THE DETERMINATION OF EASTER DAY. 



1G7 



Dispersion it was found impossible to continue such a primitive 

 system, and recourse was had to calculations, involving the use 

 of a cycle, for determination of the times of observance of the 

 religious festivals. These cycles were used up to the time of 

 the reformation of the Jewish calendar by Hillel, in a.d. 358. 

 In this system (which continues in use up to the present day), 

 the Metonic Cycle of nineteen years, with which we are already 

 familiar, is adopted as consisting of 235 calendar lunations. 

 The adopted calendar lunation (in which the moon is reckoned 

 " new " at the time of astronomical conjunction) is taken from 

 the very accurate value of a mean astronomical lunation found 

 by Hipparchus, and the calendar year is taken from the not so 

 accurate value of the length of the tropical year found by the 

 same astronomer. In the nineteen years of the cycle there 

 are twelve common years consisting each of twelve lunar 

 months, and seven embolismic years consisting each of thirteen 

 lunar months. The common years consist of 353, 354, or 

 355 days: whilst the embolismic years consist of 383, 

 384, or 385 days. The orderly recurrence of the years of 

 different lengths is regulated by elaborate rules. The 

 observance of these rules ensures that the error of the 

 Jewish reformed calendar accumulates very slowly. Assuming 

 that it was correct in the year A.D. 358, when it was first 

 established, the calendar dates are now about seven days later 

 in the year, with reference to the sun, than they were at that 

 time. 



It is easy now to see why the dates of the Passover, according 

 to the reformed Jewish calendar, sometimes fall in the month 

 following that in which Easter occurs. It is the month pre- 

 ceding Nisan — the last month of the ceremonial year — that is 

 duplicated in the embolismic years. This proceeding, of course, 

 causes Xisan 15 to occur a lunar month later than it 

 would otherwise have done, and frequently causes it to occur 

 during the lunar month subsequent to that in which Easter is 

 celebrated. 



This cursory sketch of certain features of the Jewish 

 calendar must not conclude without drawing attention to a very 

 important rule with regard to the observance of the First Day 

 of the Passover. This day is never allowed to fall on a 

 Monday, Wednesday, or Friday. The "prohibition is nowhere 

 expressly stated in the Levitical Law, but it is a Eabbinical rule, 

 which appears to have been made after the building of the 

 second Temple. It is designed to prevent the occurrence of 

 subsequent fasts or festivals on days when it would be 



