Air is forced through this hole, called a "tuyere" (Figure 48) by means of
a hand bellows, a rotary fan operated with crank or lever, or with a fan
driven from an electric motor. The harder the air is driven into the fire
above the tuyere the more oxygen is furnished and the hotter the fire
becomes.

Directly below the tuyere is an opening through which the ashes that drop
from the fire may be cleaned out.

_The Fire._--The fire is made by placing a small piece of waste soaked
in oil, kerosene or gasoline, over the tuyere, lighting the waste, then
starting the fan or blower slowly. Gradually cover the waste, while it is
burning brightly, with a layer of soft coal. The coal will catch fire and
burn after the waste has been consumed. A piece of waste half the size of a
person's hand is ample for this purpose.

The fuel should be "smithing coal." A lump of smithing coal breaks easily,
shows clean and even on all sides and should not break into layers. The
coal is broken into fine pieces and wet before being used on the fire.

The fire should be kept deep enough so that there is always three or four
inches of fire below the piece of metal to be heated and there should be
enough fire above the work so that no part of the metal being heated comes
in contact with the air. The fire should be kept as small as possible while
following these rules as to depth.

To make the fire larger, loosen the coal around the edges. To make the fire
smaller, pack wet coal around the edges in a compact mass and loosen the
fire in the center. Add fresh coal only around the edges of the fire. It
will turn to coke and can then be raked onto the fire. Blow only enough air