Til K DKTKK'MlNA'nON OF HASTE 11 DAY. 



155 



of the most remarkable achievements of that most remarkable 

 man. The Roman year had previously been a lunar year, 

 which of course requires constant readjustment by intercalation, 

 to keep it in practical harmony with the solar year. In B.C. 46, 

 it was found that the months were occurring far from the 

 seasons with which they were supposed to be connected. It 

 was necessary to make this " year of confusion " to consist of 

 445 days to get things right again. Csesar wisely abandoned 

 the lunar year altogether, but so far deferred to usage (it is said) 

 as to fix the commencement of his first reformed year on the 

 day of the following new moon instead of on the day of the 

 winter solstice. At all events a new moon actually occurred on 

 January 1, B.C. 45. The mean Julian year consists of 365J 

 mean solar days ; and as a year suitable for everyday purposes 

 cannot contain fractions of a day, the rule adopted was that 

 three years in succession should consist of 365 days, and that 

 every fourth year should consist of 366 days. Thus the average 

 length of each of the four years is 3 65 J days. The year of 

 366 days is called " bissextile " because the additional, or inter- 

 calated day, was inserted after February 24, and, in the Roman 

 method of reckoning, this day is the sixth day before the 

 Kalends of March. So that in every fourth year there were 

 two " sixth days " before the Kalends of March, and hence the 

 name " bissextile." " Leap year," the other and more familiar 

 name for the year of intercalation, is so called because the day 

 of the week corresponding to any particular day of the month, 

 after the intercalary day, advances two places with reference to 

 its position in the preceding year, instead of one place as in 

 ordinary cases. Thus January 1, 1916, is a Saturday ; but 

 since 1916 is a leap year, January 1, 1917, is a Monday, instead 

 of being a Sunday, as it would have been had 1916 been a 

 common year. 



The Julian calendar has thus the merit of great simplicity, 

 but unfortunately, as time went on, it was found to be subject 

 to considerable inaccuracy, and it was considered that reforma- 

 tion was desirable. In the middle of the 16th century it 

 appeared that the spring equinox, which ought to have occurred 

 on March 21 (the day on which it was assumed to have occurred 

 at the time of the Council of Nica?a) actually occurred on 

 March 11. Luigi Lilio, a native of Calabria, found the error of 

 the mean Julian year to amount to about three days in 400 

 years. His scheme, submitted to Pope Gregory XIII, was that 

 ten days should be dropped, so as to bring the equinox up to 

 March 21 again, and that a more accurate length of the mean 



