66 at one end, and nuts and screws at the other. The box "is thus fixed to its support. We simply place this sup"port on the ground and bind its upper part with a rope "to a tree, a stake, or a post. The front compartment is "the reservoir for the clay, presenting at its front an orifice, in which we fix the desired die with a simple bolt.

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"A wooden piston, of which the rod is jointed with a "lever, which works in a bolt at the top of the supporting "post, gives the necessary pressure. When the chest is "full of clay, we bear down on the end of the lever, "and the moulded tiles run out on a table supplied with "rollers. Raising the piston, it comes out of the box, "which is again packed with clay. The piston is replaced "in the box; pressure is again applied to the lever, and 66 so on. When the line of tiles reaches the end of the table, we lower a frame on which brass wires are stretched, and cut it into the usual lengths."

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The workmen must attend well to the degree of moist ure of the clay which is put into the machine. It should be dry enough to show no undue moisture on its surface as it comes out of the die-plate, and sufficiently moist noc

to be crumbled in passing the edge of the mould. The clay for small (thin) tiles must, necessarily, be more moist than that which is to pass through a wider aperture; and for the latter there may, with advantage, be more sand in the paste than would be practicable with the former.

After the tiles are cut into lengths, they are removed by a set of mandrils, small enough to pass easily into them, such as are shown in Fig. 45, (the number of fingers

TILES FROM MACHINE.

corresponding with the number of rows of tiles made by the machine,) and

Fig. 45.-MANDRIL FOR CARRYING are placed on shelves made of narrow strips sawn from one-inch boards, laid with spaces between them to allow a free circulation of air.

Drying and Rolling.-Care must be taken that freshly made tiles be not dried too rapidly. They should be sheltered from the sun and from strong winds. Too rapid drying has the effect of warping them out of shape, and, sometimes, of cracking the clay. To provide against this injury, the drying is done under sheds or other covering, and the side which is exposed to the prevailing winds is sometimes boarded up.

For the first drying, the tiles are placed in single layers on the shelves. When about half dried,—at which time they are usually warped more or less from their true shape, it is well to roll them. This is done by passing through them a smooth, round stick, (sufficiently smaller than the bore to enter it easily, and long enough to project five or six inches beyond each end of the tile,) and,— holding one end of the stick in each hand,-rolling them carefully on a table. This operation should be performed when the tiles are still moist enough not to be broken by the slight bending required to make them straight. After rolling, the tiles may be piled up in close layers, some

four or five feet high, (which will secure them against further warping,) and left until they are dry enough for burning, that is, as dry as they can be made by exposure to the air.

Burning.-Tiles are burned in kilns in which, by the effect of flame acting directly upon them, they are raised to a heat sufficient to melt some of their more easily fusi ble ingredients, and give to them a stone-like hardness.

Kilns are of various construction and of various sizes. As this book is not intended for the instruction of those who are engaged in the general manufacture of tiles, only for those who may find it necessary to establish local works, it will be sufficient to describe a temporary earthen kiln which may be cheaply built, and which will answer an excellent purpose, where only 100,000 or 200,000 tiles per season will be required.

Directions for its construction are set forth in a letter from Mr. T. Law Hodges, of England, to the late Earl Spencer, published in the Journal of the Royal Agricultural Society for the year 1843, as follows:

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"The form of the clay-kiln is circular, 11 feet in diame "ter, and 7 feet high. It is wholly built of damp, clayey earth, rammed firmly together, and plastered, inside and out, with loam (clay ?). The earth to form the walls is dug out around the base, leaving a circular trench about four "feet wide and as many deep, into which the fire-holes of "the kiln open. If wood be the fuel used, three fire-holes "will be sufficient; if coal, four will be needed. About “1,200 common brick will be wanted to build these fire"holes and flues; if coal is used, rather fewer bricks will "be wanted, but, then, some iron bars are necessary,― "six bars to each fire-hole.

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"The earthen walls are four feet thick at the floor of "the kiln, seven feet high, and tapering to a thickness of "two feet at the top; this will determine the slope of the

"exterior face of the kiln. The inside of the wall is car "ried up perpendicularly, and the loam plastering inside "becomes, after the first burning, like a brick wall. The "kiln may be safely erected in March, or whenever the "danger of injury from frost is over. After the summer "use of it, it must be protected, by faggots or litter, 66 against the wet and frost of winter. A kiln of these "dimensions will contain 32,500 14-inch tiles,

"In good weather, this kiln can be filled, burnt, and "discharged once in every fortnight, and fifteen kilns may be obtained in a good season, producing 487,500 "1-inch tiles, and in proportion for the other sizes.

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"It requires 2 tons 5 cwt. of good coals to burn the "above kiln, full of tiles."

A sectional view of this kiln is shown in Fig. 46, in which C, C represent sections of the outer trench; A, one

of the three fire-holes; and B, B, sections of a circular passage inside of the wall, connected with the fire-holes, and serving as a flue for the flames, which, at suitable in tervals, pass through openings into the floor of the kiln. The whole structure should be covered with a roof of rough boards, placed high enough to be out of the reach of the fire. A door in the side of the kiln serves for put

ting in and removing the tiles, and is built up, tempora rily, with bricks or clay, during the burning. Mr. Hodges estimates the cost of this kiln, all complete, at less than $25. Concerning its value, he wrote another letter in 1848, from which the following is extracted:

"The experience of four years that have elasped since 66 my letter to the late Earl Spencer, published in the 5th "volume of the proceedings of the Royal Agricultural "Society, page 57, has thoroughly tested the merits of "the temporary clay-kilns for the burning of draining"pipes described in that letter.

"I am well aware that there were persons, even among "those who came to see it, who pronounced at once upon "the construction and duration of the kiln as unworthy "of attention. How far their expectations have been real"ized, and what value belongs to their judgment, the fol "lowing short statement will exhibit :

“The kiln, in question, was constructed, in 1844, at a "cost of £5.

"It was used four times in that year, burning each "time between 18,000 and 19,000 draining pipes, of 14 "inches in diameter.

"In 1845, it was used nine times, or about once a fort "night, burning each time the same quantity of nearly "19,000 pipes.

"In 1846, the same result.

"In 1847, it has been used twelve times, always burn"ing the same quantity. In the course of the last year a 66 trifling repair in the bottom of the kiln, costing rather "less than 10 shillings, was necessary, and this is the only 66 cost for repair since its erection. It is now as good as 66 ever, and might be worked at least once a fortnight "through the ensuing season.

"The result of this experiment of four years shows not "only the practical value of this cheap kiln, but Mr "Hatcher, who superintends the brick and tile-yard at Ben