1822.] Mr. Fox on the Temperature of Mines. 445 
In taking the temperature of the water in the different levels 
of mines, care was generally observed to select the largest 
streams, and to put the thermometer at or near the places where 
they first flow into the mines, so that the influence of any heat 
from the mines seems to be put out of the question. 
It appears that in almost all the mines which have been exa- 
mined, the highest temperature has been found at the bottom, 
and it is deserving of notice, that here, in most instances that I 
have investigated since my last paper, very few workmen are 
employed ; and generally their number increases at each level in 
ascending from the bottom, as high up as one quarter, or even 
one-third of the way; so that not very far from the middle of 
mines, they are frequently the most numerous. 
At a level 180 fathoms under the surface in the United Mines, 
I find the temperature of the water which was, and had been 
during 12 months, 30 fathoms deep in the mine, was 80°, and a 
stream of water flowing into the same level, was 87°. This is 
only half a degree less than it was at the same place in 1820. 
At that time about 400 men were employed in the mine eight 
hours each day, and about 50 on an average for the remainder 
of the 24 hours. When the last observation was made, only 
about 200 men worked in the mine eight hours a day, and about 
50 during the remaining 16 hours. 
I do not dispute, that in close levels, where there is no cur- 
rent, the presence of the men increases the temperature of the 
air, yet it does not appear by the above table that the heat of 
the air is usually much greater than that of the water in the same 
places, perhaps on an average not exceeding 1° or 2°. In many 
instances, indeed, the water was from 1° to 4° warmer than the 
surrounding air, and this occurred in several mines at or near 
the deepest levels. 
Before I conclude my enumeration of facts, it may, perhaps, 
be desirable to state the temperature of the water which flows 
through the great adit, and is discharged near Nangiles mine, 
above Carnon Valley. This adit traverses the principal mining 
district of Cornwall, and extends nearly 30 miles, including its 
different ramifications, and more than five miles from one extre- 
mity to the other in one direction, and three miles in another. 
_ The temperature of the water was taken near the mouth of the 
adit about six weeks since, and was found to be 69°25°. Richard 
Thomas, land-surveyor of Falmouth (author of an interesting 
- map of a large portion of our mining district), has ascertained, 
by frequent observations, that the quantity of water discharged 
by the adit at different times of the year, has varied from 910 to 
1644 cubic feet per minute ; but as some deep mines have been 
set to work since he made his experiments, the average quantity 
is now probably greater. It appears, on making a comparison of 
the depth of the water at the time the foregoing temperature 
was ascertained, with his calculations, that the quantity dis- 
