The JULIAN CALENDAR, proposed by
Julius Caesar in 46 BC (708 AUC ),
was a reform of the
Roman calendar . It took effect on 1
BC (AUC 709), by edict. It was the predominant calendar in the Roman
world, most of Europe, and in European settlements in the Americas and
elsewhere, until it was refined and gradually replaced by the
Gregorian calendar , promulgated in 1582 by
Pope Gregory XIII
Pope Gregory XIII . The
Julian calendar gains against the mean tropical year at the rate of
one day in 128 years. For the Gregorian the figure is one day in 3,030
years. The difference in the average length of the year between
Julian (365.25 days) and Gregorian (365.2425 days) is 0.002%.
Julian calendar has a regular year of 365 days divided into 12
months, as listed in the table below . A leap day is added to February
every four years. The Julian year is, therefore, on average 365.25
days long. It was intended to approximate the tropical (solar) year .
Although Greek astronomers had known, at least since
Hipparchus , a
century before the Julian reform, that the tropical year was slightly
shorter than 365.25 days, the calendar did not compensate for this
difference. As a result, the calendar year gains about three days
every four centuries compared to observed equinox times and the
seasons. This discrepancy was corrected by the Gregorian reform of
Gregorian calendar has the same months and month lengths as
the Julian calendar, but, in the Gregorian calendar, years evenly
divisible by 100 are not leap years, except that years evenly
divisible by 400 remain leap years. Consequently—since 14 March
March Julian and until 28
February 2100 Gregorian/15
Julian calendar is currently 13 days behind the
Julian calendar has been replaced as the civil calendar by the
Gregorian calendar in almost all countries which formerly used it,
although it continued to be the civil calendar of some countries into
the 20th century. Egypt converted on 20
Turkey switched (for fiscal purposes) on 16 February/1
Russia changed on 1/14
February 1918. Greece made the change for
civil purposes on 16 February/1
March 1923, but the national day (25
March), which was a religious holiday, was to remain on the old
calendar. Most Christian denominations in the west and areas
evangelised by western churches have also replaced the Julian calendar
with the Gregorian as the basis for their liturgical calendars .
However, most branches of the Eastern
Orthodox Church still use the
Julian calendar for calculating the date of
Easter , upon which the
timing of all the other moveable feasts depends. Some Orthodox
churches have adopted the
Revised Julian calendar
Revised Julian calendar for the observance
of fixed feasts , while other Orthodox churches retain the Julian
calendar for all purposes. The
Julian calendar is still used by the
Berbers of the Maghreb in the form of the
Berber calendar , and on
Mount Athos . In the form of the
Alexandrian calendar , it is the
basis for the
Ethiopian calendar , which is the civil calendar of
During the changeover between calendars and for some time afterwards,
dual dating was used in documents and gave the date according to both
systems. In contemporary as well as modern texts that describe events
during the period of change, it is customary to clarify to which
calendar a given date refers by using an O.S. or N.S. suffix (denoting
Old Style, Julian or New Style, Gregorian).
* 1 Table of months
* 2 Motivation
* 3 Context of the reform
* 4 Julian reform
* 4.1 Realignment of the year
* 4.2 Changes to the months
* 4.3 Intercalation
* 4.4 Sacrobosco\'s theory on month lengths
* 4.5 Adoption of the
Leap year error
* 8 New Year\'s
* 9 From Julian to Gregorian
* 10 Eastern Orthodox usage
* 11 See also
* 12 Notes
* 13 Bibliography
* 14 External links
TABLE OF MONTHS
LENGTHS BEFORE 45 BC
LENGTHS AS OF 45 BC
28 (in common years)
In intercalary years:
23 if Intercalaris is variable
23/24 if Intercalaris is fixed 28 (leap years: 29)
0 (leap years: variable (27/28 days)
or fixed) Abolished
The ordinary year in the previous
Roman calendar consisted of 12
months, for a total of 355 days. In addition, a 27- or 28-day
intercalary month, the Mensis Intercalaris , was sometimes inserted
February and March. This intercalary month was formed by
inserting 22 or 23 days after the first 23 days of February; the last
five days of February, which counted down toward the start of March,
became the last five days of Intercalaris. The net effect was to add
22 or 23 days to the year, forming an intercalary year of 377 or 378
days. Some say the mensis intercalaris always had 27 days and began
on either the first or the second day after the Terminalia (23
According to the later writers
Macrobius , the ideal
intercalary cycle consisted of ordinary years of 355 days alternating
with intercalary years, alternately 377 and 378 days long. In this
system, the average Roman year would have had 366 1⁄4 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
whereby, in one 8-year period within a 24-year cycle, there were only
three intercalary years, each of 377 days (thus 11 intercalary years
out of 24). This refinement averages the length of the year to 365.25
days over 24 years.
In practice, intercalations did not occur systematically according to
any of 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 could have allowed the Roman year to
stay roughly aligned to a tropical year. However, since the pontifices
were often politicians, and because a Roman magistrate's term of
office corresponded with a calendar year, this power was prone to
abuse: a pontifex could lengthen a year in which he or one of his
political allies was in office, or refuse to lengthen one in which his
opponents were in power.
