AMERICAN INDUSTRIES SINCE COLUMBUS.
587
duced, "reverberated" more heat upon the metal; hence the name "reverberatory furnace" often applied to such structures. The walls, roof, fire-bridge, and chimney-flue are built of very refractory
Fig. 42.—Lever Shears for cutting Bar Iron.
brick, called "fire-brick." Furnaces of similar construction (sometimes called "air-furnaces") are used for melting pig iron for making heavy castings; but in these furnaces, instead of a
Fig. 43.—Front Elevation of Boiler-plate Shears.
sand bottom of the form shown at a, the furnace at this part has its bottom depressed so as to form a basin to hold the fluid
