These shales or clunches, now indurated, were originally the soft soils from which the roots of plants of the coal-measure period drew their nourishment; and they still retain the impression of such roots in great abundance, as any one may satisfy himself who takes a piece in his hand to examine it. The vegetable matter derived from roots, and from the plants themselves, give them a dark colour; but this burns away in the firing, and the bricks come out of the kiln nearly a pure white. It is almost invariably found that where the vegetation of a seam of coal grew on the spot, and was not transported, as was the case in some instances, that one of these underclays is to be found still retaining very beautiful casts of the roots of plants, and not unfrequently the seeds as well as the plants themselves that grew above them. As fire-clays, they are little if at all inferior to the famous Stourbridge clays, and they supply an invaluable material for crucibles, for bricks for the interior of our blast and puddling furnaces, for the kilns of our potteries, and for various other purposes where intense heat is required.
With regard to clays in general, and the art of working in them, it may be remarked that archæologists have told us little. They have divided the past history of the race into the stone, bronze, and iron periods, but have told us nothing of the age of clay, or of an art which we venture to say was one of the oldest invented by man. Clay and clay-workers are found everywhere; and the material is one of the most abundant provided by Nature. The first man would find it soft, yielding, and ready to his hands, with the impressions of birds and beasts, suggestive of the use to which it might be put, and the act of moulding it into form would be as natural as that of plucking fruit from a tree, or that of taking up a stone to strike a harder blow than the hand could give. Hardening it in the sun or baking it in a wood fire would be equally simple; whilst the act of fashioning a shapeless mass into an enduring form would yield so much pleasure that it would be repeated. That the art is pre-historic, and began before the race commenced a record of its doings, is evident from specimens which accompany the remains of men of whose tribe and nation we know nothing. Living beings stronger than man had been masters of the globe before he came, and ignobly perished, leaving but the impressions of their bones to tell of their existence; but man brought with him a new element by which to subjugate and subdue the materials he saw around him to his use, and left behind him more enduring monuments.
Other enduring materials pressed into the service of architects of ancient and modern times were once as incoherent a mass of atoms, and as unshapable as these clays, and were either earths, clays, or sands, which Nature by the processes of kneading, pressing, and baking, in her great laboratory, converted into stone. We find them to some extent ready shaped to hand in the quarry, and we cut them into cubes or blocks, and pile them up in buildings, according to the humour or taste of the time. Bricks are artificial stones, and in making them we follow the example Nature set us only that we cut the plastic material first of all to the size we desire it, then convert it into stone by heat; and this artificial stone, we venture to say, for durability and beauty, is equal even to Nature’s own production, and quite as suggestive to the mind. Nature’s finished material may be deemed more suitable for churches; but artificial stone, fashioned into shape by man, is quite as appropriate for a dwelling in which the highest social sanctities gather. Indeed the art of using artificial stone appears to have been roused from the torpor into which it had fallen since Roman and Flemish authorities set such good examples. People had been so long accustomed to see brickwork used only for inferior houses, and stone for buildings of greater pretensions that, till recently, English bricks have scarcely had justice done them.
The antiquity of brickmaking is so well-known that it is scarcely necessary to allude to it. It will suffice to remind the reader of the tower of Babel, built about 400 years after the period assigned to the flood. That bricks were made in Egypt at an early period of her history is well known; and that this same people had faith in their durability is clear from the fact that they impressed them with hieroglyphics, or historical records, transmitting to us the names of their kings. Mr. Smith of the British Museum, has brought home clay cylinders which the Assyrians used for writing upon. Again, the way in which Jewish writers speak of pots and potters, comparing humanity to lumps of clay fashioned into vessels of honour and dishonour, and the silly and wicked portion of humanity to potsherds, good for nothing but to be cast upon the highway, shows that they drew much of their philosophy from the art. With them, as with other nations of antiquity, the art of working in clay ranked high. Potters of the tribe of Judah “dwelt with the king.” And one very noticeable feature is the fact that the same simple means are still employed to effect the same object; for illustrations in the catacombs of Thebes show that forty centuries ago clay was kneaded with the feet, turned upon a wheel, and baked in a circular oven, as at present. The praise of those who out of rude clay fashioned things of use and beauty, and impressed upon plastic materials the living thoughts that stirred men’s minds was loudly sung, whilst the more successful cultivators of the art were honoured with medals and statues, and their names transmitted by poets and historians to posterity. The Greeks and Romans gave a dignity to the art by raising it to a level with that of sculpture. A Corinthian potter, Pliny tells us, was in his day regarded as the first who contrived making likenesses in clay by pressing the material up to the outlines his daughter had drawn of her lover’s shadow on the wall and placing it with other pottery to be hardened in the fire. Other authors ascribe to the art a higher antiquity and speak of it as the parent of sculpture. The estimation in which it was held is shown by the fact that exhibitions of the best works in clay were frequently held in Athens; and amongst the ruins of that city statues of clay have been found, some in groups, representing Grecian Mythology; and some of large size retaining portions of the paint with which they were coloured on the eyes and eyebrows. In the Townley Gallery of the British Museum, No. 38 is a statue of a Muse, three feet eleven inches high; and also a terra-cotta statue of a Muse resting her left arm upon a pile of writing tablets, which are placed upon a square column, but the head is gone. The former represents Orania, the latter Calliop, whose office it was to note down the worthy actions of the living, as it was that of Clio’s to celebrate those of departed heroes.
Celts, Etruscans, and Chinese made early and great advances in the art of using clay: the latter had even an imperial porcelain work at King-te-Ching, a hundred and eighty-four years Before Christ, and thirty years B.C. they introduced the same art into Japan.
With regard to bricks and tiles we know that among Roman and mediæval builders bricks made of clay were held in high estimation. The former enterprising people having penetrated into our valleys and excavated our hill sides in search of lead and iron were not likely to neglect the clays with which the ore for the latter was associated; and evidences of the extent to which they worked them on the banks of rivers, where such seams were exposed, particularly on the banks of those flowing through the great centres of their occupation, confirms this view. Their armies were accompanied by men learned in the art; and in the relics dug up at Malmesbury, Salisbury, Romsey, Malvern, and Uriconium, modern workers in clay may learn much of the early history of their craft. The still upstanding walls at Wroxeter, with string courses of tiles, and the numerous specimens of bricks, tesseræ, and pottery in different coloured clays, brought to light by excavations within its shadow, are interesting from the fact that some are supposed to have been manufactured from clays still in use in the neighbourhood.
At Caersws, a little village on the banks of the Severn, between Llandinam and Newtown, well made bricks, both of composite and simple clay, may be seen stamped with Roman letters, probably the initials of workmen’s names; and, as a test of the durability of both, it may be remarked that after having done duty in buildings in which the Roman masons placed them, they have been rebuilt by British workmen into the chimneys of the village. These, of course were burnt; but, favoured by the extreme dryness and heat of their own climate, the Romans, like the Egyptians, used clay mixed with chopped straw, to assist the tenacity of their bricks, which, without being at all artificially heated, have lasted thousands of years. The material of which Roman bricks in this country were formed was usually a strong clay, such as brickmakers call tile-clay; well tempered, well pressed, and well burnt, producing a heavy tough brick, indefinitely durable, and of a good deep-red colour.
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.