234 LIGHT SCIENCE FOR LEISURE HOURS. 



when considered with reference to the dimensions of 

 the earth's globe, may be spoken of as an indefinitely 

 minute quivering limited to an insignificant area, has 

 sufficed to destroy the cities and villages of whole prov- 

 inces, to cause the death of thousands of human beings, 

 and to effect a destruction of property which must be 

 estimated by millions of pounds sterling. Such a ca- 

 tastrophe as this serves indeed to show how poor and 

 weak a creature man is in presence of the grand work- 

 ings of Nature. The mere throes which accompany 

 her unseen subterranean efforts suffice to crumble man's 

 strongest buildings in a moment into dust, while the 

 unfortunate inhabitants are either crushed to death 

 among the ruins, or forced to remain shuddering spec- 

 tators of the destruction of their homes. 



At first sight it may seem paradoxical to assert 

 that earthquakes, fearfully destructive as they have 

 so often proved, are yet essentially preservative and 

 restorative phenomena; yet this is strictly the case. 

 Had no earthquakes taken place in old times, man 

 would not now be living on the face of the earth ; if 

 no earthquakes were to take place in future, the term 

 of man's existence would be limited within a range of 

 time far less than that to which it seems likely, in all 

 probability, to be extended. 



If the solid substance of the earth formed a perfect 

 sphere in ante-geologic times that is, in ages preceding 

 those to which our present geologic studies extend 



