228

SMELTING IRON FURNACES.

inverted cylinder within the cast-iron column, into which cylinder air is admitted(through a valve opened by the workman) from the furnace blast, the air passing up the

tube seen in the axis of F. The inverted air-cylinder is 3J feet in diameter, 36 f« etlong, and rises 25 feet; being made air-tight with water, it ascends in its columnar case>