Stranica 158 [158]
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 there¬
fore 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 con¬
siderable angle to the direction of vision, and thus reveals its colour,
just as the whole body of still water showed its colour to one stand¬
ing over it and looking abruptly at its level surface.