The Flow Of Gases In Furnaces

REVERBERATORY FURNACES

57

as possible, by reducing their velocity. This effect is obtained
under the crest of an inverted weir for gases, in the same manner
in which it would be done on a weir carrying water, by providing

FIG. 34.

a cistern or cutting a deeper reservoir in the weir, making an
upstream and a downstream crest.

FIG. 35.

When a weir having a thick crest (Fig. 34) is transformed into
a weir with a cistern or reservoir (Fig. 35), the velocity of flow of

\

ssa%S$s$$^^

v\S ^...-^ _..-.^- ^—*^_

n n n

FIG. 36.
the water in the reservoir is reduced, while the level of its free
surface remains the same.
In securing this result with an inverted weir for gases, all of the