_Austrian Method of Mooring._--This method of mooring, adopted by the Austrians during the war of 1866, is shown at Fig. 47. It consists of a wooden triangular platform on which several heavy weights _a_, _a_, _a_ are placed; the mine is attached to this platform by means of three wire ropes _b_, _b_, _b_, connected to the angles of the latter, and fastened to three chains, which by means of a catch holds the mine at the position required. This catch consists of a pulley attached to the extremity of the wire rope of the platform, through which the mooring chain of the mine is passed, and fastened by a key at the required depth by means of a self-acting arrangement. This key, which is of considerable weight, slips down as the mine is being hauled into position, but the moment the chain is slacked, two arms catch into a link of the chain, and so hold the mine in position. The weight of such a key is about 60 lbs. It is fitted with nuts, &c., to enable it to be taken to pieces. This plan of mooring proved very effective in the harbours of the Adriatic, where there is hardly any tide or current to twist the mooring ropes, or otherwise disturb the mines. The Austrians have lately adopted the mushroom sinker in place of the wooden platform and weights, for their anchor. _Single Rope Mooring._--This simple method of mooring has after numerous exhaustive experiments been adopted as the most practicable and effective of all others. Whenever possible, a wire instead of hempen cable should be used to connect the mine and its circuit closer to the mooring anchor, as the former is less liable to twist, kink, or wear from friction than the latter. A ground mine with circuit closer attached is represented at Fig. 48, where _a_ is the wire mooring rope, _b_ the electric cable leading from the mine to the circuit closer, _C_, and _c_ the cable leading from the firing station to the mine; _d_ is the oblong sinker attached to the mine, and _e_ the tripping chain leading to the shore, to which the cable _c_ is attached at intervals, so that by underrunning the electric cable, the tripping chain may be easily picked up, and the mine raised. [Illustration: MOORINGS FOR SUBMARINE MINES. PLATE XI] At Fig. 49 is shown a buoyant mine. The only difference in the mooring of this and the one before described, is that instead of resting on its anchor on the ground, it is moored at a certain distance above its anchor _d_, to which it is secured by a chain _e_. Fig. 50 represents an electro contact mine. _M_ is the mine with circuit closer enclosed, _a_ the wire mooring rope, _d_ the mushroom anchor, and _b_ the electric cable leading from the mine to the disconnector _D_.