Roofing tiles have been made in a similar way to bricks, one would imagine, looking at the specimens found at Wroxeter and other places from the time of Roman occupation down to the present. They are found in double layers, forming slightly projecting string-courses in the buildings, but larger and thicker than ours; some of those dug up at Wroxeter being 17 inches by 12, and 4 inches thick, whilst some are 21 inches square. One of these larger ones has the impression of the foot of an ox, evidently received whilst in the process of drying. Very many interesting specimens of bricks, tiles, and pottery are found here, and the art of working up the clays of the district has no doubt been practised from that time to the present. Formerly clays were allowed to lie during the winter to weather as it is called; and a statute now obsolete required, under a penalty, that bricks should not be made unless the clay for making them had been turned over at intervals, three times at least before the 1st of March. But brickmakers now, not having patience to wait for the action of the weather, have invented machinery to do the work, and the clay is taken direct from the pit to be crushed by iron rollers, and conveyed by coarse canvas screens to the pug-mill. This is an upright cylinder, with a revolving vertical shaft, fitted up with horizontal knives following each other at an angle so as to cut, amalgamate, temper the material, and fit it for use. The process of forming the brick itself requires more tact than the reader would imagine, as the yielding clay has to be thrown into the mould so that every part shall be filled up with a body of equal consistency. To cause the clay to leave the mould, the latter is each time dipped into water, in which case the process is called slop-moulding, or is sprinkled over with sand or coke-dust; and when so made the brick is placed lengthways with others on smooth flats, half an inch or an inch apart and allowed to dry. The best kind of bricks are subjected to considerable pressure in the mould by means of a machine, and a hollow is left inside for the mortar, to enable them to fit close in the joint. Ornamental bricks of elaborate design for architectural purposes require more delicate manipulation, and the clays for these undergo more careful preparation. Machines also are used which take the clay from the crushing-rollers, temper and thoroughly amalgamate it, and convert it into the finished article. The old methods of preparing clay for bricks and tiles, still practised by some firms, is probably the best where a good tough article is required: that is treading and hand-tempering by the workman, who kneads it with his naked feet, and “slaps” or “wedges” it by breaking off pieces and beating one against another. Machinery, however, is extensive used, and horizontal rollers are set so as to secure different degrees of fineness, in conduction with the pug-mill.