144 Internal Heat of the Crust of the Globe. 



The following Table exhibits the temperature of the bore-hole 

 at the depths specified. 



Depth below the Corresponding 

 Surface in Feet. Temperature. 



30 8.4 Reau. 



60 8.5 



100 8.8 



150 9.2 



200 9.5 



250 10.0 



300 10.5 



350 10.9 



Depth below the Corresponding 

 Surface in Feet. Temperature. 



400 11.37 Reau. 



450 11.73 



500 12,20 



500 12.63 



600 13.05 



650 13.50 



680 13.80 



It thus appears that the increase of temperature below the 

 depth of 100 feet from the surface, as far down as 680 feet, is 

 precisely 0°.875 of Reaumur (=1°.968 or 2° Fahrenheit, very 

 nearly), for every 100 feet. It will be observed, that the in- 

 crease, instead of moving per saltum, as in some other cases, 

 moves with remarkable uniformity. This, the experimenters 

 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 occa- 

 sion, was as follows : next to the upper layer of vegetable earth, 

 sand and gravel, was a gravelly and bluish clay, mingled with 

 soft sandstone (molasse). Below 120 feet commenced a succes- 

 sion of beds of marl and soft sandstone, of various thicknesses, 

 which continued without interruption to the termination of the 

 boring, 682 feet. At 220 feet there was a bed of coarse sand- 

 stone (molasse grossiere) two feet thick, with rolled pebbles, a 

 remarkable fact, considering the depth. A strong fetid sul- 

 phurous odour was also observed in the layer of yellow marl 

 mixed with sandstone, at the depth of 280 feet, that is near the 

 level of the lake, and a grain of salt was found in the sandstone 

 at this depth. The sulphurous odour again appeared at 600 feet, 

 without the presence of any sulphurous compound that would 

 account for its origin. 



