Torpedo arranged to Explode by Electricity.
To substitute the electrical method of firing the torpedo for the mechanical one, all that will be necessary is to unscrew the priming case from the centre hole of the mechanical torpedo, and screw in the electrical arrangement which contains McEvoy’s patent circuit-closer, especially adapted by him to suit this particular torpedo.
The electrical arrangement has its own exploding bolt, which differs from the other only below the safety key, which key is fitted and worked in the same manner as the mechanical one, in order that the electrical arrangement might not be disturbed by an accidental blow when launching. The insulated conducting wire is carried along the whole length of the tow-rope in the centre, forming a core. The tow-rope, as in the mechanical one, is bent on to the hemp buoy-rope by a sheet bend, the strands at the end are then unlaid, sufficiently so to form a connection between the insulated wire in the tow-rope and that projecting from the centre hole of the torpedo; this connection can be best made with McEvoy’s patent jointer. The other end of the tow-rope on the barrel of the brake passes through the hollow spindle of the brake at one extremity and is connected with the constant battery, which must be suitable for heating platinum at the distance of 100 fathoms, the return circuit being by the water. The levers act in the same manner as in the mechanical one, forcing down the bolt and thereby closing the circuit through the fuze and exploding the torpedo.
This system of exploding the torpedo may be preferred in rivers or shallow water, where it would be considered dangerous to leave a mechanical torpedo at the bottom; but it cannot be reckoned upon with the same certainty as the mechanical one. It is necessarily more costly, complicated, and delicate; the two latter conditions rendering it unsuited for the rough work it will have to encounter.
The torpedo being provided with this centre tube in addition to the usual priming case, admits of its being used upon an emergency, special ones not being at hand, for various other purposes, viz. clearing away obstructions; as land torpedoes; as stationary torpedoes, provided they are not to remain a very long time in the water. In these cases the ordinary insulated wire and jointers are all that is required. If required to be fired at will, it will be only necessary to force down the bolt sufficiently to close the circuit through the fuze and then secure it. If to be self-acting, leave the bolt up in its position, as when working at sea, to be acted upon by pressure.