1.—Increased flexibility.
2.—A greater length of cable may be coiled in a given space.
3.—A thicker coat of insulating material may be used, thereby more perfectly insulating it.
4.—It is much cheaper.
Two rudders are generally used, one below and one above the boat, as shown at U, [Fig. 122]. These rudders are operated and controlled by means of a small auxiliary engine T, [Fig. 122], which is started, stopped, and reversed by the electric current conducted through the cable Q in connection with magnets attached directly to a valve forming part of the said engine. This valve is so actuated by the magnets that when the current passes in one direction the engine T will move the rudder to starboard, and when the current acts in the opposite direction it will turn the rudder to port.
The mechanism for firing the charge in the magazine A1 is clearly shown in [Fig. 124], and operates as follows:—Projecting from the front extremity or stem of the boat is a rod or pin V, which extends through a suitable packing box W into the said magazine or charge chamber; when the boat strikes an object, the said rod is forced inward into contact with the springs or points X, thereby closing an electrical circuit and igniting a cartridge, shown at Y, in the magazine.
The charge in the magazine can also be fired at any moment by the operator on shore closing a circuit on the keyboard and thereby cutting out one of two resistance coils placed in the circuit to prevent accidental or premature discharge—that is to say, there are two resistance coils. The battery is not sufficiently powerful to fire through both resistance coils at the same time. When the boat strikes an object, the resistance coil in the magazine is cut out by the driving inward of the rod V, as above described; the battery then fires through the one on the keyboard. On the other hand, if the operator desires to fire the torpedo boat before she touches the object of attack, he manipulates the switch to cut out the coil in the keyboard, the charge then being fired through the coil in the magazine. This arrangement of the two resistance coils is very effectual in preventing accidents.
In some instances the magazine is made detachable from the hull of the boat, so that on striking an object it will descend or drop down in the water before exploding. This modification is shown at [Fig. 125] and [126].
The magazine A* is attached at its lower side to the boat by a chain or other suitable connection. At its upper edge it is held by a rod a*, as shown in [Fig. 125]. This rod is fitted to slide in dovetailed bearings, as shown at b*, and when this magazine is in its place on the boat the said rod is engaged with a catch or stop c*, but when the said rod is driven against any object it is forced back and released from the said catch or stop, and the magazine then drops, as in [Fig. 126], and is fired.
To effect the firing a ball d* is used and placed in a tube containing two springs or plates e* and arranged in an upwardly inclined position, as shown in [Fig. 125], one of the said springs being connected with the cable and the other with a wire that passes through the cartridge to earth.