An obviously isolated method is the determination of the times of day from the daily twice-recurring ebb and flow of the tides; the method is also very unsuitable, since the period of a complete tide is 12 hours 25 minutes, so that the two periods together exceed the day by nearly an hour. In fact the Eskimos of Greenland are the only people who reckon by the tides. They divide up the day according to ebb and flow, although they must always reckon differently on account of the variations of the moon[156]. Dalsager[157] also points this out and remarks that their reckoning cannot last for two consecutive days, so that they have to make a fresh division every day. The rudiments of this method are however seen among some of the tribes of Polynesia. Immediately after the above-quoted divisions of the day among the Society Islanders are mentioned “the longer periods before noon and midnight during which the sea rises, and the others following these, in which it falls”[158], and “night or the light quite gone, when the sea begins to flow towards the land, about 11 at night”[159]. The Hawaiians called the rising of the tide by such names as the rising, big, full, and surrounding sea; when the water neither rose nor fell it was called the standing sea; the ebbing sea they spoke of as the parted, retiring, and defeated sea[160]. The night is the time of complete darkness and rest, and therefore the frequently mentioned expression, ‘sleeping-time’, corresponds to night. Seldom is the whole time during which the sun remains below the horizon to be understood by it. On the Society Islands there were two expressions for day according to its extension from morning to evening twilight or from sunrise to sunset[161]. The Hawaiian judge, Fornander, follows this mode of speech when he distinguishes five periods of night, (1) about sunset, (2) between sunset and midnight, (3) midnight, (4) between midnight and sunrise, and (5) sunrise[162]. For the times between sunset and night-fall and between night and sunrise there is a rich terminology which has already been illustrated. During the night itself time-indications are for obvious reasons scanty. Often the only point distinguished is midnight, e. g. by the Kiowa[163], the Masai[164], the Shilluk[165]; ‘the silence of the land’ among the Babwende[166], ‘the back of night’ among the Hottentots[167], ‘the time of sleep’ among the Hawaiians[168]. Hence arises of itself a threefold division in which the periods of night before and after midnight are distinguished, as e. g. by the Hawaiians[169]. The usual method is to start from the day, i. e. the limit of the day, and then to proceed on both sides in the direction of midnight, as in the late evening of the Hottentots, which extends till long after sunset[170], and the ‘not yet early’ and the _tara_ (beginning at dusk and extending till the time of rest) among the Masai[171], etc. The Tahitians are credited with six divisions of the