It thus appears that the increase of temperature below the depth 

 of one hundred feet from the surface, as far down as six hundred 

 eighty feet, is precisely 0°.875 of Reaumur, (=1°.968 or 2° Fah- 

 renheit, very nearly,) for every one hundred feet. It will be ob- 

 served that the increase, instead of moving per saltum, as in some 

 other cases, moves with remarkable uniformity. This, the experi- 

 menters think, may be owing to the care which was taken in this 

 case, to remove and avoid every source of error. 



This experiment appears to be the first attempt to ascertain, with 

 any accuracy, the temperature of the earth at considerable depths, 

 among the mountains of Switzerland. 



The geological structure of the beds which were bored through 

 on this occasion, was as follows : next to the upper layer of vege- 

 table earth, sand and gravel, was a gravelly and bluish clay, mingled 

 with soft sandstone, (molasse.) Below one hundred twenty feet 

 commenced a succession of beds of marl and soft sandstone, of va- 

 rious thicknesses which continued without interruption to the termi- 

 nation of the boring, six hundred eighty two feet. At two hundred 

 twenty feet, there was abed of coarse sandstone, (molasse grossiere) 

 two feet thick, with rolled pebbles ; a remarkable fact, considering 

 the depth. A strong fetid sulphurous odour was also observed in the 

 layer of yellow marl mixed with sandstone, at the depth of two 

 hundred eighty feet, that is near the level of the lake, and ' a grain 

 of salt was found in the sandstone at this depth. The sulphurous 



