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Rh long as the salts remain in the timber; but by some authorities the salts are said to be gradually removed by the action of water, and thus in time the timber becomes a prey to insects and decay. When, however, timber is treated thoroughly by Bethell's process, its durability is greatly increased, and it is rendered proof against the attacks of every insect, including the white ant.

Fig. 133.—Planks Warped according to position in Tree.

Fig. 134.—Shrinkage of Quartering in Seasoning.

Fig. 135.—Old Method of Converting Logs into Deals.

Fig. 136.—Modern Method of Converting Logs into Deals.

A log is the trunk of a tree after the branches are lopped off. A balk is a log which has been squared by means either of sawing or adzing; the latter would be known as a hewn balk. Planks are pieces of sawn timber from 2 in. to 6 in. thick, 11 in. to 18 in. wide, and from 8 ft. and upward in length. Deals are from 2 in. to 4 in. thick and 9 in. wide. Battens are from 4½ in. to 7 in. wide, and from 2 in. to 4 in. thick. Boards are pieces of sawn timber of any length and breadth, but not exceeding 2 in. in thickness. Scantlings are pieces of timber which have been sawn to 4 in. by 4 in., 4 in. by 3 in., 4 in. by 2 in., 3 in. by 3 in., 3 in. by 2 in., etc. The smallest pieces are frequently called quarterings.

In converting timber into planks or boards the shrinkage and warping to be expected in use depend upon what part of the tree the piece is cut from. Practically, the stuff will only shrink along the curved lines of the annual rings, and not from the outside towards, the centre; so that, a tree being cut into planks, the alteration produced by seasoning is shown in Figs. 126 and 133. A piece of quartering would, in the same way, if originally die-square, become obtuse angled on two opposite edges, and acute

Fig. 137.—Converting Pitchpine Logs into Boards to show the Grain.

angled on the other two, as in Fig. 134. In the conversion of fir, the old system is shown at Fig. 135, which is objectionable on account of the centre deal containing the pith enclosed, and being therefore more subject to dry rot. Fig. 136 shows the modern method of conversion, where the 9x3 deals go to the English market, and the 9 x 1¼ to the French market. Of the remainder in each case, some is cut up into battens and fillets for slating and tiling, and similar purposes, and the rest used as fuel. The method of converting a pitchpine log so as to show the best possible grain is indicated by Fig. 137 (see also p. 48). In converting oak, the method will depend upon the purpose for which it is required. For thin stuff, where the silver grain or "flower" is desired to appear, the method