Brick

BRICK. A kind of factitious stone, made of a fatty earth formed into a parallelogram about 4 inches broad by 8 or 9 inches in length, by a wooden mould, and then baked or burnt either in a kiln or a clamp, to serve the purposes of building. Bricks appear to have been used for architectural purposes at a very remote period, as we learn from the Scriptures that the Israelites were employed to make bricks in Egypt ; and some of the most durable of the Greek and Roman monuments which have come down to us, are wholly, or in great part, constructed of this material. In the East they bake their bricks in the sun; the Romans used them crude, only leaving them a long time in the air to dry, about four or five years. In modern times, brickmaking is no where carried to greater perfection than in Holland, where most of the floors of the houses, and frequently the streets, are paved with excellent and very durable bricks. Loam and marl are in England considered the best materials for bricks. The former is a natural mixture of sand and clay, which may be converted at once into bricks; marl is a mixture of limestone and clay in various proportions. The neighbourhood of London is remarkably adapted for the making of bricks, the soil of the whole surrounding country being clay at a certain depth, gene rally below a bed of gravel, and the bottom of the Thames yielding the sand which is used in this manufacture ; but great practical carelessness seems to pervade the whole business as conducted there. The following is a description of the process as it is usually conducted around the metropolis : The earth is dug up in the autumn, and suffered to remain in a heap until the next spring, that it may be well penetrated by the air, and particularly by the winter frosts, which, by pulverising the more tenacious particles, greatly assists the operations of mixing and tempering. In making up this heap for the season, the soil and ashes, or sand, are laid in alternate layers or strata, each stratum containing such a thickness as the stiffness of the soil may admit or require. In tempering the earth, much judgment is required as to the quantity of sand to be thrown into the mass, for too much renders the bricks heavy and brittle, and too little leaves them liable to shrink and crack in the burning. The addition of sea coal ashes, as practised about London, not only makes it work easy, but saves fuel, as when the mixture is afterwards sufficiently heated these bricks are chiefly burned by the fuel contained in the clay. When the brick-making season arrives, the heap is dug up, the stony particles careftilly removed, and the mass properly tempered by a thorough incorporation and intermixture of the materials, with the addition of as little water as possible, so as to form a tough viscous paste. If, in this operation, too much water be used, the paste will become almost as dry and brittle as the soil of which it is composed. In order more effectually and regularly to mix the loam and ashes, it is now generally performed in a sort of mill, named a pug mill. This consists of a large tub or tun, fixed perpendicularly in the ground, and having an upright bar, fitted with knives, placed obliquely. The upright bar is turned by a hori zontal lever, to which a horse is attached, and the soil being put in at top, is', by the revolution of the knives, forced through a hole in the side of the tub near the bottom, whence it is removed to the mould table, which is placed under a movable shed, and is strewed with dry sand. A girl rolls out a lump some what larger than the mould will contain. The moulder receives this lump from the girl, throws it into his mould previously dipped in dry sand, and with a flat smooth stick about 8 inches long, kept for the purpose in a pan of water, he strikes off the overplus of the soil; he then turns the brick out of the mould upon a thin board rather larger than the brick, upon which it is removed by a boy, who places it on a light barrow of a particular construction, which being loaded with a certain number of bricks, they are sprinkled with sand, and wheeled to the hacks. The backs for drying are each wide enough for two bricks to be placed edgeways across, with a passage between the heads for the admission of the air, to facilitate the circulation of which the bricks are usually laid in an angular direction. The hacks are usually carried eight bricks high ; the bottom bricks at the ends are usually old ones. In showery weather the hacks must be carefully covered with wheat or rye straw, unless sheds or roofs be built over the hacks, as is done in some parts of the country, but in London this is impracticable, from the very great extent of the grounds. In fine weather the bricks will be ready for turning in a few days, in doing which they are reset more open than at first, and in six or eight days more they will be ready for burning. In the