IG COTTAGE, FARM, AND VILLA ARCHITECTURE. and to preserve the other part unfiltered, in a cistern and in a large tank, for the purposes of the water-closets, for the use of the cow and pigs, for washing and cleaning, and for the garden. It is calculated by Waistell, that the average quantity of water which falls on a square yard of surface in Britain, in a year, is 126 gallons; which, for this building, containing upwards of 100 square yards of roof, will give 12,000 gallons ; an ample quantity for the purposes mentioned. A cottage constructed on this principle, therefore, may be set down in any situation, without reference to a natural supply of water. The cistern, /, in Design I, may be of cast-iron; or of slabs grooved into each other, and made water-tight with Roman cement; or of plates of Welsh slate ; or of large flat paving tiles set in cement ; or it may be made of wood, plastered inside with cement ; or of bricks set in cement, and plastered within with the same material ; or in countries where timber is abundant, as in America, or Australia, it may be formed of thick planks, well pitched ; or it may be simply an old liquor cask. However constructed, it must have a waste-pipe ; which, when the cistern is full, will flow over into the tank or well below, shown in fig. 5. This well or tank is to be considered as the grand reservoir of the premises ; and if there should be a natural spring in it, so much the better. Should the culinary, or filtering tank, fig. 8, /, fail at any time, water may be drawn from this tank, and introduced into the filtering tank. 31. The mode of filtering is very simple, and will be easily understood from the section E F, of Design I. In this section, fig. 8, a, represents a vacant space of three inches from the bottom to b ; b, is a slate, stone, or board, pierced vvith numerous holes, say at the rate of three to an inch, of about the eighth of an inch in diameter ; c, is a mixture of clean coarse sand and powdered charcoal, or coarse burnt clay, with- out either sand or charcoal ; d, a filtering stone ; or in default of a stone of this porous nature, a plate of lead thickly pierced with holes, of one twentieth of an inch in diameter ; e, an opening by which the water of the receiving tank,/, communicates with a, at the bottom of the filtering tank ; g, an opening by which the water after it has ascended through the filter, runs over into the reserve tank, h. The filtering ot the water may be effected in a more simple manner, by placing a layer, about six inches thick, of round stones, about the size of eggs, in the bottom of the filtering tank, and over this either burnt clay, or sand and charcoal, covered by a pierced leaden plate, as before; or by a stratum of sponge, which may be substituted for the plate. It must be evident by inspecting the section (fig. 8), that when the water supplied from the roof to the receiving tank,/, rises above the level of d, it will run over, by g, into the reserve tank, h; and that the water in all the three tanks will always stand at the same level, provided the water in the tank,/, be above the level oi d. 32. The filtering material may he cleaned by having a large cock in the bottom of the receiving tank, com- municating with the waste drain ; by opening which, when the reserve cis- tern is full, the water in that cistern will rush through the filter in a con- trary direction to what it did before ; and will carry off all the impurities, either in the filter, or in the space at the bottom, a. The filtering might also be effected by placing the filter in the tank /, instead of in the centre tank ; and by introducing the water from the roof, direct to the space, a, by a pipe, through the filter; the water would then rise through the filter, and fill the tanks, e and h. A larger re- serve of filtered water would thus be obtained ; but the filter would require cleaning oftener. The great advantage of the mode we have recommended is, impurities in the bottom of the tank,/. that the water will deposit the greater part of iU
