Recovering the Torpedo.—Should the safety key have been withdrawn, great caution is necessary. Tongs, shown at [Fig. 109], for going round the upper part of the bolt, to take the place of the safety key, when once clasped and secured round the bolt, render the torpedo safe to handle; this could only be done from a boat. With the safety key in, there is no danger in hoisting it inboard again by its own tow rope, and hoisting up the buoys at the same time with a grapnel.
Different Methods of Using the Torpedo.—There are two methods of employing the torpedo, either of which may be adopted, according to circumstances.
1.—When it is towed with a length of line varying from 25 to 60 fathoms, and dipped when in position to strike the attacked vessel.
2.—When it is kept suspended from the yard, &c., and dropped at the spot, where according to the first method it would have been dipped.
In the first method, it is not necessary to withdraw the safety key till just before dipping; in the second method the safety key line is belayed at about twenty fathoms, and the key withdrawn when the line is tautened by the ship going ahead.
Tactics.—Description of the various attacks that may be made with the Harvey torpedo against a ship at anchor or under way. In the following diagrams T is the torpedo vessel, S the ship attacked.
Attacking a Vessel moored Head and Stern.—In this case the torpedo vessel steers in for the bow or quarter of the vessel attacked, according to the direction of the current, and on the side approached launches the torpedo between the moorings, as at A; leaving the tow rope slack, the torpedo vessel proceeds ahead or astern against the current, and when at a sufficient distance off, the tow rope is held fast, which will cause the torpedo to diverge into contact with the vessel attacked, as shown by [Fig. 110].
Attacking a Vessel at Anchor by Crossing her Bow.—In this case the torpedo is sufficiently diverged when near to the vessel with a good scope of tow rope out. After having crossed her bow, proceeding onwards, the tow rope will be brought obliquely across her cable, and the torpedo will swing into her, as shown at [Fig. 111]. It may be here remarked, that in all cases the depth of the explosion can be obtained by the sudden slacking of the tow rope; and the tow rope once under the keel, causes the torpedo to be hauled down near to it before exploding.