If too many intercalations were omitted, as happened after the Second
Punic War and during the Civil Wars , the calendar would drift out of
alignment with the tropical year. Moreover, because 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 the years of Julius Caesar's pontificate
before the reform, 63–46 BC, when there were only five intercalary
months (instead of eight), none of which were during the five Roman
years before 46 BC.
Caesar's reform was intended to solve this problem permanently, by
creating a calendar that remained aligned to the sun without any human
intervention. This proved useful very soon after the new calendar came
Varro used it in 37 BC to fix calendar dates for the
start of the four seasons, which would have been impossible only 8
years earlier. A century later, when Pliny dated the winter solstice
December because the sun entered the 8th degree of Capricorn on
that date, this stability had become an ordinary fact of life.
CONTEXT OF THE REFORM
Although the approximation of 365 1⁄4 days for the tropical year
had been known for a long time ancient solar calendars had used less
precise periods, resulting in gradual misalignment of the calendar
with the seasons.
The octaeteris , a cycle of 8 lunar years popularised by Cleostratus
(and also commonly attributed to Eudoxus ) which was used in some
early Greek calendars, notably in Athens , is 1.53 days longer than
eight Julian years. The length of nineteen years in the cycle of Meton
was 6,940 days, six hours longer than the mean Julian year. The mean
Julian year was the basis of the 76-year cycle devised by
student under Eudoxus) to improve the Metonic cycle.
In Persia (Iran) after the reform in the Persian calendar by
introduction of the Persian Zoroastrian (i. e. Young Avestan) calendar
in 503 BC and afterwards, the first day of the year (1
Nowruz ) slipped against the vernal equinox at the rate of
approximately one day every four years.
Likewise in the
Egyptian calendar , a fixed year of 365 days was in
use, drifting by one day against the sun in four years. An
unsuccessful attempt to add an extra day every fourth year was made in
238 BC (
Decree of Canopus ). Caesar probably experienced this
"wandering" or "vague" calendar in that country. He landed in the Nile
October 48 BC and soon became embroiled in the Ptolemaic
dynastic war, especially after Cleopatra managed to be "introduced" to
Caesar imposed a peace, and a banquet was held to celebrate the
Lucan depicted Caesar talking to a wise man called Acoreus
during the feast, stating his intention to create a calendar more
perfect than that of Eudoxus (Eudoxus was popularly credited with
having determined the length of the year to be 365 1⁄4 days).
But the war soon resumed and Caesar was attacked by the Egyptian army
for several months until he achieved victory. He then enjoyed a long
cruise on the Nile with Cleopatra before leaving the country in June
Caesar returned to
Rome in 46 BC and, according to
Plutarch , called
in the best philosophers and mathematicians of his time to solve the
problem of the calendar. Pliny says that Caesar was aided in his
reform by the astronomer Sosigenes of
Alexandria who is generally
considered the principal designer of the reform. Sosigenes may also
have been the author of the astronomical almanac published by Caesar
to facilitate the reform. Eventually, it was decided to establish a
calendar that would be a combination between the old Roman months, the
fixed length of the Egyptian calendar, and the 365 1⁄4 days of
the Greek astronomy. According to Macrobius, Caesar was assisted in
this by a certain Marcus Flavius.
REALIGNMENT OF THE YEAR
The first step of the reform was to realign the start of the calendar
year (1 January) to the tropical year by making 46 BC (708 AUC ) 445
days long, compensating for the intercalations which had been missed
during Caesar's pontificate. This year had already been extended from
355 to 378 days by the insertion of a regular intercalary month in
February. When Caesar decreed the reform, probably shortly after his
return from the African campaign in late
Quintilis (July), he added 67
more days by inserting two extraordinary intercalary months between
November and December.
These months are called Intercalaris Prior and Intercalaris Posterior
in letters of
Cicero written at the time; there is no basis for the
statement sometimes seen that they were called "
Undecimber " and
"Duodecimber ". Their individual lengths are unknown, as is the
position of the Nones and Ides within them.
Because 46 BC 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 new calendar began operation after the realignment had
been completed, in 45 BC.
CHANGES TO THE MONTHS
The Julian months were formed by adding ten days to a regular
pre-Julian Roman year of 355 days, creating a regular Julian year of
365 days. Two extra days were added to January,
Sextilis (August) and
December, and one extra day was added to April, June,
February was not changed in ordinary years, and so continued
to be the traditional 28 days. Thus, the ordinary (i.e., non leap
year) lengths of all of the months were set by the
Julian calendar to
the same values they still hold today. (See Sacrobosco\'s theory on
month lengths below for stories purporting otherwise.)
