Whether this combination would prove effective, has yet to be seen, but the buoyant mine alone was considered one of the most dangerous used by the Confederates.
Singer's Mechanical Mine.—An elevation and section of this form of mechanical mine is shown at [Fig. 10]. It consists of an air chamber a, and a powder chamber b; in the latter is fixed a rod of iron c, one end of which rests in a cup formed in a lug d, where there is a screw by means of which the rod c may be screwed against the bottom of the torpedo case, on the interior. In the cup is placed the fulminating substance. A heavy cast iron cap A B rests upon the top of the case and is prevented from falling off by a low rim of tin, which enters an aperture in the cap as at e: a wire f connects this cap with a pin g, which keeps a plunger h at rest. The head of this plunger h is directly beneath the bottom of the rod c, within the case; by means of a spring i, directly the pin g is drawn out, which is done by a hostile vessel striking against the mine and knocking off the cap A B, the plunger h is forced against the bottom of the case and drives the rod c into the cup containing the fulminate, and so explodes the torpedo. The case of these mines, as used by the Confederates, was formed of tin, and they contained from 50 to 100 lbs. of powder. A safety pin k is provided to prevent a premature explosion due to the pin g being accidentally withdrawn.
This form of submarine mine was one of the most successful and most extensively employed of all, on the part of the Confederates.
Though no accidents are stated to have occurred in placing this mine in position, yet the fact of the iron rod c having to be fixed for action, and that close against the interior of the bottom of the case, before the charge of powder has been put in, is an element of great danger, for a comparatively slight blow beneath it, which might easily occur in transport, etc., would explode the torpedo prematurely.
McEvoy's Improved Singer's Mine.—To obviate this defect Captain McEvoy has designed an improved mode of ignition for Singer's mine. This is shown at [Fig. 11]. The form of case, and arrangement of heavy cap are similar to those in Singer's mine. The mode of ignition is as follows:—In the powder chamber b is fixed a friction fuze f, which by means of a piece of wire secured to a length of chain k, k, is connected with the heavy cast iron cap A B. The piece of wire passes through a diaphragm of thin metal h, which is soldered all around, thus forming a complete watertight joint. Premature explosion is prevented by passing a link of the chain, through a slot in the bolt c, securing it there by a pin of bent wire l. The dotted line of chain k, k, shows its position during the process of mooring this form of Singer's torpedo. The manner of lowering this and also Singer's mine is shown at [Fig. 12]. A buoy x, is attached by means of a line, in the former case to the pin l, [Fig. 12], in the latter case to the pin k, [Fig. 10], the pulling out of either, sets their respective mines in action.
SINGER'S AND McEVOY'S MECHANICAL MINES.
Mathieson's Cement Safety Plug.—In the place of the safety pin l, [Fig. 11], employed by Captain McEvoy in his improved form of Singer's mine, Quartermaster-Sergeant Mathieson, late Royal Engineers, employs a plug or disc of soluble cement, so arranged that the action of the sea-water after the mine has been placed in position destroys the plug or disc, and so frees the chain which is connected with the fuze and the heavy cap of the torpedo. This plan does away with the necessity of using a buoy and line as shown in [Fig. 12], and also affords ample time for the men engaged in mooring the mine to get far away before it is ready for action.
Mechanical Mine.—The extempore mechanical submarine mine, shown at [Fig. 13], will be found to possess all the qualities which are necessary to a perfect mine of that description.
It is extremely simple, it can be readily and quickly made, all the materials of which it is constructed are at hand on board every man-of-war, and it is certain in its action.