Lead . 
19 9 
about six inches ; the length of the fire-place is four feet, 
equal to the width of the throat ; its width two feet, and 
depth three feet, from the grate up to the throat of the fur- 
nace. The rest of the hearth is a concave surface nine 
feet long, four and a half feet wide at the throat of the 
furnace, seven feet four inches wide at the distance of two 
feet from the throat, seven feet two inches in the middle 
of the hearth, five feet eleven inches at two feet distance 
from the chimney, and two feet ten where the fame enters 
the chimney at two apertures, each ten inches square* 
These apertures terminate in the oblique part of the chim- 
ney, the section of which is 16 inches square, which com- 
municates with the main chimney, the section of which is 
twenty inches square, supposing a straight horizontal line, 
drawn from the lower plane of the throat of the chimney 
to the opposite side of the furnace ; the lowest part of the 
concave hearth, which is in the middle of this cavity, is 
nineteen inches below this line, the roof of the furnace be- 
ing seventeen inches above the same line : the rest of the 
hearth is conformably concave. 
On each side of the furnace are three openings, each 
about ten inches square, provided with iron doors, to be 
removed as occasion may require. They are arranged at 
equal distances from each other, between the commence- 
ment of the hollow hearth and the entrance into the chim- 
ney. The lower part of these apertures is on a level with 
the horizontal line above alluded to, being for the purpose 
of stirring and raking the ore, &c. Besides the larger 
openings there are two small apertures, one below the 
large middle opening, and nearly on a level with the bot- 
tom of the furnace ; the other under that next to the chim- 
ney, at some distance above the first aperture. The first 
is a tap-hole for the lead, and the second for the scoria. 
The ore is introduced by a vessel in the shape of a hopper, 
placed in the roof of the furnace* 
