(: M2 ) 
Art. VII. —Notice in regard to the Temperature of Mines. By 
Mathew Miller, Esq. 51st Light Infantry, M. W. S *. 
TP HE late experiments on the temperature of mines made in 
Corn wall, and in other countries, having given rise to various 
speculations in regard to the distribution of heat in the crust of 
the earth, all of which appear to me to be unsatisfactory, I now 
beg leave to offer for consideration of the Society, an explana- 
tion, which does not seem liable to the objections that have been 
opposed to the others. 
In every mine, with the exception of a few, which are level- 
free, the ventilation is carried on by causing the air at the sur- 
face to descend, and traverse the works, and then ascend. Now, 
it is evident, that if a portion of air from the surface be carried 
down to the bottom of the mine, it will be condensed in propor- 
tion to the depth of the mine, and, in consequence of this conden- 
sation, will become heated, and the degree of heat will of course 
be in proportion to the depth of the mine. The air thus heated 
traverses the works, and imparts its heat to the strata ; it then 
ascends, and is succeeded by a fresh portion of air from the sur- 
face, which in the same way becomes heated, and imparts its 
heat to the strata, and they, in turn, communicate it all around. 
Thus, in a long course of working in a deep mine, the air at the 
bottom is heated, and also the rocks to a considerable depth ; 
and when the working ceases, the mine takes a long time to lose 
its temperature ; and this is found to be the case, particularly 
when the mine becomes full of water, the water being found at 
first of a high temperature, and gradually to lose its heat, which 
is in consequence of the strata imparting theirs to the water, and 
as soon as they have given out all their heat, the water indicates 
the mean temperature nearly of the place. 
The reverse takes place in an old mine when reworked ; in 
that case, the temperature rises gradually as the working con- 
tinues : and in those mines which are not worked, but in which 
* Extracted from the Memoirs of the Wernerian Natural History Society , 
vol. iv. Part 2. 
