44 
On Water Supplies suited to 
rivers, and lakes are below the premises to be supplied, and 
then it becomes necessary to raise the water by mechanical 
means. These may be divided into animal-power, water-power, 
wind-power, and heat-power. 
Under animal-power, we must consider pumps worked by 
human beings, and those worked by horses or cattle. 
Pumps are usually divided into two classes ; lift-pumps, 
which deliver their water at the level on which the operator 
stands ; and force pumps, which send it much higher. The 
lift-pump is generally the simplest and cheapest, being mostly 
■open topped, and consists of a barrel into which is fitted a 
bucket, armed with a valve opening upwards, and a suction 
pipe attached to the barrel and fitted with a " foot valve," also 
opening upwards. The force-pump has a closed top ; the 
bucket rod works through a packed gland, and a rising pipe 
branches from the upper end of the barrel, and is usually fitted 
with a valve opening upwards, though such valve is not essential 
to the pump. 
For small powers, the pump is generally worked by a lever 
or " pump-handle " ; in the case of more serious work, two or 
three pumps are placed side by side and worked by cranks so 
arranged that the barrels lift consecutively, and are actuated by 
winch handles and regulated by a fly-wheel. 
The effort necessary to perform any work is measured by foot- 
pounds, that is to say, the unit bv which work is measured is 
the effort necessary to lift one pound one foot high, and the rate 
of work is measured by the number of foot-pounds done per 
minute. Thus, a horse-power is 33,000 foot-pounds of work 
performed in one minute ; a man-power working 10 hours per 
day at such steady work as pumping is 2000 foot-pounds per 
minute or less than ^ of a horse-power. 
In estimating the power required to do a certain amount of 
pumping, two allowances have to be made. 
First, for the friction, or internal resistances inherent to the 
machine worked. This depends very much on the structure 
of the apparatus and the perfection of its workmanship, but in 
small hand-pumps, about 70 per cent, of useful work may be 
calculated on, so that a man-power may be taken at 1400 foot- 
pounds per minute, measured in water lifted. The second 
allowance is for the friction of the rising pipe. Suppose the dead 
lift to be 50 feet, a man pumping would lift loot pounds 
^ ^ ^ 50 leet X 10 pounds 
= 2*8 gallons per minute. Suppose the pipe were 2000 feet 
long and 1-inch bor.e, our diagram (Fig. 3) would give a gradient. 
of about 1 in 90, or a resistance of =22 '2 feet, so that the 
