CANNON (continued)

The metal of cannon is not equally thick in all parts, but is in some measure proportioned to the force of the powder which it is to resist. At the breech, where the effort is strongest, the thickness of the metal is equal to the diameter of the corresponding shot. At the first reinforce, where this begins to slacken, the thickness is somewhat less than at the breech:

at the second, where the force is still further diminished, the thickness is more reduced than at the first: and, by the same rule, the chase has less thickness than the second reinforce. The thickness of the chase gradually diminishes from the trunnions to the mouth of the piece; so that if a cannon was without cascabel, trunnion, and mouldings, it would exactly resemble the frustum of a cone, or a cone deprived of the small end.

In a vessel of war, cannon are placed on a sort of wheeled sledge, called the carriage, of which fig. 16. plate VII. is the plan, and fig. 17. the elevation. This carriage is composed of two large pieces of plank, called sides or cheeks, connected together by means of cross-pieces, which are either, bolts, axle-trees, or transoms. The two axle-trees are fixed across under the fore and hinder parts of the carriage, being supported at their extremities by solid wooden wheels called trucks. The transom is placed directly over the fore axle-tree, and exactly in the middle of the heighth of the cheeks or side-pieces. The heighth of the transom is equal to two diameters of the shot, and the breadth to one diameter.

Plate VII

Reference Works