From
Wikipedia, the free encyclopedia.
The Julian calendar was introduced in
46 BC
by
Julius Caesar and took force in
45 BC
(709
ab urbe condita). It was chosen after consultation with the
Alexandrian astronomer
Sosigenes and was probably designed to approximate the
tropical year, known at least since
Hipparchus. It has a regular year of 365 days divided into 12
months, and a
leap day is added to
February every four years. Hence the Julian year is on average
365.25 days long.
The Julian
calendar remained in use into the 20th century in some countries
and is still used by many national Orthodox churches. However, too
many leap days are added with respect to the astronomical seasons on
this scheme. On average, the astronomical solstices and the
equinoxes advance by about 11 minutes per year against the Julian
year, causing the calendar to gain a day about every 134 years.
While
Hipparchus and presumably
Sosigenes were aware of the discrepancy, although not of its
correct value, it was evidently felt to be of little importance.
However, it accumulated significantly over time, and eventually led
to the reform of
1582,
which replaced the Julian calendar with the more accurate
Gregorian calendar.
The notation
"Old Style" (OS) is sometimes used to indicate a date in the
Julian calendar, as opposed to "New Style", which indicates a date
in the Gregorian Calendar. This notation is used when there might
otherwise be confusion about which date is found in a text.
From Roman to Julian
The ordinary year in the previous
Roman calendar consisted of 12 months, for a total of 355 days.
In addition, an intercalary month, the
Mensis Intercalaris, was sometimes inserted between February and
March. This intercalary month was formed by inserting 22 days before
the last five days of February, creating a 27-day month. It began
after a truncated February having 23 or 24 days, so that it had the
effect of adding 22 or 23 days to the year, forming an intercalary
year of 377 or 378 days.
According to the later writers
Censorinus and
Macrobius, the ideal intercalary cycle consisted of ordinary
years of 355 days alternating with intercalary years, which were
alternately 377 and 378 days long. On this system, the average Roman
year would have had 366¼ days over four years, giving it an average
drift of one day per year relative to any solstice or equinox.
Macrobius describes a further refinement wherein, for 8 years
out of 24, there were only three intercalary years each of 377 days.
This refinement averages the length of the year to 365¼ days over 24
years. In practice, intercalations did not occur schematically
according to these ideal systems, but were determined by the
pontifices. So far as can be determined from the historical
evidence, they were much less regular than these ideal schemes
suggest. They usually occurred every second or third year, but were
sometimes omitted for much longer, and occasionally occurred in two
consecutive years.
If managed correctly this system allowed the Roman
year, on average, to stay roughly aligned to a tropical year.
However, if too many intercalations were omitted, as happened after
the Second Punic War and during the Civil Wars, the calendar would
drift rapidly out of alignment with the tropical year. Moreover,
since intercalations were often determined quite late, the average
Roman citizen often did not know the date, particularly if he were
some distance from the city. For these reasons, the last years of
the pre-Julian calendar were later known as years of confusion.
The problems became particularly acute during Julius Caesar's
pontificate,
63 BC
to 46 BC,
when there were only five intercalary months, whereas there should
have been eight, and none at all during the five Roman years before
46 BC.
The Julian reform was intended to correct this
problem permanently. Before it took effect, the missed
intercalations during Julius Caesar's pontificate were made up by
inserting 67 days (22+23+22) between November and December of 46 BC
in the form of two months, in addition to 23 days which had already
been added to February. Thus 90 days were added to this last year of
the Roman Republican calendar, giving it 445 days. Because it was
the last of a series of irregular years, this extra-long year was,
and is, referred to as the last year of confusion. The first
year of operation of the new calendar was
45 BC.
Leap years error
Despite the new calendar being much simpler than
the Roman calendar, the pontifices apparently misunderstood the
algorithm. They added a leap day every three years, instead of every
four years. According to Macrobius, the error was the result of
counting inclusively, so that the four year cycle was considered as
including both the first and fourth years. This resulted in too many
leap days.
Caesar Augustus remedied this discrepancy by restoring the
correct frequency after 36 years of this mistake. He also skipped
several leap days in order to realign the year.
The historic sequence of leap years (i.e. years
with a leap day) in this period is not given explicitly by any
ancient source, although the existence of the triennial leap year
cycle is confirmed by an inscription that dates from 9 or 8 BC. The
chronologist
Joseph Scaliger established in 1583 that the Augustan reform was
instituted in 8 BC, and inferred that the sequence of leap years was
42, 39, 36, 33, 30, 27, 24, 21, 18, 15, 12, 9 BC, AD 8, 12 etc. This
proposal is still the most widely accepted solution. It has also
sometimes been suggested that 45 BC was a leap year.
