The rolling, forging, and swaging rooms are all connected, and form, as it were, one extended apartment. In this are placed hundreds of forges, furnaces, trip-hammers, rolling-mills, dropping-machines, and trimming-machines,—besides scores of sledge-hammers, wielded by stalwart arms. The noise here is so great that no effort of the voice avails to make itself heard, and I doubt if even the loudest thunder would make any appreciable addition to the general clangor. Small iron carts, filled with hot iron, are incessantly whirling around you; red-hot sparks, or melting drops of iron, are flying about the room in all directions; the air is hot to suffocation, and sulphurous from the burning of bituminous coal; while hundreds of swarthy faces, begrimed with grease and dirt, are dripping with sweat: so that you can scarce avoid the suspicion that you have at last stumbled into the infernal regions, and are constantly wondering why some of Pluto's imps do not seize you and plunge you into some horrible furnace, or chop you up under a trip-hammer.
Having survived the examination of this department, you follow your guide from the forging-room down a winding flight of iron steps to the water-wheels, which are situated forty feet under ground. These wheels are so arranged that they can be run together or separately; they are generally run together, and in connection with the immense low-pressure engine.
After the barrels are bored, turned, milled, and straightened, they are next to be polished. For this purpose they are placed in upright frames, each frame containing five barrels. The polishing is done by means of hard, wooden rubbers, provided with a plentiful supply of lard-oil and emery. The rubbers are placed horizontally, with their grooved ends pressing by means of springs against the barrels, which are drawn between them by a very regular and rapid vertical motion. The barrels are also turned around slowly and continuously by a lateral movement, which insures a uniform polish. They are allowed to remain in the first polishing-machines fifteen minutes, and are then placed in a similar machine and go through a second polishing, differing from the first simply in the absence of the pulverized emery,—oil only being used upon the rubbers during this finishing operation. The musket is now completed, with the exception of the rifling, and some slight polishing to be done by hand at the muzzle and breech.
Two polishing-machines are used for ramrods, similar in construction to those above described,—ten rods being polished at once. The bayonet is polished upon emery-wheels. These wheels are made of wood bound with leather, upon which there is placed a sizing composed of glue and pulverized emery. The polishing by this process is very rapid.
The number of workmen employed at the water-shops is ten hundred and forty. The last time the writer had occasion to visit them was upon the recurrence of an important occasion to the workmen employed there, namely, pay-day. A temporary wooden structure has been erected contiguous to the shops for the purpose of paying-off, and upon this occasion it bore, from time to time, various placards, announcing which shop was being paid, according as the paymaster arrived in succession at the various departments. Within the densely thronged shops, and amidst the deafening noise of hundreds of trip-hammers, perambulated a herald, with bell in hand, and placard raised upon a pole, upon which was painted a huge capital letter, thus designating, in alphabetical order, the names of the workmen whose turn had arrived to affix their signatures to rolls for a month's work, and receive in exchange a sheaf of Uncle Sam's greenbacks.
The works at the water-shops are surrounded by a high wooden fence, and guarded by a small force of watchmen armed with muskets. Should occasion require, however, a force of five thousand men, armed with the best of small arms, could be mustered at once from among the workmen in the armory and the citizens of the town. Ammunition of all kinds is stored within the establishment, sufficient for all emergencies.
I stated the number of pieces used in the construction of a musket to be forty-nine; but this conveys no idea of the number of separate operations which are performed upon it. The latter amount to over four hundred, no two of which are by the same hand. Indeed, so distinct are the various processes by which the grand result is obtained, that an artisan employed upon one part of a musket may have no knowledge of the process by which another part is fabricated. This, in fact, is the case to a very large extent. Many persons employed upon particular parts of the work in this establishment have never even seen other parts manufactured, and in general the workmen understand only the process of making the portions upon which they are engaged. The different parts are of various grades in respect to character and price, and are regularly rated, and the work done upon them is paid for by the piece. It will scarcely be expected that I should describe all the processes included in the four hundred separate operations performed in the manufacture of the musket, and I shall therefore content myself with alluding to a few of the most important or curious among them.
The gun-barrel, after it arrives at the works on the hill from the water-shops, is taken to the old armory buildings to be rifled. For this purpose it is placed in a horizontal position in an iron frame, and held there very firmly. The instruments which perform the rifling are short steel cutters placed within three apertures situated near the end of an iron tube which is carried through the bore of the barrel by a slow rotary and progressive motion. The cutters are narrow bars of steel, having upon one side three diagonal protuberances of about one-sixteenth of an inch in height and half an inch in width, ground to a very sharp edge at the top. It is these which produce the rifling. The three cutters, when inserted within the iron cylinder, form upon their inner surface a small cavity which decreases towards the top. Into this is inserted a small iron rod attached to the machine and revolving with it, but so controlled by a connecting cog-wheel that the rod is pressed at every revolution a little farther into the cavity between the cutters. The effect of this operation is to increase the pressure of the cutters upon the inner surface of the barrel, and thus gradually deepen the corrugations produced by the rifling. The rods make twelve revolutions in a minute, and it occupies thirty minutes to rifle a barrel. There are twenty-seven of these rifling-machines in constant operation day and night. This process is the last which takes place within the barrel, and it leaves the bore in a highly polished and brilliant condition.
Among the innumerable machines which arrest the attention of the visitor by the beauty and grace of their operations is the broaching-machine. This is designed to cut out and polish the inner surface of the bands which encompass the barrel and stock. These bands are irregular in shape, and cannot, therefore, be bored out as the barrel is. When they emerge from the drop, or swaging-machine, they are somewhat rough both interiorly and exteriorly, and then undergo a series of operations which leave them in a highly finished condition. The first of these is called broaching. A cavity is made under a huge press in which the band is placed. The broach consists of a steel tool about ten inches in length, and of the exact diameter and form of the interior of the band, and is armed upon its entire length with concentric rings composed of very short and sharp knives. The broach, being placed over the cavity of the band, is slowly subjected to the pressure of the two-ten press, and is thus forced completely through the band, cutting it out as smoothly and easily as if it were composed of lead. The bands are then milled upon the outside by a process called profiling, drilled for the rings, placed upon mandrels to insure the exact shape required, filed, polished, case-hardened, and thus finished.
The hammer passes through a great number of processes before it is completed. It is first forged, then dropped, trimmed, punched, drifted, milled, turned, filed, and lastly case-hardened.