12 | 6 | 2 8 | 1 0 | 205 | 1000 | -- ---------+-------+-------+------------+------+-------+---------- Brass guns are invariably lighter, and considered less likely to burst. Gun metal, technically so called, is a compound of copper and tin, in the proportion of five, eight, and ten pounds of the latter to 100 pounds of the former. The peculiar property of the tin is to give hardness and solidity to the mass. The greater proportions are used principally for mortars, as they require a greater degree of hardness than other guns. A peculiar property attaches to the using of brass guns. If a considerable number of rounds be fired in rapid succession, the bore of the gun becomes to a certain extent elliptical. This peculiarity arises entirely from the extreme windage allowed by the present established rules of British gunnery; and is produced by the tendency of the shot, when propelled by the explosive force, to strike upwards from the breech, and then rebound downwards, and so on till it reaches the muzzle. Iron guns are not liable to this (although the same cause exists) from the unductile nature of the cast iron. Brass guns are, after certain use, recast: this is done solid, with the cascable of the gun downwards, to give a greater density to the metal at the breech. The boring and turning are performed simultaneously by a very simple arrangement. At the siege of Badajos, the firing continued for 104 hours, and the number of rounds that each gun fired averaged 1,249; and at the siege of Sebastian, the quantity fired by each gun was about 350 rounds, in 15-1/2 hours. These guns being of iron, none of them were rendered unserviceable; though three times the number of brass guns would not have been equal to such long and rapid firing. All brass guns are bouched with a bolt of copper at the vent, on the same principle as flint guns for sporting were formerly with gold or platina; copper withstanding the rapid escape of the flame better than the gun-metal. The charges, ranges, &c., are as follows:-- EXTREME AND POINT BLANK RANGE OF BRASS ORDNANCE, CHARGE, &C.