The wheel department is one of the most interesting sights in the Arsenal. Here the most ingenious machinery has been brought together to insure sound and speedy production. Formerly the wheels were made entirely by hand; now they are turned out without the aid of a single skilled wheelwright. What is called the copying process, produces the nave and spokes of the wheel, three or four of which are seen working side by side, and the whole batch under the care of only one man. The circular rim of the wheel, or felloe, is cut out of the solid block by an ingenious ribbon-saw, imported from France. This saw is merely a narrow band of steel, toothed on one edge and running over a wheel like an ordinary leathern band attached to shafting. The exquisite manner in which it fashions the most intricate patterns from thick slabs of wood is really surprising. The felloes, after being thus roughly formed, are stacked to season in a shed by themselves, where they are piled one upon the other in vast pillars, down vistas of which the visitor passes, full of amazement at their number. There are at present in store some sixty thousand of these felloes and an equal number of naves, with their due complement of spokes. As wheels are required, their component parts are brought to the shop, finished and mortised by machinery, and then lightly adjusted to each other. They are immediately placed within the grip of six hydraulic presses, which are so arranged as to thrust towards a common centre. Directly the wheel is adjusted within them, you hear the hiss of the resistless engines, whose motive power is only a few pints of water; the solid timbers groan, the joints painfully accommodate themselves to each other, and in less time than the process takes to describe, the wheel is lifted out solidly jointed, and only awaiting the tire to travel at once under its superincumbent gun. The wheels of gun, limber, and ammunition carriages are all made of exactly the same size, in order that they may be interchangeable in case of accident.