490 MACHETECHNICS. 



surrounding the muzzle or mouth. The interior cavity is called the 

 bore ; the diameter of which is the calibre of the piece. 



A light brass six-pounder, carrying iron balls of six pounds in 

 weight, has a calibre of 3| inches; and is usually made about 17 

 calibres, or 5 feet long ; weighing about 6 cwt. Mountain pieces, of 

 small calibre, are sometimes made shorter in proportion ; and batter- 

 ing pieces, for sieges, are often made longer ; the weight, in this 

 case, being no serious objection, and the force of the powder being 

 rendered more fully available. The limits of length, for guns, are 

 from 11 to 26 calibres. A brass twenty-four-pounder, has a calibre 

 of 5| inches, and is about 8 feet long ; weighing about 42 cwt. A 

 twenty-four pound carronade, would be about 4 feet long ; and 

 weigh only 13 cwt. A brass howitzer, of 5f inch calibre, is nearly 

 3 feet long, and weighs nearly 8 cwt. ; this kind of cannon being used 

 for firing shells horizontally ; shells which explode like bombs. A 

 brass mortar, of 10 inch calibre, is about 33 inches long, and weighs 

 about 10 cwt. : but mortars of the same calibre, for sea service, are 

 made far heavier. 



The best iron cannon, are cast entirely solid, with the muzzle 

 upward, in a vertical mould formed in the ground : the melted metal, 

 from the different furnaces, flowing down a lateral passage, and 

 entering at the bottom of the mould ; by which arrangement the slag 

 rises more completely, and the metal is more pure. The interior is 

 then bored out, from the solid mass, by means of powerful machinery. 

 The carriage, for field guns, consists of two flasks, framed to the 

 axle tree, and connected by transoms, the breast transom at the front 

 end ; the pointing transom at the base of the gun : and the trail 

 transom at the rear end or trail of the carriage, which, during the 

 firing, rests upon the ground.* When travelling, the trail is raised 

 and rests upon the limber, which resembles the forward wheels, 

 axle, and tongue of a common waggon : the gun then pointing to the 

 rear. Garrison, and sea coast carriages, also consist of two flasks, 

 supporting the gun between them, resting upon its trunnions : but, 

 instead of wheels, they have small trucks, to allow of their recoil; 

 and they are placed on a traversing platform, to admit of their being 

 pointed to the right or left. Mortars, are supported on -a heavy bed, 

 or platform, moveable only by handspikes, or mechanical powers. 

 Of small arms, and their construction, it will be unnecessary here to 

 speak. 



2. The term Ammunition, properly signifies the various mate- 

 rials which are used in loading fire arms : but, in a wider sense, it 

 may comprehend various other combustibles, used in warfare ; the 

 preparation of all which constitutes the art of Military Pyrotechny. 

 Gunpowder, is a mechanical mixture of nitre, sulphur, and charcoal; 

 which owes its efficiency to the sulphurous acid, carbonic acid, and 

 other gases, which it generates in exploding. That which is used 

 for war, generally contains six parts by weight of nitre, to one of 

 sulphur, and one of charcoal. The purified and pulverized materials, 



* In the more recent gun carriages, the flasks, called cheeks are shortened ; and a 

 piece of squared wood, called the stock, is inserted between them, the curved extre- 

 mity of which forms the trail. 



