Firing a Torpedo from the Surface.—The torpedo possesses sufficient buoyancy to float with a small portion of its upper surface above water; such being the case, it is only necessary to set the various adjustments, point it in the required direction, and by hand turn back the lever on the upper part of the weapon (which opens a communication between the air chamber and the engines), when it will instantly dart off and very rapidly attain the depth it is set for.
Method of Firing a Fish Torpedo from a Boat.—To manipulate a fish torpedo from a boat, it may be carried in a light frame, which can be lowered or raised by means of a pair of davits. When required to discharge the torpedo, the frame containing it is lowered into the water, so as to bring the torpedo about two feet below the surface, the head being somewhat lower than the tail.
Thornycroft's Method of Firing Fish Torpedoes from a Boat.—Another method, which has been patented by Mr. J. I. Thornycroft, of the firm of J. I. Thornycroft and Co., steam launch builders, and which is fitted to the torpedo boats built by them for foreign governments, is shown in elevation and plan at [Fig. 120] and [121].
The apparatus consists of two or more bent levers A securely and rigidly fixed on a shaft B, which works in bearings fixed on the deck of the vessel C from which the torpedo is to be discharged. On the ends of the levers A furthest from the shaft B are pivoted other levers D, to which the cradle or case E for sustaining the torpedo is suspended. The other ends of each of these levers are connected to the vessel by means of rods or tubes F, jointed at each end in such a way that when the shaft B is made to revolve in its bearings, the case containing the torpedo is guided over the side of the vessel and close to it, and is held in a position convenient for discharging the torpedo, as shown at [Fig. 120].
The shaft B may be made to revolve by means of ropes G and pulleys H attached to the levers A, or by hydraulic or steam pressure, as may be found most convenient.
The torpedo case can be towed alongside the vessel if necessary without deranging the apparatus. The torpedo case is carried in the angles of the bent levers, and is stowed away so that neither it nor the suspending levers project at all beyond the hull of the vessel; also when lowered, the levers and suspending rods fold over one another so as to occupy very little space, and the torpedo is suspended close to the hull.
Also the torpedo during the operation of lowering as well as when in a firing position remains close to the side of the vessel, thereby obviating any risk or inconvenience from excessive leverage which would have a tendency to capsize the boat.
For especially built torpedo launches, the above mode of carrying and launching the fish torpedo is certainly the best yet devised.
Woolwich Fish Torpedo.—In the Woolwich torpedo, the engines exert a force of nearly 60 indicated horses, and work up to 1000 revolutions per minute; the total weight of the torpedo fully charged (33 lbs. of gun-cotton) is about 500 lbs.