No new torpedo invention should be adopted, however theoretically perfect it may be, until it has been subjected to a very severe practical test, under conditions as nearly analogous to those that would occur on active service as it would be possible to obtain. The vast importance of a carefully planned and executed system of submarine _defence_ is an established fact, and it only remains to discover what are the best weapons for, and most practicable mode of manipulating a system of submarine offence, to establish torpedo warfare in all its branches as a necessary function of naval warfare. It would be a mere waste of time to dwell on the Anglo-French and American wars of the beginning of this century (1797-1812); though during that period various attempts were made by Fulton and others to destroy hostile vessels by means of submarine infernal machines, inasmuch as they all partook more or less of the nature of experiments, and were all failures, but come at once to the Crimean war (1854-1856), when what may be termed a systematic employment of torpedoes for harbour defence was first employed. CRIMEAN WAR (1854-56). _Defence of Sebastopol Harbour, &c._--The Russians employed a large quantity of submarine mines, both electrical and mechanical, principally the latter, in their defence of the harbours of Sebastopol, Sveaborg, and Cronstadt. According to General Delafield, U.S.A., the arrangement of the mechanical mines was entirely new, the conception and idea of an eminent Russian chemist, Professor Jacobi. _Electrical Mines._--No mention is made by the General of the employment of electrical mines, but the fact of a hulk being captured by the Allies at Yenikale, with a number of torpedoes on board, and all the arrangements necessary to explode them by electricity, such as Voltaic piles, electric fuzes, several miles of conducting wire, &c., is sufficient proof of this type of submarine mine being extensively used by the Russians in their harbour defences. Many of their mechanical mines were picked up by the Allies, several of which were found to have their safety caps on. Owing to this neglect, and the smallness of the charge of the torpedoes (only some 25 lbs. of gunpowder), it is not to be wondered at that no serious injury was done to any ships of the allied squadron. Deterred most probably by the failures of Bushnell, Fulton, and others in previous years with the submarine and other torpedo boat attacks, nothing of this description was attempted by either side. _Russian Mechanical Mines._--The Russian mechanical mines consisted of barrels of powder fitted with fuzes, so arranged that a blow would smash a glass tube containing sulphuric acid, causing the acid to mix with some chlorate of potash, resulting in combustion and the explosion of the mine. AUSTRO-ITALIAN WAR (1859).