[Illustration: FIG. 149.--The water lift.] In order to be assured of a supply of water over periods of atmospheric quiet, the well-water tank must be sufficiently large to supply water for 3 or 4 days; but in case of emergency water may be pumped by hand. A nearer view of the water lift is shown in Fig. 149. In the figure, the right-hand cylinder with its valve _V_ is the water engine which furnishes the power for operating the pump, enclosed in the left-hand cylinder. The water pressure of the main supply furnishes the energy which drives the engine, the piston rod of which is attached to the pump piston. The engine receives its supply of water through the pipe marked Inlet and the waste water is discharged to the sewer by the waste pipe on the opposite side of the cylinder. The operation of the lift is governed by an automatic regulator which so controls the engine that it starts pumping whenever the pressure in the system falls to a certain point. The regulator marked Adjustable Regulator in the drawing may be adjusted to suit the water pressure desired in the distributing system. [Illustration: 1 Air Chamber Nut 2 Brass Tube for Air Chamber 3 Air Chamber 4 Brass Cock 5 Cap Screw 6 Leather Washer 7 Handle Pin 8 Pitman 9 Handle 10 Brass Covered Piston Rod 11 Fulcrum 12 Fulcrum Pin 13 Brass Stuffing Nut 14 Cap 15 Fulcrum Ring 16 Fulcrum Ring Pin 17 Plunger 18 Cylinder 19 Cap Screw 20 Lower Valve 21 Brass Valve Seat 22 Base 23 Bottom Brass Ferrule 24 Bottom Nut FIG. 150.--The terms by which the parts of a force pump are designated.] CHAPTER VIII SEWAGE DISPOSAL The disposal of sewage, in a convenient and sanitary manner is a problem of serious importance in the equipment of isolated dwellings with modern household conveniences. The manner of heating, lighting and of water supply are questions of selection among a number of established systems, but the problem of sewage disposal must in a great measure be determined by local conditions. Unless the natural surroundings are such as will permit sewage to be emptied directly into a stream of considerable volume, the problem of its safe disposal becomes one of serious importance. Sewage is understood to mean the fluid waste from the kitchen, toilet and laundry and has nothing whatever to do with garbage. Sewage disposal has to do with conducting away the house waste and disposing of it in a sanitary manner. Sewage disposal does not necessarily have anything to do with sewage purification; although a sewage disposal plant may be so constructed as to discharge a purified effluent, it usually is understood to have to do alone with its disposal in a manner that does not offend the aesthetic sense. A simple sewage plant is anything that will take the sewage away from the house in such a way as to produce no unsightly accumulations that will decay and produce offensive odors.