Other solutions have been proposed from time to
time.
Kepler proposed in 1614 that the correct sequence of leap years
was 43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10 BC, AD 8, 12 etc.
In 1883 the German chronologist Matzat proposed 44, 41, 38, 35, 32,
29, 26, 23, 20, 17, 14, 11 BC, AD 4, 8, 12 etc., based on a passage
in
Dio Cassius that mentions a leap day in 41 BC that was said to
be contrary to (Caesar's) rule. In the 1960s Radke argued the
reform was actually instituted when Augustus became pontifex maximus
in 12 BC, suggesting the sequence 45, 42, 39, 36, 33, 30, 27, 24,
21, 18, 15, 12 BC, AD 4, 8, 12 etc.
In 1999, an Egyptian
papyrus was published which gives an
ephemeris table for 24 BC with both Roman and Egyptian dates.
From this it can be shown that the most likely sequence was in fact
44, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11, 8 BC, AD 4, 8, 12
etc, very close to that proposed by Matzat. This sequence shows that
the standard Julian leap year sequence began in AD 4, the twelfth
year of the Augustan reform. Also, under this sequence the actual
Roman year coincided with the proleptic Julian year between 32 and
26 BC. This suggests that one aim of the realignment portion of the
Augustan reform was to ensure that key dates of his career, notably
the fall of Alexandria on
1
August 30
BC, were unaffected by his correction.
Roman dates before 32 BC were typically a day or
two before the day with the same Julian date, so
1
January in the Roman calendar of the first year of the Julian
reform actually fell on
31 December
46 BC (Julian date). A curious effect of this is that Caesar's
assassination on the Ides (15th day) of March in 44 BC fell on
14
March 44
BC in the Julian calendar.
Naming of the months
Immediately after the Julian reform, the twelve
months of the Roman calendar were named Ianuarius, Februarius,
Martius, Aprilis, Maius, Iunius, Quintilis, Sextilis, September,
October, November, and December, just as they were before the
reform. Their lengths were set to their modern values. The old
intercalary month, the
Mensis Intercalaris, was abolished and replaced with a single
intercalary day at the same point (i.e. five days before the end of
Februarius). The first month of the year continued to be Ianuarius,
as it had been since 153 BC.
The Romans later renamed months after
Caesar
and
Augustus, renaming Quintilis (originally, "the Fifth month",
with March = month 1) as Iulius (July) in
44 BC
and Sextilis ("Sixth month") as Augustus (August) in
8 BC.
(Note that the letter
J was not
invented until the
17th century). Quintilis was renamed to honour Caesar because it
was the month of his birth. According to a senatusconsultum
quoted by Macrobius, Sextilis was renamed to honour Augustus because
several of the most significant events in his rise to power,
culminating in the fall of Alexandria, fell in that month.
Other months were renamed by other emperors, but
apparently none of the later changes survived their deaths.
Caligula renamed September ("Seventh month") as
Germanicus;
Nero
renamed Aprilis (April) as Neroneus, Maius (May) as Claudius and
Iunius (June) as Germanicus; and
Domitian renamed September as
Germanicus and October ("Eighth month") as Domitianus. At other
times, September was also renamed as
Antoninus and
Tacitus, and November ("Ninth month") was renamed
Faustina and Romanus.
Commodus was unique in renaming all twelve months after his own
adopted names (January to December): Amazonius, Invictus, Felix,
Pius, Lucius, Aelius, Aurelius, Commodus, Augustus, Herculeus,
Romanus, and Exsuperatorius.
Much more lasting than the ephemeral month names
of the post-Augustan Roman emperors were the names introduced by
Charlemagne. He renamed all of the months agriculturally into
Old High German. They were used until the
15th century, and with some modifications until the late
18th century in Germany and in the Netherlands
(January-December): Wintarmanoth (winter month), Hornung (spring),
Lentzinmanoth (Lent month), Ostarmanoth (Easter month), Winnemanoth
(grazing month), Brachmanoth (plowing month), Heuvimanoth (hay
month), Aranmanoth (harvest month), Witumanoth (wood month),
Windumemanoth (vintage month), Herbistmanoth (autumn/harvest month),
and Heilagmanoth (holy month). Translations of these month names are
still used to this day in some Slavic languages, such as Polish.
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:
- 30, 29, 30, 29, 30, 29, 30, 29, 30, 29, 30, and
29, totaling 354 days.
