Bases on which the Tables of Concordance are Founded.
BEFORE the Julian reform, the Roman year comprised 355 days, divided into twelve months, namely: Januarius, 29 days; Februarius, 28; Martius, 31; Aprilis, 29; Maius, 31; Junius, 29; Quintilis, 31; Sextilis, 29; September, 29; October, 31; November, 29; December, 29.
Every other year, an intercalation of 22 or 23 days alternately was to be added after the 23rd day of February.
The mean year being thus too long by one day, 24 days were to be subtracted in the last eight years of a period of 24 years. We shall not here have to take this correction into consideration.
The intercalation appears to have been regularly followed from A.U.C. 691 (that of Cicero’s consulship) until 702, when it was of 23 days. In the middle of the troubles, the intercalation was omitted in the years 704, 706, and 708.
Towards the end of the year 708, Cæsar remedied the disorder by placing extraordinarily between November and December 67 days, and by introducing a new mode of intercalation.
The year 708 is the last of the confusion.
The year 709 is the first of the Julian style.
Historical Data which the Concordance must Satisfy.
Cicero relates that at the beginning of his consulship the planet Jupiter lighted the whole sky. (De Divin., I. 11.) Cicero entered on office on the Calends of January in the year of Rome 691; that is, on the 14th of December, 64 B.C. Jupiter had reached opposition eleven days before, on the 3rd of December.[931]