274 WAVES OF THE SEA 



shore, instead of up-stream and away from the 

 shore, as the stationary waves are. The travelling 

 waves were not conspicuous, however, and I was 

 not able to detect similar ones (facing down- 

 stream) in the deep waters of the Whirlpool 

 Rapids . 



In the upper rapids of Niagara regular trains 

 of waves are not prominent. The most noticeable 

 waves are such as that beyond the last '" Sister 

 Island," where a huge mass of water surmounts 

 a rocky protuberance, to leeward of which the 

 water curls back in a fine cusp. 



In a little sheltered channel among the islands, 

 where the water flowed less tumultuously, much 

 better examples could be seen of a regular train 

 of waves. From Lunar Island I saw one of the 

 cusped waves near the brink of the American Falls 

 break periodically, thus : 



In 57 seconds the wave broke 7 times ; 



62 i> ji D 11 



corresponding to periods of 8.14 and 7.77 seconds 

 respectively. This is in the same part of the river 

 where I observed the progressive waves. I post- 

 pone until another section the account of certain 

 phenomena of the actual falls, and, passing by 

 without remark the 2 -mile stretch of deep water 



