Page:Popular Science Monthly Volume 45.djvu/851

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ASTRONOMY OF THE INCAS.

offered in October, and in November the princely youth who were to be given arms in the next month had their ears pierced.[1]

These Peruvian ceremonials were very like those which Ovid has described. They were not the only ones; an edict of the Inca Pachacutec mentions three regular festivals occurring in each lunar month; there were also days for fairs and markets, and a rest day occurring every nine or ten days, like the nondines of the Romans, but not corresponding either with the quarters of the moon or the week, although the phases of the moon were well known to the Incas. As their lunar year fell behind the true time, they rectified their calendar constantly, trying to make it conform roughly with the phases of the moon.

The hours were not determinate spaces of time corresponding with a mathematical division of the day, but simple indications of such conditions as dawn, or morning, noon, sunset, and night.

The astronomical observations of the Incas were at first very elementary and empirical. They marked the day when the sun passed over the zenith. An experiment of the simplest character will be sufficient to account for the conclusions they drew from this observation. If we plant a stick vertically, and observe the shadow which it casts when shone upon by the sun, we shall find that at noon toward the end of December, this shadow is very long and directed toward the north; then it diminishes gradually till the day when it is shortest at noon. In the Southern hemisphere the shadow follows an inverse direction to this, and is longest at noon in June and shortest in December. The days when the shadow is longest, beyond the tropics, are the same for all places in the same hemisphere. But the days when there is no shadow at noon are not the same for all latitudes in the same hemisphere within the tropics. A day's difference exists for every forty kilometres. For this reason the Incas established observations at different distances from north to south, over the whole extent of their empire.

In order to verify the equinoxes, the amantas, or astronomers, arranged richly sculptured columns in the courts of the temples of the sun. On the approach of the equinox, they observed the shadow projected by the columns. These were placed in the center of a large circle through which a line, exactly oriented by experiment, ran from east to west. When they saw that the shadow struck this line in the middle, and that at noon the column was bathed with light on every side, they announced the equinoctial day. They then adorned the columns with flowers and fragrant herbs, and brought offerings of gold, silver, precious stones, and fruit to the god. The gnomon, or column, was surmounted


  1. Desjardins.