COMBUSTION AND BOILER SETTINGS
reaches the smoke flue connection. The relative difference in the
density of the gases at these two points is as great as the difference
in density of wood and granite, and it is a matter of common
knowledge that granite will sink in water while wood will float.
In the same manner the hottest gases will tend to float above
cooler gases. Convection currents and conduction will naturally
-*—*»— Chilled Gases •<------Hottest Gases
FIG. 169.—Diagram of Gas Flow in Stirling Boiler with Broken Baffle.
tend to equalize the extreme temperature differences, if the
supply, of heated gases is not maintained, but equalization in this
manner would be comparatively slow.
Fig. 168 shows the type of boiler with the broken baffle,
baffled according to the builder's catalogue with arrows to show
the circulation of the gases. The heated gases rising from the