The importance of cylinder diameter will be better understood by comparison. A total lift of 100 feet, with cylinder 2 inches in diameter, gives 135 pounds, which, with the handle leverage at 6 to 1, will be lifted with from 22 to 25 pounds' force according to kind of rod, tightness of stuffing box, size of lift pipe, etc. With the same outfit and conditions, merely substitute a cylinder of 4 inches' diameter, and 540 pounds will then require to be lifted, which, with the same ratio of leverage, calls for over 90 pounds' force on the handle to lift the water. Then, if the lift pipe is materially smaller than the cylinder, the increase in velocity, when the cylinder water enters the lift pipe calls for an additional force that would astonish one. This should make it plain why so many pump standards are wrecked, bolts worn off, holes worn oblong, handles broken, cylinders continually needing new valves, and owners disgusted; it is all due to the lack of proper proportion of parts, and the enormous amount of needless work thus occasioned.
Total lift is the distance from the level of the source pumped from, to the point of discharge. This includes height to elevated tank, if there be one, and the distance from cylinder to water, if the cylinder is above the water; yet many mechanics are inclined to ignore the latter on the ground that the atmosphere lifts the water to the cylinder. It does, in fact; but the power of the vacuum which permits the atmos phere to lift the water, is as great as the weight of water so lifted, and the vacuum itself is produced and maintained by the energy of the person pumping.
The pump being outside for the purpose of sprinkling, filling ves sels, etc., need not interfere with employing it to deliver water under ground to the house and up to elevated tank. A cock-spout, a packed stuffing box, and a line of pipe below freezing from lift pipe to tank, are the essentials. Delivery to tank should be made over top of tank; and the line should have a cock and drain so that the tank pipe can be emptied when desired, and so that full force for sprinkling can be had by cutting off the tank line. When pumping to the tank, it is merely necessary to have the cock-spout closed and the shut-off of the tank line turned on.
The advantages of having the pump indoors, at the sink, are, (1) that water may be pumped for use directly; and (2) that it is not necessary to go outside in bad weather in order to fill the tank. The indoor pump will also conveniently serve ordinary purposes when other water fixtures of the house are out of repair.
Small gasoline engines, by means of pumping jacks or other methods of actuating, are often used to operate pumps. Hot-air engines are also frequently used for pumping purposes, such as lift ing water to upper floors of buildings whenever the city pressure may be inadequate.
Windmills are a favorite means of operating outside pumps in localities where the mean wind velocity is high enough to run them economically. Light winds, and water at great depths, both con tribute to increasing the size and cost of mills; while spasmodic winds require great storage capacity. If the mean wind velocity is under 7 miles per hour, mills are suited to very light pumping only. Windmills require self-priming pumps—that is, pumps that are always ready to pump water without adding priming or working rapidly to get water to the cylinder. They are also provided with governors to avoid pumping after the tank is full, and with means which high winds will automatically operate, for folding the mill out of the wind. Light winds and severe duty are counterbalanced to some extent by gearing the wheel for higher speed than is communi cated to the actuating rod.