Torpedo

Torpedoes are divided into three classes: Mobile Torpedoes are of the Whitehead or Howell type, which possess their own motive power; Auto-Mobile, or Controllable Torpedoes, in which the motive power is furnished by gases and their movements controlled by electricity; Boat or Spar Torpedoes are carried on the ends of spars projecting from the bows of steam launches, and exploded by electricity from the boat, the idea being to push them below the water-line of an enemy's vessel and explode them while in contact. There is also a kind of torpedo called Submarine Mine, which rests on the bottom and is used to defend channels and entrances to harbors. Gun cotton is the explosive used in all naval torpedoes.