Page:A Lady's Cruise in a French Man-of-War.djvu/239

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211
IMMUTABLE TIDES.

full; while at sunrise and sunset—in other words, at six o'clock morning and evening—throughout the year, it is low water. The rise and fall rarely exceeds two feet; but periodically, at an interval of about six months, a mighty sea comes rolling in from the west or south-west, and, sweeping over the reef, bursts violently on the shore.

I do not know whether any scientific theory has been propounded concerning this tidal eccentricity, which is perhaps the most remarkable thing connected with the group.

I believe some writers have tried to account for it by reference to the trade-winds, which blow so steadily at certain hours of the day; but these must have been very inaccurate observers, as the tides rise and fall with equal regularity in the most sultry calm or the most riotous sea-breeze. In fact they are sometimes rather higher in dead calms, and on the leeward side of the isles, which are sheltered from the trade-winds. In any case, these blow only in the daytime, and die away entirely at night. Curiously enough, they do not even affect the periodical flood-tides, or rather tidal waves, of which I spoke just now, as these invariably come from the westward, whereas the trade-winds blow steadily from the east. So punctual is the daily rise and fall of the tides, that the accustomed eyes of the people can discern the hour of the day by a glance at the shore or the reef, as at a marine chronometer, which here never loses or gains time.

The peculiar charm of this, as concerns the reef, is that the low tide, which is the hour of delight, always occurs at the coolest hours of morning and evening, so there is no temptation to incur sunstroke by exposure to the noontide rays. And the reef at Tahiti is, beyond all question, the richest I have seen. It seems to me that all the marvels of the Fijian reef are here reproduced on a magnified scale—the mysterious zoophytes are larger, their colours more intense, the forms of the fish more varied and eccentric, and their scaly dress striped and zigzagged with patterns like those on an ingenious clown, or perhaps suggestive of quaint heraldry.

To-night I saw some gigantic specimens of that wonderful starfish we first found in Fiji, with fifteen arms covered with very