vicinity of London bricks are commonly burned in clamps. In building the clamps, the bricks are laid after the manner of arches in • the kilns, with a vacancy between every two bricks for the fire to play through. The flue is about the width of a brick, carried straight up on both sides for about three feet; it is then nearly filled with dry hams or wood, on which is laid a covering of sea coal and cinders (or, as they are termed, breeze); the arch is then overspanned, and layers of breeze are strewed over the clamp, as well as between the rows of bricks. When the clamp is about six feet wide, another flue is made in every respect similar to the first. This is repeated at every distance of six feet throughout the clamp, which, when completed, is surrounded with old bricks, if there be any on the grounds, if not, with some of the driest of the unbaked ones reserved for the purpose; on the to of all, a thick layer of breeze is laid. The wood is then kindled, which sets fire to the coal; and when all is consumed, which will be in about twenty or thirty days if the weather be tolerable, the bricks are concluded to be sufficiently burned. To prevent the fire burning too furiously, the mouths of the flues are stopped with old bricks, and the outside of the whole clamp plastered with clay ; and against any side particularly exposed to the rain, &c. screens are laid, made of reeds worked into frames about six feet high, and of a width to admit of being moved about with ease. This is the mode of manufacturing the ordinary descriptions of bricks; but the superior sort, termed washed maims or snarls, are tempered with greater care and attention. For this purpose a circular recess is built about four feet high, and from ten to twelve feet diameter, paved at bottom, with a horse wheel placed in its centre, from which a beam extends to the outside for the horse to turn it by. The earth is then raised to a level with the top of the recess, and forms a platform for the horse to walk upon. Contiguous to the recess a well is formed for supplying the recess with water, which is raised by pump worked by the horse wheel. A harrow made to fit the interior of the recess, thick set with long iron teeth, and well loaded, is chained to the beam of the wheel to which the horse is harnessed. The soil prepared in the heap in the usual manner is brought in barrows, and distributed regularly round the recess, and a quantity of chalk is added, and a certain portion of water; and the horse being set in motion, drags the harrow, which forces its way into the soil, admits the water into it, and by tearing and sepa rating the particles, not only mixes the ingredients, but also affords an opportunity for stones and other heavy matters to fall to the bottom. Fresh clay, chalk, and

water, continue to be added until the recess is full. On one side of the recess, and as near it as possible, several hollow square pits are prepared about 18 inches or 2 feet deep. The soil, reduced to a kind of liquid paste, is discharged from the recess by a sluice, and conveyed by wooden troughs to this pit. In these pits the fluid soil diffuses itself, settling of an equal thickness, and remains until wanted for use, the superfluous moisture being drained or evaporated away by exposure to the atmosphere. The remainder of the process is the same as for the common sort of bricks. In the country, bricks are always burned in kilns, whereby much waste is prevented, less fuel is consumed, and the bricks are more expeditiously burned. A kiln is usually 13 feet long by 10 feet 6 inches wide, about 12 feet in height, and will burn 20,000 bricks at a time. The walls are about 14 inches square, and incline inwards towards the top. The bricks are set on flat arches, having holes left between them resembling lattice work. The bricks being set in the kiln, and covered with pieces of broken bricks or tiles, some wood is put in and kindled to dry them gradually ; this is continued till the bricks are pretty dry, which is known by the smoke turning from a darkish to a transparent colour. The burning then takes place, and is effected by putting in brush-wood, furze, heath, faggots, &c. ; but before these are put in, the mouths of the kiln are stopped with pieces of brick called shinlog, piled one upon another, and closed over with wet brick earth. This shinlog is carried just high enough to leave room sufficient to thrust in a faggot at a time ; the fire is then made up, and continued till the arches assume a whitish appearance, and the flames appear through the top of the kiln, upon which the fire is slackened, and the kiln cooled by degrees. This process is continued, alternately heating and slackening, till the bricks are thoroughly burned, which is usually in the space of forty-eight hours. Many attempts have been made of late years to supersede, by the aid of machinery, a portion of the manual labour now