chimney for a few seconds, and the gas, if any, will be immediately drawn
up the chimney. Next place on the bottom of the combustion chamber a piece
of cotton waste, or a handful of shavings saturated with petroleum and
burning with a flame. Then by opening first the steam valve of the spray
injector, and next the petroleum valve gently, the very first spray of oil
coming on the flaming waste immediately ignites without any explosion
whatever; after which the quantity of fuel can be increased at pleasure.
By looking at the top of the chimney, the supply of petroleum can be
regulated by observing the smoke. The general rule is to allow a
transparent light smoke to escape, thus showing that neither too much air
is being admitted nor too little. The combustion is quite under the
control of the driver, and the regulation can be so effected as to prevent
smoke altogether. While running, it is indispensable that the driver and
fireman should act together, the latter having at his side of the engine
the four handles for regulating the fire, namely, the steam wheel and the
petroleum wheel for the spray injector, and the two ash-pan door handles
in which there are notches for regulating the air admission. Each
alteration in the position of the reversing lever or screw, as well as in
the degree of opening of the steam regulator or the blast pipe, requires a
corresponding alteration of the fire. Generally the driver generally
passes the word when he intends shutting off steam, so that the alteration
in the firing can be effected before the steam is actually shut off; and
in this way the regulation of the fire and that of the steam are virtually
done together. All this care is necessary to prevent smoke, which is
nothing less than a waste of fuel. When, for instance, the train arrives
at the top of a bank, which it has to go down with the brakes on, exactly
at the moment of the driver shutting off the steam and shifting the
reversing lever into full forward gear, the petroleum and steam are shut
off from the spray injector, the ash-pan doors are closed, and if the
incline be a long one, the revolving iron damper over the chimney top is
moved into position, closing the chimney, though not hermetically. The
accumulated heat is thereby retained in the fire-box; and the steam even
rises in pressure, from the action of the accumulated heat alone. As soon
as the train reaches the bottom of the incline and steam is again
required, the first