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:
- 31, 29 (30), 31, 30, 31, 30, 31, 30, 31, 30,
31, and 30
He then said Augustus changed this to:
- 31, 28 (29), 31, 30, 31, 30, 31, 31, 30, 31,
30, and 31
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:
- 29, 28, 31, 29, 31, 29, 31, 29, 29, 31, 29, and
29
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.
Year numbering
The dominant method that the Romans used to
identify a year for dating purposes was to name it after the two
consuls who took office in it. Since
153 BC,
they had taken office on
1
January, and Julius Caesar did not change the beginning of the
year. Thus this consular year was an eponymous or named year. Roman
years were named this way until the last consul was appointed in
541. Only
rarely did the Romans number the year from the
founding of the city (of Rome), ab urbe condita (AUC).
This method was used by Roman historians to determine the number of
years from one event to another, not to date a year. Different
historians had several different dates for the founding. The
Fasti
Capitolini, an inscription containing an official list of
the consuls which was published by Augustus, used an
epoch
of 752
BC. The epoch used by
Varro,
753 BC,
has been adopted by modern historians. Indeed,
Renaissance editors often added it to the manuscripts that they
published, giving the false impression that the Romans numbered
their years. Most modern historians tacitly assume that it began on
the day the consuls took office, and ancient documents such as the
Fasti Capitolini which use other AUC systems do so in the
same way. However, the Varronian AUC year did not formally begin on
1
January, but on Founder's Day,
21
April. This prevented the early Roman church from celebrating
Easter after
21
April because the festivities associated with Founder's Day
conflicted with the solemnity of
Lent,
which was observed until the Saturday before Easter Sunday.
In addition to consular years, the Romans
sometimes used the regnal year of the emperor. Anno Diocletiani,
named after
Diocletian, was often used by the
Alexandrian Christians to number their Easters during the
fourth and
fifth centuries. In AD
537,
Justinian required that henceforth the date must include the
name of the emperor, in addition to the
indiction and the consul (the latter ending only four years
later). The indiction caused the
Byzantine year to begin on
1 September, which is still used in the
Eastern Orthodox Church for the beginning of the
liturgical year. In AD 525
Dionysius Exiguus proposed the system of
anno Domini, which gradually spread through the western
Christian world, once the system was adopted by
Bede.
Years were numbered from the supposed date of the incarnation or
annunciation of
Jesus
on
25 March, although this soon changed to Christmas, then back to
Annunciation Day in Britain, and the numbered year even began on
Easter in France.
From Julian to Gregorian
The Julian calendar was in general use in Europe
from the times of the
Roman Empire until
1582,
when
Pope Gregory XIII promulgated the
Gregorian Calendar, which was soon adopted by most Catholic
countries. The Protestant countries followed later, and the
countries of Eastern Europe even later.
Great Britain had Thursday
14 September
1752
follow Wednesday
2 September
1752.
Sweden
adopted the new style calendar in 1753, but also for a twelve-year
period starting in 1700 used a
modified Julian Calendar.
Russia
remained on the Julian calendar until after the
Russian Revolution (which is thus called the 'October
Revolution' but occurred in November according to the Gregorian
calendar), in
1917,
while
Greece continued to use it until 1923.
Although all Eastern European countries had
adopted the Gregorian calendar on or before 1923, their national
Eastern Orthodox churches had not. A
revised Julian calendar was proposed during a synod in
Constantinople in May of
1923,
consisting of a solar part which was and will be identical to the
Gregorian calendar until the year 2800, and a lunar part which
calculated Easter astronomically at
Jerusalem. All Orthodox churches refused to accept the lunar
part, so almost all Orthodox churches continue to celebrate Easter
according to the Julian calendar (the
Finnish Orthodox Church uses the Gregorian Easter). The solar
part was only accepted by some Orthodox churches, those of
Constantinople,
Alexandria,
Antioch,
Greece,
Cyprus,
Romania,
Poland,
Bulgaria (in
1963),
and the
Orthodox Church in America (although some OCA parishes are
permitted to use the Julian calendar). Thus, these churches
celebrate the Nativity on the same day that Western Christians do,
25 December Gregorian until 2800. The Orthodox churches of
Jerusalem,
Russia,
Serbia,
Georgia,
Ukraine, and the
Greek Old Calendarists continue to use the Julian calendar for
their fixed dates, thus they celebrate the Nativity on
25 December Julian (7
January Gregorian until 2100).
See also
External links
![[1]](http://www.personal.psu.edu/users/w/x/wxk116/RomanCalendar/Fasti4.gif){kind=link}