y than is
obtainable under operating conditions in hand-fired furnaces with a
better grade of fuel. The better efficiency obtainable with a good
stoker is due to more even and continuous firing as against the
intermittent firing of hand-fired furnaces; constant air supply as
against a variation in this supply to meet varying furnace conditions in
hand-fired furnaces; and the doing away to a great extent with the
necessity of working the fires.

Stokers under ordinary operating conditions will give more nearly
smokeless combustion than will hand-fired furnaces and for this reason
must often be installed regardless of other considerations. While a
constant air supply for a given power is theoretically secured by the
use of a stoker, and in many instances the draft is automatically
governed, the air supply should, nevertheless, be as carefully watched
and checked by flue gas analyses as in the case of hand-fired furnaces.

There is a tendency in all stokers to cause the loss of some good fuel
or siftings in the ashpit, but suitable arrangements may be made to
reclaim this.

In respect to efficiency of combustion, other conditions being equal,
there will be no appreciable difference with the different types of
stokers, provided that the proper type is used for the grade of fuel to
be burned and the conditions of operation to be fulfilled. No stoker
will satisfactorily handle all classes of fuel, and in making a
selection, care should be taken that the type is suited to the fuel and
the operating conditions. A cheap stoker is a poor investment. Only the
best stoker suited to the conditions which are to be met should be
adopted, for if there is to be a saving, it will more than cover the
cost of the best over the cheaper stoker.

Mechanical Stokers are of three general types: 1st, overfeed; 2nd,
underfeed; and 3rd, traveling grate. The traveling grate stokers are
sometimes classed as overfeed but properly should be classed by
themselves as under certain conditions they are of the underfeed rather
than the overfeed type.

Overfeed Stokers in general may be divided into two classes, the
distinction being in the direction in which the coal is fed relative to
the furnaces. In one class the coal is fed into hoppers at the front end
of the furnace onto grates with an inclination downward toward the rear
of about 45 degrees. These grates are reciprocated, being made to take
alternately level and inclined positions and this mot