WOOD.
Wood is an article of universal application; its lightness, strength, and the facility with which it can be worked, render it almost invaluable; although in ship-building and many of its applications to house-building iron has to some extent superseded it, yet there are so many other ways in which it is indispensable, that it may be looked upon as one of the greatest boons to mankind. There is scarcely a use to which wood may not be applied, whether as fuel for fires, timber for building, furniture both useful and ornamental, various parts of machinery, vessels to contain wine and other fluids, handles to instruments, (for in cold climates and cold weather metal cannot be handled with impunity), and indeed for all uses in which lightness, dryness, warmth, and variety of form are desirable, wood serves as an excellent material. The kind of trees that produce wood fit for building and other useful purposes are those called by the botanists exogenous. Amongst which the pine tribe, oak, ash, elm, and beech, stand pre-eminent; while mahogany, walnut, and rosewood are chiefly used for ornamental purposes; box-tree wood is also very useful on account of its closeness and evenness of grain; it is the wood used by engravers.
Wood when first cut is wet and heavy, but, by being exposed to the air, it shrinks and the sap dries up in it, it is therefore liable to swell and become damp in moist situations this is detrimental to its usefulness; most woods therefore are improved by being soaked a long time in water, this cleanses it from saline and extractive matters which keeps the wood damp, but which, when separated, allow the wood to shrink and harden permanently, this process is called seasoning, the same effect may be produced by exposure to the air and rain, it is generally resorted to when the timber is cut up into smaller pieces. The structure of wood is porous, hence its lightness, it has also a grain which runs the whole length of the wood in circles round its centre to the surface, one of these circles is produced every year while the tree is growing; wood is therefore capable of being cleft in the direction of the grain by a wedge, in this way builder’s laths are made. Wood cannot be cleft across the grain, but must be cut by sawing or otherwise. The pine or fir tribe produce the largest and straightest timber, but it is not so strong nor so durable as oak and many other woods.
Some specimens of the Araucaria Excelsa or Norfolk Island pine, have stems upwards of three hundred feet high, and in the Crystal Palace is the bark of another gigantic tree the Wellingtonia Gigantea.