Various - Harper's New Monthly Magazine, Volume 2, No. 12, May, 1851.

The separate plates of which a boiler is composed are fastened together by means of massive rivets, and it is necessary, accordingly, to punch rows of holes along the edges of the plates for the insertion of the rivets. This process may be seen on the left in the above engraving. Two men are holding the plate which is to be punched. The punch is driven through the plate by means of the great lever, which forms the upper part of the engine. The upright part in front is driven forward by means of the cam in the large wheel behind, a part of which only is seen in the engraving. This cam raises the long arm of the lever by means of the pulley in the end of it, and so drives the point of the punch through the plate. There is a support for the plate behind it, between the plate and the man, with a small opening in it, into which the punch enters, driving before it the round button of iron which it has cut from the plate.

On the right, in the above engraving, is a punching engine worked by men, the other being driven by steam power. These machines are sufficient to make all the ordinary perforations required in boiler-plates. Larger holes, when required, have to be bored by a drill, as represented in the following engraving.

The view below represents the interior of one of the great boiler rooms where the boilers are put together by riveting the plates to each other at their edges. Some men stand inside, holding heavy sledges against the heads of the rivets, while others on the outside, with other sledges, beat down the part of the iron which protrudes, so as to form another head to each rivet, on the outside. This process can be seen distinctly in the boiler nearest to the observer in the view below. The planks which are seen crossing each other in the open end, are temporary braces, put in to preserve the cylindrical form of the mass, to prevent the iron from bending itself by its own weight, before the iron heads are put in.

Sometimes operations must be performed upon the sides of the boiler requiring the force of machinery. To effect this purpose, shafts carried by the central engine to which we have already alluded, are attached to the walls in various parts of the room, as seen in the engraving. Connected with these shafts are various drilling and boring machines, which can at any time be set in motion, or put to rest, by being thrown in or out of gear. One of these machines is seen on the right of the boiler above referred to, and another in the left-hand corner of the room quite in the back-ground. Near the fore-ground, on the left, is seen a forge, where any small mass of iron may be heated, as occasion may require.

The semi-cylindrical piece which lies in the centre of the room, toward the fore-ground, is part of a locomotive boiler, and is of course much smaller in size than the others, though it is constructed in the same manner with the large boilers used for sea-going ships. The process of riveting, as will be seen by the engraving, is the same. One man holds up against the under side of the plate a support for the rivet, while two men with hammers form a head above – striking alternately upon the iron which protrudes.

From the boiler we proceed to the cylinder, which is in fact the heart of the engine, – the seat and centre of its power. It is to the cylinder that the steam, quietly generated in the boiler, comes to exercise its energy, by driving, alternately up and down, the ponderous piston. The cylinder must be strong so as to resist the vast expansive force which is exercised within it. It must be stiff, so as to preserve in all circumstances its exact form. It must be substantial, so as to allow of being turned and polished on its interior surface with mathematical precision, in order that the piston in ascending and descending, may glide smoothly up and down, without looseness, and at the same time without friction. To answer these conditions it is necessary that it should be formed of cast iron.

The cylinders are cast, accordingly, in the iron foundry, which, as will be seen by the plan, is on the left, as the visitor enters the works. There is a range of monstrous cranes extending through the interior of the room, as represented in the plan, one of which is exhibited conspicuously in the engraving below. At different places in the ground, beneath this foundry, for it has no floor, there have been excavated deep pits, some of which are twelve feet in diameter and eighteen feet deep, the sides of which are secured by strong inclosures, formed of plates of boiler iron riveted together. These pits are filled with moulding sand – a composition of a damp and tenacious character, used in moulding. The mould is made and lowered into one of these pits, the pit is filled up, the sand being rammed as hard as possible all around it. When all is ready, the top of the mould, with the cross by which it is to be lifted and lowered surmounting it, presents the appearance represented on the right hand lower corner of the engraving below.

A reservoir to contain the melted metal necessary for the casting is then placed in a convenient position near it, with a channel or conduit leading from it to the mould. This reservoir may be seen in the engraving near the centre of the view, at the foot of the crane. An inclined plane is then laid, as seen in the engraving, to the left of the reservoir, up which the workmen carry the molten metal in ladles, which, though they do not appear very large, it requires five men to carry. A party carrying such a ladle may be seen in the engraving in the back-ground on the left. These ladles are filled from the various furnaces, the iron throwing out an intense heat, and projecting the most brilliant scintillations in every direction, as it flows. In the case of the largest castings it requires sometimes four or five hours to get together, from the furnaces, a sufficient supply of metal. The largest reservoir thus filled will hold about thirty tons of iron.

The flowing of the metal from the reservoir to the mould in a great casting, forms a magnificent spectacle. The vast mass of molten iron in the reservoir, the stream flowing down the conduit, throwing out the most brilliant corruscations, the gaseous flames issuing from the upper portions of the mould, and the currents of melted iron which sometimes overflow and spread, like mimic streams of lava, over the ground, present in their combination quite an imposing pyrotechnic display. In fact there is a chance for the visitor, in the case of castings of a certain kind, that he may be treated to an explosion as a part of the spectacle. The imprisoned vapors and gases which are formed in the mould below, break out sometimes with considerable violence, scattering the burning and scintillating metal in every direction around.

When the casting is completed it is of course allowed to remain undisturbed until the iron has had time to cool, and then the whole mass is to be dug out of the pit in which it is imbedded. So much heat, however, still remains in the iron and in the sand surrounding it, that the mould itself and the twenty or thirty men engaged in disinterring it, are enveloped in dense clouds of vapor which rise all around them while the operation is proceeding.

It is necessary that the sand which surrounds these moulds should be rammed down in the most compact and solid manner to sustain the sides of the mould and enable them to resist the enormous pressure to which it is subject, especially in the lower portions, while the iron continues fluid. In the case of iron, the weight of four inches in height is equivalent to the pressure of a pound upon the square inch. In a pit, therefore, eighteen feet deep, as some of the pits at this foundry are, we should have a pressure at the bottom of fifty-four pounds to the inch. Now, in the most powerful sea-going steamers, the pressure of steam at which the engines are worked, is seldom more than eighteen pounds to the inch; that of the Cunard line is said to be from twelve to fifteen, and that of the Collins line from fifteen to eighteen. In other words there is a pressure to be resisted at the lower ends of these long castings equal to three times that at which the most powerful low pressure engines are worked, and which sometimes results in such terrific explosions.