DEFENSIVE TORPEDO WARFARE.--MECHANICAL MINES.--MECHANICAL FUZES.--MOORING MECHANICAL MINES. BY defensive torpedo warfare is meant the protection of harbours, rivers, etc., by means of various descriptions of torpedoes moored beneath the surface of the water. Submarine, or sea mine, is the term that has been generally adopted to designate this particular species of torpedo. _Submarine Mines.--Defence in Future Wars._--The very conspicuous part played by submarine mines, in the many wars that have taken place since the introduction of the torpedo as a legitimate mode of Naval warfare, when their manipulation was comparatively little understood, and construction very imperfect, proves that, with the experience so gained, and the vast improvements that have been, and are daily being effected, in all that appertains to the art of torpedo warfare, the protection of harbours, etc., will in future wars depend in a great measure on the adoption of a systematic and extensive employment of submarine mines. The utility and power of this mode of coast defence has been fully exemplified in actual war, more especially during the Franco-German war (1870-1) and the late Turco-Russian war (1877-8). _Torpedoes in the Franco-German War._--In the former instance, the superiority of the French over the Germans, in the matter of ships, was more than neutralised, by the use on the part of the latter of electrical, mechanical, and dummy mines for the protection of their harbours, etc. In regard to the utility of the latter, it is on record that a certain German port was entirely defended by dummy mines, the Burgomaster of that place having been unable to obtain men to place the active mechanical ones in position, owing to the numerous and serious accidents that had previously occurred in other German ports at the commencement of the war, in mooring the latter kind of submarine mine. The effect, so far as keeping the French fleet at a distance was concerned, was precisely the same, as though active instead of dummy mines had been employed, thus still further proving the vast moral power possessed by torpedoes. _Torpedoes in the Russo-Turkish War._--In the war of 1877, the Turks, though possessing a powerful fleet in the Black Sea and flotilla on the Danube, made little or no use of their superiority over the Russians in this respect. They failed to even attempt to destroy the bridges formed by the Russians over the Danube, nor did they make any attempt to capture Poti, re-take Kustendje, or to create diversions on the Russian coast in the Black Sea. Had the latter service alone been effectually carried out, by which means, a large force of the enemy would have been held in check, immense help would have been afforded to the Ottoman armies in Europe and Asia. Again, during the whole of the war, the Russian port of Odessa was never sighted, and Sebastopol only once by the Ottoman fleet.