This engine has already been so accurately described by a variety of authors, that it may seem unnecessary to give a particular description of it here. As it forms, however, so important an article in all the military operations of the marine, it cannot, consistently with our plan, be omitted in this place.
Cannon then may be defined a long, conical fire-arm of brass or iron, concave within, and smaller at the muzzle, or face, than at the opposite end.
The principal parts of a sea-cannon, as represented in plate [VII]. fig. 3, are, 1st. The breech, A C, and its button, or cascabel, A h, called by seamen the pomiglion. The breech is generally understood to be the solid metal from the bottom of the concave cylinder to the cascabel, which is the extremity of the cannon opposite to its muzzle.
2d. The trunnions, T, which project on each side like arms, and serve to support the cannon near the middle of its length: on these it may be poised, and held almost in equilibrio. As the metal is thicker at the breech than towards the mouth, the trunnions are placed nearer to that end than the other.
3d. The bore, or caliber, which is comprehended between the dotted lines, and particularly expressed in the longitudinal section of a thirty-two-pounder, fig. 15. This represents the interior or concave cylinder, wherein the powder and shot are lodged with which the cannon is charged: the entrance of the bore is called the mouth.
Names of the other parts, including the above plate [VII]. fig. 3.
A B, the length of the cannon.
A E, the first reinforce.
E F, the second reinforce.
F B, the chace.