76 S. S. Haldeman onthe Construction of Blast-furnaces 
ved, 
_ The cavity of the hearth, (HA, fig. 1, 2) where the metal as 
reduced and retained, bears a very small proportion.to the sizeof 
the stack. In the figures, which are drawn to a scale of one-eighth 
Figs. % 
of an inch to a foot, it is two feet wide, and five and a half feet 
long, but enlarges upwards in a slight degree. The back at 
front of the hearth are separated by a partial partition called the 
temp, (m, fig. 1, 2,) made of fire-bricks, and which does not ex- 
tend to the bottom of the hearth. The horizontal dotted line, 
_ (h, fig. 2) shows the level'to which the smélted materials ean rise 
