Page:Encyclopædia Britannica, Ninth Edition, v. 11.djvu/327

GUNNERY 311 countries. Wrought iron is rapidly supplanting wood in the construction of carriages, and there are signs that it will in its turn be in great measure superseded by a mild steel. The subject of gun carriages is too long and too complicated to be treated in detail here, but, as guns are of no use FIG. 38. 9-pounder Field Gun Carriage (elevation). without carriages from which to fire them, it is necessary to give some idea of the chief modes of mounting modern artillery. Figs. 38, 39 show the details of the 9-pounder rifled muzzle-loader carriage. It consists of three parts, the wheels, the axle, and the trail. The wheels have oaken FIG. 39. 9-pounder Field Gun Carriage (plan). spokes and ash felloes, the tire is of wrought iron, the nave and pipe box (which holds the end of the axletree arm) of a mixture of copper, tin, and zinc. The dish is consider able, amounting to 2 inches in the 5-foot wheel. There is little strut, so that the lowest spoke is nearly vertical, and the tire forms a frustum of a cone, instead of being a Field cylinder. The object of this form is to obtain lateral S un ca: strength, especially in travelling on uneven ground. The nng< axletree bed is of wrought iron, constituting, with the axle, a beam of box-girder section, the axletree forming the bottom. The trail consists of two side brackets, fixed by FIG. 40. 9-pounder Limber (elevation). two transoms, two bolts, and the trail piece carrying the trail eye. The brackets are made of plate iron, riveted to a frame of angle iron. The axle carries two seats for gunners ; into the trail are fitted the elevating screw and wheel, and the drag shoe with chain hangs below. Fig. 38 shows the gun and carriage in the firing position ; when it is desired to move it to any distance exceeding a FIG. 41. 9-pounder Limber (plan). few yards, the point of the trail is raised, the limber is brought up, the trail eye is passed over the limber hook and keyed fast. The gun carriage and limber then form a four- wheeled vehicle, and travel as such. Figs. 40, 41 show the limber, which consists of wheels and axletree similar to FIG. 42. 9-inch Gun Wrought Iron Carriage and Dwarf Platform. those of the gun carriage, ammunition boxes, platform, and a pair of shafts. In the British service each gun carriage and limber are drawn by three or four pairs of horses, according to the nature of the piece. The driver of each pair mounts the near horse ; the off wheel horse is between the shafts. In some countries pole draught is preferred. Fig. 42 shows a 9-inch gun mounted on a wrought iron

carriage and dwarf platform. This arrangement may be