The Julian reform did not change the method used to account days of
the month in the pre-
Julian calendar , based on the Kalends, Nones and
Ides, nor did it change the positions of these three dates within the
Macrobius states that the extra days were added immediately
before the last day of each month to avoid disturbing the position of
the established religious ceremonies relative to the Nones and Ides of
the month. However, since Roman dates after the Ides of the month
counted down toward the start of the next month, the extra days had
the effect of raising the initial value of the count of the day
following the Ides in the lengthened months. Thus, in January,
December the 14th day of the month became a.d. XIX Kal.
instead of a.d. XVII Kal., while in April, June,
November it became a.d. XVIII Kal.
Romans of the time born after the Ides of a month responded
differently to the effect of this change on their birthdays. Mark
Antony kept his birthday on 14 January, which changed its date from
a.d. XVII Kal. Feb to a.d. XIX Kal. Feb, a date that had previously
Livia kept the date of her birthday unchanged at a.d. III
Kal. Feb., which moved it from 28 to 30 January, a day that had
previously not existed.
Augustus kept his on 23 September, but both
the old date (a.d. VIII Kal. Oct.) and the new (a.d. IX Kal. Oct.)
were celebrated in some places.
The inserted days were all initially characterised as dies fasti (F
Roman calendar ). The character of a few festival days was
changed. In the early Julio-Claudian period a large number of
festivals were decreed to celebrate events of dynastic importance,
which caused the character of the associated dates to be changed to
NP. However, this practice was discontinued around the reign of
Claudius , and the practice of characterising days fell into disuse
around the end of the first century AD: the Antonine jurist Gaius
speaks of dies nefasti as a thing of the past.
The old intercalary month was abolished. The new leap day was dated
as ante diem bis sextum Kalendas Martias ('the sixth doubled before
the Kalends of March'), usually abbreviated as a.d. bis VI Kal. Mart.;
hence it is called in English the bissextile day. The year in which it
occurred was termed annus bissextus, in English the bissextile year.
There is debate about the exact position of the bissextile day in the
early Julian calendar. The earliest direct evidence is a statement of
the 2nd century jurist Celsus , who states that there were two halves
of a 48-hour day, and that the intercalated day was the "posterior"
half. An inscription from AD 168 states that a.d. V Kal. Mart. was the
day after the bissextile day. The 19th century chronologist Ideler
argued that Celsus used the term "posterior" in a technical fashion to
refer to the earlier of the two days, which requires the inscription
to refer to the whole 48-hour day as the bissextile. Some later
historians share this view. Others, following Mommsen , take the view
that Celsus was using the ordinary
Latin (and English) meaning of
"posterior". A third view is that neither half of the 48-hour "bis
sextum" was originally formally designated as intercalated, but that
the need to do so arose as the concept of a 48-hour day became
There is no doubt that the bissextile day eventually became the
earlier of the two days for most purposes. In 238
that it was inserted after the Terminalia (23 February) and was
followed by the last five days of February, i.e., a.d. VI, V, IV, III
and prid. Kal. Mart. (which would be 24 to 28
February in a common
year and the 25th to 29th in a leap year). Hence he regarded the
bissextum as the first half of the doubled day. All later writers,
Macrobius about 430,
Bede in 725, and other medieval
computists (calculators of Easter) followed this rule, as does the
liturgical calendar of the Roman Catholic Church. However, Celsus'
definition continued to be used for legal purposes. It was
incorporated into Justinian\'s Digest , and in the English statute De
anno et die bissextili of 1236, which was not formally repealed until
The effect of the bissextile day on the nundinal cycle is not
discussed in the sources. According to Dio Cassius, a leap day was
inserted in 41 BC to ensure that the first market day of 40 BC did not
fall on 1 January, which implies that the old 8-day cycle was not
immediately affected by the Julian reform. However, he also reports
that in AD 44, and on some previous occasions, the market day was
changed to avoid a conflict with a religious festival. This may
indicate that a single nundinal letter was assigned to both halves of
the 48-hour bissextile day by this time, so that the
the market day might fall on the same date but on different days. In
any case, the 8-day nundinal cycle began to be displaced by the 7-day
week in the first century AD, and dominical letters began to appear
alongside nundinal letters in the fasti.
During the late
Middle Ages days in the month came to be numbered in
consecutive day order. Consequently, the leap day was considered to be
the last day in
February in leap years, i.e., 29 February, which is
its current position.
SACROBOSCO\'S THEORY ON MONTH LENGTHS
The Julian reform set the lengths of the months to their modern
values. However, a 13th-century scholar,
Sacrobosco , proposed a
different explanation for the lengths of Julian months which is still
widely repeated but is certainly wrong.
According to Sacrobosco, the month lengths for ordinary years in the
Roman Republican calendar, from
January to December, were: 30, 29,
30, 29, 30, 29, 30, 29, 30, 29, 30, 29.
Sacrobosco then thought that
Julius Caesar added one day to every
month except February, a total of 11 more days to regular months,
giving the ordinary Julian year of 365 days. A single leap day could
now be added to this extra short February: 31, 29/30, 31, 30, 31, 30,
31, 30, 31, 30, 31, 30.
