“The spar-torpedo is the dagger which a determined man plunges into the body of an enemy who does not protect himself with a coat of mail; the Whitehead torpedo is the bullet which, easy to discharge from afar, kills the enemy in its path.”—Lieut. C. ARNAULT. Although twenty-five Federal vessels are known to have been sunk and destroyed, and nine others more or less injured by various kinds of torpedoes during the great war of secession, the many objections to the employment of the spar-torpedo were only too evident. The necessarily close proximity of the craft attacking and the ship attacked, resulted in some cases in the destruction of the former as well as the latter, and inventive minds therefore set to work to devise a submarine weapon which could be discharged at the enemy from a distance. The result was the automobile fish torpedo, an instrument of warfare which is to be found in every navy, and the sole armament of the modern submarine boat. In a history of under-water warfare, a description of the Whitehead torpedo, which is in reality a crewless submarine boat, must find a place, but a word may be said beforehand respecting the difference between the “Mine” and the “Torpedo.” The mine is a stationary charge of explosive contained in a case moored beneath the surface of the water. The torpedo is a case of explosive, which by some means or other is provided with the power of aggression, either on or below the surface. The mine awaits the enemy, in fine, whilst the torpedo goes to seek him. Into the details of Submarine Mining it is not proposed to enter here. Torpedoes are divided into two classes—(1) Uncontrollable. (2) Controllable. Class I. comprises Projectile, Rocket, Drifting, and Automobile torpedoes; the last named are now practically the only kind of uncontrollable torpedo employed. In nearly all navies the “Whitehead” is the type adopted; the German uses the “Schwartzkopff,” which differs only from the former in that it is made of phosphor-bronze instead of steel. Controllable torpedoes comprise Spar, Towing, Dirigible, Locomotive and Automobile. Great Britain has adopted the Brennan locomotive torpedo for coast defence only, and she still retains the spar-torpedo, although it is doubtful if it would ever be used in a naval engagement. [Sidenote: The Whitehead Torpedo.]