Mr Hen wood on the temperature of Mines. 235 



.•sous whose attention was directed to this subject. At their 

 request, Mr Thomas Lean, brother of the latter, and then agent 

 ;at Huel Abraham Mine, was requested to make some experi- 

 ments on the temperature of that mine, of which he forwarded 

 Jthe results to Mr Fox ; although he subsequently published 

 them, * before the communication of Mr Fox''s paper on the , 

 *feame subject, to the Cornwall Geological Society in 1819 "f*. 

 rlti this paper, Mr Fox inserted these and other experiments, 

 •made about the same time in various mines, and insisted on 

 the general fact of an increase of temperature at considerable 

 depths in the earth. 



^ At the same meeting of that society, a paper on the same 

 Subject was communicated by John Forbes, M. D. J ; but al- 

 though they agreed in the facts which had been adduced, his 

 •kiferences were different, indeed opposed to those of Mr Fox, as 

 to there being evidence of a native heat of the earth itself. The 

 observed elevation of temperature he attributed to the presence 

 of workmen, combustion of candles, &c. and in support of this 

 opinion he entered into elaborate calculations. His subse- 

 quent inquiries led him to a different conclusion ; and in a se- 

 cond memior, read to the same society in 1820, he admitted 

 the existence of a terrestrial heat, independent of adventitious 

 circumstances ; although he still thought the observed eleva- 

 tion of temperature was materially affected by these causes. 

 This gentleman's publication contained the facts in both these 

 papers, but not the conclusions which appeared in the first of 

 them. 



A second communication from Mr Fox was laid before the 

 society at the same meeting, in which many more observations 

 were adduced in support of his original conclusions §. 



In 1819, Mr Bald's observations on the temperatures ob- 

 served in some of the coal mines in the North of England were 

 laid before the Koyal Society of Edinburgh ||, of which the 



• Phil. Mag. xlii. 204. 



t Cornwall GeoL Trans, ii. 14; Annals, N. S. xxii. 41 ; and Phil. 

 Mag. Ixi. 



% Cor-nwall G. Tram: ii. 159 ; Annals, xxii. 447 ; and Phil. Mag. Ixi. 436. 

 § Cornwall G. Trans, ii. 19 ; Annals, xxii.; and Phil. Mag. Ixi. 

 II Edin. Phil. Journal., I 134 ; and Phil. Mag. Ixii. 105. 



