to govern the admission and exit of steam or other heating medium to and from the interior of the same, each of the valves being threaded or otherwise adapted for the attachment of a flexible coupling or hose a3, by which communication may be established with a steam-boiler or other heater, or with the rack of another drying-car.

Drip-cocks a1, one or more, may be provided for relieving the rack from any water of condensation that may accumu late therein.

The form of rack shown in the drawings consists of a series of pipes arranged longitudinally, and connected by end manifolds a, having internal partitions, which provide

a continuous passage, in alternate directions, through all the pipes; but the arrangement and method of construction may be varied, according to the judgment of the constructor.

The tubular rack A is mounted upon running-gear, consisting of wheels B and axles b, the wheels being either fast or loose upon the axles, as preferred. In the instance shown the axles rotate in bearings b', secured to the lower side of a rectangular frame B', to the top of which the rack A is secured by straps 2. Such arrangement of a separate frame supporting the drying-rack is deemed preferable for use in cases where two or more cars are to be coupled together and moved with their contents from place to place, as the pipe-joints are thereby relieved from longitudinal strain, and convenient means for attaching the axle-boxes and coupling the cars together are provided.

It will be obvious, however, that when desired for the purpose of reducing weight and cost of construction, the drying-rack may serve as the sole framing of the car, and the wheels can either be made to revolve on journals formed upon the end manifolds, or with or upon axles supported in bearings connected to the manifolds, or to the pipes themselves.

Vertical bars a or slatted side pieces of any desired form may be secured to the car, to afford lateral support to the articles placed upon the rack.

In the transverse section, Fig. 81, the car is shown as provided with three separate tubular racks, arranged one above the other, which construction will be found desirable, where a large amount of heating-surface is required.

The pipes of the upper racks are connected at their ends by elbows or fittings a', and are supported by transverse straps secured to the vertical bars a3.

After the bricks have been properly dried, the next step is to place them in the kiln to be burned.

The setting of the machine-made bricks is usually done by the day; there should be no wheeling, as is the case with hand-made bricks.

One laborer to push in all the cars for one gang, and three men in the kiln, are the usual complement of one machine-setting gang.

Two of the three men in the kiln should be setters, as one of them can be working in the "bottom" or building the arches, while one is tossing, and the other setting the bricks on the lower bench. When it is desired to put on the top bench, one man can toss, one stand between the tosser and setter, and one set the bricks.

In very large works it is not unusual to have four of these gangs in one kiln at the same time; twenty-five thousand bricks is the usual amount set by each gang. In some works, where all the machinery is in perfect running order, the proprietor requires a certain number of bricks to be made and handled for a day's work; and as soon as this is accomplished, be it in eight, nine, or ten hours, the men are at liberty. In one large brick-yard, producing bricks by the machine process, located in the city of Washington, D. C., the number of perfect bricks required to be made and set is eighty-eight thousand; as soon as this is accom

plished, all hands in the works stop, including laborers in the clay banks, horses and carts, etc.

It is not often that the time exceeds nine hours.

The bricks made by this company are rubbed in moulding sand, the same as that used for hand-made bricks, and as the bricks are damp, the sand adheres well, and in the kiln the color of the stock, after burning, is uniform. The description which has been given in the preceding chapter, in regard to the burning of bricks, applies to machine-made bricks as well as to hand-made stock, with the important differences: that the firing at the first stages should be slower, and in the setting or finish the firings should be more frequent, and heavier.

Pressed or front bricks are produced by a combination of the hand-made and the machine processes. The finishing

of this class is sometimes done in a press run by steam power, but the usual way is to mould the bricks by hand and make them slightly larger than the size of the pressbox in which they are to be finished.

The moulding, drying, and pressing of front bricks are conducted entirely under shelter; the hand-press gang is composed of the three members, the moulder, who also does the pressing, the temperer, who also does the wheeling of the clay, and the off-bearer, who also rubs the finished bricks with very fine moulding sand.

A day's work for the press-gang is to temper the clay, mould, press, and finish one thousand one hundred and sixty-seven bricks. Pressed bricks are seldom hacked on edge in the sheds, but are laid flatwise, each pile being a

separate one, and a space of about three inches is left around each hack; they hold shape better in this manner of drying than if hacked on edge, and after they have been pressed they are hacked differently, as will be explained.

For the information of brick-makers in distant places, where pressed bricks have not been made, we elaborate further upon the general plan of making them by hand.

It is important that the clay should be well tempered, the clay-tempering-wheel producing the best. The bricks should be moulded free of flaws or sand-cracks, and the mould, when in use, should be kept well cleaned. Those in general use in Philadelphia are known as the "single cast-iron moulds." The moulding sand is an important item in making pressed bricks, as the color and smoothness of the brick depend on it. A sieve having about sixty meshes to the lineal inch is used for preparing the sand for moulding the bricks. The bricks are placed flat on the floor, and when pretty dry, a light sieving of sand is put over the faces. They are then turned over that they may dry more regularly. Sheds built expressly for the purpose are also used for pressed bricks. The roof is made to open so as to admit wind and sun when required. A good roof for this purpose is shown in Chapter IV., Figs. 14, 18, 20, 25, and 26. Where the bricks dry too fast, a piece of damp carpet can be laid over them and sprinkled occasionally with water. When the bricks are in a proper state for pressing-say, when they can be handled without fingermarks-the is taken to the bricks. Placing the press on boards, the bricks are carefully put into the mould, great care being exercised that they are not marked in dropping

press