The notion of destroying ships or other structures by explosions of gunpowder, contained in vessels made to float on the surface of the water, or submerged beneath it, is not of very modern origin. Two hundred and fifty years ago the English tried “floating petards” at the siege of Rochelle. During the American War of Independence similar contrivances were used against the British, and from time to time since then “torpedoes,” as they were first termed by Fulton, have been employed in warfare in various forms; but up to quite a recent period the use of torpedoes does not appear to have been attended with any decided success, and it is probable that but for the deplorable Civil War in the United States we should have heard little of this invention. During that bitter fratricidal struggle, however, when so much ingenuity was displayed in the contrivance of subsidiary means of attack and defence, the torpedo came prominently into notice, having been employed by the Confederates with the most marked effects. It is said that thirty-nine Federal ships were blown up by Confederate torpedoes, and the official reports own to twenty-five having been so destroyed. This caused the American Government to turn their attention to the torpedo, and they became so convinced of the importance of this class of war engine that they built boats expressly for torpedo warfare, and equipped six _Monitors_ for the same purpose. It has been well remarked that the torpedo plays the same part in naval warfare as does the mine in operations by land. This exactly describes the purpose of the torpedo where it is used defensively, but the comparison fails to suggest its capabilities as a weapon of offence. There are few occasions where a mine is made the means of attack, while the torpedo readily admits of such an employment, and, used in this way, it may become a conspicuous feature of future naval engagements. Many forms of this war engine have been invented, but all may be classified, in the first place, under two heads: viz., stationary torpedoes, and mobile or offensive torpedoes; while independent distinctions may be made according to the manner of firing the charge; or, again, according to the mode of determining the instant of the explosion. The stationary torpedo may be fixed to a pile or a raft, or attached to a weight; the offensive torpedo may be either allowed to float or drift against the hostile ships, or it may be propelled by machinery, or attached to a spar of an ironclad or other vessel. The charge may be fired by a match, by percussion, by friction, by electricity, or by some contrivance for bringing chemicals into contact which act strongly upon each other, and thus generate sufficient heat to ignite the charge. The instant of explosion may be determined by the contact of the torpedo with the hostile structure (in which case it is said to be “self-acting”), or by clockwork, or at the will of persons directing the operations. In some