revert to the articles, Drilling, Harrow, Hoe, Plough, Spade, &c.
TIMBER, a term denoting every species of wood, that is felled and seasoned, with the view of being employed in building houses, vessels, and other structures.
Of the different kinds of timber-trees, such as Oak, Ash, Beech, &c. we have already treated in the progress of this work, and stated the most appropriate methods of rearing them: hence, we shall at present confine our attention to the proper times for felling, seasoning, and preserving timber.
The age at which timber-trees ought to be cut down, varies according their nature, and the purposes for which they are designed.—Mr. Marshall observes, that poplars may stand from 30 to 50 years; ash and elm-trees, from 50 to 100 years; but oaks should on no account be felled, till they have attained the age of from 100 to 200 years. The durability of timber, however, depends on the soil and sub-soil, on which the trees have been produced: thus, in loose or absorbent lands, the oak and elm decay at an earlier period than those grown in cool and more retentive ground; but, in dry loams with a rocky sub-soil, the oak rapidly decays, after it has attained the age of two centuries.—Farther, the Cypress, Cedar, and Mahogany, are supposed to be indestructible by time, or the depredations of insects, in whatever exposure they may have been raised; and the Alder endures the action of water, for many years longer than any other species of timber: hence it is deservedly employed for piles in constructing dams; in order to secure the banks of rivers.
The season for felling oak, or fir-timber, commences toward the end of April; though the winter is often preferred for that purpose, and likewise for cutting down ash and elm-trees; as it furnishes labour to persons who would otherwise be unemployed. All branches or limbs, that may injure the trees in their fall, ought previously to be lopped, and the trunk cut down close to the ground, unless it be grubbed or rooted up; which latter method is preferable, as well as more profitable; because timber, produced from old stocks, is of inferior value.
After the trees are felled, it will be advisable to season them, previously to working the timber: it has, therefore, been recommended to pile them, one upon another, with small blocks of wood between each, in an open but not too exposed situation; so that the sun and air may penetrate every part; the surface, or uppermost trees, being plastered with cow-dung, to prevent them from cracking. Another method is that of burying the timber in the earth; but the most effectual mode of seasoning it, by heat, is performed at Venice, where the trees are exposed to a strong fire, at which they are continually turned round by means of an engine, till they become charred, or covered with a black crust: by this expedient, the internal part of the wood is so hardened, as to resist equally the effects of earth and water, for a long series of years, without receiving any injury.
When boards or planks have been properly dried, additional care becomes necessary to preserve them
