Any one born on the 29th February, 1864, will have his birthday again on the same day of the week, a Monday, in 1892, that is, after an interval of 28 years, as is seen in the middle column of [Table 2]; and after that he will have it again on a Monday in 1904, 1932, etc.
HISTORICAL NOTES.
Romulus, the founder of Rome, established a year consisting of ten months, named Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November, and December; but in the succeeding reign, that of Numa, two months were added, called Januarius and Februarius.
Julius Cæsar, aided by Sosigenes, an Alexandrian astronomer, instituted the Julian Calendar, which has come down to our own epoch. It was then decided to give an additional day to every fourth year. The date of the reform was 45 B.C., which was the Roman year 708, dating from the foundation of Rome. The Julian year began on the 1st of January, 708 A.U.C., and ended on the 31st of December, 709 A.U.C. In the first 48 years of the reform there prevailed some confusion about the bissextile or leap years, because during the first 36 years every third year was reckoned a leap year (12 intercalations had taken place instead of 9); but, in order to rectify the error, the next 12 years (i.e. 9 B.C. to 3 A.D. inclusive), elapsed without an intercalary day, by decree of Cæsar Augustus, who also changed the names of Quintilis and Sextilis into Julius and Augustus, in honour of his uncle and himself. Thus the Roman years, 757, 761, 765, 769, etc., which were the years A.D. 4, 8, 12, 16, etc., were counted as leap years, and about all succeeding dates there is no doubt.
‘It was probably,’ writes Mr. Bond, of the Record Office, in his valuable work, ‘the original intention of Cæsar to commence the new year with the shortest day, the winter solstice at Rome, in the year 46 B.C. (common era), occurring on the 24th December of the Julian calendar. His motive for delaying the commencement for seven days longer, instead of taking the following day, was no doubt the desire to gratify the superstition of the Romans, by causing the commencement of the first year of the reformed calendar to fall on the day of the new moon, for it is found that the mean new moon occurred at Rome on the 1st of January, 45 B.C. (common era), at 6 h. 16 m. p.m.’
The Christian era was introduced in Italy, in the 6th century, by Dionysius the Little, a Roman abbot, and began to be used in Gaul in the 8th, though it was not generally followed in that country till a century later. From extant charters it is known to have been in use in England before the close of the 8th century. ‘At first, in A.D. 533,’ says Mr. Bond, ‘the era began with the 25th of March, but was subsequently reckoned from Christmas Day, the 25th of December, and in the 13th century, in some countries, was reckoned from the 1st of January according to the Julian era.’
The exact length of the mean solar or civil year is
365 d. 5 h. 48 m. 46 s.,
therefore the Julian year, being 365 days and 6 hours, departs from the course of the seasons at the rate of 11 m. 14 s., and consequently Aloysius Lilius, from Calabria, a physician and mathematician of Verona, projected a plan for amending the calendar, which induced Pope Gregory XIII. to introduce the plan on the 5th October, 1582, according to the former style, which day was decreed to be called the 15th October. These 10 days rectified the error of the past, in accordance with the day of the equinox, the 21st March. The error of the future, which was that an additional day every fourth year was too much, but that 129 years must elapse before the redundance would cause the equinox to be one day behind its time, was rectified thus: Adding 129 years to the year 1582 there results the year 1711, and it was decreed that the year 1700, which would, by the Julian Calendar, be a leap year, should be a common year, but, as stated below, it was still kept as a leap year in England, and appears as such in [Table 1]. In like manner 1800 was made a common year, and as in 1969 the 21st March would be a day behind the vernal equinox, it will be set right by making 1900 a common year. Another period of 129 years would extend to 2098, which will be remedied by making 2100 a common instead of a leap year.
Thus the equinox will be kept right by making three successive secular years common years; and the secular leap years will be those of which the first two figures are divisible by 4 without a remainder, as 2000, 2400, 2800, etc.