THE GEOLOGIST. 
lode in this deep level, at its eastern extremity, was 90° 5' ; the contiguoua 
granite, 91" 5' ; the air, 91" 5' ; a snmll spring of water ilowing from the lode, 
93° 5'. In 1837, the deepest level iu this mine was 262 fathoms, or 1,572 feet, 
beneath the surface, and the temperature of the rock was tlicn 82° 5'. 
Dolcoath (in the parish of Cambornej is a very productive mine of copper ami 
tin, and now yields miich of the latter in its deepest part, the containing rock 
being granite, with killas near the surface. The deepest level on the north lode 
was 272 fathoms below the surface, and extended only about four fathoms on 
each side of the engine-shaft ; the rock at its eastern end was 73* 5'; the air, 
71° 7' ; and the water, 73°. At the western end, it was 73° on one side of the 
level, and 73° -5' on the other; the air, 73° ; and the water, the quantity of which 
was very small, 72° 7'. At about three fathoms further south, and at the same 
depth, another lode was worked, the level extending to about fourteen fathoms 
to the westward of the eugine-shaft. The granite was found to be at 79° 5' ; and 
the water, which was much more abundant than iu the other level, 79° o' ; while 
the air was at 78°. 
In 1.821-22, the deepest level iu Dolcoath was 230 fathoms from the surface, 
and Mr. Fox then had an accurate thermometer, 4 feet long, kept in it for more 
than a year, with the bulb suuk 3 fet t in the lode ; and it varied from 75° and 
75° 5' to 76° 5' and 77° ; an occasional influx of water having caused a temporary 
ri.fe of the mercury to the extent of a degree or more. 
The water near .the bottom of the engine-shaft in 1822 was at 82° at 239 
fathoms below the surlace ; and last year (1857) it was 82° . 5', at 278 fathoms 
deep. • 
The deepest level of the Levant copper and tin mine, in St. Just parish, is 255 
fathoms below the surface of the ground, and nearly 230 fathoms beneath the 
sea-level, having been extended horizontally under it through killas. The tempe- 
rature of the rock near the end of the level was 84" 7' on one side and 85° 5' on 
the other; the water, 85° 5'; the air, 85". In 1853, the temperature of the 
rock in this level, when it was not extended so fiir westward under the sea, was 
reported to be 87", and the graniie rock at the same level, eastward of the shaft, 
74°. 
Botallack copper and tin mine is in the same parish. The western levels extend 
through killas far under the Atlantic, one of them more than half-a-mile from the 
shore. The deepest level was 188 fathoms from the ground and 180 under the sea- 
level ; the rock near the ond being 79° on one side and 79° 5' on the other ; the 
air, 81°. 
These results exhibit great differences in the rates of increase in the temperature 
in different mines, and also in difi'erent parts of the same mine, as will be better 
seen in the following table, prepared by Mr. Fox, in which the experiments made 
in the deepest levels are arranged in order of their respective depths, and which 
exhibits the initios in feet, in descending from the surface in which tlie tempera- 
ture was augmented 1° Fahr. Irom 50", the mean temperature of the climate : — 
Mines. 
Par Consols (tin part) ... 
Botallack, G. and T 
Par Consols (copper part) 
Dolcoath, C. and T 
Levant, C. and T 
Levant, C. and T 
Levant, C, and T 
Tresavean, C .. 
Dolcoath, C. and T 
Dolcoath, another lode... 
Tresavean, C 
3 a 
~ .o 
Dates. 
Temperatures. 
Increase of 
1° in 
descending. 
Eock 
768 
1837 
74° 
-50 = 
24° 
32 feet. 
Killas. 
1128 
1837 
79 
-50 = 
29 
39 „ 
Killas. 
1248 
1837 
81 
-50= 
34 
36-7 „ 
Killas. 
1380 
1822 
75-5 
-50= 
25-5 
54 „ 
Granite. 
153C 
1853 
71 
-50 = 
21 
63-7 „ 
Granite. 
153G:i8:i3 
87 
-50 = 
37 
41-3 „ 
Killas. 
1530 1857 
85 
-50 = 
35 
43-7 „ 
Killas. 
157211837 
82-5 
-50= 
32-5 
48-4 „ 
Granite. 
16321857 
73 
-50 = 
23 
71 „ 
Granite. 
103211857 
79-5 
-50 = 
29-5 
55-3 „ 
Granite. 
2112 
1853 
90-5 
-50 = 
40-5 
52-1 ,. 
Granite. 
