The Julian Calendar

LATN 6030 - CaesarHermanus R. Lemmer

Wednesday, 23 June 2010

Introduction to the Roman Calendar

How to Write a Roman Calendar Date

• Kalends = 1st of the month• Nones = 5th of the month (7th of March, May, July, and

October)– So called because it occurs nine days before the Ides.– This is because March, May, July, and October originally had

two more days than other months did. • Ides = 13th of the month (15th of March, May, July,

October)• pridie = the day before one of these• a.d. iii = two days before one of these• a.d. iv = three days before one of these, etc.

The Origins of the Names of the Months (Censorinus 22.9-15)

• Theory 1: Romulus gave the names to the months.

• Theory 2: The names were Latin in origin.

• N.B. in the time of Romulus, January and February did not exist.

The Origins of the Names of the Months (Censorinus 22.9-15)

• March = from Mars• April = either from Aphrodite or from aperio, to open • May = either from maioresor in honor of Maia, whose sacrifice

was that month.• June = either from iuniores or from Juno, who was honored that

month.• Quinctilis (July) – December = ordinal numbers

– Quinctilis renamed July after Julius Caesar in 44 BC– Sextilis renamed August after Augustus Caesar in 8 BC

• January = named after Janus• February = from the ritual occurring in that month in which

Romans purified themselves with hot salt, februum.

The Evolution of the Julian Calendar

The Pre-Julian Calendar

• Romulus: 10-month calendar– The year started at the full moon closest to Arcturus.– January and February unaccounted for

• NumaPompilius: 12-month calendar with intercalary month– March, May, July, October had 31 days– All other months except February had 29 days.– February had 28 days, with an occasional intercalary

month lasting 22-23 days.

The Pre-Julian Calendar: the Fundamental Problem

• The calendar had fallen out of line. – Throughout the Roman Republic, pontiffs

randomly inserted days or even months into the calendar.

– Julius Caesar saw that the calendar gave a date that falls during the spring when he was putting his troops in their winter quarters.

What Julius Caesar Did(Suetonius Julius 40)

• Made the length of the year 365 days.• Added a “leap-year day” every 4 years. – a.d. VI KalendasMartias happened twice. – On our calendar, this would be the same as having 24

February last for two days.– This would have been great in 2004, a leap year in

which Mardi Gras occurred on 24 February.• Added two months between November and

December, so that 1 January would fall at the appropriate time.

How Julius Caesar Fixed It

• The astronomer Sosigenes advised Julius Caesar that the year was 365¼ days long.

• Julius Caesar made the calendar 365 days long, with a 366-day year every four years.

• The year 46 B.C. (708 A.U.C.) was made 445 days long.• Starting with March, each month would alternate 31

days and 30 days, except February, which would have 29 days each year, 30 in leap years.

• August is 31 days long today because Augustus Caesar took a day from February and tacked it on to August.

How Julius Caesar Fixed It

Month (under Julius / under Augustus)January (31 / 31) July (31 / 31)February (29 / 28, August (30 / 31)

30 / 29 in leap year)March (31 / 31) September (31 / 30)April (30 / 30) October (30 / 31)May (31 / 31) November (31 / 30)June (30 / 30) December (30 / 31)

This will only work with Julius Caesar’s original calendar reforms!

The Calendar Today

• We still use the calendar Julius and Augustus Caesar made.

• By 1582, the calendar fell inaccurate by 10 days.• In 1582, Pope Gregory XIII reformed the calendar

by– removing 10 days from the calendar, so that

Thursday, 4 Oct. 1582 was followed by Friday, 15 Oct. 1582.

– stipulating that years ending in “00” are not leap years except when divisible by 400.

The Julian Calendar Today

• Julian calendar in use in Orthodox church– The Orthodox Church saw the earliest possible Easter date this

year (22 March)– The Western church last saw Easter on 22 March in 1818. This

will not happen again until 2285.• Julian calendar was used in

– England and U.S. until 1752– Japan until 1873– China until 1912– Turkey until 1916– Yugoslavia and Romania until 1919– Greece until 1923

Primary Sources

• Censorinus, De die natali• Ovid, Fasti• Pluatch, Life of Numa• Suetonius, Life of Julius Caesar, Section 40

Secondary Sources• Bushell, W.F. “Calendar Reform.” The Mathematical Gazette,

45.352 (May 1961), 117-124.• Castle, W.E. “Calendars and Calendar Reform.” Scientific Monthly

56. (Feb. 1943), 163-168.• Dershowitz, Nachum and Edward M. Reingold. Calendrical

Calculations. New York: Cambridge University Press (1997)• Michels, Agnes Kirsopp. “The ‘Calendar of Numa’ and the Pre-

Julian Calendar.” TAPA 80 (1949), 320-346.• Morrow, Martha G. “Reforms in Our Calendar.” The Science News-

Letter 53.7 (Feb. 14, 1948), 106-107.• Simpson, D.P. Cassell’s Latin Dictionary. New York: Wiley

Publishing Inc. (1968)