He then said
Augustus changed this, by taking one day from February
to add it to Sextilis, and then modifying the alternation of the
following months, to: 31, 28/29, 31, 30, 31, 30, 31, 31, 30, 31, 30,
so that the length of
Augustus (August) would not be shorter than
(and therefore inferior to) the length of Iulius (July), giving us the
irregular month lengths which are still in use.
There is abundant evidence disproving this theory. First, a wall
painting of a
Roman calendar predating the Julian reform has survived,
which confirms the literary accounts that the months were already
Julius Caesar reformed them, with an ordinary year of
355 days, not 354, with month lengths arranged as: 29, 28, 31, 29,
31, 29, 31, 29, 29, 31, 29, 29.
Also, the Julian reform did not change the dates of the Nones and
Ides . In particular, the Ides were 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 March,
July were originally 30 days long and
that the length of
October was changed from 29 to 30 days by Caesar
and to 31 days by Augustus. Further, Sacrobosco's theory is explicitly
contradicted by the 3rd and 5th century authors
Macrobius, and it is inconsistent with seasonal lengths given by
Varro, writing in 37 BC, before
Sextilis was renamed for
8 BC, with the 31-day
Sextilis given by an Egyptian papyrus from 24
BC, and with the 28-day
February shown in the
Fasti Caeretani, which
is dated before 12 BC.
ADOPTION OF THE JULIAN CALENDAR
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Caesar's reform only applied to the
Roman calendar . However, in the
following decades many of the local civic and provincial calendars of
the empire and neighbouring client kingdoms were aligned to the Julian
calendar by transforming them into calendars with years of 365 days
with an extra day intercalated every four years. The reformed
calendars typically retained many features of the unreformed
calendars. In many cases, the New
Year was not on 1 January, the leap
day was not on the bissextile day, the old month names were retained,
the lengths of the reformed months did not match the lengths of Julian
months, and, even if they did, their first days did not match the
first day of the corresponding Julian month. Nevertheless, since the
reformed calendars had fixed relationships to each other and to the
Julian calendar, the process of converting dates between them became
quite straightforward, through the use of conversion tables known as
hemerologia. Several of the reformed calendars are only known through
The three most important of these calendars are the Alexandrian
calendar, the Asian calendar and the Syro-Macedonian calendar. Other
reformed calendars are known from Cappadocia, Cyprus and the cities of
Syria and Palestine. Most reformed calendars were adopted under
Augustus, though the calendar of
Nabatea was reformed after the
kingdom became the
Roman province of Arabia in AD 106. There is no
evidence that local calendars were aligned to the
Julian calendar in
the western empire. Unreformed calendars continued to be used in Gaul
, Greece, Macedon, the Balkans and parts of Palestine, most notably in
Alexandrian calendar adapted the
Egyptian calendar by adding a
6th epagomenal day as the last day of the year in every fourth year,
falling on 29
August preceding a Julian bissextile day. It was
otherwise identical to the Egyptian calendar. The first leap day was
in 22 BC, and they occurred every four years from the beginning, even
though Roman leap days occurred every three years at this time (see
Leap year error ). This calendar influenced the structure of several
other reformed calendars, such as those of the cities of Gaza and
Ascalon in Palestine, Salamis in Cyprus, and the province of Arabia.
It was adopted by the Coptic church and remains in use both as the
liturgical calendar of the Coptic church and as the civil calendar of
The Asian calendar was an adaptation of the Macedonian calendar used
in the province of Asia and, with minor variations, in nearby cities
and provinces. It is known in detail through the survival of decrees
promulgating it issued in 8 BC by the proconsul Paullus Fabius Maximus
. It renamed the first month Dios as Kaisar, and arranged the months
such that each month started on the ninth day before the kalends of
the corresponding Roman month; thus the year began on 23 September,
Augustus' birthday. Since Greek months typically had 29 or 30 days,
the extra day of 31 day months was named Sebaste—the emperor's
day—and was the first day of these months. The leap day was a second
Sebaste day in the month of Xandikos, i.e., 24 February. This calendar
remained in use at least until the middle of the fifth century AD.
The Syro - Macedonian calendar was an adaptation of the Macedonian
calendar used in
Antioch and other parts of Syria. The months were
exactly aligned to the Julian calendar, but they retained their
Macedonian names and the year began in Dios =
November until the fifth
century, when the start of the year was moved to Gorpiaios =
These reformed calendars generally remained in use until the fifth or
sixth century. Around that time most of them were replaced as civil
calendars by the Julian calendar, but with a year starting in
September to reflect the year of the indiction cycle.
Julian calendar spread beyond the borders of the Roman Empire
through its use as the Christian liturgical calendar. When a people or
a country was converted to Christianity, they generally also adopted
the Christian calendar of the church responsible for conversion. Thus,
Christian Nubia and
Ethiopia adopted the Alexandrian calendar, while
Christian Europe adopted the Julian calendar, in either the Catholic
or Orthodox variant. Starting in the 16th century, European
settlements in the Americas and elsewhere likewise inherited the
Julian calendar of the mother country, until they adopted the
Gregorian reform. The last country to adopt the
Julian calendar was
the Ottoman Empire, which used it for financial purposes for some time
under the name
Rumi calendar and dropped the "escape years" which tied
it to Muslim chronology in 1840.
