32 2 Observations on Sulterraneous Heat. 



the ground requires nearly a degree of diminution ; so that 

 Wt may estimate the mean temperature as 11*5°. 



My observations were made on the 5th of September 1806. 

 During the whole of the day the sky was serene and cloud- 

 less. The temperature taken in the shade at mid-day was 19°. 

 In detailing the rest of my observations, I shall lay down 

 the position of the points at which they were made, as well 

 as what appeared to me to influence the temperature. By 

 the side of each thermometrical expression I shall give the 

 depth below the surface of the point to which it refers : 



1st, In the first gallery, called the level of 50 feet, near 

 the pit .by which we descend, in a place where there is but 

 a feeble current of air, a little water which was upon the 

 ground indicated, — Temperature 13'1°. Depth l6 m . 



2d, In the gallery of St. George, under the intersection 

 of three branches of the ridge, in a kind of culdesac, far 

 distant from the place occupied by the miners, where there 

 was no current of air, but from the upper part of it a great 

 quantity of water filtered. This water gave, — Temperature 

 11-9°. Depth 39 n . 



3d, The water of filtration which fell into this gallery 

 (Sr. George's) indicated, on being brought to the mouth of 

 the pit, — Temperature 12*1°. Depth 39 m . 



4th, Thirty-six metres lower down, at the level of la 

 Boullaye, towards the extremity of a long gallery, where 

 there is neither a current of air nor a single workman ; in 

 the water I found, — Temperature 11*9°. Depth J5 m . 



5th, At the very bottom of St. George's pit, in the hole 

 wherein the waters collect which have fallen from above; 

 the water indicated, — Temperature 14-2°. Depth 142 m . 



6th, The air above this water, — Temperature 15°. Depth 

 141 m . 



7th, In the hole at the bottom of the pit St. Barbe, (at 

 the other extremity of the mine,) in the water I found, — 

 Temperature 13*5°. Depth 150 m . 



8th, In the air above this- water, — Temperature 14*4°. 

 Depth ,150 m . 



9th, The water of the old excavations adjoining,. — Tern- 

 - perature 13*3°. 



KB. 



