Note 588 — LIFE OF C. CÆSAR. (continued 2)

The reformation of the Kalendar was effected in B.C. 46. Dion Cassius (43. c. 26) says that Cæsar was instructed on this subject during his residence at Alexandria in Egypt. The Egyptians had a year of 365 days from a very early date (Herodotus, ii. 4). In this year (B.C. 46) Cæsar intercalated two months of 67 days between November and December, and as this was the year in which, according to the old fashion, the intercalary month of 23 days had been inserted in February, the whole intercalation in this year was 90 days. Cæsar made the reformed year consist of 365 days, and he directed one day to be intercalated in every fourth year (quarto quoque anno) in order that the civil year, which began on the 1st of January, might agree with the solar year. The old practice of intercalating a month was of course dropped. The year B.C. 46 was a year of 445 days. By this reformation, says Dion Cassius, all error was avoided except a very small one, and he adds, that to correct the accumulations of this error, it would only be necessary to intercalate one day in 1461 years. But this is a mistake; for in 1460 years there would be an error of nearly eleven days too much. Ten days were actually dropped between the 4th and 15th of October, 1582, by Gregory XIII., with the sanction of the Council of Trent.

A curious mistake was soon made at Rome by the Pontifices who had the regulation of the Kalendar. The rule was to intercalate a day in every fourth year (quarto quoque anno). Now such expressions are ambiguous in Latin, as is shown by numerous examples. (Savigny, System des heut. Röm. Rechts, iv. 329.) The expression might mean that both the year one and the year four were to be included in the interpretation of this rule; and the Pontifices interpreted it accordingly. Thus, after intercalating in year one, they intercalated again in year four, instead of in year five. In the time of Augustus, B.C. 8. the error was corrected, and the civil year was set right by dropping the three intercalary days which came next after that year, three being the number of days in excess that had been intercalated. For the future the rule of Cæsar was correctly interpreted. Dion Cassius in expressing the rule as to intercalation uses the phrase, διὰ πέντε ἐτῶν.

The subject of Cæsar's reformation is explained in the notes to Dion Cassius (43. c. 26), ed. Reimarus, and in the article Calendar (Dictionary of Greek and Roman Antiquities) by Professor Key.