ON SUBTERRANEAN HtAT. 



5. At the bottc m oF St. George's shaft, in Tempe- Depth, 

 the well in which the watei-s that penetrate 



into the lower parts of the mine around it are 



rollected ....... .^ 55.7O 463 • '6 



6. Tiie air over this water 57*2° 460.-3 



7 In the well at the bottom of St. Barbe's 



shaft, at the other extremity of the mine .... 54*5° 489. '6 

 ' 8. In the air above this water 56-1^ 489. '^ 



9. The waters of the old excavations, that, 

 rah into this well • « . • * • • • • • 54*1? 



N. B. These waters arising from filtratidns 

 that take place chiefly in the' upper parts of 

 the old workisig^s are cold; and as they form 

 the greater part of those that' enter into St, 

 Barbe's well , they av^ the occasion of the low- 

 ness of the temperature shown by the water 

 in it, 



10. In an excavation but little distant from 

 the bottom of St. Barbe's shaft, called the 

 oven gallery, the sides of which are alnpst 

 every where interspersed with radiated pyrites 

 partly effloresced, the thermometer left a quar- 

 ter of an hour in a small hollow made in the 

 midst of the pyrites, and which contained a 



great deal of white sulphate, indicated. ..... 56*5° 457 



11. Afterward pint iijto a small hole, from 

 which a pretty strong spring issued, it equally 

 marked • • 56-5° 457 



The observatlor)s 2, 3, and 4, incontestably prove, that 

 the heat of the rock in the upper parts of the mine is 51*8°. 

 The waters indicating this certainly acquired the tenipera- 

 ture of the rock in filtering through it; and this tempera- 

 ture does not dift^r in any sensible degree from that indi- 

 cated by theory. If the first observation shoved a little 

 higher temperature, it is because it was made in a place, 

 where air from without, and consequently warm, as the ex- 

 periments were made at th^ end of summer, was continually 

 passing. 



Observations 5 and 6 show, that the temperature of th^ 



lower 



151 



Tabulated 

 temperatures 

 and depths, 

 with remarks. 



General de- 

 ductions. 



Superficial 

 temperature; 

 agreeable to 

 theory. 



Temperature 



