_Answer._--Having filled the boiler with water to the usual height, that
is to say, about four inches over the crown of the fire-tube, I throw in
several shovelfuls of coal or coke towards the bridge, left and right,
keeping the centre clear; then I place the firewood in the centre, throw
some coals on it, light up, and shut the door. Then I open the
side-gauge cocks to allow the heated air to escape, and keep them open
till all the air has cleared out and steam taken the place of it; by
this time the fire will require more fuel, and when the steam is high
enough I connect her by opening the stop-valve a little at a time till
it is wide open and ready for work.
2. _Question._--Supposing there are boilers working on each side of the
one you got steam up in, how would you act?
_Answer._--I would light the fire by putting in a few shovelfuls of live
coal from one of them instead of using firewood; that is all the
difference I would make.
3. _Question._--What is the cause of the rapid motion of the water in
the gauge-glass at times? Is that motion general throughout the boiler?
_Answer._--No; air enters the boiler with the feed-water, and the
gauge-glass tube being in the vicinity of the incoming water, some of
the air enters the glass and flies up rapidly through the top cock and
into the boiler again; in fact there is very little motion of the water
in the boiler at any time while working. I have proved this to be so,
and in this manner: the boiler cleaners having finished the cleaning,
hurriedly scrambled out of the boiler and left several tools they had
been using on the crown of the fire-box, namely, a bass hand brush, a
tin can, and a tin candlestick, and a small iron pail; the manhole cover
was put on and boiler filled and put to work before the things were
thought of, and then it was too late and they had to remain there until
the next cleaning time, which was thirteen weeks; and when the boiler
was at last blown out and the manhole cover removed, the things were on
the crown of the fire-box exactly as they were left three months
previously. In order to satisfy myself of this, to me, extraordinary
discovery, I placed several articles on the crown of the fire-box,
things that could not stop up the blow-off pipe if they were swept off,
and got up steam as usual, and after three months' hard steaming I blew
out the water and steam, took off the manhole cover, and there were the
things as I had left them thirteen weeks previously; of course they were
all coated with fine mud, but no signs of having moved a hair's breadth.
4. _Question._--But water in an open caldron with a fire under it, as in
the steam boiler, will madly sweep the sides and bottom with terrific
ebullition. How would you account for the great agitation in the open
caldron while the steam boiler had hardly any, although both vessels had
fierce fires under them?
_Answer._--In the matter of the open caldron the action of the water has
no resistance but that of the atmosphere, whereas in the steam boiler
the movement of the water is resisted from the moment it is heated, for
then a vapour rises above it, and, as the heat increases, the resistance
to the movement of the water is proportionally increased, and as the
heat of the steam increases the pressure on the water increases
proportionally all through, the steam being above the water. Any old
stoker knows that when getting steam up in a boiler the lower parts are
often only warm when there may be eight or ten lb. on the square inch in
the upper portions; when the water begins to boil the steam rises in the
form of minute globular particles, and remains above the water until
there is an outlet for it by opening the stop-valve or through the
safety-valve; and as the pressure is the same throughout every part,
nook and corner, and angle, there can be no dominating force to cause
any agitation within the boiler.