Julian calendar: Encyclopedia II - Julian calendar - Lengths of the months

Julian calendar - Lengths of the months

According to the 13th century scholar Sacrobosco, the original scheme for the months in the Julian Calendar was very regular, alternately long and short. From January through December, the month lengths according to Sacrobosco for the Roman Republican calendar were:

He then thought that Julius Caesar added one day to every month except February, a total of 11 more days, giving the year 365 days. A leap day could now be added to the extra short February:

He then said Augustus changed this to:

giving us the irregular month lengths which we still use today, so that the length of Augustus would not be shorter than (and therefore inferior to) the length of Iulius.

Although this theory is still widely repeated, it is certainly wrong. First, a wall painting of a Roman Republican calendar has survived [1] which confirms the literary accounts that the months were already irregular before Julius Caesar reformed it:

Also, the Julian reform did not change the dates of the Nones and Ides. In particular, the Ides are late (on the 15th rather than 13th) in March, May, July and October, showing that these months always had 31 days in the Roman calendar, whereas Sacrobosco's theory requires that the length of October was changed. Further, Sacrobosco's theory is explicitly contradicted by the third and fifth century authors Censorinus and Macrobius, and, finally, it is inconsistent with seasonal lengths given by Varro, writing in 37 BC, before the Augustan reform, with the 31-day Sextilis given by the new Egyptian papyrus from 24 BC, and with the 28-day February shown in the Fasti Caeretani, which is dated before 12 BC.

Adapted from the Wikipedia article "Lengths of the months", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki