SUBTERRANEAN CHEMICAL FORCES. 409 



raneous with the deposition of our stratified 

 rocks ; while there is not the slightest evidence 

 that ever the earth was in a state of liquid fusion 

 throughout. According to the estimate of Mr. 

 Lyell, there are about two thousand volcanic 

 eruptions every century, which in six thousand 

 years would make 120 thousand. 



If then it be admitted, that an equal amount 

 of caloric is removed by thousands of hot 

 springs, it is evident that such an enormous 

 loss, if not compensated by the waters of the 

 ocean, (which receive their temperature from the 

 sun,) would cause a sensible diminution of the 

 internal heat of the globe, and consequently, "of 

 its volume. But it is acknowledged by Fourier, 

 Laplace, and Arago, that the temperature of the 

 earth has not varied the -3-5-0 th of a degree in two 

 thousand years. This conclusion was deduced 

 from the fact, that the length of the day has not 

 diminished perceptibly since the time of Anaxa- 

 goras, which it is maintained must have been the 

 case, had any diminution of the earth's volume 

 taken place. 



With the exception of Mr. Lyell and Dr. 

 Daubeny, nearly all geologists of the present 

 day have embraced the hypothesis of a central 

 fire, maintaining that the superficial crust of 

 the earth is supported by a mass of incandescent 

 lava. Baron Fourier supposed, (for he certainly 

 never proved it,) that the earth was originally 

 projected in a state of fusion or of incande- 



