EXPERIMENTS ON VEINS AND MINES. 135 
western extremity of the deepest level or gallery, about 190 
fathoms under the sea level, and four feet from the lode, when 
No. 1 showed a temperature of 78°, and No. 2, 72°°5 ; a stream 
of water which flowed into another part of this level to the east- 
ward of the shaft, and in granite, was at 78°°5, and the air in 
the level only 67°. 
The Consolidated Mines are situated in the parish of Gwen- 
nap, and nearly thirty miles to the 
eastward of Levant. The depth is 
290 fathoms from the surface, and 
237 below the level of the sea at 
half-tide; the rock is “killas.”’ 
There is a “‘ cross-cut,’ or gallery 
proceeding from the bottom of the 
deepest shaft (Pearce’s), marked 
P.S. in the section Fig. 2, at right 
angles to the lode, which it inter- 
sects at N., the lode underlying to- 
wards the north L.N. The thermo- 
meters No. 1 and 2 were placed at a, 
24 fathoms from N.., the bulb of the 
former in a hole three feet deep, 
and that of the latter in another an 
inch deep, the holes having been 
filled round the thermometers with 
clay, &c. Under these circum- 
stances No. 1 indicated a tempera- 
ture of 85*°3, and No. 2 of 84°. 
The thermometers were then simi- 
larly arranged at 4, ten fathoms 
from N., and No. 1 gave 86°°3, and iy 
the other 85°. These experiments re r s 
were made before the cross-cut was 
completed as far as N. When, however, the lode was inter- 
sected atthat place, both thermometers were placed in the manner 
already described in the lode itself at c, when No. 1 indicated 
a temperature of 92°, and No. 2 of 88°. Here the thermo- 
meters were kept only two hours, but in all the other experi- 
ments in both mines they remained in their places more than 
twenty-four hours ; and when No. 1 was taken out of the deep 
holes, and allowed to stand awhile in the “ cross-cut,” the mer- 
cury always fell at leasta degree. Only two men were at work 
at a time in or near this part of the mine. The increase of 
temperature in the lode, may, I conceive, be attributed to the 
greater facility afforded by it for the ascent of currents of warni 
