The Julian Calendar

[ Home ] [ Up ]

The early Roman civil year consisted of ten months beginning with March and ending with December. The lunar month used by the early Romans alternated between 30 and 29 days accounting for a year of 295 days. About 700 BCE two additional months became part of the calendar�January and February. Later the lunar month became obsolete as months of 30 and 31 days, except for February, became adopted.

Julius Caesar in BCE 46 modified the 365-day calendar by requiring every fourth year to have 366 days. The months of the Julian calendar remain the same as those in the Gregorian calendar.

The Roman method of numbering days appears somewhat unusual. Each day became reckoned from the period to follow�calends, nomes, and ides.

The First Month in the Roman Julian Calendar -- March
Day of the Month	Name of the Day	Day of the Month	Name of the Day
1	calends	17	16th day before the calends
2	4th day before the nomes	18	15th day before the calends
3	3rd day before the nomes	19	14th day before the calends
4	eve of the nomes	20	13th day before the calends
5	nomes	21	12th day before calends
6	8th day before the ides	22	11th day before calends
7	7th day before the ides	23	10th day before calends
8	6th day before the ides	24	9th day before calends
9	5th day before the ides	25	8th day before calends
10	4th day before the ides	26	7th day before calends
11	3rd day before the ides	27	6th day before calends
12	eve of the ides	28	5th day before calends
13	ides	29	4th day before calends
14	19th day before calends	30	3rd day before calends
15	18th day before calends	31	eve of the calends
16	17th day before calends

A solar year may be defined as the time it takes the earth to make one orbit about the sun. A normal Gregorian year contains 365 days, but one orbit of the earth takes an extra 5 hours, 48 minutes, and 46 seconds to complete every year (Zinberg 1963:29). If nothing were done to compensate for this extra 1/4 day every year, every 120 years the seasons would have shifted by one month.

To adjust for this extra time accumulation the Julian calendar, adopted by Julius Caesar, added a 29th day to February every fourth year because a partial day could not be added every year. This extended the year to 366 days every four years, commonly known as a leap year. The Julian calendar also divided the year into 12 months that varied between 28 and 31 days.

The Roman Julian Calendar
Number of the Month	Name of the Month	Number of days in the month
First	March	31
Second	April	30
Third	May	31
Fourth	June	30
Fifth	July	31
Sixth	August	31
Seventh	September	30
Eighth	October	31
Ninth	November	30
Tenth	December	31
Eleventh	January	31
Twelfth	February	28 (29 every fourth year)

The addition of 24 hours every four years exceeds the accumulated four-year difference by 44 minutes and 56 seconds. Multiplying 4 years by 5 hours 48 minutes 46 seconds yields 23 hours 15 minutes 4 seconds. This correction of 24 hours 0 minutes 0 seconds every four years is therefore excessive by 44 minutes 56 seconds. See Zinberg 1963:29). This extra time accumulated until Pope Gregory XIII, in 1582 CE, reformed the Julian calendar (see The Gregorian Calendar).

[ Home ] [ Up ]