Stranica 140 [140]
OCR
78 LIGHT AND WATER when, as is often the case after stormy weather, the sea assumes an almost milky appearance owing to the great quantity of minute particles of chalk floating in the water, the shadows cast by passing clouds are very conspicuous. As the local colour is revealed by strong illumination from above, so it loses in proportion as the reflexions with which it has to contend, are themselves brilliant. Everyone is familiar with the difficulty of seeing objects in the dusk through the closed window of a well-lighted room, until a blind or curtain has been drawn to cut off the bright reflexions on the window-pane; and, in the same way, strong reflexions on the surface of water prevent us from seeing beneath the surface. We have observed that, if the sun is hidden, the colour of the water near us is often barely perceptible; and this is in great measure due . to the fact that the reflexion-picture here consists (in all probability) of blue sky or highly luminous clouds; and we also found that the colour of the water was most apparent in the reflexions of the trees, for the reflexion-picture there being dark or feebly illuminated, the colour of the water had again a chance to show itself. Hence the explanation of the well-known fact that it is in the reflexions of dark objects, such as heavy foliage or the tarred side of a boat, that we most clearly perceive the colour of water.’ This fact is often expressed by saying that bright objects are reflected in their natural colours, whilst those that are very dark appear the colour of the water—a say’ Or, if the water be very shallow, that the bottom is most plainly visible.
