524 GEOLOGY OF OHIO. 
an air-lift. The hopper is of a cylindrical form, 14 inches diameter, in 
the lower part of which is placed the lip-ring upon which the bell closes. 
By this arrangement it will be observed we get a large area in the 
hopper, and do not encroach on the space around the platform for the 
easy manipulation of the charging buggies. Over this hopper is placed 
a cast-iron arch, upon which the hoisting lever is seated. To this bell 
are attached two safety-rods, which pass through the arch above men- 
tioned, and have malleable iron handles attached to their ends. In 
case the main rod should break, these two rods would catch the bell 
before it could drop into the furnace. The down-comer is 7 feet in 
diameter, lined with fire-brick to a clear opening of 6 feet. On the 
bottom of this down-comer we have constructed an arrangement for 
catching dust. By this arrangement it will be observed the gas is 
forced to the extreme bottom of the down-comer, thence upward over 
a cross-wall built in this chamber, and thence downward to the flue 
under ground. By this reversed passage of the gases a great percentage 
of the dust is settled. This down-comer is provided with a winding 
stairway, so that in case the hoisting apparatus cannot be operated the 
top of the furnace can be reached in this way. We further provide for 
each one of these down-comers a butterfly damper, which is coursed 
with water, and built in the down-comer.” 
The other furnaces of the Mahoning Valley are built in respect to 
the mantel, tuyeres and general lines somewhat on the same arrange- 
ment. The coil, tuyere, or blow-pipes are in almost universal use. 
At the Grafton Works at Leetonia, the tuyeres are made at the 
furnaces. The method of making these tuyeres is to coil wrought-iron 
pipe in a rather straight cone, the pipe being brought back on the out- 
side of the coil; within this is set a cone of thin sheet-iron, and the 
whole is then set in a sand mold, and melted iron cast around the pipe, 
thus consolidating the whole into a solid block. 
The use of a fore-hearth and dam in these furnaces is entirely given 
up, most of the newer furnaces being provided with a simple opening 
into the bottom of the hearth, somewhat conical, and possibly a foot 
wide by a foot and a half in height, through which the iron is tapped. 
The slag is removed from these furnaces by an opening below the tuyere, 
and situated either in front or on the side of the furnace. The ad- 
vantages of thus closing the hearth of the furnace are the saving of 
time in casting, and the more (regular working. The substituting of 
