a long travel before meeting the tube surfaces. A fuel
bed from 4 to 6 inches in depth can be maintained, and the coal should
be fired in small quantities by the alternate method. Above certain
rates of combustion clinker forms rapidly, and a steam jet in the ashpit
for softening this clinker is often desirable. A considerable draft
should be available, but it should be carefully regulated by the boiler
damper to suit the condition of the fire. Smokelessness with hand firing
with this class of fuel is a practical impossibility. It has a strong
tendency to foul the heating surfaces rapidly and these surfaces should
be cleaned frequently. Shaking grates, intelligently handled, aid in
cleaning the fires, but their manipulation must be carefully watched to
prevent good coal being lost in the ashpit.

Stokers--The term "automatic stoker" oftentimes conveys the erroneous
impression that such an apparatus takes care of itself, and it must be
thoroughly understood that any stoker requires expert attention to as
high if not higher degree than do hand-fired furnaces.

Stoker-fired furnaces have many advantages over hand firing, but where a
stoker installation is contemplated there are many factors to be
considered. It is true that stokers feed coal to the fire automatically,
but if the coal has first to be fed to the stoker hopper by hand, its
automatic advantage is lost. This is as true of the removal of ash from
a stoker. In a general way, it may be stated that a stoker installation
is not advantageous except possibly for diminishing smoke, unless the
automatic feature is carried to the handling of the coal and ash, as
where coal and ash handling apparatus is not installed there is no
saving in labor. In large plants, however, stokers used in conjunction
with the modern methods of coal storage and coal and ash handling, make
possible a large labor saving. In small plants the labor saving for
stokers over hand-fired furnaces is negligible, and the expense of the
installation no less proportionately than in large plants. Stokers are,
therefore, advisable in small plants only where the saving in fuel will
be large, or where the smoke question is important.

Interest on investment, repairs, depreciation and steam required for
blast and stoker drive must all be considered. The upkeep cost will, in
general, be higher than for hand-fired furnaces. Stokers, however, make
possible the use of cheaper fuels with as high or higher econom