IRON MANUFACTURE. 527 
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lowered by a crank motion, worked by a man at the top of the furnace. 
At some of the furnaces this is replaced by a steam cylinder which acts 
directly on the lever supporting the bell, and is controlled at the bot- 
tom of the furnace by a valve. Water is applied in almost every way 
for cooling and protecting the lower walls of the furnace; one plan in 
use at some of the furnaces of the Hocking Valley district is to surround 
the hearth-walls below the tuyeres with a sheet-iron ring or drum, the 
space between which and the furnace, possibly 8 to 10 inches in width, 
being filled with gravel and kept wet. The surrounding of the hearth by 
cast-iron plates, in which water circulates through coil pipes, is also 
considerably employed, as well as the bedding in the bosh walls, of flat 
iron plates similarly cooled, as in the furnaces of the Cleveland Rolling 
Mill Company. 7 
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