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COLOURS IN STILL WATER . 77
of colour. But if the sun is high and shining brightly
on the water, the whole pond (except in the shadows)
shows its greenish colour, and that chiefly in the dark
tree-reflexions. The reflexion of the tree-stem on the
farther side of the pond seems, when the sun is hid¬
den, to be identical in colour with the real stem, but
as soon as the sunlight strikes the water again, its
gray is mingled with green. Wherever a shadow
falls across the surface, the colour of the water is less
prominent, and therefore the reflexion-picture there
is more prominent.
So that in drawing shadows on still water, we
must make the reflexions seen in the shadows clearer
and purer in colour than those seen outsidethem. It
follows that if the water is very clear and practically
colourless, there will be hardly any noticeable dif¬
ference between shadow and sunshine. Indeed we
may safely say that no difference would be visible
were it not for minute particles of dust—or even
seeds or leaves—that may be floating on the sur¬
face. On the other hand, when the water is very
turbid, the shadows falling upon it are quite obvious.
Plate X XX VI isa photograph of a very muddy pond
in bright sunlight. The outline of the shadow of the
. tree in the foreground is clearly defined. Within this
shadow the image of the trees on the opposite bank
appears nearly as plainly as it would in clear water;
but beyond the shadow, that is to say, wherever
direct sunlight falls on the pond, the muddy colour
of the water is so strongly brought out that the re¬
flexions, or at any rate the darker parts of them, are
scarcely distinguishable. In the English Channel,