LEAP YEAR ERROR
Although the new calendar was much simpler than the pre-Julian
calendar, the pontifices initially added a leap day every three years,
instead of every four. There are accounts of this in Solinus, Pliny,
Ammianus, Suetonius, and Censorinus.
Macrobius gives the following account of the introduction of the
"Caesar’s regulation of the civil year to accord with his revised
measurement was proclaimed publicly by edict, and the arrangement
might have continued to stand had not the correction itself of the
calendar led the priests to introduce a new error of their own; for
they proceeded to insert the intercalary day, which represented the
four quarter-days, at the beginning of each fourth year instead of at
its end, although the intercalation ought to have been made at the end
of each fourth year and before the beginning of the fifth.
"This error continued for thirty-six years by which time twelve
intercalary days had been inserted instead of the number actually due,
namely nine. But when this error was at length recognised, it too was
corrected, by an order of Augustus, that twelve years should be
allowed to pass without an intercalary day, since the sequence of
twelve such years would account for the three days which, in the
course of thirty-six years, had been introduced by the premature
actions of the priests."
So, according to Macrobius,
* the year was considered to begin after the Terminalia, (23
* the calendar was operated correctly from its introduction on 1
January 45 BC until the beginning of the fourth year (
February 42 BC)
at which point the priests inserted the first intercalation,
* Caesar’s intention was to make the first intercalation at the
beginning of the fifth year (
February 41 BC),
* the priests made a further eleven intercalations after 42 BC at
three-year intervals so that the twelfth intercalation fell in 9 BC,
* had Caesar’s intention been followed there would have been
intercalations every four years after 41 BC, so that the ninth
intercalation would have been in 9 BC,
* after 9 BC, there were twelve years without leap years , so that
the leap days Caesar would have had in 5 BC, 1 BC and AD 4 were
* after AD 4 the calendar was operated as Caesar intended, so that
the next leap year was AD 8 and then leap years followed every fourth
Some people have had different ideas as to how the leap years went.
The above scheme is that of Scaliger in the table below. He
established that the Augustan reform was instituted in 8 BC. The table
shows for each reconstruction the implied proleptic Julian date for
the first day of Caesar's reformed calendar (Kal. Ian. AUC 709) and
the first Julian date on which the
Roman calendar date matches the
Julian calendar after the completion of Augustus' reform.
Alexander Jones claims that the correct
Julian calendar was in use in
Egypt in 24 BC, implying that the first day of the reform in both
Egypt and Rome, 1
January 45 BC, was the Julian date 1
January if 45
BC was a leap year and 2
January if it was not. This necessitates
fourteen leap days up to and including AD 8 if 45 BC was a leap year
and thirteen if it was not.
Pierre Brind'Amour argued that "only one day was intercalated
between 1/1/45 and 1/1/40 (disregarding a momentary 'fiddling' in
December of 41 to avoid the nundinum falling on Kal. Ian."
TRIENNIAL LEAP YEARS (BC)
FIRST JULIAN DAY
FIRST ALIGNED DAY
QUADRIENNIAL LEAP YEAR RESUMES
44, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11, 8
31 Dec 46 BC
25 Feb 1 BC
45, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11
2 Jan 45 BC
25 Feb AD 4
44, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11
1 Jan 45 BC
25 Feb 1 BC
45, 42, 39, 36, 33, 30, 27, 24, 21, 18, 15, 12, 9
1 Jan 45 BC
25 Feb AD 4
43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10
2 Jan 45 BC
25 Feb AD 4
43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10
1 Jan 45 BC
25 Feb 1 BC
45, 42, 39, 36, 33, 30, 27, 24, 21, 18, 15, 12
1 Jan 45 BC
25 Feb 1 BC
43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10
2 Jan 45 BC
25 Feb AD 4
42, 39, 36, 33, 30, 27, 24, 21, 18, 15, 12, 9
2 Jan 45 BC
25 Feb AD 4
In 1999 a papyrus was discovered which gives the dates of
astronomical phenomena in 24 BC in both the Egyptian and Roman
calendars. From 30
August 26 BC (Julian) Egypt had two calendars: the
old Egyptian in which every year had 365 days and the new Alexandrian
in which every fourth year had 366 days. Up to 28
August 22 BC
(Julian) the date in both calendars was the same. The dates in the
Alexandrian and Julian calendars are in one-to-one correspondence
except for the period from 29
August in the year preceding a Julian
leap year to the following 24 February. From a comparison of the
astronomical data with the Egyptian and Roman dates Alexander Jones
concluded that the Egyptian astronomers (as opposed to travellers from
Rome) used the correct Julian calendar.
