309 
Report on some Observations on Subterranean Temperature. 
By Roserr Were Fox, Esq. 
Havine already given, through the Philosophical Magazine*, 
a summary of tne observations on subterranean temperature 
which I had previously published from time to time, I must, in 
complying with the unexpected invitation of the British Asso- 
ciation, necessarily include in the present Report many of the 
details contained in that memoir. 
Early in the year 1815, my friend Joel Lean stated to me 
his conviction, that the high temperature observed in our 
mines existed in the earth itself, increasing with the depth; 
and shortly afterwards his brother Thomas Lean, at our joint 
request, kindly made many experiments in Huel Abraham 
Copper Mine, of which he was the manager, in order to test 
the correctness of this view. The results obtained by him 
tended to confirm it very unequivocally; and so did another 
series, made in the same year at my request, in Dolcoath 
Mine, by John Rule, jun., one of the superintendents. Many 
other individuals have since obligingly carried on similar ob- 
servations for me in different mines, all showing that the sub- 
terranean temperature increases, in some proportion to the 
depth from the surface. The ratio of its increase at different 
depths, and the causes which exercise a greater or less influ- 
ence upon it, have, however, hitherto been undecided. 
I have elsewhere endeavoured to show, that the rate of in- 
crease is not so considerable at deeper excavations as at those 
which are shallower ; and the subjoined Tables will, I think, 
exhibit this point in a satisfactory manner, as far, at least, as 
the results obtained in some of the mines of Cornwall and 
Devonshire, which I have published from time to time, may be 
considered an authority. 
* Phil. Mag. 1837, vol. ii. p. 520. 
Tabe I. 
