MODEL COTTAGES. 19 15 -j^i^^j"— i h, and passed over a pulley at k, and the end of this cord may be fixed to the upper part of the door of the water-closet, at such a distance from the hinge, say a foot, as will suffice to lift up the valve, g ; or the same purpose might be eflfected by a lever, fig. 15, /, which would be acted on every time the door was opened. 39. JVhen the cistern is unavoidably placed on a level with the basin, the opening for the admission of water must be much larger than in the first case. This opening may be closed by a valve, similar to that marked g, in fig. 13 ; but a better mode is to have a lever valve, fig. 16, 7n, which will also be operated upon by the door every time that it is either opened or shut. In every case in which it is intended that a common or lever valve should be operated on by a door, the latter ooght to have a spring bolt (a contrivance for shutting the door, which will be afterwards figured and described), to shut it, lest at any time it should be left open by neglect. There are different methods of constructing a privy to be used without water. One is, to have a basin, as in a water-closet ; and to continue down from it, a tube so far into the cesspool below, as to prevent the rising through it of air, and consequently of smell. If all the waste water of the house is, as it ought to be, poured into the basin, neither that nor the tube will ever be choked up ; and, in that case, this construction may be considered one of the best for preventing smell. The next mode is to have no basin ; but to take care that the surface of the cess- pool exposed to the air, is no larger than is necessary ; and that no crevices are left in the seat, so as to admit of a current of air passing over the surface of the cesspool. There ought, both in this case and in the other, to be two covers to the hole in the seat ; one of a circular form, to fit into the opening, and the other, larger and square, to be affixed by hinges to the back board, so as to shut down over the whole seat. The windows in all water-closets ought to be close to the ceiling ; both to prevent the persons within from being seen, and to admit of a more effectual ventilation. 40. General Estimate. What is called a general estimate of the expense of a building is calculated at a certain rate per cubic foot, while a specific estimate is made up of the separate estimates of each particular article. The rate or price at which a general estimate is calcu- lated, depends upon a vai-iety of circumstances ; but in every situation, the principal points by which it is affected (all others being the same) are, — first, the irregularity of the outline of the ground plan, and of the elevation ; secondly, the number of angles in the roof, or the number of separate roofs ; and thirdly, the ornamental or carved work, both within and without the building. Tiie nearer the whole mass of a building approximates to the form of a cube, and the nearer all its separate parts approach to that form, the lower will be the rate per foot. One roof of the simplest form may always be calculated at a lower price than a varied roof, or several roofs. In Britain, buildings are divided into three classes: called, first, second, and third-rate buildings. Cottages, and such dwellings as are contained in this Book, belong to the third-rate class, and are generally calculated at from four-pence to six- pence a foot for London. From the amount thus obtained, fifteen or tv.enty per cent, is generally deducted, and the total thus found is the amount of the general estimate. 41. The cubic contents of this htulding are 16,833 feet ; and the following is the manner in which these contents are calculated : —
