Description of Lewis's Drifting Torpedo.—"Lewis's" drifting torpedo, designed for the express purpose of destroying booms or other floating obstructions placed round a vessel at anchor for the purposes of defence, is shown at [Fig. 101]. It consists of a box a, containing the charge and fitted with several detonating fuzes. This box is attached to one side of a beam b, and within 6 inches of one extremity, the beam being about 20 feet long and 7 inches square; to the opposite side, of the same end of the beam b a heavy weight c, resting in a shoe d, is attached by a long iron rod e, which reaches to the other extremity of the beam, and is there connected to a bell-crank lever and spring f, a pressure on which detaches the weight c; a chain g, 18 feet long, connects the weight loosely with the upper end of the beam, and another chain h, 9 feet 6 inches long, connects it with a point more than 2 feet below the centre of the beam. The apparatus is so constructed that it floats nearly vertical with the top of the beam just above the surface of the water.

On the machine drifting against the boom or other obstruction, the spring or lever f at the upper extremity is pressed down, thus releasing the weight c, which falling, becomes suspended by the two chains g and h, and brings the beam into an inclined position. The weight of this mass of iron and the chain suspending it are suddenly brought to bear on the top of the beam, dragging it under water and clear of the boom, &c. At the same time the lower end, released from the weight, rises, and the whole apparatus is carried forward by the current against the side of the vessel, on striking which the torpedo is exploded.

Description of McEvoy's Drifting Torpedo.—"McEvoy's" drifting torpedo is intended to be floated, singly or in groups, by the aid of tides or currents against vessels at anchor, bridges, &c.

At [Fig. 102] is shown a plan of this form of drifting torpedo.

It consists of the body of the torpedo a, which contains the charge, at the side of which is placed the loading hole b; c is the tube containing the priming charge; d is the framework surrounding and protecting the wheel or screw e; f is the fuze pillar, in the centre of which is a steel rod g, and on the top a thin steel plate h is placed; i is the nipple for the percussion cap; k is a horizontal bar, turning and resting on top of the fuze pillar f; m is the lever for supporting the hammer n when it is set; l is the screw barrel supporting the wheel or screw e; o is a safety pin; q is the supporting chain, and p the spring for working the hammer n.

By means of a buoy or log of wood, from which the torpedo is suspended, it can be adjusted so that the explosion shall occur at the requisite depth.

To prepare the torpedo for use, unscrew the fuze pillar f, take off the horizontal bar k, place a percussion cup on the nipple i, and screw it tightly against the end of the steel rod g. The fuze pillar is then ready for use, and should be screwed into the body a. Then fill the torpedo with the explosive and close the loading hole b. The hammer n is then set by drawing it back and bringing the end of the lever m against it, at the same time running the screw barrel l under the lever m, so that its end catches the screw of the barrel, as shown in the figure. The safety pin o is then put in its place and secured by a few parts of thread, which by a sharp jerk on the safety line will be easily broken.

[DRIFTING TORPEDOES.]