Hot and Thermal Sprhigs. 285 



increase of temperature in the earth. The mining officers of 

 Schemnitz remarked to him that they had nothing to suffer, 

 either from heat or cold in the mines, so long as there was a 

 good circulation of air ; but when such was wanting, it inva- 

 riably became warmer. From Mr Schapelraan, the director of 

 the mines (Bergmeister) at Herrengrundt in Hungary, Kircher 

 learnt that when the mines are dry, their temperature increases 

 with the depth, because it is impossible, on account of their 

 depth, to give them a sufficient ventilation ; but that when 

 they contain water, although deep, they are not so warm. 

 Boerhave * also mentions the increase of temperature towards 

 the centre, and Mairan-f first set up the hypothesis of the 

 existence of fire in the interior of the earth. 



Regular observations of temperature in mines began in the 

 middle of the last century, and have been very much multiplied 

 since that time. Either the temperature of the springs, or that 

 of the water which flowed from the adit, was usually observed ; 

 but the number of the observations was inconsiderable, and the 

 results are tliemselves very uncertain, since the waters may 

 bring cold from above or heat from below with them J ; or else 

 they observed the temperature of the air on the rock. We pos- 

 sess observations of this sort in great numbers, and in depths 

 of 1278 feet 11 inches, 1598 feet 8 inches (1200 to 1500 feet 

 French feet ?). 



The first observations were made towards the middle of the 

 last century in France, at the instigation of Mairan, § in the 

 mines of Giromagny, near Befort, in the Vosges. In the year 

 1806, D'Aubuisson || made some observations in the lead and 

 silver mines of Poullaouen and Huetgoet, in Bretagne ; and 

 from 1822 to 181^5, Cordierf did the same, in the coal mines 

 of the departments of Tarn, Nievre, and Calvados. 

 From Switzerland, we have the observations of De Saussure,** 



• Elementa Chemise, Lipsise, 1732, vol. i. p. 403. 

 ■}■ Mem. de I'Academie pour 1719. 



X The former case seems to be the more frequent. 



§ Dissertation sur la glace, a Paris, 1749, in 12mo, p. CO. 



II Joum. des Mines, voL xxi. p. CO. 



Tf Annal. des Mines, deuxieme series, vol. ii. p. 53-139. 



* * Voyages dans les Alpes, § 10C8. 



VOL. XXIV. NO. XLVIII.— APlllL 1838. 



