respecting the Tcmperatui-e of Mines. 447 



111 undated the lowei* galleries of this mine. Tlie inference 

 stems here irresistible." 



" The temperature of 55° was found by Dr. Da-sy and my- 

 self in the water of the abandoned mines of Huel Boo- and 

 Hnel Fortune." 



" In adopting the inevitable conclusion of the inadequacy 

 of all the extraneous sources of temperature in mines, at pre- 

 sent known to us, to account for the degree of heat found in 

 them, and in the water discharged from them, it must be al- 

 lowed that this extraneous temperature has a considerable ef- 

 fect in modifying the results observed in many parts of them. 

 In proof of this I may refer to almost every page of my jour- 

 nals; and I mention it here chiefly for the purpose of impress- 

 ing the necessity of keeping the fact in view, in making future 

 observations in mines, and in drawing inferences from those 

 already made." 



" It is much more easy to be convinced of the fact of an in- 

 crease of temperature, than to ascertain its precise amount, at 

 any particular depth. Indeed, this part of our inquiry is ex- 

 tremely difficult, and for several very obvious reasons. The 

 principal of these seem to be, 1. The impossibility in any part 

 of a mine, of determining, with any thing like precision, tlie 

 exact amount of temperature produced by the extraneous 

 causes existing there : 2. The tendency of heated air to ascend, 

 and of water, and perhaps the gases from gunpowder, to de- 

 scend, thereby carrying the temperature of one part of a mine 

 into another : 3. The great discrepancy (perhaps a conse- 

 quence of the tvto former causes) between observations at si- 

 milar depths, in the same mine, or in different mines, under 

 circumstances apparently very similar. But although almost 

 every page of my journals shows the difficulty of fixing the 

 precise degree of temperature at particular depdis, I think they 

 prove irretragably the progressive increase of this as we ad- 

 vance downwards." 



" Perhaps one of the most conclusive and striking proofs of 

 tlie increase of temperature as we recede from the surface of 

 the earth, will be aiforded by the relative tem})crature of the 

 pumj) water of the same mines at different times. The only 

 trials of this kind diat have been made, to my knowledge, are 

 the following: In 1819 the pump water of Huel Neptune, 

 then of the depth of 540 feet, was G0°: in 1822, when the 

 depdi was 750 feet, it was 62°. In 1819 the water of Botal- 

 lack, then 510 feet in dcpdi, was G2°: in 1822, when the mine 

 was G70 leet deeji, it was G7°. No material change in the con- 

 dition of these mines had taken place during the interval, ex- 

 cept die increase of depth, to which the augmentation of Uie 

 temperature could be attributed." [To be continued.] 



