ten causes the valve to leak.

21. _Question._--When the water in the gauge-glass appears motionless
while the boiler is working, what does it portend, and how would you
proceed to rectify the stagnation of the water?

_Answer._--It portends that the passage for the water is choked and
requires clearing, and I would lose no time in commencing to rectify the
stoppage; as a stoker who is responsible for the safety of the boiler I
am always prepared for emergencies. I commence by shutting both cocks of
the glass, the steam and the water, and unscrew the small bolt in the
water gauge, which is fixed there for the purpose of clearing the tube
that conveys the water to the glass, and with an iron wire in one hand,
I open the water cock with the other hand, and push the wire into the
small hole from which I took the bolt, giving several pushes and pulls
while the water and steam are flying out, until the tube is quite clear;
then I withdraw the wire, shut the cock, and serve the steam cock in
like manner; and while I was doing all this the bottom cock of the gauge
(the blow-out cock) was open from the beginning. Then I commence to put
the pressure on the glass by warming it with steam from the top cock
slowly; then I open the water cock a little, and so on, alternately;
then I commence shutting the blow-out cock a little. By these
man[oe]uvres the pressure on the glass is put on gradually instead of
popping it on too suddenly and breaking the glass, as is often done by
the _more-haste-the-less-speed_ stoker; now I shut the bottom cock and
open the other two, and the water bounds into the glass quite frisky,
and the boiler is safe for the present.

22. _Question._--What would be the consequence if the steam cock of the
water gauge was choked, while the water cock was clear, or vice versa?

_Answer._--The consequence would be most serious for the boiler, as the
water would be forced up into the glass by the steam under it, and would
make it appear as if too much water was in the boiler, and the stoker
would proceed in the usual way to blow out some of this, apparently,
surplus water; and then watch to see it come down to the working level
in the glass, but he watches in vain--it will never come down. He might
empty the boiler dry, and the water in the glass will be there as long
as a breath of steam remains in the boiler to keep it up. And in the
event of the water-cock being choked while the steam-cock was clear the
cons