By boiling, for some hours, the spokes of wheels in vitriol water, they are not subject to rottenness in the parts where they enter the stocks. After boiling them in this manner, they are dried as perfectly as possible, and then, in the accustomed way, painted with oil color.
1149. Cheap and excellent Composition for preserving Weather Boarding, Paling, and all other Works liable to be injured by the Weather.—Well burnt lime will soon become slaked by exposure in the open air, or even if confined in a situation not remarkably dry, so as to crumble of itself into powder. This is called air-slaked lime, in contradistinction to that which is slaked in the usual way, by being mixed with water. For the purpose of making the present composition to preserve all sorts of wood-work exposed to the vicissitudes of the weather, take three parts of this air-slaked lime, two of wood-ashes, and one of fine sand; pass them through a fine sieve, and add as much linseed-oil to the composition as will bring it to a proper consistence for working with a painter's brush. As particular care must be taken to mix it perfectly, it should be ground on a stone slab with a proper muller, in the same manner as painters grind their white-lead, &c.; but where these conveniences are not at hand, the ingredients may be mixed in a large pan, and well beat up with a wooden spatula. Two coats of this composition being necessary, the first may be rather thin; but the second should be as thick as it can conveniently be worked. This most excellent composition for preserving wood, when exposed to the injuries of the weather, is highly preferable to the customary method of laying on tar and ochre.
1150. To make durable Barn-floors.—A durable barn-floor may be made of well-burnt polished brick on edge, placed in the herring-bone form, on a pavement of stone three inches and a half in thickness; or oaken plank two inches and a half in thickness; or even of well-tempered indurated loam, of a proper substance, not less than eight inches, and laid upon dry materials or bottom. Any of them will make a durable barn-floor, provided it is kept free from wet, wagon-wheels, and horses' feet. The best threshing-floor for small farms of 150 acres is made of sound plank. In large farms (say 300 acres and upwards) the threshing machine should supersede the flail.
1151. The Virtues of Poplar Wood for the Flooring of Granaries.—The Lombard poplar is recommended as a timber adapted for flooring granaries, which is said to prevent the destruction of corn by weevils and insects. Poplar wood will not easily take fire.
1152. Improved Ventilators for Rooms.—Different methods are adopted for ventilating, or changing the air of rooms.—Thus:
Mr. Tid admitted fresh air into a room by taking out the middle upper sash pane of glass, and fixing in its place a frame box, with a round hole in its middle, about six or seven inches diameter, in which hole is fixed, behind each other, a set of sails, of very thin, broad copper plates, which spread over and cover the circular hole, so as to make the air, which enters the room, and turning round these sails, to spread round in thin sheets sideway, and so not to incommode persons by blowing directly upon them, as it would do if it were not hindered by the sails. This well-known contrivance has generally been employed in public buildings, but is very disagreeable in good rooms; instead, of it, therefore, the late Mr. Whitehurst substituted another, which was, to open a small square or rectangular hole, in the party wall of the room, in the upper part, near the ceiling, at a corner or part distant from the fire; before it he placed a thin piece of metal, or pasteboard, &c., attached to the wall in its lower part, just before the hole, but declining from it upwards, so as to give the air that enters by the hole a direction upwards against the ceiling, along which it sweeps, and disperses itself through the room, without blowing in a current against any person. This method is very useful to cure smoky chimneys, by thus admitting, conveniently, fresh air. A picture, placed before the hole, prevents the sight of it from disfiguring the room.