propeller driven by compressed air. It is discharged from a carriage on the deck of a man-of-war, and explodes on impact against the object aimed at. The secret of the construction has been sold by the inventor to the Austrian, Russian, and English navies. (2.) The Harvey "towing torpedo." which is towed out at an angle from the side of the attacking ship, and maneuvered so as to come in contact with the Lottom of the ship attacked, It. is exploded either mechanically on contact, or by means of an electric fu'e, the wire being inserted in the towing line. (3.) Boom or out rigger torpedoes, which are carried on long booms in the bows of boats or steam launches, and tints driven against the side of a hostile ship and exploded. Torpedo boats are becoming a special feature of European navies; they are swift steamers not more than 60 ft. long, lying low in the water, and steaming up to 19 knots an hour. Admiral Porter has designed for the American navy an ocean-going torpedo steamer of larger size, but similar build.
For fuller information on this wide subject, see "Torpedoes" in Fraser's Magazine, April, 1872; and the illustrated articles by A. H. Atteridge and cap. Dede Brown in the PaRular Science Review, April, 1873 and Oct. 1875; also the illustrations it the 111u-strata .London News, June 16, 1877.