g. Breeching-bolts, with rings, through which the breechings pass.
h. Loops, or eye-bolts, to which the gun-tackles are hooked.
i. The fore axle-tree, with its trucks, k.
l. The hind axle-tree, with its trucks, k.
The wheels are firmly retained upon their axle-trees by means of iron bolts passing through the latter without the wheels: these bolts are called linch-pins.
The breadth of the wheels is always equal to that of the cheeks; but the height of the cheeks and diameter of the trucks must conform to the height of the gun-ports above the deck. The carriages of the lower tiers should therefore be so formed, that when the breech of the cannon lies upon the hind axle-tree, the muzzle of the piece should touch above the port, as expressed in fig. 19. which represents a cannon secured by its tackles and breechings, to prevent it from straining the ship as she rolls in a stormy sea.
Cannon are charged by putting down into the bottom first a quantity of powder, one third or one half the weight of the ball. This is done with an instrument, fig. 7. termed a ladle which is a kind of cylindrical spoon, generally made of copper, and fixed to the end of a staff, called its handle. Upon the powder is put in a wad of rope-yarn, formed like a ball, which is pressed down upon the powder with the instrument expressed by fig. 17. called a rammer. Upon this wad is put the ball or shot; and to secure it in its place, another wad is firmly pressed down upon it, which operation is called ramming-home the wad and shot. The touch-hole of the piece is then filled with powder, from the upper-part of which a little train is laid that communicates with it. The use of this train is to prevent the explosion of the powder from operating directly upon the instrument employed to fire the piece, which in that case might be forced out of the hand of the gunner.
In the modern pieces, a little gutter or channel is framed on the upper part of the breech, to prevent the train from being dispersed by the wind. This channel reaches from the touch-hole to the base-ring.
The cannon being pointed to its object, or the place which it is intended to strike, the train is fired, and the flame immediately conveyed to the powder in the touch-hole, by which it is further communicated to that in the piece. The powder being kindled, immediately expands so as to occupy a much greater space than when in grains, and thus dilated it makes an effort on every side to force itself out. The ball making less resistance than the sides of the piece, upon which the powder presses at the same time, is driven out by its whole effort, and acquires that violent motion which is well known to the world.
In plate [VII]. all the instruments necessary for charging cannon are exhibited. Besides these already described, there is the spunge, fig. 10. which is used to clean the piece after firing, and to extinguish any sparks that may remain behind. In the land-service, the handle of the spunge is nothing else than a long wooden staff; but in ships of war this handle, that usually contains the rammer at its other end, is a piece of rope well stiffened by spun-yarn, which is for this purpose firmly wound about it. By this convenience the rammer becomes flexible, so that the piece is charged within the ship, as the person who loads it may bend and accommodate the length of the rammer to the distance between the muzzle and the ship’s side; being at the same time sheltered from the enemy’s musquetry, to which he would be exposed when using a wooden rammer without the ship. To spunge a piece therefore is to introduce this instrument into the bore, and thrusting it home to the farthest end thereof, to clean the whole cavity. The figures 8 and 9 represent spunges of a different kind; one of which is formed of sheep-skin, and the other of the strongest bristles of a hog. See the article Exercise.