Timber

in military architecture, includes all kinds of felled and seasoned wood used in the several parts of building, . Oak , of all the different kinds of timber known for building, is preferred by the European nations; because, when well seasoned and dry, it is very tough and hard: it does not split so easy as other timber, and bears a much greater weight than any other. When it is used under cover, it never perishes, no more than in water; on the contrary, the older it grows the harder it becomes; and when it is exposed to the weather, it exceeds all other timbers for durability. English oak is said to be the best, American the next, then Norway, and lastly Germany. But there are various kinds of American oaks. Elm , if felled between November and February, is all spine, or heart, and no sap, and is of singular use in places where it is always wet or dry. It is very tough and pliable; it is easily worked, and does not readily split: it bears driving of bolts and nails into it better than any other wood; for which reason it is prepared for artillery uses. Beech is likewise a very useful wood; it is very tough and white when young, and of great strength, but liable to warp very much when exposed to the weather, and to be worm eaten when used within doors. It is frequently used for axle-trees, fellies, and all kinds of wheelwright work: but where it is kept constantly wet, and free from air, it will outlast oak. Ash. Its use is almost universal. It serves in buildings, or for any other uses where it is skreened from the weather: hand-spikes and oars are chiefly made of it; and indeed it is the wood that is most fit for this, or any other purpose, which requires toughne and pliability. Fir , commonly known by the name of pine is much used in building, especially within doors. It wants but little seasoning, and is much stronger while the resinous particles are not exhausted, than when it is very dry: it will last long under water. Chesnut-tree , especially wild chesnut, is by many esteemed to be as good as oak. But the best of all timber for shipbuilding is the Teak of Asia; it endures water four times as long as oak, is much more easily wrought; iron spikes drove into it do not rust. There are many other kinds of wood, used in military works, not mentioned here. Preserving of TIMBER . When boards, . are dried, seasoned, and fixed in their places, care is to be taken to defend and preserve them: to which the smearing them with linseed oil, tar, or the like oleaginous matter, contributes much. The Dutch preserve their gates, port cull ices, draw-bridges, sluices, . by coating them over with a mixture of pitch and tar, whereon they strew small pieces of cockle and other shells, beaten almost to powder, and mixed with sea sand, which incrusts and arms it wonderfully against wind and weather. Seasoning of TIMBER . As soon as felled, it should be laid in some dry airy place, but out of reach of too much wind or sun, which, in exce , will subject it to crack and fly. It is not to be set upright, but laid along, one tree upon another, only with some short blocks between, to give it the better airing, and prevent it becoming mouldy, which will rot the surface and produce mushrooms on it. Some persons daub the trees all over with cow-dung, which occasions their drying equally, and prevents their cracking, as they are otherwise very apt to do. Some recommend the burying timber in the earth, as the best method of seasoning it; and others have found it a fine preservative to bury their timber under the wheat in their granaries; but this cannot be made a general practice. In Norway they season their deal planks, by laying them in salt water for three or four days, when new sawed, and drying them in the sun: this is found a great advantage to them; but neither this, nor any thing else, can prevent their shrinking. Timber should always be seasoned, when it is intended for piles and other pieces that are to stand under the earth or water. The Venetians first found out this method; and the way they do it is this: they put the piece to be seasoned in a strong and violent flame, turning it continually round by means of an engine, taking it out when it is every where covered with a black coaly crust: by this means the internal part of the wood is so hardened, that neither earth nor water can damage it for a long time after.