Lime for plastering walls was made from shells, river peb bles, or a sort Of pumnice-stone ; the best sort of lime was accounted that made from white stone, which was demise and hard, and lost one-third of its weight in burning in a kiln, where it was kept about sixty hours. Their niOrtar was com posed of one part lime and three parts of pit, or two of river sand.
Metals used were, I. Iron for chains. hinges, handles, and nails. :2. Lead for roofs and pipes. 3. Copper and brass were still more used for many of these limn-poses : or, 4. Copper, brass, and lead, mixed into a bronze for statues, bases, and capitals of columns, and in doors.
Amongst the moderns, change of climate, the convenience of local productions, and the habits of mankind, have from time to tine led to considerable changes in the kinds of materials used for the various purposes of architecture, as well as in their modes of preparation, and the application of them. With regard to timber, oak, for the greatest strength and durability, should be chosen from those soils where it has taken the longest time in arriving at maturity; and of two pieces equally dry, that should be chosen which has the greatest specific gravity, or that which will have its specific gravity least changed by being soaked in water : this observation will indeed apply to timber in general. A decay of the top is almost a certain indication of a decay of the tree; and a decayed branch, or rotten stump, bespeaks a defect in that part of the tree where it is situated. In a shnilar soil, trees which grow near the outside of a forest will be more durable than those near the middle of it ; and in the same tree, the side which grew towards the north will be stronger than the south side.
When perfection of strength and texture is alone consulted, all sorts of timber are cut down in the winter, being at that time freest of sap, and most readily seasoned, and rendered fit for the purposes of building ; but on account of the bark of the oak being of great use in tanning leather, that wood is always, in England, cut in the spring, from April to June, according to the state of the season, and soon after the sap begins to ascend and the leaf to appear ; if cut before the sap rises, the bark adheres to the wood, and cannot be stripped off, and if left until the leaf is quite expanded, the bark is valuable ; when the tree is felled and suffered to lio in the trunk, it will shrink in size ; but this is probably from its discharging water, because, it a dry tree be laid in a damp place, it will increase both in weight and size. The part called
sap varies in quantity in different trees ; it is least in bad soils, where the growth is slow, and is of very little use.
Oak used in damp situations, appears to decay gradually from the external surfitee to the centre of the tree ; the out side ring or addition it received in the last year of its growth decaying first, and afterwards that next within it, and then the following one. This appears to proceed from two causes; first, from the outward ring being, where whole trees are used, first exposed to the action of the atmosphere. which cannot reach the second until the first is destroyed ; secondly, from the central part of the tree having arrived at a greater degree of maturity than the outward rings, which are many years younger. But this must be understood only of trees which are not past their prime before they are cut down; for when a tree begins to decay from age, that part of the tree which is oldest, namely, the central part, decays first ; to this succeeds the parts which are next oldest, being the ring next the centre, and the other annual rings in succession gradually approaching the bark. A judicious builder will, thcrefore, in the choice ()Ibis timber, always carefully examine the central part of the tree, especially that part which is next the root, and more particularly if the tree be large, and have the appearance of great age.
The best mode of seasoning oak is to put it in water. This, if in the log, should be done for a whole year or more, but, if cut in planks, less time is necessary ; in either case alter nate soaking and drying is to be preferred. This, in planks, is very practicable ; but, in regard to logs, one soaking and drying gradually in the shade, is, on account of the gm-eat labour attending the operation. most generally practised. After the planks have been soaked in water, they arc dried by placing a strong pole in a horizontal position, at such a height as will admit of one end of each plank being placed on the ground, and the other to rest against it edgewise; placing a plank first on one side of the pole, and another on the other side alternately, thus leaving a space for the air to pass freely between them; and being exposed edgewise to the sun, they are not liable to split.