ON THE TEMPERATURE OF DEEP MINES IN CORNWALL. 97. 
up to the adit e, f, from the bottom or “sump” d (figs. 1 & 2), and from 
cisterns placed at various intervals in the shaft, the water which enters the, 
levels being conducted into the cisterns, and thereby prevented from falling 
to the bottom of the shaft. From the adit, the water is discharged into a 
valley, or near the sea shore. The horizontal lines in fig. 1 represent “eross- 
cuts” or N. and S. levels, which connect the engine-shaft with the levels at 
right angles to them, as shown in fig. 2. These latter, on the course of the 
lode, are usually about ten fathoms apart, and they are connected together 
by many short shafts inclined with the lode. There are also other shafts 
from the surface to the deep levels, through which the ore is drawn up, 
ventilation promoted, &c. In most of the deep mines several lodes are. 
worked, and each by means of a similar series of levels, shafts, &c., which 
are connected with the former series by “cross-cuts,” so that one engine-shaft 
may often serve for two or more lodes. The deepest levels in a mine are 
generally much less extended than those above them, as shown in fig. 2, and 
the quantity of water in them is often comparatively small, the upper water 
being in a great degree cut off by the superior levels, and conveyed to the 
cisterns through the latter. The temperature of the water that flows into 
the ends of the deepest levels is generally as high, or nearly so, as that. of the 
rocks and lode, and more often higher, which it may be presumed it would 
not be if much of the upper water were mixed with it. Most of the experi- 
ments were made at or near the ends of the deepest level in each of the 
respective mines, as at E. and W., fig. 2. 
The thermometers employed were obtained for me by Professor Phillips, 
from Casella, and were, I need scarcely say, accurately graduated. 
They were placed in holes from 15 to 20 inches deep in the rocks and 
lodes, which were carefully closed up with clay, tow, or cotton. After 
the thermometers had been so left from half an hour to an hour, they 
were withdrawn for an instant for the temperature to be read off, and 
were often again left in the holes for some time longer; but as no further 
change was observed at the second reading, this precaution was latterly. 
dispensed with. 
In taking the temperature of the water, the most copious springs at their 
sources or influx into the levels were selected, if near the stations where the 
other observations were made; and the temperature of the surrounding air. 
was also ascertained. 
The mines visited are situated in different parts of the county, ranging 
from near Fowey, to St. Just, a little to the north of the Land’s End, a distance 
of about fifty miles. 
To begin with Fowey Consols* copper mine, situated near Fowey, as 
being the most easterly one. 
The deepest level in this mine was reported to be 228 fathoms under the 
surface, and about 298 fathoms below the sea-level; but the influx of water 
interfered with any experiments being made in this part of the mine, which 
is the more to be regretted, as perhaps there are few if any mines elsewhere 
so deep in reference’ to the level of the sea, although there are many deeper 
from the surface of the ground. 
At 268 fathoms below the surface, water issued from a copper lode at, 
_ * Capt. J. Puckey calculates that the total length of all the levels on 
the courses of the lodes in this mine amounts tO .....-..ceeeeeesseeee 153 miles. 
Of the cross-courses or levels, N. and S. .....seeeesseeees 22 miles 
2 And of the shafts POO POO REET OTe ee POEHOEUDE RETO RD ODES Ese OEOOSeeneereeeeeerer Pete ee 7 miles 
brass, 182 miles in all, 
1857. ¥ ! 
