S6 M. L. Cordier, Examlnat'wn of recent Experiments 



the proper temperature of the rock situated at the same level, 

 unless the mass of water is of great depth, for then the surface 

 of the fluid might manifest a heat which would belong to a 

 lower level. In all cases, the markings that have been collect- 

 ed make a sufficient approach to accuracy^ to render it indispen- 

 sable to inquire what are the numbers that express the increase 

 of subterranean temperature which may be deduced from them. 

 Of this the following table, containing the results of nine obser- 

 vations made in Brittany, Saxony, and England, apprises us. 



TABLE of Observations made on the Temperature of' the Wa- 

 ter of great Inundations in Mines. 



Places, Authors, 



and 



Dates of Observations. 



Cornwall. 

 Mr Fox, 

 Published in 1822. 



Saxony. 

 Daubuisson, 

 End of winter 1802. 



Brittany. 



Daubuisson, 

 5th Sept. 1806. 



MINES. 



'4 



f Copper Mine of North "^ 

 Huel Virgin (inun- V 

 dation very deep), j 



Do.ofNangiles(inunda- 1 

 tion very deep), . j 



Do. of Gwennap (inun- ( 

 dation 420 feet deep), ] 



Mine of Tintang (inun- 

 dation nearly draw 

 off, only 59 feet deep) 

 - Copper Mine of Huel-"^ 

 Alaid (inundation i 

 drawing off, not more | 

 than 180 feet deep), J 



Copper and Tin Mine^ 

 of Tin croft (inunda- ! 

 tion drawing off, not f 

 more than 59 ft. deep), J 



United Mines Tin \ 

 Mines (inundation 180 t 

 feet deep), . . . j 



1 



Lead and Silver Mines "\ 

 of Junghohe Birke t 

 (inundation 118 feet r 

 deep), .... ) 



Do. of Huelgoet (inun- ) 

 dation 52 feet deep), / 



Depths 



of 

 Stations. 



Feet. 

 234.3 



528.2 

 G00.4 



643.1 

 756.6 



756,6 

 1080.7 



1044.0 



780.9 



Temp. 



Subter. 

 Lakes. 



60.1 



57.9 

 60.1 



63.5 

 60.1 



63.0 

 80.1 



63.0 



65.8 



Mean 

 Temp, of 

 Country 



50 



50 

 50 



50 

 50 



50 

 50 



46.4 



51.8 



la . 

 o.s'3 



Feet. 

 23.2 



66.8 

 59.4 



47.6 

 74.9 



58.2 

 35.9 



62.7 



55.8 



According to this table, the depth, corresponding to the in- 

 crease of 1° Fahr. of heat, would be, in round numbers, as fol- 

 lows : By seven observations, made in seven mines of Cornwall, 

 from 75 to 23 feet, mean 52 feet ; by one observation in a mine 



