The machine is built to withstand the hard usage to which this class of machinery is subjected, the entire construction is of iron, the shafts are large, and good bearings are provided for them in long boxes. The base is good and has broad feet; the ample size and height of the tempering cylinder A gives the machine a good capacity for tempering; on the top of the cylinder is strongly bolted a heavy frame, thereby affording a steady bearing for the tempering shaft B, and also carrying the pinion shaft E, insuring permanent alignment of the driving gears.

There is a safety appliance in front of the clod-cutter, which is a gate or mouthpiece pivoted at each end; this mouthpiece is held in position by a vertical spring which engages the end of the arm L. Should a stone or other obstacle come in contact with the mouthpiece during the movement of the mould, the arm L would slip by the spring, allowing the mouthpiece to swing on the pivots, thereby allowing the obstacle to pass out, and no damage having occurred to the machine or mould, nor interruption to the working. The mouthpiece can be replaced by bearing down on the handle attached to the arm L, and should any obstacle present itself and be too large to pass through the mouthpiece, then the end of the cast-iron breaking-rod, which connects with the hooked arm K at the bottom of the machine breaks off, stopping the movement of the mould, when the large obstruction may be removed, after which the breaking-rod is again moved forward, connecting the end with the hooked arm.

Fig. 62 indicates the manner of securing the wiper or

"pusher" to the shaft, each of the two parts independent of the other, by means of pins which pass through projecting ears and also through the hub of each wiper. By this arrangement one or both wipers may, in case of breakage or

wear, be replaced through a large door in the back of the machine without removing the whole tempering shaft.

The weight of the machine is about 6700 pounds, but lighter machines are also produced by the same makers for horse-power and also for hand-power, the clay for the latter being tempered in some independent manner.

The power required to operate the steam-power machine shown in Fig. 61 is about fifteen horse, the product of the machine with that amount of power is about four thousand five hundred bricks per hour.

The prices of these machines, etc., on board the cars or boat at Croton Landing, N. Y., are as follows:

Before considering the second class or expressing machines, which may be used for making either bricks, pipes, hollow flooring, and roofing tiles, terra-cotta lumber, etc., there is one point of importance that should be remarked upon, which is this: Bricks or hollow forms of earthenware that are expressed from the die of a machine and cut off by either wires or knives, are smooth and perfect in form provided the clay be not only free from lumps and plastic, but uniform and free from adventitious particles. If the clay contains stone or gravel that is not faithfully pulverized, and the senseless habit of mixing ashes or coal with the tempered clay is to be introduced, then the action made by the wires or knife will drag out more or less of these solid particles, and the ends will be very rough and the thickness sometimes uneven.

In Fig. 63, Nos. 1 to 19, are shown different forms of bricks, tiles, and other devices, which are made by some tempered-clay machines, the clay being expressed in the proper form, and then cut into any desired lengths upon a suitable arrangement of rollers.

For other forms of tiles see those in the hollow fireproof floors, shown in Figs. 120 and 121, Chapter VI.

Sometimes the clay pulverizers that will answer for preparing clay for damp or dry-clay machines will not disintegrate for tempered-clay machines. Clays of a very stony nature, too stony to be made into bricks with the stones in, or clays containing limestone in such quantities as to materially injure the bricks, require in such cases a different kind of clay mill to be employed, by which the stones are removed.