An inscription has been discovered which orders a new calendar to be
used in Asia to replace the previous Greek lunar calendar. According
to one translation
"Intercalation shall commence on the day after 14 Peritius as it is
currently constituted in the third year following promulgation of the
decree. Xanthicus shall have 32 days in this intercalary year."
This is historically correct. It was decreed by the proconsul that
the first day of the year in the new calendar shall be Augustus'
birthday, a.d. IX Kal. Oct. Every month begins on the ninth day before
the kalends. The date of introduction, the day after 14 Peritius, was
1 Dystrus, the next month. The month after that was Xanthicus. Thus
Xanthicus began on a.d. IX Kal. Mart., and normally contained 31 days.
In leap year, however, it contained an extra "Sebaste day", the Roman
leap day, and thus had 32 days. From the lunar nature of the old
calendar we can fix the starting date of the new one as 24 January,
a.d. IX Kal. Feb 5 BC in the Julian calendar, which was a leap year.
Thus from inception the dates of the reformed Asian calendar are in
one-to-one correspondence with the Julian.
Another translation of this inscription is
"Intercalation shall commence on the day after the fourteenth day in
the current month of Peritius , occurring every third year. Xanthicus
shall have 32 days in this intercalary year."
This would move the starting date back three years to 8 BC, and from
the lunar synchronism back to 26
January (Julian). But since the
corresponding Roman date in the inscription is 24 January, this must
be according to the incorrect calendar which in 8 BC
ordered to be corrected by the omission of leap days. As the authors
of the previous paper point out, with the correct four-year cycle
being used in Egypt and the three-year cycle abolished in
Rome it is
Augustus would have ordered the three-year cycle to be
introduced in Asia.
The Julian reform did not immediately cause the names of any months
to be changed. The old intercalary month was abolished and replaced
with a single intercalary day at the same point (i.e., five days
before the end of February).
January continued to be the first month
of the year.
The Romans later renamed months after
Julius Caesar and Augustus,
Quintilis as "Iulius" (July) in 44 BC and
"Augustus" (August) in 8 BC.
Quintilis was renamed to honour Caesar
because it was the month of his birth. According to a senatus
consultum 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, occurred in that month.
Other months were renamed by other emperors, but apparently none of
the later changes survived their deaths. In AD 37,
September as "Germanicus" after his father ; in AD 65,
April as "Neroneus",
May as "Claudius" and
June as "Germanicus"; and
in AD 84
September as "Germanicus" and
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". The emperor
Tacitus is said to have ordered that September, the month of his birth
and accession, be renamed after him, but the story is doubtful since
he did not become emperor before
November 275. Similar honorific
month names were implemented in many of the provincial calendars that
were aligned to the Julian calendar.
Other name changes were proposed but were never implemented. Tiberius
rejected a senatorial proposal to rename
September as "Tiberius" and
October as "Livius", after his mother Livia.
Antoninus Pius rejected
a senatorial decree renaming
September as "Antoninus" and
"Faustina", after his empress .
Much more lasting than the ephemeral month names of the post-Augustan
Roman emperors were the Old High German names introduced by
Charlemagne . According to his biographer,
Charlemagne renamed all of
the months agriculturally into German. These names were used until
the 15th century, over 700 years after his rule, and continued, with
some modifications, to see some use as "traditional" month names until
the late 18th century. The names (
January to December) were:
Wintarmanoth ("winter month"), Hornung, Lentzinmanoth ("spring
Lent month"), Ostarmanoth ("
Easter month"), Wonnemanoth
("joy-month", a corruption of Winnimanoth "pasture-month"),
Brachmanoth ("fallow-month"), Heuuimanoth ("hay month"), Aranmanoth
("reaping month"), Witumanoth ("wood month"), Windumemanoth ("vintage
month"), Herbistmanoth ("harvest month"), and Heilagmanoth ("holy
The calendar month names used in western and northern Europe, in
Byzantium, and by the
Berbers , were derived from the
However, in eastern Europe older seasonal month names continued to be
used into the 19th century, and in some cases are still in use, in
many languages, including: Belarusian , Bulgarian , Croatian , Czech ,
Finnish, Georgian , Lithuanian , Macedonian , Polish , Romanian ,
Slovene , Ukrainian . When the
Ottoman Empire adopted the Julian
calendar, in the form of the Rumi calendar, the month names reflected
The principal 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, so this eponymous or named year was called the consular year.
Since 153 BC, they had taken office on 1 January, the start of the
calendar year. The calendar year is the order that the months were
listed in calendars or fasti displayed on painted walls or on stone
tablets, and has been
December since about 450 BC according
Ovid or since about 713 BC according to
Roman calendar ).
Julius Caesar did not change the beginning of either
the consular year or the calendar year. In addition to consular years,
the Romans sometimes used the regnal year of the emperor, and by the
late 4th century documents were also being dated according to the
15-year cycle of the indiction . In 537, Justinian required that
henceforth the date must include the name of the emperor and his
regnal year, in addition to the indiction and the consul, while also
allowing the use of local eras .
