HISTORY OF CHRONOLOGY. 765 



an historian of the early ages of the Church, invented a new cycle to 

 which chronologers might refer all dates. It consisted of the mul- 

 tiple of the years of the three cycles of the sun, moon, and indiction, 

 28x19x15 = 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, ac- 

 cording 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 value and importance, had it not been superseded by the adoption of 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 fii-st 

 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 j)aschal 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 cor- 

 rect 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, 



