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Page:Popular Science Monthly Volume 18.djvu/785

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HISTORY OF CHRONOLOGY.

an historian of the early ages of the Church, invented a new cycle to which chronologers might refer all dates. It consisted of the multiple of the years of the three cycles of the sun, moon, and indiction, 281915 7,890, and taking these cycles, as settled by the early Church councils, and tracing them backward, he found they would begin together in the year 710 before the creation of the world, according to our received account. This cycle would have been of great value and importance, had it not been superseded by the adoption of the Christian epoch, which, as already said, has made the use of all former epochs and eras unnecessary. The cycle just described is known by the name of the "Julian period."

Several of the ancient cycles were, however, used by the early Church in fixing what are called the "movable feasts"; these being regulated not by the solar year, as Christmas or the 4th of July is, but by the lunar year. But, as most of these feasts depend upon or are regulated by Easter, we need consider this one only. In the early days the churches of Asia kept their Easter upon the day on which the Jews celebrated their passover, i. e., on the fourteenth day of their first month, which began with the new moon next after the vernal equinox. The Western churches celebrated on the Sunday following the Jewish festival, both to celebrate the day and to distinguish between Jews and Christians. This difference having finally caused great dissensions in the Church, Constantine had a canon passed at the Council of Nice, that Easter should everywhere be observed upon the same day; and, to prevent disputes thereafter, four paschal canons were also passed, to the effect that "Easter shall always be observed on the first Sunday after the full moon which happens on or next after the 21st of March, which was then the time of the vernal equinox; and, if this full moon happen on Sunday, the Sunday following shall be Easter Sunday."

Then was called into requisition the lunar cycle, and tables were made showing the day of every month in every year, of the cycle on which a new moon would occur, and this table would have been correct for ever had the Julian year been correct and had the moon's cycle been nineteen years to the hour. The former, we have already seen, was not quite correct; and the new moon, although it occurs on the same day of the year every nineteenth year, does not occur at the same hour, but about one and a half hour earlier, which difference in a long course of years makes the tables all wrong and useless. In 1582, when the calendar was corrected, the computed equinoxes had been brought forward ten days, so that the full moon, on or after the 21st of March, was not always the first moon after the true vernal equinox—i. e., was not the moon which the Church canon prescribed. The reformation of the calendar, by dropping ten days, brought back the equinox to March 21st, as it was at the time of the Nicene Council.

Immediately after this council the Bishop of Alexandria, in Egypt,