In 309 and 310, and from time to time thereafter, no consuls were
appointed. When this happened, the consular date was given a count of
years since the last consul (so-called "post-consular" dating). After
541, only the reigning emperor held the consulate, typically for only
one year in his reign, and so post-consular dating became the norm.
Similar post-consular dates were also known in the west in the early
6th century. The system of consular dating, long obsolete, was
formally abolished in the law code of Leo VI , issued in 888.
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, Censorinus, writing in the 3rd century
AD, states that, in his time, the AUC year began with the
celebrated on 21 April, which was regarded as the actual anniversary
of the foundation of Rome.
Many local eras, such as the
Era of Actium and the
Spanish Era , were
adopted for the
Julian calendar or its local equivalent in the
provinces and cities of the Roman Empire. Some of these were used for
a considerable time. Perhaps the best known is the
Era of Martyrs ,
sometimes also called Anno Diocletiani (after
Diocletian ), which was
associated with the
Alexandrian calendar and often used by the
Alexandrian Christians to number their Easters during the 4th and 5th
centuries, and continues to be used by the Coptic and Ethiopian
In the eastern Mediterranean, the efforts of Christian chronographers
such as Annianus of
Alexandria to date the Biblical creation of the
world led to the introduction of
Anno Mundi eras based on this event.
The most important of these was the
Etos Kosmou , used throughout the
Byzantine world from the 10th century and in
Russia until 1700. In the
west, the kingdoms succeeding the empire initially used indictions and
regnal years , alone or in combination. The chronicler Prosper of
Aquitaine , in the fifth century, used an era dated from the Passion
of Christ , but this era was not widely adopted. Dionysius Exiguus
proposed the system of
Anno Domini in 525. This era gradually spread
through the western Christian world, once the system was adopted by
Julian calendar was also used in some Muslim countries. The Rumi
Julian calendar used in the later years of the Ottoman
Empire , adopted an era derived from the lunar AH year equivalent to
AD 1840, i.e., the effective Rumi epoch was AD 585. In recent years,
some users of the
Berber calendar have adopted an era starting in 950
BC, the approximate date that the Libyan pharaoh
Sheshonq I came to
power in Egypt.
NEW YEAR\'S DAY
Roman calendar began the year on 1 January, and this remained the
start of the year after the Julian reform. However, even after local
calendars were aligned to the Julian calendar, they started the new
year on different dates. The
Alexandrian calendar in Egypt started on
August after an Alexandrian leap year). Several local
provincial calendars were aligned to start on the birthday of
Augustus, 23 September. The indiction caused the Byzantine year, which
used the Julian calendar, to begin on 1 September; this date is still
used in the Eastern
Orthodox Church for the beginning of the
liturgical year. When the
Julian calendar was adopted in AD 988 by
Vladimir I of Kiev
Vladimir I of Kiev , the year was numbered
Anno Mundi 6496, beginning
on 1 March, six months after the start of the Byzantine Anno Mundi
year with the same number. In 1492 (AM 7000),
Ivan III , according to
church tradition, realigned the start of the year to 1 September, so
that AM 7000 only lasted for six months in Russia, from 1
March to 31
Middle Ages 1
January retained the name New Year\'s Day
(or an equivalent name) in all western European countries (affiliated
Roman Catholic Church ), since the medieval calendar
continued to display the months from
December (in twelve
columns containing 28 to 31 days each), just as the Romans had.
However, most of those countries began their numbered year on 25
December (the Nativity of
Jesus ), 25
March (the Incarnation of Jesus
), or even Easter, as in
France (see the
Liturgical year article for
In Anglo-Saxon England, the year most commonly began on 25 December,
which, as (approximately) the winter solstice , had marked the start
of the year in pagan times, though 25
March (the equinox ) is
occasionally documented in the 11th century. Sometimes the start of
the year was reckoned as 24 September, the start of the so-called
"western indiction" introduced by Bede. These practices changed after
the Norman conquest. From 1087 to 1155 the English year began on 1
January, and from 1155 to 1751 began on 25 March. In 1752 it was
moved back to 1 January. (See
Calendar (New Style) Act 1750 ).
Even before 1752, 1
January was sometimes treated as the start of the
new year – for example by Pepys – while the "year starting 25th
March was called the Civil or Legal Year". To reduce
misunderstandings on the date, it was not uncommon for a date between
January and 24
March to be written as "1661/62". This was to explain
to the reader that the year was 1661 counting from
March and 1662
January as the start of the year. (For more detail, see
Dual dating ).
Most western European countries shifted the first day of their
numbered year to 1
January while they were still using the Julian
calendar, before they adopted the Gregorian calendar, many during the
16th century. The following table shows the years in which various
countries adopted 1
January as the start of the year. Eastern European
countries, with populations showing allegiance to the Orthodox Church
, began the year on 1
September from about 988. The
Rumi calendar used
Ottoman Empire began the civil year on 1
March until 1918.
