104 WAVES OF THE SEA 



a considerable distance analyses the originally com- 

 plex, irregular waves into series of simple, regular 

 waves of graduated length. The longer and 

 swifter are in front, the shorter and slower are 

 in the rear. But this is not all, for the shorter com- 

 ponents flatten out very quickly as they travel, 

 whereas the longer components preserve their 

 height with but little diminution for long distances. 

 Consider now the effect of this upon the surface- 

 water at a place far distant from the windward 

 shore. The short -length (and therefore short - 

 period) waves will reach this place so flattened 

 that they will produce no appreciable effect, and 

 may, therefore, be regarded as not reaching it at 

 all, and the water will heave with a long -period 

 undulation, the surface exhibiting therefore only 

 long, swift waves. Now, this gravitational travel, 

 with its accompanying analysis of the wave -com- 

 ponents, must go on in just the same way when 

 the wind is blowing as it does after storms. There- 

 fore at a considerable distance from the windward 

 shore the state attained by the sea during a storm 

 does not depend only upon what the wind does 

 there, but also upon the transmission by gravity, 

 independently of the wind, of the longer -period 

 components of the irregular waves which the storm 

 has created to windward. The greater the length 



