TILES AND PAVEMENTS. A tile is a kind of thin brick, or plate of baked clay, used chiefly for covering roofs, but occasionally for paving floors, constructing drains, &c. The English name, aud those by which tiles are known in other European languages, are derived from the Latin tegula, which contains the erune element as !ego, to cover.
Among the Greeks and Romans roofing-tiles were originally made, like bricks, of baked clay ; but later, tiles of marble were made of tench larger dimensions than was praeticable In clay, and consequently the effect produced by their parallel joints might be brought into harmony with the rest of the building. A still more expensive and magnificent method of roofing occasionally adopted consisted in the use of tiles made of bronze and gilt. Tiles were originally made flat, or with nothing more than the hook or nozzle underneath the upper border, which fulfilled the purpose of fixing them upon the rafters. They were subsequently formed with a raised border along each side, on the upper surface, and tho sides of the tile were made to converge towards the lower end, in order that the raised sides or ledges might not prevent the successive rows of tiles from overlapping each other neatly. The lines of junction between the flat tiles were covered by small semi-cylindrical tiles, called Imbriees, the rows of which, extending from the ridge to the gutter, divided the surface of the roof into a series of channels, along which water descended to the gutter. Both the tegulfr and the imbrices terminated at the edge of the roof in ornamental pieces. Another kind of ancient tiling, men tioned by Pliny under the name of pavonaesum, consisted of tiles of a semicircular form at their lower edges, which, when laid in overlapping rows, somewhat resembled the feathers in the train of a peacock.
The process of making tiles is so similar to that of briek-making I that it will be sufficient to observe that only the best qualities of brick-earth are fit for the purpose. Since the year 1833 no excise-duty has been levied upon the manufacture of tiles. The roofing-tiles used in this country arc chiefly of two sorts: namely, plane-tiles, which are flat, of a rectangular form,and usually about 104 inches long, 6 inches wide, and 5.8ths of an inch thick ; and pan-tiles, which also have a rect angular outline, but are bent in such a manner that, when laid on the roof, the greater part of their surface forms a concave channel for the descent of water, while one side forms a narrow convex ridge which overlaps the edge of the adjoining tile. These are usually 134 or 141 inches long, and about P inches wide, measured in a straight line from side to aide. Plane-tiles are made with a hole near their upper extremity to receive a wooden peg, by which they are hung upon the laths of the roof. They are laid either with or without mortar, in such a mintier that the successive rows overlap each other about 0 inches. Pan-tilea have no holes, but are hung upon the laths by ledges formed at their upper edges ; they do not require so great an over-lap as plane-tiles, Tiles of a semi-cylindrical form, laid in mortar, are for covering ridges if the convex side be uppermost, and for covering gutters if the concave.
Paving-tiles are usually square, and of greater thickness than those for roofing. Drain-tiles are commonly made in the form of an arch,
and are laid or bedded upon flat tiles, called soles. The substitution of drain pipes for is noticed under DRAINAGE. Machinery is now extensively employed in the manufacture of tiles, similar in principle to the brick-making machinery noticed under Blum. • What are called Encaustic Tiles, are productions midway in constitu tion between pottery and brick, and midway in artistic character between mosaic and plane-tiles [Mosaic ; TESSERA]. Decorative paving-tiles of baked pottery were much used in the middle ages ; but their manufac ture in England was almost forgotten until the late Mr. Minton revived it. The Temple Church, in London, was one of the first buildings in which the revival was exhibited ; aud since that period (about twenty years ago) the use of such tiles, principally for pavements, has extended largely. Pressure is brought to bear in their making, thereby rendering them much harder and less porous than ordinary tiles. One mode of making them is as follows : Supposing each square tile to exhibit a yellow device on a brown ground, the brown portion is formed of a suitable kind of stiff clay, pressed in a mould to a thickness of about one inch. The mould not only gives the form, hut also produces depressions about a quarter of an inch deep, marking out the device. Heavy pressure is employed to harden the clay, and to give sharpness to the device. The yellow clay to fill up the depressions is mixed to the consistence of honey, and is applied chiefly by means of a kind of trowel. The clays are selected with much care, in order that they may shrink equally in drying ; and they are allowed a long time to dry in the open air, before being baked. The surface is well scraped and cleaned before firing. The tiles are either left dead, or are glazed In the same manner as pottery and earthenware. If more than two colours are exhibited, the process is necessarily more complicated. To form a pavement, the tiles are usually imbedded in cement, and are roughened or in some way hollowed on the under surface to increase the hold.
Many other modes have been partially adopted for the production of ornamental paving-tilee. Mr. C. Wyatt at one time made pavemente of atone inlaid in coloured cements. Other inventors substituted pieces of terra-cotta for the stone. Mr. Blashfield has tried cements coloured with metallio oxides, and bitumen coloured in like manner. Messrs. Singer and Pether have made pavements, by rolling out prepared clay into sheets, cutting it into small cubes, combining these cubes accord ing to their colours, forming them into a slab having a defined pattern, and laying down the slab as a pavement ; the cubes on this plan aro usually about en inch square on each side, and are made into slabs about half a yard square. Cubes or tesserto have since been made of exceed , ing hardness, by a process due to Mr. Prosser; he pulverises fire-clay end felspar, or flint, and subjects them while dry to intense pres sure between two steel dies; the colour is introduced either by mixture with the powder, or by being thrown into the oven while baking. Those cubes or tesserie produce a pavement of exceeding hardness and durability.