rivets and makes her
leak, if she never leaked before. I have frequently known boilers to be
filled with water over-night to be ready for lighting up in the morning,
and have found the gauge-glass empty; this puzzled me at first, but on
opening the blow-out cock of the water-gauge the air rushed into it with
a gurgling noise, then I knew there was water in the boiler held up by
the vacuum, but I soon altered that by opening the side-cocks, and
letting air into her which soon killed the vacuum, and down came the
water into the glass again to the proper level. When getting steam up, I
always open one of the side gauge cocks and keep it open until steam
issues from it; that permits the foul air to escape and prevents a
vacuum being created; there used to be a vacuum valve in the vicinity of
the steam dome, that opened inwards and prevented a vacuum from being
created.

9. _Question._--If you had only one boiler and one engine at work, how
would you manage to clean your one fire without letting the steam go
down?

_Answer._--When pushed for steam, which usually occurs when the fire is
getting dirty, I get ready all the tools and some of the best of the
coals, and having a bright fire I take the long poker and skim all the
fire to one side and throw a couple of shovelfuls of coals evenly over
it and rake out all the clinkers on the opposite side, then with the
long poker (some people call it Kennedy) I skim all the fire over to the
opposite side and throw a couple of shovelfuls of coals evenly over the
bright fire, and rake out the clinkers on the other side, then I spread
the fire evenly over the bars and sprinkle some more coals over all, and
shut the door. This performance from first to last need not take more
than ten minutes, and the boiler was making steam all the time, and at
the finish I had a better fire than at the beginning, and the steam
hardly lost a pound; but the job must be done quickly.

10. _Question._--What is the cause of the humming noise that issues from
a steam boiler at times, and how would you prevent it?

_Answer._--It is caused chiefly through bad stoking, in having an uneven
fire, full of holes, or crooked bars, the cold air rushing through where
there is the least resistance, and into the tubes, causes the humming
noise--a locomotive nearing home after her day's work has very little
fire on the bars and will generally hum, so there is some excuse for
her, but none for a stationary boiler.