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48 LIGHT AND WATER surface of the sea affected in tone by a bank of cloud lying low down on the horizon ; or again, to draw well-defined streaks as due to very high! clouds, for we have seen that the upper parts of the sky affect large widths of sea. Above the limit at which the sun streak vanishes, the lower the clouds the better defined are the streaks which they cast. The latter are often most fascinating to watch in their rapid changes, as when thrown by brilliant white clouds floating in a blue sky on to water rippled by a light and shifting breeze. As in the instance of the rock reflexions described above, we may again be puzzled for a moment by the presence or absence of a streak in an unexpected quarter. Two or three insignificant clouds combine to form an unmistakable streak, whilst a bright conspicuous mass—too high, or too low, or possibly neutralized by some dark mass above or below it—casts none. Itis curious to see how an almost horizontal layer of clouds only slightly thicker or darker in places throws definite streaks across the nearly smooth water, so determined is nature to convert horizontal into vertical. ‘‘If we see on an extent of lightly swelling water surface the image of a bank of white clouds, with masses of higher accumulation at intervals, the water will not usually reflect the whole bank in an elongated form, but it will commonly take the eminent parts, and reflect them in long straight columns of defined breadth, and miss " By “high clouds” are meant those at a great angular elevation above the horizon. A streak cast by such a high cloud would not reach as far as the horizon, for a streak could hardly extend deyond the object causing it.
