Charring of wood is known to be a most effectual mode of preservation against rutting.
The incorruptibility of charcoal is attested by numerous unquestionable facts. At the destruction of the tinnous temple at Ephesus, it was found to be erected on piles that had been charred ; and the charcoal in Herculaneum, after almost 2,000 years, was entire and undiminished.
To this property of charred wood Sir C. Wren does not seem to have attended, when about to build St. Paul's. It is said, he thought piles were not to be depended on for a foun dation, excepting when always wet ; and therefore dug to a great depth through a dry soil, in order to come at a solid tbundation for part of that cathedral.
Charcoal has also been found useful as a defence to the surface of wood, when used as a paint. We lately had a good instance of the effect of sand used for this purpose. At Stud ly Royal, we saw a temple to appearance of stone, but which, on examination, we found to be wood covered with paint and dusted over with sand. We were informed it had stood about 50 years ; and the deception was still so complete, that the spectators supposed the pillars to be stone, till minutely examined.
The following table of the properties of different kinds of timber is extracted from Tredgold's valuable work on Car pentry, and will be found to contain, in a condensed form, every information as to the comparative merits of the various descriptions of wood used for building or similar purposes:— For marble, being plentiful in Italy and France, these countries have been able to 'flake a considerable use of it, e‘ en in the malli walls of their edifices; but being seldom found in sufficient quantities, and of proper quality., in the Illore northern parts of Europe. it has been here chiefly con fined to interior columns, pavements, chimney. pieces, and sometime-, stairs.
Tile kinds 01' stone are as various as the countries in which the buildings are constructed. Sand-stone being very gene rally found stratified, even in thin lamina). being readily cut into Midi rent forms, and being, if properly selected and used sufficiently durable, it has, in northern countries. been in most frequent use. It is a general ac•onimnillient of coal strata, mid is also often foundI waere the latter does not occur.
It vatic), in its component 'farts, being at different places argillaceuus, siliceous, and calcareous. Its position in the earth assumes all directions, from the horizontal to a vertical plane. The proportional thickness of its strata, laminae, or beds, varies from that of thin slate to many feet each. The upper beds are usually very thin or soft, or both ; stati hard, they are employeil in Moor paventents,.and covering oofs. Under these the beds generally, in gnat ries, increase in thickness, hal due's, and tenacity. The pifsitisal of the lamina) always requires strict attention, that the Wei ked stoat; may, if possible, be laid in the building upon its natural bed ; for although SWOP instances Oerar, as iu the Isle of l'oltland and at Grin-hill, in Shropshire. where the didei ence is not ay' reit Li? great. yet in all stone {even granite) It is sufficiently. wt II known to workmen. Some. statue, as that of Bath, is so soft \\ hen taken out of the quarry a, to be. very conveniently worked with tools resembling those used by carpenters; y et when exposed for some tittle to the aullusphere, it hard and durable. 'Nis last, infieed, cannot be deemed said-stone, being nearly altogether cu Besides the helOre-mentioned, there is a very beautiful stone, dug in the bibs near Dilatable, in the parish of Tot teultoo, from whence the stone receives its name. It has the appearance of indurated chalk. It is easily worked, and hardens. if) expo•)] e to the weather. It should, however. be placed upon a plinth of some other stone, or kept by other means bum courant with the ground ; otherwise it is, in this situation, liable to be injured by the frosts. The house of the Duke of Bedtbrd, at Woburn Abbey, is built chiefly. with this Aisle, as are yahoos other large houses in the neigh bourhood of the gnat ries. limit's of its durability may Le seen in many 01(.1 churches. From the closeness of its tex ture, the beauty of its colour, and the thcility with which it is worked into mouldings, &e., it is peculiarly fit fur house building, both externally and intern:thy.