RATIONAL CONSTRUCTION OF FURNACES
• f f
the hot-blast valve was connected to the lower part of the stove.
It may be readily seen that the currents of gas and air in this
apparatus were circulated in the wrong direction; that is, in the
opposite direction to the natural convection currents.
Cowper afterward perceived the error in the gas circulation
in his early design, and in later designs the currents of gas and air
were circulated in the correct direction (Fig. 70). Combustion
took place in a central or eccentrically placed chamber, the hot
gases rising to the dome where they were reversed and subdivided
among a number of parallel passes down through the checkerwork.
Uniting in a lower chamber, they, were then carried away through
the chimney valve. The cold blast entered the stove chamber
below the checkerwork, through which it passed upward in a
number of parallel streams to the dome of the stove. There it
changed its direction and passed downward through the combus-
tion chamber to the hot-blast valve. The Cowper hot-blast stove
retains this general arrangement to the present day.
It would be difficult to find any apparatus which has passed
through as many modifications of design as have these stoves;
however, very few of these modifications have come into extended
use, because practically all of them have been based upon an
entirely false idea in regard to the laws governing the circulation
of gases while heating and cooling.
The single weak point of the Cowper hot-blast stove lies in the
location of the combustion chamber, which, in
the form of a vertical tube, or chamber, occupies
a very large amount of space and is very poorly
adapted for the purpose for which it is employed.
The attempts to improve the design of these
stoves should be directed toward the elimination
of this tube for the combustion chamber. The
space located immediately below the dome of the
stove might be employed for a combustion cham-
ber, as is suggested below. Moore's patent (Fig.
60) shows a single-pass construction of this char-
acter, but is badly worked out. In Moore's
stove the hot gases of combustion pass upward,
in the opposite direction to their natural convection
The first modification of the Cowper stove was made by