nish a good source
of supply for water to a building or community of buildings. The
writer recently worked on a system of piping that supplied 15 or 20
buildings. The water supply came from a brook that was higher than
the houses. Each house had a separate pipe leading down from the
brook into a tank from which the house was piped. The owner of the
brook applied business ethics to the privileges of taking water
from it. He had a scale of prices, and the highest-priced location
was an inch or so below the bed of the brook, the next price was
level with the bottom, the next cheaper 2 inches above the bottom.
As the surface was reached, the privilege cost less. In the dry
time of the year those at the bottom of the brook always had water
while those at the top location had to wait for the water to rise,
and had to do without water during the dry time. Where the stream
is on a lower level than the building a hydraulic ram can be used.

RIVERS AND LAKES.--Rivers and lakes make an abundant supply for
water systems. A sluggish-moving river is bad, also a river that is
used for carrying off the sewage of a town. Special provision is
now made for the using of water that is polluted. A lake that is
supplied by springs is by far the best source of supply. The water
is pumped from the river or lake into a reservoir and then flows by
gravity into mains and from the mains into the buildings. The water
should always be filtered before it is allowed to enter the
distributing mains.

WATER PRESSURE.--Pressure at a fixture or outlet so that the water
will flow is generally obtained by the force of gravity. When this
method is not sufficient, a pneumatic system is employed. This
method is employed to force the water to the top floors or to
supply the whole building in high structures. The pneumatic system
requires a pump, an air-tight tank, and pipes to the various
outlets. The water pumped into the air-tight tank will occupy part
of the space generally occupied by the air. The air cannot escape
and is, therefore, compressed. Continued pumping will compress the
air until the limit of the apparatus is reached. If a valve or
faucet that is connected with the tank is opened, the air will
expand and force the water out of the opening. This explains in a
general way the operation of a pneumatic water-supply system. Water
can be pumped into this air-tight tank from a well, cistern, river,
lake, or from the city supply mains.

[Illustration