termed an externally heated oven. As the ends of the pipes get red hot
the water is converted into superheated steam, which being under high
pressure soon raises the chamber to baking heat, say 450 deg. to 500
deg. F. In an oven of this description the heat can be continuously
maintained, and batch after batch can be baked without refiring. The
only drawback is that a flash heat cannot be raised. In another type
of externally fired oven the heat is conveyed by flues placed at the
bottom and top of the oven, which discharge into a chimney. Excellent
results have been attained with ovens of this kind. The distribution
of the heat can be well regulated; for instance, it is quite possible
to build ovens to be cooler at the back than front, an arrangement
which is useful when the bread is withdrawn by means of a hand peel.
As the baker has to withdraw each loaf one at a time, it is clear that
the withdrawal of the batch through the oven door must take time,
probably not less than half-an-hour. Hence the bread drawn from near
the oven's mouth may be underbaked as compared with that at the back
of the chamber. The latter, on the other hand, may be overbaked and
deficient in weight.

By means of a draw-plate, however, an oven can be expeditiously
charged. This appliance consists of a sliding plate or tray, mounted
on wheels running on rails, which is drawn out of the oven loaded with
bread, and then returned. The plate itself is often made of iron, but
one well-known oven is fitted with a withdrawable iron frame, in which
are laid, edge to edge, tiles of a special make, which are cemented in
place, and form a continuous baking surface. This seems an excellent
arrangement, as the baker has all the advantages of a brick oven, that
is to say, his bread is baked both on top and bottom by heat evolved
from tiled surfaces, and the undoubted drawbacks incidental to baking
bread on an iron surface are avoided. A draw-plate fitted to an oven
capable of baking a batch made from a sack (280 lb) of flour can be
run out, charged and run in again, in about two minutes. The
draw-plate has the incidental advantage, by expediting the loading and
discharge of the oven, of ensuring a more uniform baking of the batch,
and therefore of minimizing the loss of weight. Some bakers have gone
so far as to estimate the saving in this respect from the use of a
draw-plate at half an ou