cornburent to a point where they will combine in the flame.
In the early types of Siemens furnaces there were usually five
ports side by side, two for gas and three for air. Figs. 144, 145
and 146 show later designs of ports which were used respectively
FIG. 147.—Dropped Roof of Early Furnace Design.
FIG.. 148,—Heating Chamber with Raised Roof.
FIG. 149.—Heating Chamber with Baised Straight Hoof.
FIG. 150.-—Heating Chamber with Straight Hoof.
with the heating chambers shown in Figs. 148, 149 and 150.
Figs. 144 and 148 were used at the Lyswa Works (Qural), Russia,
while Figs. 145, 149, 146 and 150 were used in American fur-
naces, the last being the later design. A noticeable feature of
the Russian furnace is that .the bath occupies about 0.60 of the