THE COLORS OF WATER. 249 



may be permitted to consider here a few of the conditions that 

 have an influence on the general effect. 



A still-water surface forms a mirror which reflects those colors 

 of the horizon that fall upon it at the same angle as that under 

 which the eye stands to it. When I am at the shore of a quiet sea, 

 or of a still lake, the water beams with the colors of the horizon. 

 In a bay surrounded by woods, I see a deep gray ; on the broad 

 surface at sunset, the liveliest yellows and reds ; looking straight 

 down from my boat, the blue of the sky over my head. 



These reflected colors concern the physicist the least, for he 

 knows that every reflecting surface returns them ; but they inter- 

 est the painter almost exclusively. They constitute the tone of 

 his landscape ; they enliven the otherwise monotonous, dead sur- 

 face, and he as well as the looker at his picture receives chiefly 

 the impression of them. They are for the most part the colors 

 of the lower horizon, for the point of view of the spectator is 

 usually only a few metres above the level of the water. 



Thus with the smooth mirror. But the scene changes immedi- 

 ately upon the slightest agitation. It is very seldom that the sea 

 is quite still. The waves form hills and valleys, their surfaces are 

 more or less inclined, and they reflect not the horizon with its 

 down-toned colors, but the more saturated tints of the zenith. 

 Whoever has seen the Mediterranean Sea or the Lake of Geneva 

 under a cloudless sunset, and a slight rippling of the waves, will 

 recollect that the surfaces glowing with burning yellows and reds, 

 are broken up by sharp, deep-blue lines ; they are the wave-val- 

 leys, which, by reason of their oblique inclination, turn the blue 

 colors of the zenith into the eye. But this is not all. With the 

 smooth mirror surface, and lower point of view, the eye not only 

 receives the rays reflected from the surface, but it pierces through 

 the inclined parts of the wave-valleys into the mass of the water, 

 and thus perceives the proper color of the water, more intensely 

 as the small surface of the wave-valley stands more perpendicu- 

 larly to the eye. If the waves are very short, and follow one 

 another rapidly, this impression of the color of the water will 

 overcome that of the reflection. I can satisfy myself of this fact 

 at any time. 



The windows on the western front of my house look toward 

 the Arve, which is here crossed by a dam that causes a fall of 

 about a metre. Above the dam, the glacier-stream, colored a 

 grayish yellow in summer and green in winter, is perfectly 

 smooth; and from my windows, which are situated about six 

 metres above the river, I can see hardly any but the mirror colors, 

 yet a little mingled with the proper color of water, which appears 

 considerably stronger when the sky is covered and its glaring 

 light does not as the painters are accustomed to say " eat up " 



