AND OTHER WATER WAVES 103 



First comes the simultaneous creation of a 

 uniform pattern of minute waves all over the sur- 

 face, then the growth of the waves to leeward, 

 so that after a time there is a certain size of wave 

 corresponding to the distance from the windward 

 shore, which size is not afterwards exceeded. The 

 growth of these larger waves at any place is accom- 

 panied by the failure and partial obliteration of 

 the shorter waves which were there before, and 

 this is due to the circumstance that the growth in 

 height of the shorter waves is hampered by the 

 vortex or eddy of the air caused by the larger 

 series of waves. At each position there is finally 

 a definite length of wave which is the dominant 

 wave for that locality for the actual force of wind 

 i.e., the class of wave which so dominates the 

 eye that any shorter wave there appears as a mere 

 ripple upon its surface and any longer wave is only 

 to be detected by the presence of a sort of heaving 

 motion which runs through the whole system of 

 the dominant waves. On small sheets of water, or 

 near the windward shore at sea, this swell is insig- 

 nificant, but as the length of fetch of the wind 

 increases it becomes an important part of the whole 

 disturbance. This fact is most easily understood 

 if we consider what happens when the wind ceases 

 and the waves are left to themselves. Travel over 



