ORDNANCE. All 'great un9 used in War, such as cannons, howitzer; and inortars, are called by the general name bf ordnance. t,he materials of which ordnance it formed are iron and brash, properly bionic, the latter metal being Composed of and tin, iii the Prepetti'cin of front S to 12 parts of tin to 100 parts of copper. Iron guns are stronger than those made of brass, and conse quently they are better able to resist the effects of the long-continued firing which takes place at the sieges of fortresses. Biass guns, on the other hand, being lighter, are more eon veniently transported from place to place with troops in the field. Ordnance is now cast either in loam or in dry sand ; a model, or pattern,, of the gan„being made of Wood or brass, about Which the Mould is formed. In twelve hours after being 'Cast the mould May be removed and the giui itiay be bored. Iron pins are Cast from pig-metal of different •quidities, wiiich are melted tegethei in order to produce a possessing only that degree of harchiest Which Will permit the boring to be effectecL .Ordnanee of cast-iron and of gun-metal being apt to furl at the Vent in consequence of the heat Produced by rapid firing, the vent hi 'guilt of cast-iron is drilled in a bolt of ivronght-iron, and in thnse Of gun-metal hi a bolt, of pure copper; the bolts are then screwed into the piecei for Which they were intended.
The length Of a Cannon it divided into six parts 'Which it behiiid the base ring (the Of greatestdiaineter) at the larger i end is called the easeable ; and froth the base ring to the next rrionldings towards the smaller end, is the vent field. The two succeeding portions, separated one another by a moulding, are called the firSt and second l'ein Arce ; and near the extremity of the latter are situated the tractions, two Cylinders at right angles to the axis Of tho gin, and by which it rests oh lit carriage. Froth, the "Second rein rofce moulding to 'another near the smaller extremity of the gun is the chase, and the last portion is called the • muzzle. The hollini of the gun is called the bore, and the diameter of the bore is designated the calibre of the piece. It has of late been found practicable to di minish etinsiderablY the quantity of Metal in iron guns ; and for this 'Minato 'genie of the Ordnance then existing Was icaniedyp (scraped Vat), so as to bring ditch kitid Of grin to the next highest 'Calibre: Thus the old lion fl-Poiiiidere hint been converted into 9-pbuild ers; 18-petuidert into and so on.
The applicatieli of leeks to naval ordnance was introduced by Sii Charlet Douglas, and their efficiency has since been fully recognised. A lock carrying 'bye Midi; invented by Lieut. Gen: Sir Howard Defiglasi in 1818, was after Wardi introthiced, and Percussioh locks are nevi much uteri in the British service.
The following are the lengtlifi 'and' i'veighti of different kinds of iron and brash bidnance, known by particular nam6S The carriages for ordnance are of several kinds, according to the nature of the gun or the manner in which it is employed. Field gun-carriages consist of two cheeks, or side pieces, of elm, firmly attached together by transoms, and resting on the axle-tree of the wheels ; the trail; consisting of a solid piece of oak, is firmly attached at one end to the side pieces, near the and its other ex tremity rests on the ground when the gun is in a state for action, The limber is a bed, With shafts, mounted on two wheels, and car rying two ammunition boxes for the service of the gun ; the horses are harnessed to the limber, and the gum with its carriage is drawn after the limber. An ammunition waggon also accompanies each piece of ordnance, and there are others always in reserve. Field howitzer carriages and their limbers are similar to those just mentioned, but stronger, and the cheeks of tht carriage are farther asunder. The tra Yelling carriages for siege•ordnance are made wholly of oak, and the limber carries no am munition. Carriages for garrison service and for the navy consist of two short cheeks or brackets, connected by transoms, and they move on four truck-wheels. Mortars are placed upon solid beds of wood or iron, which are made as heavy as is consistent with the power of transporting them from place to place, for the sake of obtaining steadiness when the piece is fired.