When the earth is mixed in this way, it becomes brick-clay, and is taken in barrows up a sloping board, to the pug mill. The pug mill is a great tub, the top of which is larger than the bottom, and in the centre of it there revolves an upright iron shaft fitted with knives. These knives cut and break the clay as it passes through the mill, and they also force it downwards till it reaches the bottom, where it passes through a hole on to a machine called the Cuckhold, which is a sort of table containing a trough where the clay is cut into lumps ready for the moulder. [Illustration: Pug Mill.] [Illustration: Barrow for carrying baked Bricks.] [Illustration: Kick and Stockboard. Mould. Board for Moulding. Strike. Brick-mould.] The moulder who shapes the clay into bricks uses moulding sand,—a peculiar sort of sand brought from the bed of the river, and spread out in the sun, where it is turned over and over till it is quite dry. It prevents the clay from shrinking, gives a harder surface to the bricks, and prevents them from sticking to the mould, or to each other; it also gives the London bricks their grey colour. The moulder stands at the moulding stool, which has a rim at each end to keep the moulding sand from falling off, and has a stockboard, which forms the bottom of the brick-mould, and a page, or two iron rods nailed at each end to wooden rails, used to slide the raw bricks from the moulder to the place from which the “taking-off boy” takes them to place on the “hack barrow,” by which they are carried away. The moulder is served with the lumps of clay by the “clot moulder.” The “brick-mould” is a kind of box without top or bottom, and the moulder dashes the tempered clay into the mould with sufficient force to make the clay completely fill it; after which the superfluous clay is removed from the surface of the mould with the strike. The brick is then turned out on to a pallet or board, on which it is wheeled by the boy to the “hack ground,” where the bricks are built up to dry in low walls called “hacks.” The brick moulds are made of brass or iron, and often of wood. Sometimes the bricks are dried on a floor under a shed, but often in the open air, where they are covered with straw, reed-flats, or canvas and tarpauline screens, to protect them from wet, frost, or excessive heat. The bricks are afterwards burnt either in “clamps” or in “kilns.” In clamp burning the bricks are built up close together, and the bottom ones only are heated with burning breeze or cinders, the heat spreading to those at the top. A kiln is a sort of large chamber in which the bricks are loosely stacked with spaces between them for the heat to pass through, and they are baked by fires placed either in arched furnaces under the floors of the kiln, or in fire holes made in the side walls. The kilns are built of various shapes, and one of the principal arts in the trade of the Brickmaker is to construct them