202 FRAGMENTS OF SCIENCE 



have the coalescence of waves with waves. Where crest 

 and furrow cross each other, the motion is annulled; where 

 furrow and furrow cross, the river is plowed to a greater 

 depth; and where crest and crest aid each other, we have 

 that astonishing leap of the water which breaks the cohe- 

 sion of the crests, and tosses them shattered into the air. 

 From the water level the cause of the action is not so 

 easily seen; but from the summit of the cliff the lateral 

 generation of the waves, and their propagation to the cen- 

 tre, are perfectly obvious. If this explanation be correct, 

 the phenomena observed at the Whirlpool Eapids form one 

 of the grandest illustrations of the principle of interference. 

 The Nile "cataract," Mr. Huxley informs me, offers more 

 moderate examples of the same action. 



At some distance below the Whirlpool Kapids we have 

 the celebrated whirlpool itself. Here the river makes a 

 sudden bend to the northeast, forming nearly a right angle 

 with its previous direction. The water strikes the concave 

 bank with great force, and scoops it incessantly away. A 

 vast basin has been thus formed, in which the sweep of 

 the river prolongs itself in gyratory currents. Bodies and 

 trees which have come over the falls are stated to circulate 

 here for days without finding the outlet. From various 

 points of the cliffs above this is curiously hidden. The 

 rush of the river into the whirlpool is obvious enough ; and 

 though you imagine the outlet must be visible, if one existed, 

 you cannot find it. Turning, however, round the bend of 

 the precipice to the northeast, the outlet comes into view. 



The Niagara season was over; the chatter of sight- seers 

 had ceased, and the scene presented itself as one of holy 

 seclusion and beauty. I went down to the river's edge, 

 where the weird loneliness seemed to increase. The basin 



