BRICK, a well known substance, four inches broad, and eight or nine long, made by means of a wooden mould, and then baked or burnt in a kiln, to serve the pur poses of building.
Bricks are of great antiquity, as ap pears by the sacred writings, the tower and walls of Babylon being built with them. In the east they baked their bricks in the sun ; the Romans used them un burnt, only leaving them to dry for four or five years in the air. The general pro cess of the manufacture of bricks here is as follows : the earth should be dug in the autumn ; it should lie during the whole of the winter exposed to the feast, as the action ofvthe air, in and dividing theparticles of the earth, facilitates the subsequent opemmais of mixing and tempering. During this time the earth should be repeatedly turned and worked with- the spade. In the spring, the clay is broken in pieces and thrown into shallow pits, where it is wa tered, and suffered to remain soaking for several days. The next step is, that of tempering the clay, which is generally performed by the treading of men or ox en. In the neighbourhood of London, however, this operation is performed by means of a horse-mill. The tempering of the clay is the most laborious part of the process, and that on which the per fection of the manufacture essentiall) de pends. It is to neglect in this part that we are chiefly to attribute the bad qua lity of modern bricks, in comparison with the ancient. All the stones should be removed, and the clay brought to a per fectly homogeneous paste, using the least possible quantity of water. The earth, being sufficiently prepared in the pits, is brought to the bench of the moulder, who works the clay into the brick-moulds, and strikes off the superfluous earth. The bricks are delivered from the mould, and ranged on the ground; and when they have acquired a sufficient hardness to ad mit of handling, they are dressed with a knife, and stacked or built up in long dwarf walls, and thatched over, where they remain to dry.
The method of burning bricks. Bricks are burnt either in a kiln or clamp. Those that are burnt in a kiln are first set or placed in it, and then the kiln being co vered with pieces of bricks, they put in some wood, to dry them with a gentle fire ; and this they continue till the bricks are pretty dry, which is very easily known by those accustomed to the business: they then leave off putting in wood, and proceed to make ready forburning, which is performed by putting in brush, furze, spray, heath, brake, or fern faggots; but before they put in any faggots, they dam up the mouth or mouths of the kiln with pieces of bricks, piled up One upon anoth er, and close it up with wet brick-earth, instead of mortar ; then they proceed to put in more faggots, till the kiln and its arches look white, and the fire appears at the top of the kiln ; upon which they slacken the fire for an hour, and let all cool by degrees. This they continue to
do, alternately heating and slacking, till the ware be thoroughly burnt, .which is usually effected in forty-eight hours.
About London, thrty chiefly burn in clamps, built of the':cricks themselves, after the manner of arches in kilns, with a vacancy between each brick, for the fire to play through ; Mit with this difference, that instead of arching, they span it over, by making the bricks project one over another, and on both sides of the place, for the wood and coals to lie in till they meet, and are bounded by the bricks at the top, which close all up. The place for the fuel is carried up straight on both sides till about 3 feet high ; when they almost fill it with wood, and over that lay a covering of .sea-coal, and then overspan the arch ; but they strew sea-coal also over the clamp, betwixt all the rows of bricks ; lastly, they kindle the wood, which gives fire to the coal, and when all is burnt, then they con clude the bricks are sufficiently burnt.
The different kinds of bricks made in this country are principally place bricks, grey and red stocks, marl facing bricks, and cutting bricks. The place bricks and stocks are used in common walling ; the marls are made in the neighbourhood of London, and used in the outside of build ings; these are very beautiful bricks, of a fine yellow colour, hard and well burnt, and in every respect superior to the stocks. The finest kind of marl and red bricks are called cutting bricks, they are used in the arches over windows and doors, being rubbed to a centre and guag ed to a height. There is also a fine kind of white bricks made near Ipswich, which are used for facing, and sometimes brought to London for that purpose. The Windsor bricks, or fire bricks, which are made at Hedgerly, a village near Windsor, are red bricks, containing a very large proportion of sand ; these are used for coating furnaces and lining the ovens of glass houses, where they stand the utmost fury of the fire. Dutch clinkers are also imported, long narrow bricks, of a brimstone colour, very hard, and well burnt ; they are frequently warped, and appear almost vitrified by the heat.