382 SEE— THE NEW THEORY OF EARTHQUAKES iNovember 15. 



of the terrestrial globe. For, if so, how are we to explain the 

 digging out of ocean trenches and the elevation of the adjacent 

 crust into a mountain range, as often happens in the depths of the 

 sea? If any kind of wrinkling due to secular cooling were at work, 

 it seems certain that the inland regions could not escape the same 

 influence. 



The difficulty experienced in accounting for the vibrations of 

 the great earthquake at San Francisco, on the hypothesis that a 

 rock had snapped or slipped, is thus fully sustained. If such a 

 cause had given rise to the earthquake, the vibrations would have 

 been of simpler character, accompanied by less rotatory motion, 

 and the whole disturbance would have been less violent and of 

 much shorler duration. It may be asserted with confidence that no 

 vibrations arising from the snapping of rocks would have been 

 sufficiently powerful or long continued to shake down cities and 

 spread universal devastation over the land. Above all, such effects 

 of secular cooling could not explain a general phenomenon like the 

 uplifting of the mountains as veritable walls about the margins of 

 the sea. Nothing but the expulsion of lava from under the sea 

 would be adequate to account for this upheaval of the crust, and it 

 is hard to see how any thing but the shaking incident to this en- 

 forced and prolonged subterranean movement could devastate the 

 land and disturb the whole world. In the expulsion of lava from 

 beneath the sea, the true cause of earthquakes is clearly recog- 

 nized, and all the most important phenomena connected with the 

 physics of the globe are correctly assigned to the secular leakage 

 of the ocean bottoms, which necessarily is greatest where the sea 

 is deepest. This hypothesis alone is adequate to account for all 

 the phenomena of nature. The unity and harmony and mutual 

 dependence shown to exist among the most diverse phenomena 

 observed at the surface of the earth is the best proof of a common 

 underlying cause, and such a theory will strongly commend itself 

 to the natural philosopher who seeks in the abundance and variety 

 of nature indications of a single fundamental law. 



How great is the change in the new point of view may be seen 

 from the following discussion by Professor J. W. Gregory, taken 

 from the " London Sunday at Home," 1906 : 



