72 COTTAGE, FARM, AND VILLA ARCHITECTURE. given, but the following, by Waistell, is one of the most complete, either for a farm-house or for a substantial cottage. 151. WaistcU's Tank is circular in the ground plan, with the sides built like a well. " The bottom should be in the form of a flat dome reversed, and the top also domical, with an opening left in the centre of suflScient size to admit a man to clean it out occasionally ; the top of this opening should be a little above the surface of the ground, and should be covered with an oak flap, with several holes bored in it for ventilation ; or the cover may be an iron grating, horizontal and a little elevated, or conical. These tanks may be constructed oi" various dimensions ; the depth and width should be nearly equal ; a hole should also be left for the service-pipe, or that which conveys the water into the 118 tank, and also for the pipe for the pump, if the water be drawn out by that means. The water may be filtered previously to its entering the tank ; the hole for the service-pipe ought, therefore, to be near the top, and on that side most convenient for the filtering chamber ; this may be about four feet in diameter, and three feet deep ; across this, about twelve inches from the side next the tank, as at fig. 118, /, a slate partition from the top to within about six inches from the bottom should be fixed ; at the bottom of the box should be put clean coarse sand or pounded charcoal, about a foot in thickness. The pipe or opening from the filter to the reservoir should be of ample dimensions, and be made at about eighteen or twenty inches from the bottom, in the small division or space behind the slate. Above this opening, and in any part most convenient, as at m, in the large division of the filter, should be an opening or drain to carry off the water when the 119 tank is full. This filter should also have a cover, that it may be cleaned out, and fresh sand, or some other purifier, put in as often as may be found requisite. Of course, the water, as it comes from the roof, is to be first conveyed into the large division of the filtering chamber, on the opposite side to the slate partition, as at fig. 119, n, and passing through the sand it rises in the small division purified, when it is fit to pass into the tank by the tube, o. If there are two or more of these filtering chambers, or if they are of greater depth, the water may be passed through the greater quantity of sand, &c. in them, and be still more purified. Both the tanks and the filtering chambers should be water tight ; if constructed of brick, the inner course may be built in Roman cement, and afterwards the whole of the inside covered with a coat of about three quarters of an inch thick of the same material. Water from drains formed in the ground for the purpose of collecting it for domestic pur- poses, may be purified by passing it through a sand filter previously to its entering the tank or reservoir. Sponge and flannel may also be used as filters. In constructing tanks of the above description, care must be taken to have the earth closely filled around the brick-work, and to allow sufiicient time for the work to get properly settled previously to admitting any great weight of water. Cisterns "for water formed of blue slate, or Yorkshire paving stones, are much better than those made of wood, and lined with lead." — WaisteU's Designs for Farm Buildings. 152. The Construction of the Walls and Roof of this dwelling is very similar to that of Design VII. The wall is carried up with a parapet or blocking course, fig. 120, p, be- hind which is the gutter, q. This gutter is usually covered with lead ; but in countries like Russia, where cast-iron is abundant, it may be very conveniently formed of that metal, in connexion with the entire covering of the roof. A patent was some time ago taken out for this mode of covering roofs in England, by Carter, of Exeter, of which it may 121 be useful here to give the substance. ^pnEHSMiiniinB )sl 153. Carter's Cast-iron Roofs are £ ^ A /_ formed of three descriptions of cast-iron " ' r plates, fig. 121, r, s, t. These forms answer every purpose for flat roofs which have not pavilion ends. One of them, r, is formed with three of its sides turned up and one turned down, and is called the roof plate. This plate is tapered narrower towards the lip by twice
