188 
Lead , 
shire . In this furnace, ore and charcoal, or ore and what 
they call white coal, which is wood dried but not charred, 
being placed in alternate layers, upon a hearth properly 
constructed, the fire is raised by the blast of a bellows, 
moved by a water wheel ; the ore is soon smelted by the 
violence of the fire, and the lead as it is produced trickles 
down a proper channel, into a place contrived for its re- 
ception, There are not at present, I believe, above one 
or two of these ore hearths in the whole county of Der- 
by ; this kind of furnace, however, is not likely to go en- 
tirely out of use, since it is frequently applied to the ex- 
tracting lead from the slag which is produced either at the 
ore hearth , or the cupola furnace, and it is then called a 
slag hearth ; and the lead thus obtained is called slag 
lead: the fire in a slag hearth is made of the cinder of pit- 
coal instead of charcoal of wood. 
The furnace called a cupol or cupola , in which ores are 
smelted by the fiame of pitcoal, is said to have been in- 
vented about the year 1798, by a physician named Wright \ 
though Beecher may, perhaps, be thought to have a prior 
claim to its invention or introduction from Germany 0 
But whoever was the first inventor of the cupola, it is now 
in general use, not only in Derbyshire and other counties, 
for the smelting of ores of lead, but both at home and 
abroad, where it is called the English furnace, for the 
smelting of copper ores. This furnace is so contrived, 
that the ore is melted, not by coming into immediate con- 
tact w ith the fuel, but by the reverberation of the flame 
upon it. The bottom of the furnace on which the lead 
ore is placed, is somewhat concave, shelving from the 
sides towards the middle ; its roof is low and arched, re- 
sembling the roof of a baker’s oven ; the fire is placed at 
one end of the furnace, upon an iron grate, to the bottom 
of which the air has free access ; at the other end oppo- 
site to the fire-place, is a high perpendicular chimney ; the 
