Stranica 158 [158]
OCR
92 LIGHT AND WATER and in the same way we see it, though in a less degree in every wave surface turned towards us. The stronger the ripple, the more steeply the little waves stand up to face us, and so the more noticeable this colour becomes." Against this, however, must be set the consideration that the effect referred to at the beginning of this chapter, namely, that the rippled parts reflect to the eye chiefly light from the higher, and therefore probably darker, regions of the sky, will, of course, unless the sky be uniform in tone (which is seldom the case) somewhat obscure the perception of this further effect. The waters of our English lakes and rivers are comparatively clear and colourless, and it is therefore only when they are in a turbid state that they offer an tlustration of this point; with the sea, on many parts of the coast, it is otherwise; there the water generally carries enough solid matter to reveal its colour, and thus, in sunshine, at any rate, the result we are considering is conspicuously produced. This is perhaps most readily observed when adjacent portions of the sea present different colours. The * It will be remembered that in the experiments described on page 75 we found that the blue water, when looked at very obliquely, seemed practically colourless. If we now take the same basin of blue water and placing the eye in the same position (as shown in Fig. 27) stir the water, so as to give movement to the surface, we shall find that its colour at once appears on the near sides of the little waves. Though we are looking obliquely at the surface of the water as a whole, each ripple presents a surface inclined at a considerable angle to the direction of vision, and thus reveals its colour, just as the whole body of still water showed its colour to one standing over it and looking abruptly at its level surface.
