NIAGARA 201 



of the individual waves is here most strikingly displayed. 

 Vast pyramidal heaps leap incessantly from the river, some 

 of them with such energy as to jerk their summits into the 

 air, where they hang momentarily suspended in crowds of 

 liquid spherules. The sun shone for a few minutes. At 

 times the wind, coming up the river, searched and sifted the 

 spray, carrying away the lighter drops and leaving the heav- 

 ier ones behind. Wafted in the proper direction, rainbows 

 appeared and disappeared fitfully in the lighter mist. In 

 other directions the common gleam of the sunshine from 

 the waves and their shattered crests was exquisitely beau- 

 tiful. The complexity of the action was still further illus- 

 trated by the fact, that in some cases, as if by the exercise 

 of a local explosive force, the drops were shot radially from 

 a particular centre, forming around it a kind of halo. 



The first impression, and, indeed, the current explana- 

 tion, of these rapids is, that the central bed of the river 

 is cumbered with large bowlders, and that the jostling, 

 tossing and wild leaping of the water there are due to its 

 impact against these obstacles. I doubt this explanation. 

 At all events, there is another sufficient reason to be taken 

 into account. Bowlders derived from the adjacent cliffs 

 visibly cumber the sides of the river. Against these the 

 water rises and sinks rhythmically but violently, large 

 waves being thus produced. On the generation of each 

 wave, there is an immediate compounding of the wave- 

 motion with the river-motion. The ridges, which in still 

 water would proceed in circular curves round the centre 

 of disturbance, cross the river obliquely, and the result 

 is that at the centre waves commingle which have really 

 been generated at the sides. In the first instance, we had 

 a composition of wave-motion with river-motion; here we 



