is about i oo yards, and the depth nearly
as much. The bottom is very irregular,
mafles of rider or vein ftone interfering ;
while the richer copper ore runs into holes,
and crevices, in ftranee and various direc-
tions. The fhiftus lies in irregular ftrata, and
is covered with a bed of gravelly heterogenous
matter, full of chert.
Copper ore is got for about two {hillings
a ton, and is laid in heaps of five or fix
hundred tons ; in the fides of which ovens
or fires are placed, and the fulphur in the
ore foon taking fire, it continues roafting
for fix or nine months,. and is then forwarded
for fmelting. The produce of the
mine is very poor, about feven and a half
per cent, fometimes more, and fometimes
fo little as five per cent. Patches appear of
fine cubic mundic.
Great quantities of fulphur are made.
In the fubliming houfes the ore is covered
vered with earth, and brick tunnels are
formed on the top or fides, to receive the
fulphur.
On examining this immenfe mine, it does
not appear-like a vein. About 500 yards
to the eaft, the Cornifh Company have funk
a fhaft of 40 fathom, but have only found
fmall particles, and firings of ore. They
have alfo driven north and fouth ; but have
not met with any vein.
In fome places the ore rifes within eight
inches of the furface; and immediately
above is a red cruft, which has every ap-.
pearance of vitrified fcorias, has marks of
fufion, being cellular, glazed, and like a
feruginoua pumice. It is fometimes a little
irredifeent, has a ftyptic vitriolated earthy
fmell; and probably contains vitriolic acid,
with iron and fometimes lead.
The area of ground, containing the whole
works, is at leaft a fquare mile in compafs.
The