A. Yes; the fireman's oil valve should be opened just wide enough to
permit a sufficient amount of oil to be fed to produce a good fire, but
not wide enough to waste oil or produce a volume of black smoke.

17. Q. How can you judge whether the combustion is good or bad, so the
valve may be regulated accordingly?

A. By the color of the fire in the fire-box. When it is a dull red
color, the temperature is below 1,000 degrees and combustion is
incomplete, dense black smoke will issue from the stack. If it is a
bright red, the temperature will be about 1,800 degrees and combustion
very good, and no black smoke will appear from the stack.

18. Q. How should the flues be cleaned from soot when running, and about
how often is this necessary?

A. By placing a small quantity of sand in an elbow shaped funnel or
horn, and by inserting same in an opening provided in fire door while
engine is working hard, allowing the exhaust to draw the sand through
the flues, thus cutting soot and gum from them in its passage and
discharging it from the stack. It is necessary that the flues be cleaned
of soot on leaving terminals or sidings where the engine has been at
rest for any length of time, and also as often as found necessary to aid
the engine in steaming. This depends to a great extent upon the degree
of perfection with which combustion is obtained. Attention should also
be given flues just prior to entering points where engine is to be put
in roundhouse or otherwise detained in order to leave the flues clean,
as this will aid in putting engine under steam with little delay where
the blower alone is to be relied on for draft.