CHAPTER III 



OUR MOLTEN GLOBE 



Few scientific inquiries excite greater interest than those 

 recent researches which have so greatly extended our 

 knowledge of the stars and nebulae, whether by deter- 

 mining the direction and velocity of their motions, or 

 ascertaining their physical constitution and probable tem- 

 perature. In comparison with this considerable amount 

 of knowledge of such distant bodies, it seems strange that 

 so little comparatively is known of the structure and in- 

 ternal constitution of the globe on which we live, and that 

 much difference of opinion should still exist on the funda- 

 mental question whether its interior is liquid or solid, 

 whether it is intensely hot or comparatively cool. Yet the 

 definite solution of this problem is a matter of the greatest 

 theoretical interest, since it would not only elucidate many 

 geological phenomena, but might possibly serve as a guide 

 in our interpretation of appearances presented by the 

 other planets and even by more remote bodies ; while it 

 is not unlikely that it may soon become a practical ques- 

 tion of the highest importance, inasmuch as it may lead 

 us to the acquisition of a new source of heat, in many 

 ways superior to that produced by the combustion of fuel, 

 and practically inexhaustible. 



It is only during the present century that facts have 

 been accumulating in various directions, bearing more or 

 less directly on the question of the earth's internal condi- 

 tion. These have been partially dealt with, both by 

 geologists and by physicists ; but the problem is such a 



