AND OTHER WATER WAVES 293 



kind of swelling of the river, which co -existed with 

 the shorter period waves which were coming in on 

 the shore all the time, is due to the intermittent 

 disengagement of masses of swirling water from 

 the great whirlpool up above. Some confirmation 

 of this view is afforded first, by watching the up- 

 wellings which take place in the whirlpool near the 

 exit, and also by the appearances of such masses 

 of swirling water lower down the Foster's Flats 

 Rapids, where there are fewer standing waves. It 

 is not uncommon here to see a cyclone and an 

 anticyclone of water drifting down -stream side by 

 side with a difference of level (reckoned from the 

 crown of the anticyclone to the pit of the cyclone) 

 of probably 5 feet or 6 feet. In these there is 

 horizontal circulation of water about vertical axes. 



Thus in the deeper waters of Niagara I never 

 saw any repetition of down-stream progressive 

 waves such as I believed I had detected in the 

 shallow water above the American Falls. This 

 might be explained either by their non-existence 

 or by their being too flat to be visible in deep 

 water . 



In the next chapter I shall give an account of 

 the circumstances under which a stream of water 

 flows in a series of down -stream bores. 



