HIGH TEMPERATURE OF THE INTERIOR. 113 



chemical force lend no countenance to the 

 fanciful creations of fable.* 



Let us now set before the reader some of those 

 natural phenomena which seem to help us to 

 some sort of acquaintance with the chemistry of 

 the interior. And we may first allude to the 

 remarkable facts which have been discovered 

 relative to the temperature of the crust of the 

 earth. If a thermometer is taken with us as 

 we descend into a mine, and carefully examined, 

 it will indicate a gradual rise of temperature 

 proportionate to the depth of the descent. 

 If we were to make the descent in winter, the 

 increase would be very sensible even to the 

 surface of the body. The actual increase has 

 been ascertained by a number of experiments 

 made in different countries, and amounts pretty 

 constantly to one degree of Fahrenheit's scale, 

 for every fifty or sixty feet in depth. A 

 thermometer placed in a hole cut in the solid 

 rock, at the vast depth of 1,380 feet, was 

 observed to register on the average 68, while at 

 the same time the mean temperature of the 

 surface was only 50. It is a familiar fact also 



* Fable has peopled the deep abyss with men, animals, 

 and plants, and has conjectured even the existence of two 

 planets, which have been called Pluto and Proserpine, to 

 give light to this charming world within the world ! Leslie 

 and Halley affirmed that it was a hollow sphere, made up of 

 stories like a house. 



I 



