4.—Mode of attaching the spar simple and very secure.

[LAY'S LOCOMOTIVE TORPEDO.]

In [Fig. 142], a is the case, capable of containing some 33 lbs. of gun-cotton; b is the tube through which the three wires w, w1, and w2 are led; c is the socket in which the wooden or steel spar is introduced and secured, d is the striker, which is attached to a brass contact plate within the head of the case a in such a manner that any pressure either on the head or side of the striker d will force the aforesaid plate in contact with the two studs to which the battery wires are attached; e is a cradle affixed to the striker d to ensure its action on contact being made by the torpedo with the attacked vessel; the explosive is inserted at f, the socket c being made to screw on and off.

When a hollow steel spar is used, the battery wires are sometimes led through the interior of the torpedo and the spar, by which means they are well protected; the only objection to this method of leading the wires being the probability of injury to them, should the spar be broken on contact, or by a shot.

McEvoy's Arrangement of Torpedo Wires.—At [Fig. 143] is shown the arrangement of wires as devised by Captain McEvoy, whereby the spar torpedo may be exploded at will or on contact. c and z are the poles of the firing battery, to which are attached respectively the wires d and d2; f is the fuze, which is placed in the centre of the charge, and to the poles of which the wire d2 is attached, the other end of this wire being connected with the stud s; to the stud s1 is attached the other end of the wire d, and at the point c in the same wire is inserted a contact breaker; another wire d1 is connected to the wires d and d2 at the points r and r2 respectively, and at the point k in this same wire is inserted a firing key, which latter is shown in section at [Fig. 144], from which the mode of connecting the two ends of the wires and of using the key will be at once apparent. The contact breaker is somewhat similar to the firing key, but there is no spring in it, contact being made or broken by screwing the two parts together or apart. The object of the contact breaker is to prevent the torpedo being exploded by contact, and so to place the control of the weapon entirely in the hands of the operator. As will be seen from [Fig. 143], if contact is broken at c, it is impossible to fire the torpedo unless the firing key k be pressed in; but should contact be made at c, then either by means of the firing key k, or by the torpedo striking the hostile vessel, its ignition will be effected.

The foregoing method of arranging the spar torpedo wires is certainly very neat and effective, and is at the present time in extensive use. As yet it has not been adopted by the English government, they still preferring to fire the spar torpedo at will alone.