made. For a long time stoves were used mainly for heating purposes, as
many housewives preferred to cook at the open fireplace. However, this
method of cooking has practically disappeared and a stove of some kind
is in use for cooking in every home.

63. For each fuel in common use there are many specially constructed
stoves, each having some advantageous feature; yet all stoves
constructed for the same fuel are practically the same in principle. In
order that fuel will burn and produce heat, it must have air, because
fuel, whether it is wood, coal, or gas, is composed largely of _carbon_
and air largely of _oxygen_, and it is the rapid union of these two
chemical elements that produces heat. Therefore, in order that each
stove may work properly, some way in which to furnish air for the fire
in the firebox must be provided. For this reason, every stove for
cooking contains passageways for air and is connected with a chimney,
which contains a flue, or passage, that leads to the outer air. When the
air in a stove becomes heated, it rises, and as it ascends cold air
rushes through the passageways of the stove to take its place. It is the
flue, however, that permits of the necessary draft and carries off
unburned gases. At times it is necessary to regulate the amount of air
that enters, and in order that this may be done each stove is provided
with _dampers_. These devices are located in the air passages and they
are so designed as to close off the air or allow the desired amount to
enter. By means of these dampers it is possible also to force the heat
around the stove oven, against the top of the stove, or up the chimney
flue. A knowledge of the ways in which to manipulate these dampers is
absolutely necessary if correct results are to be obtained from a stove.
The flue, however, should receive due consideration. If a stove is to
give its best service, the flue, in addition to being well constructed,
should be free from obstructions and kept in good condition. Indeed, the