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OCR
COLOURS IN STILL WATER — 79 ing that must not be taken too literally. For the reflexion in the foreground of-even a white object, as, for instance, that of the nearest duck in Plate XX XIV, may be strongly tinged with the colour of the water, and, on the other hand, when looking very obliquely, this colour is quite invisible, even in the reflexions of very dark objects. But within certain limits of the angle of vision it is true enough. Though at the other side of the water we see no green in the reflexion of the sky, we do see it distinctly in the reflexion of the dark wall beyond. The image of a black sail shows much local colour, that of a white sail alongside of it hardly any. The effect can also be imitated, as on page 73, by means of a piece of coloured glass. At an oblique angle, when the red or blue colour of the glass cannot be seen in the reflexion of the sky, it is still visible in the reflexions of dark objects, as the bars of the window frame. No one who has ever been rowed into a sea-cave can have failed to notice as he enters the unusual brilliancy of the colour of the water within it. In this case practically all light is cut off from above, so that the rocky bottom, 1Iluminated from the opening behind, shows off the colour of the water to the greatest advantage.’ If we wish to find an object lying at the bottom of ' As a continuation of the experiment on page 75, we may look (from the second position, Fig. 27), at the reflexions of different coloured articles, such as books of various colours and shades, and we shall still find that the darker the object, the more the colour of the water shows in the reflexion. The image of a dark brown or dull green book appears much changed by the admixture of the blue of the water, whilst a light-coloured object is repeated almost exactly in the reflexion.
