on Subterranean Temperature. S9 



There is, therefore, reason to consider experiments of this 

 kind as very inaccurate. I only adduce the results which are 

 consigned in the following table, as approximations which it 

 may he U8eful to take into consideration. 



3^, Lastly, in another mine in Cornwall, that of Dalcoath, a 

 thermometer was kept for eighteen months, sunk to the depth 

 of 3 feet 3 inches in the rock of a gallery. I have not been able 

 to procure the details of this important experiment; but, it is to 

 be presumed, that so zealous an observer as Mr Fox, who in- 

 stituted it, would have bestowed the necessary pains upon it. 

 At the same time, unless the bottom of a gallery was chosen, 

 and unless the experiment was made, not only at a distance from 

 works in activity, but also from all old works, there will be 

 chances of uncertainty. There is, therefore, no absolute de- 

 pendence upon the accuracy of the result, although we cannot 

 refuse to admit it as highly approximative. I consign the indi- 

 cation afforded by this experiment in the following table, which 

 contains all that relates to experiments made in the rock of the 

 excavations. This table contains nine results obtained in Sax- 

 ony and Cornwall. 



TABLE of' Observations made on the Temperature of the RocJc 



in Mines. 



