Observation of the annual course of the sun
An observation of the annual course of the sun, therefore, unlike that of the stars -- which everywhere, no matter where, can be performed immediately -- demands a fixed place and special aids to determination. It follows that the observation of the solstices and equinoxes belongs to a much higher stage of civilization than does that of the stars. . . . It is used by the Eskimos, who have a very highly developed sense of place, and know how to make good maps. Moreover, where the sun in winter stands very low on the horizon, and for a time altogether disappears beneath it, the conditions are very favourable for the observation of its return. Older authors say that by the rays of the sun on the rocks the Eskimos can tell with tolerable accuracy when it is the shortest day; more recently we have been told of the Ammasalik that they can calculate beforehand the time of the shortest day -- and that accurately to the day -- not only from the solstitial point, but also from the position of Altair in the morning twilight. They begin their spring when the sun rises at the same spot as Altair. . . . The Incas erected artificial marks. There were in Cuzco sixteen towers, eight to the west and eight to the east, arranged in groups of four. The two middle ones were smaller than the others, and the distance between the towers was eight, ten or twenty feet. The space between the little towers through which the sun passed at sunrise and sunset was the point of the solstices. In order to verify this the Inca chose a favourable spot from which he observed carefully whether the sun rose and set between the little towers to east and west. For the observation of the equinoxes richly ornamented pillars were set up in the open space before the temple of the sun. When the time approached, the shadow of the pillars was carefully observed. The open space was circular, and a line was drawn through its centre from east to west. Long experience had taught them where to look for the equinoctial point, and by the distance of the shadow from this point they judged of the approach of the equinox. When from sunrise to sunset the shadow was to be seen on both sides of the pillar and not at all to the south of it, they took that day as the day of the equinox. This last account is for Quito, which lies just under the equator. At the spring equinox the maize was reaped and a feast was celebrated, at the autumn equinox the people celebrated one of their principal feasts. The months were calculated from the winter solstice. . . . One would suspect that this Melanesian science, like the knowledge of the stars, is borrowed from the Polynesians: for the latter understood the annual course of the sun. In Tahiti the place of the sunrise was called tataheita, that of the sunset topa-t-era. The annual movement of the sun from the south towards the north was recognized, and so was the fact that all these points of the daily approach to the zenith lay in a line. This meridian was called t'era-hwattea, the northern point of it tu-errau, and the opposite point above the horizon, or the south, toa. According to other sources the December solstice was called rua-maoro or rua-roa, the June solstice rua-poto. The Hawaiians called the northern limit of the sun in the ecliptic "the black, shining road of Kane," and the southern limit "the black, shining road of Kanaloa." The equator was named "the bright road of the spider" or "the road to the navel of Wakea," equivalent to "the centre of the world." How the Polynesians came to recognize the tropics and the equator is unfortunately unknown, but certainly they did it like other peoples by observing the solstices and equinoxes at certain landmarks. . . . Agricultural peoples in particular have developed various methods of this kind. The rice-cultivating peoples of the East Indies use various methods in order to determine the important time of sowing. Of the observation of the stars we have already spoken. Among the Kayen of Sarawak an old priest determines the official time of sowing from the position of the sun by erecting at the side of the house two oblong stones, one larger and one smaller, and then observing the moment when the sun, in the lengthening of the line of connexion between these two stones, sets behind the opposite hill. The sowing-day is the only one determined by astronomical methods. In other respects the time-reckoning is a more or less arbitrary one, and is dependent on the agriculture. Of the hollows in a block of stone at Batu Sala, in the river-bed of the upper Mahakam, it is said that they originated in the fact that the priestesses of the neighbouring tribes used formerly to sit on the stone every year in order to observe when the sun would set behind a certain peak of the opposite mountain. This date then decided the time for the beginning of the sowing. . . . The Kenyah observe the position of the sun. Their instrument is a straight cylindrical pole of hardwood, fixed vertically in the ground and carefully adjusted with the aid of plumb-lines; the possibility of its sinking deeper into the earth is prevented. The pole is a little longer than the outstretched arms of its maker and stands on a cleared space by the house, surrounded by a strong fence. The observer has further a flat stick on which lengths measured from his body are marked off by notches. The other side has a larger number of notches, of which one marks the greatest length of the midday shadow, the next one its length three days after it has begun to shorten, and so on. The shadow is measured every midday. As it grows shorter after reaching its maximal length the man observes it with special care, and announces to the village that the time for preparing the land is near at hand. In Bali and Java the seasons are determined by the aid of a gnomon of rude construction, having a dial divided into twelve parts.
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