208 LIGHT SCIENCE FOR LEISURE HOURS. 



and then the wave will break upon the beach and roll 

 far in upon the land.' This is precisely what happened 

 when the great wave reached the eastern shores of 

 New Zealand, which are known to shelve down to 

 very shallow water, continuing far away to sea towards 

 the east : 



At about half-past three on the morning of August 14 

 the water began to retreat in a singular manner from 

 the Port of Lyttelton, on the eastern shores of the 

 southernmost of the New Zealand Islands. At length 

 the whole port was left entirely dry, and so remained 

 for about twenty minutes. Then the water was seen 

 returning like a wall of foam ten or twelve feet in 

 height, which rushed with a tremendous noise upon 

 the port and town. Towards five o'clock the water 

 again retired, very slowly as before, not reaching its 

 lowest ebb until six. An hour later, a second huge 

 wave inundated the port. Four times the sea retired 

 and returned with great power at intervals of about 

 two hours. Afterwards the oscillation of the water was 

 less considerable, but it had not wholly ceased until 

 August 17, and only on the 18th did the regular ebb 

 and flow of the tide recommence. 



Around the Samoan group the water rose and fell 

 once in every fifteen minutes, while on the shores of 

 New Zealand each oscillation lasted no less than two 

 hours. Doubtless the different depths of water, the 

 irregular conformation of the island groups, and other 

 like circumstances, were principally concerned in pro- 

 ducing these singular variations. Yet they do not 



