, the water-cock first,
then I would open the blow-out cock (at the bottom of the gauge-glass)
and keep it open to the finish, and commence unscrewing the nuts,
clearing them of any bits of india-rubber that adhered to them, also the
sockets. Get one of the half dozen glasses already cut, and my string of
rubber rings, enter two rings on the bottom end of the glass, slip the
nut over them, slip two rings on the top part of the glass after having
slipped the nut on, and enter the rings in the sockets, then screw up
both top and bottom nuts by hand alternately, and when screwed up
evenly, open the steam cock a shade to warm the glass, and when it is
hot enough, open it more and commence closing the blow-out cock, by
tapping it lightly by hand, then open the steam cock a little more and
open the water cock a little also, and shut off the blow-out cock, and
presently the water enters the glass, and both top and bottom cocks may
now be opened to their full extent, and the job is done.

7. _Question._--How would you cut a water gauge-glass to the proper
length?

_Answer._--I usually cut a piece of iron wire the length the glass
should be, in this way: I measure the length from under the top nut to
the top of the bottom nut, and cut my iron wire to that measurement;
then I cut several glasses in my spare time, instead of doing it when
the glass breaks. I mark a circle where I wish to cut the glass, and
with a three-corner file I run it round this circle to a depth of the
16th of an inch, and break it off on the edge of the vice, bench, or
other solid woodwork; of course this iron-wire gauge will perhaps only
answer for this particular boiler, but in some stoke-hold the boilers
are all alike with regard to the gauge-glasses.

8. _Question._--What is the cause of a vacuum in a boiler? And how does
it affect her injuriously?

_Answer._--The vacuum is mostly caused by letting cold water into a hot
boiler, the hotter the boiler the stronger the vacuum; when the water is
hotter than the boiler, there will be little vacuum; a strong vacuum in
the boiler will cause the air outside to press on the boiler in
proportion--the stronger the vacuum inside, the greater the pressure
outside. In this circumstance the pressure is misplaced for the boiler
was constructed to bear an internal pressure and not an external
pressure. And in getting steam up the pressure on the boiler has to be
reversed, and this tends to loosen the plates and