AND OTHER WATER WAVES 337 



smooth surface. The broken water of the cataract 

 passes too swiftly for the eye to follow its motion, 

 and the streaky appearance is evidently due to 

 this circumstance. On thrusting my hand into the 

 flying water of a small cascade which comes foam- 

 ing down through the Forest of Chillon I found 

 that the real intermittence of the optically con- 

 tinuous motion was at once apparent, for instead 

 of being subjected to a pressure, as from a 

 current, the hand experienced a succession of 

 sharp buffets . 



In a cataract descending the right bank of the 

 Gorge of the Chauderon, at Montreux, I saw well 

 the transition from the rush of the cataract to the 

 leap of the waterfall. Along reaches of lesser 

 steepness the water kept to its bed, yet all whitely 

 foaming, being tofn to drops by friction with its 

 bed ; but steeper reaches were leaped by the shower 

 of water, the leap being what one calls a waterfall. 

 By a cataract I mean that extreme case of a torrent 

 in which the water is all foaming. 



A low waterfall of i foot or 2 feet in height, 

 unless delivering water already in violent motion, 

 generally presents to the eye a number of brilliant 

 vertical stripes, having a lustre as of polished metal, 

 continuous from top to bottom, and practically 

 steady in position. 



17 



