ust be duly
considered in a pipe of small size, increases very rapidly as the
velocity of the flow increases. It is always a great temptation to use a
small pipe, since the cost of the pipe increases rapidly as the diameter
increases, but it is penny wise and pound foolish to lay a line of pipe
several thousand feet long to furnish water to a house and find when
completed that the amount of water furnished by the pipe is on account
of friction only a small dribble. In a previous chapter we estimated
that the flow of water, in order to furnish three faucets at a
reasonable rate, ought to be at least two thousand gallons a day or
about one and a half gallons a minute, and the effect of a reduced size
of pipe on the head necessary to carry a definite amount of water was
shown.

The cost of cast-iron pipe should not be more than thirty cents per
running foot for four-inch pipe and fifty cents per running foot for
six-inch pipe. To this must be added the cost of about seven pounds or
ten pounds respectively of lead for each joint and the cost of all the
labor involved. The price of terra-cotta pipe is much less, as already
indicated, so that it is quite worth while to expend some additional
effort on making the tile pipe joints water-tight, if it allows the
cheaper pipe to be substituted for the more expensive iron pipe.

_Pumping._

Although the present methods of securing water for isolated farm
buildings will not corroborate the statement it is safe to say that the
proper method of obtaining a water-supply is always to make use of a
pond or stream at such an elevation that water will flow to the house by
gravity, provided this is possible. Only when the conditions are such
that a gravity supply is impossible and water from a well or stream at
some lower elevation becomes inevitable is pumping properly resorted to.

The advantage of a gravity supply is twofold. First, the daily charges
for maintenance are practically nothing, so that when once the intake
and the pipe line have been installed, there will be no additional
charges. When pumping is resorted to, on the other hand, there must be a
daily expenditure which, even if small, in the course of a year amounts
to the interest on a large sum of money. For example, suppose that the
cost for supplies for a small pumping engine was only ten cents per day,
not counting in the cost of labor. This would amount to $36.50 a year,
which at 5 per cent is the interest on $730. I