815 gal. × 10 lb. × 30 ft. lift ------------------------------- = 7·4 H.P. 33,000 [Illustration: 6. Lift Pump.] Fig. 6 shows a vertical section of the simple lift-pump. _a_ is the working barrel, bored true, to enable the piston or bucket _b_ to move up and down, air-tight. The usual length of barrel in a common pump is 10 in. and the diameters are 2, 2½, 3, 3½, 4, 5, and 6 in.; a 3 in. barrel is called a 3 in. pump. The stroke is the length of the barrel; but a crank, 5 in. projection from the centre of a shaft, will give a 10 in. stroke at one revolution; but in the common pump shown, use is made of a lever pump handle, whose short arm _c d_ is about 6 in. long, and the long arm or handle _d e_ is usually 36 in., making the power as 6 to 1; _f_ is the fulcrum or prop. Improved pumps have a joint at _f_, which causes the piston to work in a perpendicular line, instead of grinding against the side of the barrel. The head _g_ of the pump is made a little larger than the barrel, to enable the piston to pass freely to the barrel cylinder; in wrought-iron pumps, the nozzle is riveted to the heads, and unless the head is larger than the barrel these rivets would prevent the piston from passing, and injure the leather packing on the bucket. The nozzle _h_, fixed at the lower part of head, is to run off the water at each rise of the piston. There is 1 valve _i_ at the bottom of the barrel, and another in the bucket _b_. The suction pipe _k_ should be ⅔ the diameter of the pump barrel. A rose _l_ is fixed at the end of the suction pipe to keep out any solid matter that might be drawn into the pump and stop the action of the valves. The suction pipe must be fixed with great care. The joints must be air-tight: if of cast flange-pipe, which is the most durable, a packing of hemp, with white and red lead, and screwed up with 4 nuts and screws, or a washer of vulcanised rubber ⅜ in. thick, with screw bolts, is best. If the suction pipe is of gas-tube, the sockets must all be taken off, and a paint of boiled oil and red-lead be put on the screwed end, then a string of raw hemp bound round and well screwed up with the gas tongs, making a sure joint for cold water, steam, or gas.