232 LIGHT SCIENCE FOR LEISURE HOURS. 



have passed tlirongli Bass's Straits, between Australia 

 and Yan Diemen's Land, and so have lost a considera- 

 ble portion of its force and dimensions. When we re- 

 member that had not the effects of the earth -shock on 

 the water been limited by the shores of South America, 

 a wave of disturbance equal in extent to that which 

 travelled westward would have swept toward the east, 

 we see that the force of the shock was sufficient to have 

 disturbed the waters of an ocean covering the whole 

 surface of the earth. For the sea-waves w r hich reached 

 Yokohama in one direction and Port Fairy in another 

 had each traversed a distance nearly equal to half the 

 earth's circumference ; so that if the surface of the 

 earth were all sea, waves setting out in opposite direc- 

 tions from the centre of disturbance would have met 

 each other at the antipodes of their starting-point. 



It is impossible to contemplate the effects which 

 followed the great earthquake the passage of a sea- 

 wave of enormous volume over fully one-third of the 

 earth's surface, and the force with which, on the far- 

 thermost limits of its range, the wave rolled in upon 

 shores more than 10,000 miles from its starting-place 

 without feeling that those geologists are right who 

 deny that the subterranean forces of the earth are 

 diminishing in intensity. It may be difficult, perhaps, 

 to look on the effects which are ascribed to ancient 

 earth-throes without imagining for a while that the 

 power of modern earthquakes is altogether less. But 



