Caisson

In gunnery, is a carriage used for conveying ammunition for a field battery. It is a four-wheeled carriage, consisting of two parts, one of which is a limber similar to that of a gun-carriage, and connected in a similar way by a wooden stock and lunette. On the axle-body of the rear part, and parallel to the stock, are placed three rails upon which are fastened two ammunition-boxes, one behind the other, and similar to the one on the limber; so that the cai on has three ammunition-boxes, which will seat nine cannoneers. The interior compartments of the ammunition-boxes vary according to the nature of the ammunition with which they are loaded. In the rear of the last box is placed a spare wheel-axle of iron, with a chain and toggle at the end of it. On the rear end of the middle rail is placed a carriage-hook similar to a pintle-hook, to which the lunette of a gun-carriage whose limber has become disabled may be attached, and the gun carried off the field. The cai on has the same turning capacity and mobility as the gun-carriage, so that it can follow the piece in all its manœuvres, if nece ary. It also carries a spare wheel, spare pole, etc. See Ordnance, Carriages for, The Cai on .