228 LIGHT SCIENCE FOR LEISURE HOURS. 



Shortly before midnight the Marquesas Isles and 

 the low-lying Tuamotu group were visited "by the 

 great wave, and some of these islands were completely 

 submerged by it. The lonely Opara Isle, where the 

 steamers which run between Panama and New Zealand 

 have their coaling-station, was visited at about half- 

 past eleven in the evening by a billow which swept 

 away a portion of the coal-depot. Afterward great 

 waves came rolling in at intervals of about twenty 

 minutes, and several days elapsed before the sea re- 

 sumed its ordinary ebb and flow. 



It was not until about half-past two on the morning 

 of August 14th, that the Samoa Isles (sometimes called 

 the Navigator Islands) were visited by the great wave. 

 The watchmen startled the inhabitants from their sleep 

 by the cry that the sea was about to overwhelm them ; 

 and already, when the terrified people rushed from 

 their houses, the sea was found to have risen far above 

 the highest water-mark. But it presently began to 

 sink again, and then commenced a series of oscillations, 

 which lasted for several days, and were of a very re- 

 markable nature. Once in every quarter of an hour 

 the sea rose and fell, but it was noticed that it rose 

 twice as rapidly as it sank. This peculiarity is well 

 worth remarking. The eminent physicist Mallet 

 speaks thus (we follow Lyell's quotation) about the 

 waves which traverse an open sea : " The great sea- 

 wave, advancing at the rate of several miles in a 



