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The Romans. The first Roman calendar was said to have been created by Romulus at the founding of Rome in 753 B.C.E. The original Roman calendar was based on the lunar month, and the year was thought to contain ten lunar months. Later, Numa Pompilius added the months January and February (Januarius and Februarius). Tarquinius Priscus (616-579 B.C.E.), an Etruscan king, made further refinements. His calendar was 355 days long, with an extra month after February every two years. This extra month was at first called Mercedinus, "payment for work," and was a time when land leases were paid. Later, this extra month was known as Intercalans. The Pontifex Maximus would determine the length of Intercalans, to bring the calndar in line with the Solar Year.
To accomodate this quarter-day discrepancy, Julius Caesar adopted a calendar of 365 days like the Egyptians, but made every fourth year a leap year on the advice of Egyptian astronomer Sosigenes of Alexandria. This new calendar was strictly based on the Solar Year, with no attempt to reconcile it with the Lunar Month. Julius Caesar began the year in his new calendar on 1 January, and upon instituting his calendar in 46 B.C.E., added 90 days so that the Vernal (Spring) Equinox would begin on 25 March. Before this calendar reform, the Roman New Year was on 1 March. From this old beginning of the year we still use the names September, October, November, and December that marked the seventh, eighth, ninth, and tenth months, resposectively, in the pre-Julian calendar of Rome. Even though Julius Caesar declared the year to begin on 1 January, some locations still marked the beginning of the year as 1 March or 25 March. Today we know that the solar year is closer to 365.242190 days (365 days, 5 hours, 48 minutes, 45.2 seconds). The Julian Calendar was therefore off by about 11 minutes each year. This error wasn't enough to become noticeable during the days of the Roman Empire. The small error was later corrected by Pope Gregory XIII in 1575 (see The Gregorian Calendar, below). |
There were three important days in a Roman month: Calends, Nones, and Ides. These days harkened back to a time when the Romans used a lunar calendar. Originally, Calends was the day of the first crescent after a New Moon, Nones the day of the Moon's First Quarter, and Ides the day of the Full Moon. Calends is the First of a month; Ides occurs on the 13th or 15th of the month (depending on the month's length); and Nones always occurs eight days before Ides. Under the solar Julian calendar, these days kept their original names but were no longer associted wth lunar phases.
Days were counted down until the next Calends, Nones, or Ides. As an example, 2 January was counted as the fourth day before Nones, 3 January as the third day before Nones, and 4 January as the day before Nones. No day was referred to as the second day before Caleds, Nones, or Ides; those days as counted by the Romans were considered to begin the first day of their period, and they considered the second day before one of them identical in meaning to the day before.
| Days of the Julian Calendar | ||||
|---|---|---|---|---|
| January August December |
February | March May July October |
April June September November |
|
| 1 | Calends | Calends | Calends | Calends |
| 2 | IV | IV | VI | IV |
| 3 | III | III | V | III |
| 4 | II | II | IV | II |
| 5 | Nones | Nones | III | Nones |
| 6 | VIII | VIII | II | VIII |
| 7 | VII | VII | Nones | VII |
| 8 | VI | VI | VIII | VI |
| 9 | V | V | VII | V |
| 10 | IV | IV | VI | IV |
| 11 | III | III | V | III |
| 12 | II | II | IV | II |
| 13 | Ides | Ides | III | Ides |
| 14 | XIX | XVI | II | XVIII |
| 15 | XVIII | XV | Ides | XVII |
| 16 | XVII | XIV | XVII | XVI |
| 17 | XVI | XIII | XVI | XV |
| 18 | XV | XII | XV | XIV |
| 19 | XIV | XI | XIV | XIII |
| 20 | XIII | X | XIII | XII |
| 21 | XII | IX | XII | XI |
| 22 | XI | VIII | XI | X |
| 23 | X | VII | X | IX |
| 24 | IX | VI | IX | VIII |
| 25 | VIII | V | VIII | VII |
| 26 | VII | IV | VII | VI |
| 27 | VI | III | VI | V |
| 28 | V | II | V | IV |
| 29 | IV | IV | III | |
| 30 | III | III | II | |
| 31 | II | II | ||
In a leap year, a day was inserted between VII Ides (23 February) and VI Ides (24 February). Julius Caesar kept this intercalary date the same as in the existing Roman calendar. Romans considered this an unlucky day. In a Roman leap year, 24 February was "ante diem sextus Calendae Martii" (the sixth day before the Calends of March) and the following day was "ante diem bis sextus Calendae Martii" (the second ("bis") sixth day before the Calends of March). Later, the Gregorian Calendar would preserve bis VI Calendae Martii as the leap day.
To this day a leap year is still sometimes referred to as a bisextile year, and the French phrase for a leap year is "année bissextile" (bis-sextile year). The phrase "leap year" originated in old England. The leap day was not originally counted under English law, and so was "leapt" over.
In ancient Rome, 45 B.C.E. might or might not have been a leap year. Thereafter, leap years occurred in 42 B.C.E., 39 B.C.E., 36 B.C.E., 33 B.C.E., 30 B.C.E., 27 B.C.E., 24 B.C.E., 21 B.C.E., 18 B.C.E., 15 B.C.E., 12 B.C.E., 9 B.C.E., 8 C.E., and then every four years.
The English word "calendar" comes from the Roman First of the Month, calends. On Calends ("callings"), a Roman priest would call to Juno five or seven times, depending on whether the Nones would be on the fifth or seventh days of each month. Calends might have originially been the day of the first visible crescent after the New Moon. Nones, as just described, fell on the fifth or seventh day of the month. Nones was actually the "ninth" day before (but including) the Ides in the middle of the month. Public festivals for the month would be announced on the Nones. The Ides (for the Latin for "divide") fell in the middle of each month: in March, May, July (then Sextilis), and October, Ides was on the fifteenth of the month. In all other months, Ides was on the thirteenth. The Ides might have originially been days of the Full Moon. The days before Calends, Nones, and Ides were known as pridie Calendas, pridie Nonas, and pridie Idus, respectively.
The days of the Roman week were:
The Roman year began on the First of March. Some of our English month names still reflect this: September, October, November, and December were respectively the seventh (septem), eighth (octo), ninth (novem), and tenth (decem) months of the Roman calendar.
Romans numbered their years ab urbe condita, "from the city's [Rome's] founding," which was 753 B.C.E. Years in this scheme are noted as A.U.C.
Julius Caesar began the Roman Summer season in May, at the heliacal rising of the Pleiades constellation (the date when the Pleiades appeared in the sky just before the Sun rose).
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According to Pliny the Elder, there were three calendars in the Roman
Empire at the time of Julius Caesar (shown at left): the Chaldean, Egyptian,
and Greek calendars. All of these calendars could trace their origins to
the Babylonian calendar. Pliny the Elder also tells us that Julius Caesar
adopted a strictly solar calendar on the advice of the Egyptian astronomer
Sosigenes of Alexandria. Sosigenes calculated the Solar Year to have 365.25
days (365 days and 6 hours).