asize the need to understand thoroughly this
piping sketch, and to become so familiar with it that it can
readily be put to use. The value of a mechanic is determined by the
quality and the quantity of work that he can turn out; and a
mechanic who can lay out his work and see it completed before he
starts, and then proceeds to install his work, is by far of more
value to his employer than the man who can see only far enough
ahead to cut out two or three measurements and spends most of his
time walking between the vise and place of installing the pipe.

TESTING.--The system of gas piping must be tested before the pipes
have been covered by the advance of building operations. If the job
is of considerable size, the job can be tested in sections, and if
found tight the sections can be covered. The necessity of having
the piping rigidily secured can be appropriately explained here. If
the test has been made and the system found tight and some pipe
that is not securely anchored is accidentally or otherwise pushed
out of place and bent by some of the mechanics working about the
building, a leak may be caused and yet not discovered until the
final test is made after the plastering is finished. The expense
and trouble thus caused is considerable and could have been avoided
by simply putting in the proper supports for the pipe.

To test the piping, an air pump and a gage connected with the pipes
are placed in a convenient position. The job should now be
thoroughly gone over, making sure that all plugs and caps are on
and that no outlet is open, also that all pipe that is to be put in
has been installed. After this has been attended to, the pump is
operated until 10 pounds is registered on the gage. The connection
leading to the pump and the piping is now shut off. If the gage
drops rapidly, there is a bad leak in the system. This leak should
be found without difficulty and repaired. If the gage drops slowly,
it denotes a very small leak, such as a sand hole or a bad thread.
This kind of leak is more troublesome to find. When it has been
found, the pipe or fitting causing the leak should be taken out and
replaced. If black caps have been used to cap the outlets, the
chances are that a sand hole will be found in one of them. Nothing
but galvanized fittings should be used. In case the small leak
mentioned above cannot be found by going over the pipe once, there
are other means of locating the leak. Two of the methods used, I
wil