employed in the manufacture of bricks; and although only the most recent of the machines invented for this purpose have been found to answer in practice, several of them are worthy of notice. The engraving on the following page repre sents Messrs. Choice and Gibson's brickmakmg machine. a a a a is an upright frame, with cross beams at top and bottom ; b c are two vertical shafts, carrying two horizontal spur wheels d and e, the teeth of which take into one another; these are put in motion by the horse shaft f, or any other convenient power. Near the bottom of the shaft b is fixed a large cast iron collar g, having three deep mortices; into each of these the end of an iron arm h is fitted, with a bolt passing through them to form a centre, as in a hinge joint. To the other extremity of each of the arms h is firmly fixed, by screw-bolts, a cast-iron mould box i, having three divisions for three bricks, in which work three stocks or false bottoms, having upright bolts passing through holes in the top. By the revolution of the shaft, these mould boxes, with their arms, are successively carried up and over the risers k k k, which form circular curves in the plan, and appear so in the perspective, but are in reality inclined planes. At I, near the bottom of the shaft, is a small bevelled wheel, which actuates a pinion fixed on the spindle of the drum wheel m that passes under the floor of the machine; an endless strap passing round the drum m, and another placed at the required distance, continually carries the bricks forward to their destination as fast as they are made, and deposited upon it. o is a crank of lever, attached by a joint to the framing, as shown, at the upper end of which is fixed a roller ; by the revolution of the wheel above the three circular bars or cams r r r, attached to the wheel, successively act upon the roller, and depress the crank o, which first raises the rod and weight g, and afterwards, as soon as the crank is relieved of the pressure, allows it to drop and strike the mould boxes, by which the bricks are discharged out of them. s is a box of oast iron, containing water, into which the mould boxes dip ; t is a cushion, upon which they next fall in succession, by which the superfluous water is taken off; and j is a box of dry sand, into which the mould boxes afterwards fall, their surfaces becoming in consequence slightly coated with sand previous to becoming charged with clay. The horizontal wheel a worked by d actuates the shaft e bearing the knives in the pug mill. At the lower end of the shaft c is fixed the large circular revolving bottom plate a, the periphery of which being furnished with teeth or cogs, as shown, take into the teeth of a circular revolving plate v, over which, as the mould box passes, the lower surface of the bricks becomes smoothed. At x is a small frame, working up and down in a casing, with a pulley and counter balance weight, like a sash window ; it is raised by the crank g as each mould box passes, when three little boards are placed across the frame by a boy, for the reception of the bricks. When these are deposited by the means described, the frame drops below the level of the endless strap n; the latter then receives them, and carries them off to their destination. At s is fixed a flat box, which acts as a gauge to regulate the thickness of the stratum of clay revolving upon the bottom plate n of the pug mill. The operation of this machine is as follows: the clay being worked in the ordinary manner through the pug mill, it passes out at the mouth, (not shown, being on the opposite side,) from thence under a flap which partly regulates the quantity on the bottom plate, and next under the gauge, which determines it precisely. A mould box having passed over the highest inclined plane or riser k first falls on the stratum of clay, and chops out three bricks, filling the moulds therewith by the false bottoms rising up to the determined point from the pressure of the clay against them ; the moulds, with the bricks in them, then slide over the polishing plate r, (which is kept wet by water constantly dripping upon it from a tub); from thence the moulds pass on to the frame x, when the weight g strikes against the protruded bolts of the false bottoms, and pushes out the bricks upon the boards on the frame ; the frame then descends two or three inches by their weight, and delivers the boards upon the endless strap, which, being constantly in motion, carries the bricks away to be deposited on the hacks. The mould box being discharged is then carried upon its roller up the first riser k, drops into the water, thence rises again, falls upon the cushion, next into the sand box, whence ascending again, the highest inclined plane being duly prepared, it falls again upon the bottom plate of the pug mill, and chops out three more bricks, during which period each mould box has operated in a similar manner.