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 or with louvred sides—that is, with sides after the fashion of Venetian blinds—proves satisfactory. In stacking timber horizontally, it should be laid perfectly flat and level in breadth and straight in length. The usual plan is to lay "sleepers" or cross-bearers on the ground, and then stack upon these. The ground on which the timber is to be seasoned should be properly drained so as to carry off driving rain. It should also be protected from vegetable growth; therefore

Fig. 128.—Single "Sturtevant" Apartment Drying Kiln, Section.

it is a good plan to have the ground covered with asphalted paving, or with a layer of smith's or furnace ashes to prevent vegetable growth contaminating the stacked timber and bringing about wet rot, or in some cases from becoming the source of the development of dry rot after the timber has been inserted in a building. The lowest layer of timber should rest upon bearers which should be arranged all in one plane—that is, out of winding, otherwise the timber stacked upon them would become permanently twisted. This is very important. The timber should be stacked in layers, with a space between each piece in the same row, and strips of wood about ½ in. by 1 in. between each layer, about 2 ft. or 4 ft. apart (Fig. 127), or arranged in some similar manner, the object to be kept in view being to allow free circulation of air round nearly the whole of each piece, gradually carrying off a greater part of the sap and moisture from the timber. To prevent planks and boards splitting from the ends up the centre, they are clamped by nailing strips of wood to the ends as indicated at (Fig. 127). Timber seasoned as above is said to retain properties that render it stronger, heavier, more elastic and flexible, and much more durable than timber seasoned by artificial processes.

Artificially Seasoning Timber.—There are various artificial processes of seasoning in use which expedite the work and shorten the time necessary between felling and using, but the strength and toughness of the timber are reduced. The methods are—desiccating, or using hot-air chambers, smoking, steaming, and boiling. To reduce the risk of splitting the ends in the drying process, they are clamped—that is, thin pieces are nailed over the end grain so that the ends may dry uniformly with the other