rigidly kept down to about ten or twelve guineas. The latter seems
a particularly hard condition, when it is remembered that the only
improved baker's oven in practical use at the present day is the steam
oven invented by Mr. Perkins, which costs two or three hundred pounds to
erect. Mr. Booer also had in mind the necessity that everything possible
for a coal oven must likewise be performed by a gas oven; and in this
respect he set himself to surpass the costly Perkins oven, which will
not bake the common "batch" or household bread, generally the principal
article of sale, more especially in populous and poor neighborhoods. The
peculiar efficacy of the common coal fire in this respect proceeds from
the essential principle of action of a brick oven, which is found simply
in the fact that the work is done entirely by heat previously imparted
to the tile bottom, roof, and sides of the oven, and thence radiated to
the bread. No other kind of heat will bake batch-bread--i.e., loaves
packed in contact with one another--which requires to be thoroughly
soaked by a radiant heat in a close atmosphere of its own steam. Now,
as a coal fire is eminently qualified to impart, by radiation and
otherwise, this necessary store of heat to the brickwork, it is plainly
a difficulty to effect the same purpose with a fuel which, of
itself, can scarcely radiate heat at all. The system of the gas
cooking-oven--the utilization of the heat of the combustion products as
formed--is clearly inapplicable here; for a different kind of heat is
needed, under conditions that would not sustain continuous combustion.
Therefore, there is nothing for it but to heat the bottom and sides
of the brick oven by the direct contact of powerful gas-flames; thus
supplanting the coal fire, but leaving the actual work of baking to be
done afterward by stored-up heat in the regular way.

Having settled the general principles of a system of this kind, there
still remain a number of scarcely less important details, in the dealing