Upon the thorough preparation of this part of the carriage its safety depends. The wheels of omnibuses are always allowed to remain two years before they are used, and by permitting them this grace they behave well when at work, generally running over 43,000 miles of ground before they are worn out. The wheels of gun-carriages require to be even better prepared and seasoned, as they have to bear the weight of enormous guns, and have often to run over the roughest ground, without being in any way relieved from sudden shocks by springs. Upon this store of mellow wood the different factories draw; and the railway which traverses every portion of it speedily conveys the raw material to the benches of the workmen. As the visitor passes up the main avenues of these splendid shops he is bewildered with the activity of the swarms of artizans, the whirling of shafting, and the grating sounds of circular saws. Clouds of sawdust are flying about, and in a moment cover the intruder from head to foot. The immense amount of work sometimes required to be performed at a brief notice has necessitated the introduction of machinery into this branch of handicraft, which heretofore was entirely carried on by manual labour. Let us take the ammunition and powder cases for instance; these have to be provided by the hundred thousand in time of war, and accordingly we find machinery employed in every direction to shorten the work. Circular saws cut the planks into the required size to form the sides and tops and bottoms of the cases; as these issue from the different machines, they are conveyed away upon a circular band of canvas, placed at right angles, to a broader band which runs from one end of the factory to the other: down this band, as on a broad stream, the various pieces sail until they reach the receptacle, from which they are again conveyed to the machinery which is to put them together. Here the drilling, mortising, and dowelling processes are carried on by wholesale with an exactitude and speed which would astonish the joiner of the old school. Upwards of a thousand ammunition boxes formed of cedar, for repelling the wood-eating white ants of the East, are now being prepared daily for the use of the Indian army. The powder-boxes for the navy are made of a hexagonal form, to enable them to fit into the ship's hold like cells of honeycomb. They are carefully lined either with pewter or copper, and when filled are hermetically sealed with wax. The limber-boxes for the field artillery are also made here in large quantities. These receptacles are of a far more elaborate character than the powder-cases, as they are fitted to take all the stores requisite for immediate action, which are stowed away in their different compartments, as neatly as the articles in a gentleman's dressing-case. The common cartridge barrels are shaped out of the solid wood almost as fast as you can look. One machine cuts the oak into staves, curved to the right form;