cement joints. When the roots get inside of the pipe they grow
until the pipe is stopped up. As the roots cannot be forced or
wired out, the sewer must be relaid. The writer has seen a solid
mass of roots 10 feet long taken out of a tile sewer.

In case terra-cotta is laid in filled-in ground, there is only one
way to insure the pipe from breaking. The pipe should be laid on
planks. Then, if the ground settles, the pipe will not be broken.

WATER CONNECTION AND SERVICE

TAPPING MAIN.--The water service for a building is put in at the
same time as the sewer is connected and run into the house. For a
1-1/4-service pipe a 1/2-inch tap is furnished. The water company
taps the main, at the expense of the plumber, and inserts a
corporation cock.

[Illustration: FIG. 42.--Showing water main and sewer in same
ditch.]

DIGGING TRENCH.--The trench for the water main should be dug at
least 4-1/2 feet deep or below frost level and the trench should be
kept straight. When the sewer is put in at the same time, one side
of the sewer trench can be cut out after it is filled up to the
level of the water main. The water pipe can then be laid on this
shelf at least 2 feet away from the original trench of sewer.
Sometimes the surface of the ground must not be disturbed. In this
case small holes are dug and the pipe is pushed through or driven
through under that portion not dug. These places are often
tunnelled (see Fig. 42).

In digging in city streets, care should be taken not to destroy any
of the numerous pipes encountered.

LAYING PIPE

The trench should be dug straight out from the house so the pipe
can be laid and the main tapped straight out from the building. The
water companies keep a record of these taps so that in case of
trouble the street can be opened and the water shut off. In laying
the water service, the pipe from the curb to the main should be
laid first. This takes in all the pipe in the street. At the main
there is a shut-off in the tap. Another stop with T or wheel handle
must be placed just inside the curb line. This is called a curb
cock (see Fig. 43). One trench either outside or inside of the curb
should be at least 15 feet long so that a full length of pipe can
be laid in the trench. It is generally impossible to open a trench
the full length the pipe is to be run. A trench 10 feet long is
dug, then 8 feet left, and another 10- or 8-foot trench is dug and
the two are connected with a small tunnel a