be told whether it is in the second check or hot water check by opening
the little drain cock. If the water which goes out through it is cold,
the trouble is in the second check; but, if hot water and steam are
blown out through this little drain cock, the trouble is in the hot
water check, or the one next to the boiler. This check must never be
tampered with without first turning the stop cock between this check and
the boiler. The valve can then be taken out and the obstruction
removed. Be very careful never to take out the hot water check without
closing the stop cock, for if you do you will get badly scalded; and
never start the pump without opening this valve, for if you do, it will
burst the pump.

The obstruction under the valves is sometimes hard to find. A young man
in southern Iowa got badly fooled by a little pebble about the size of a
pea, which got into the pipe, and when he started his pump the pebble
would be forced up under the check and let the water back. When he took
the check out the pebble was not there, for it had dropped back into the
pipe. You will see that it is necessary to make a careful examinations
and not get mad, pick up a wrench and whack away at the check valve,
bruising it so that it will not work. Remember that it would work if it
could, and make up your mind to find out why, it don't work. A few years
ago I was called several miles to see an engine on which the pump would
not work. The engine had been idle for two days and the engineer had
been trying all that time to make the pump work. I took the cap off of
the horizontal check, just forward of the pump barrel, and took the
valve out and discovered that the check was reversed. I told the
engineer that if he would put the check in so that the water could get
through, he would have no more trouble. This fellow had lost his head.
He was completely rattled. He insisted that "the valve had always been
on that way," although the engine had been run two years.