this
country in the 19th century.

[Illustration: Figure 19.--BACKHEAD of the _Pioneer_. (Smithsonian photo
48069F.)]

Of all the mechanisms on a 19th-century locomotive, the feed pump was
the most troublesome. If an engineer could think of nothing else to
complain about, he could usually call attention to a defective pump and
not be found a liar. Because of this, injectors were adopted after their
introduction in 1860. It is surprising that the _Pioneer_, which was in
regular service as late as 1880 and has been under steam many times
since for numerous exhibitions, was never fitted with one of these
devices. Because its stroke is short and the plunger is in less rapid
motion, the present eccentric arrangement is more complex but less prone
to disorder than the simpler but faster crosshead pump.

[Illustration: Figure 20.--FEEDWATER PUMP of the _Pioneer_. (Smithsonian
photo 63344.)]

The check valves are placed slightly below the centerline of the boiler
(fig. 18). These valves are an unfinished bronze casting and appear to
be of a recent pattern, probably dating from the 1901 renovation. At the
time the engine was built, it was usual to house these valves in an
ornamental spun-brass casing. The smokestack is of the bonnet type
commonly used on wood-burning locomotives in this country between about
1845 and 1870. The exhaust steam from the cylinders is directed up the
straight stack (shown in phantom in fig. 27) by the blast pipe. This
creates a partial vacuum in the smokebox that draws the fire, gases,
ash, and smoke through the boiler tubes from the firebox. The force of
the exhausting steam blows them out the stack. At the top of the
straight stack is a deflecting cone which slows the velocity of the
exhaust and changes its direction causing it to go down into the
funnel-shaped outer casing of the stack. Here, the heavy embers and
cinders are collected and prevented from directly discharging into the
countryside as dangerous firebrands. Wire netting is stretched overtop
of the deflecting cone to catch the lighter, more volatile embers which
may defy the action of the cone. The term "bonnet stack" results from
the fact that this netting is similar in shape to a lady's bonnet. The
cinders thus accumulated in the stack's hopper could be emptied by
opening a plug at the base of the stack.

While the deflecting cone was regarded highly as a spark arrester and
used practically to the exclusion of any other arrangem