272 WAVES OF THE SEA 



flows, then if the speed of the current be suddenly 

 diminished, the speed of the waves will be too 

 great, and they will charge up-stream. Thus, if 

 the current be subject to fluctuation, as the first 

 observation seemed to indicate, we should expect 

 the " standing " waves to fluctuate about a mean 

 position . 



A third fact, also, best observed in mountain 

 streams e.g., the Lutschine, at Grindelwald, in 

 Switzerland was that in the shallows of little bays 

 there was always a succession of progressive waves 

 rushing towards the shore, as waves come in on 

 a sloping sea-beach. These " rollers " in the little 

 bays were evidently connected with the oscillation 

 or throbbing of the stream. A long series of these 

 " rollers " was timed just below Speybridge, near 

 Grantown, N.B., when the " Galloping Spey " was 

 swollen by melting snow and ice, in February, 

 1900. They were only roughly periodic. They 

 rolled in upon the shore in a direction about at 

 right angles to the current their direction being, 

 of course, conditioned by the shallowing of the 

 water ; and it was of interest to observe that these 

 waves rippled the sand at right angles to their 

 motion, although the current drifted the sand- 

 grains parallel to the ripple ridges. 



Beyond the frequent repetition of these three 



