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.
The effect of the sudden outbreak of the late war was, perhaps, more beneficially felt upon the laboratory department of the Arsenal than any other. Shells, of all the stores of war, were most deficient when the army left for Varna, and the want increased as soon as actual campaigning commenced. The authorities accordingly permitted Captain Boxer to erect a model manufactory of shells in the autumn of 1855. This he did with surprising rapidity, and proved to their satisfaction that these formidable missiles could be manufactured five pounds a ton cheaper than they could be procured from the contractors--an important saving on an article of which several hundred tons had to be supplied per day. The success of this experiment led to the erection of the splendid shell-foundry which is now attached to the Arsenal, and which is capable of turning out sufficient shells for all the armies of the world. Here may be seen the process by which the old scrap iron of the establishment is transformed into the finished shot and shell, and transferred by its own weight to the transport ready to convey it to the seat of war. The smelting process is carried on in a dozen enormous cupola furnaces, into which the iron and coal are heaped indiscriminately. The fierce heat generated by the blast rapidly melts the iron, which is then allowed to flow into the shell-moulds. From the moment the metal enters these moulds, the shell, in war time, never touches the ground till it is landed at its port of debarkation! The rough shells, after they have cooled a little, are forwarded by railway to the cleaning-room, where they are placed in a revolving iron barrel, seven feet long and seven feet in diameter. This machine circulates with rapidity, and the friction of the contained shells speedily cleanses them of all sand and dirt. From this point they roll through all the succeeding stages of their manufacture. A slightly-inclined plane receives them at the cleaning-drum, and conducts them one by one to the machinery fixed in the great room of the laboratory department. Upwards of ten thousand shells per day passed through this apartment during the late war, and were, on their passage, drilled and "bushed," or fitted with the socket made to receive the fuse. This simple fact will alone serve to show how energetically the work was carried on to meet the wants of the great siege. The shells, having rolled through the labyrinth of successive machines which operate upon them, now move onward to the painting department, where they receive a coating of black varnish, which prevents oxidation. Hence they continue their journey right across the open ground of the Arsenal to the pier, under the platform of which they keep their course inside an iron tube which leads immediately into the barge alongside the transport in the river. From this barge, into which they sometimes shoot with a considerable impulse, they roll again, through the open port of the ship, to their appointed place in the hold.