VIEWS OF RUNNING WATER. 649 



a regular dam or gliding over a smooth, rock, the irregularities of 

 the latter may produce lines in the direction of the current ; but 

 true painters make only the most moderate use of the straight line. 

 Are there not more grounds of resemblance between the 

 points A and B or a and /? which appertain, however, to different 

 generators than between the points A and a of the same generator ? 

 Suppose the liquid sheet decomposed into its elementary veins ; 

 each of them is differently constituted in its several parts. At its 



Fig. 5. 



origin it is full, uniform, and transparent ; lower down it shows 

 real or apparent swellings and contractions ; and still farther down 

 it resolves itself into distinct drops. The water-sheet should con- 

 sequently have an entirely different constitution at A from that at 

 a, but the same at A and at B. It is proper, therefore, to repre- 

 sent as similar, not the points of the same parabola, but those of 

 the same horizontal range ; so, in the reflection of surrounding 

 objects, the surface at the upper part of the parabola, making a 

 smaller angle with the horizon, would produce a different effect 

 from that at the lower part. At A and B it would reflect chiefly 

 the sky ; at a and b, perhaps, the rocks ; while at a and /? it would 

 be white and reflect nothing. 



Independently of phenomena which we are still to study, and 

 paradoxical as it may appear, we can say that, if there are bands 

 or zones in a cascade, they are rather horizontal than vertical. 

 Our design vi, Fig. 5, still false and incomplete in many respects, 

 looks more like a real fall of water than the design v, Fig. 5, 

 with which we started. By this horizontal rather than vertical 

 disposition of the effects of light, color, and reflections, the image 

 gains much in life and truth. 



When the eye has become accustomed, by repeated observa- 

 tions, to the peculiarities of the liquid elements, it can at last dis- 

 tinguish, in each jet of any velocity, a jerking or vibratory move- 

 ment, a kind of trepidation or pulsation, directed horizontally, up 

 and down, or down and up. It was believed formerly to be an 

 optical illusion ; but instantaneous photography and other obser- 



