Lead. 
189 
direction of the flame, when all the apertures in the sides 
of the furnace are closed up, is necessarily determined, 
by the stream of air which enters at the grate, towards 
the chimney, and in tending thither it strikes upon the 
roof of the furnace, and being reverberated from thence 
upon the ore, it sqon melts it. 
It is not always an easy matter to meet with a current 
of water sufficient to move the bellows required in smelt- 
ing on an hearth furnace ; and to carry the ore from the 
mine where it is dug to a considerable distance to be 
smelted, is attended with great ex pence ; this expence is 
saved by smelting in the cupola furnace, which not requir- 
ing the use of bellows, may be constructed any where* 
Wood is very scarce in every mining county in England ; 
and though pitcoal costs ten or twelve shillings a ton in 
Derbyshire, (1787) yet they can smelt a definite quantity 
of ore in the cupola, at a far less expence by means of 
pitcoal, than of wood.— The flame which plays upon the 
surface of the ore and smelts it in a cupola furnace, is not 
driven against it with much violence; by this means 
small particles of ore, called belland , may be smelted in a 
cupola furnace with great convenience, which would be- 
driven away, if exposed to the fierce blast of a pair of 
bellows in a hearth furnace. These are some of the ad- 
vantages attending the use of a cupola in preference to a 
hearth furnace ; and to these may be added one superior 
to all the rest,— the preservation of the workmen’s lives ; 
the noxious particles of lead are carried up the chimney 
in a cupola, whilst they are driven in the face of the hearth 
smelter at every blast of the bellows.* 
They generally put into the cupola furnace a ton of ore, 
previously beat small and properly dressed, at one time ; 
* In the neighbourhood also of blast furnaces, the chimney is 
lined, and the adjacent ground covered with the white oxyd of 
lead which is lost to the smelter. T. C B 