January Adoption of
Republic of Venice
Holy Roman Empire
Dutch Republic except
British Empire excluding Scotland
Ottoman Empire (
FROM JULIAN TO GREGORIAN
Julian calendar was in general use in Europe and northern Africa
until 1582, when
Pope Gregory XIII
Pope Gregory XIII promulgated the Gregorian calendar.
Reform was required because too many leap days are added with respect
to the astronomical seasons on the Julian scheme. On average, the
astronomical solstices and the equinoxes advance by about 11 minutes
per year against the Julian year. As a result, the calculated date of
Easter gradually moved out of alignment with the
This is a visual example of the official date change from the Julian
calendar to the Gregorian.
Hipparchus and presumably Sosigenes were aware of the
discrepancy, although not of its correct value, it was evidently felt
to be of little importance at the time of the Julian reform. However,
it accumulated significantly over time: the
Julian calendar gained a
day about every 134 years. By 1582, it was ten days out of alignment
from where it supposedly had been in 325 during the Council of Nicaea
Gregorian calendar was soon adopted by most Catholic countries
(e.g., Spain, Portugal, Poland, most of Italy). Protestant countries
followed later, and some countries of eastern Europe even later. In
British Empire (including the American colonies ), Wednesday 2
September 1752 was followed by Thursday 14
September 1752. For 12
years from 1700
Sweden used a modified
Julian calendar , and adopted
Gregorian calendar in 1753.
Since the Julian and Gregorian calendars were long used
simultaneously, although in different places, calendar dates in the
transition period are often ambiguous, unless it is specified which
calendar was being used. In some circumstances, double dates might be
used, one in each calendar. The notation "Old Style" (O.S.) is
sometimes used to indicate a date in the Julian calendar, as opposed
to "New Style" (N.S.) , which either represents the Julian date with
the start of the year as 1
January or a full mapping onto the
Gregorian calendar. This notation is used to clarify dates from
countries which continued to use the
Julian calendar after the
Gregorian reform, such as Great Britain, which did not switch to the
reformed calendar until 1752, or Russia, which did not switch until
Throughout the long transition period, the
Julian calendar has
continued to diverge from the Gregorian. This has happened in
whole-day steps, as leap days which were dropped in certain centennial
years in the
Gregorian calendar continued to be present in the Julian
calendar. Thus, in the year 1700 the difference increased to 11 days;
in 1800, 12; and in 1900, 13. Since 2000 was a leap year according to
both the Julian and Gregorian calendars, the difference of 13 days did
not change in that year: 29
February 2000 (Gregorian) fell on 16
February 2000 (Julian). This difference will persist until the last
February 2100 (Gregorian), since 2100 is not a Gregorian leap
year, but is a Julian leap year. Monday 1
March 2100 (Gregorian) falls
on Monday 16
February 2100 (Julian).
EASTERN ORTHODOX USAGE
Russian icon of the Theophany (the baptism of
Jesus by John the
Baptist ) (6 January), the highest-ranked feast which occurs on the
fixed cycle of the
Eastern Orthodox liturgical calendar .
Although most Eastern Orthodox countries (most of them in eastern or
southeastern Europe ) had adopted the
Gregorian calendar by 1924,
their national churches had not. The "Revised Julian calendar" was
endorsed by a synod in
May 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
Jerusalem . All Orthodox churches refused to accept
the lunar part, so almost all Orthodox churches continue to celebrate
Easter according to the
Julian calendar (with the exception of the
Orthodox Church and the Finnish
Orthodox Church ).
The solar part of the
Revised Julian calendar
Revised Julian calendar was accepted by only
some Orthodox churches. Those that did accept it, with hope for
improved dialogue and negotiations with the western denominations,
were the Ecumenical Patriarchate of
Constantinople , the Patriarchates
Antioch , the Orthodox Churches of Greece , Cyprus ,
Romania , Poland (from 1924 to 2014 but remain permitted to use the
Revised Julian calendar
Revised Julian calendar in parishes that want it), Bulgaria (the last
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 2799.
The Orthodox Churches of
Serbia , Montenegro ,
Poland (from 15
June 2014), Macedonia , Georgia , Ukraine , and the
Greek Old Calendarists and other groups continue to use the Julian
calendar, thus they celebrate the Nativity on 25
(which is 7
January Gregorian until 2100). The Russian Orthodox Church
has some parishes in the west which celebrate the Nativity on 25
December Gregorian until 2799.
Parishes of the
Orthodox Church in America Bulgarian Diocese , both
before and after the 1976 transfer of that diocese from the Russian
Orthodox Church Outside
Russia to the
Orthodox Church in America, were
permitted to use this date. Some
Old Calendarist groups which stand in
opposition to the state churches of their homelands will use the Great
Feast of the Theophany (6
January Gregorian) as a
day for religious processions and the
Great Blessing of Waters , to
publicise their cause.
Oriental Orthodox Churches generally use the local calendar of
their homelands. However, when calculating the Nativity Feast, most
observe the Julian calendar. This was traditionally for the sake of
unity throughout Christendom. In the west, some Oriental Orthodox
Churches either use the
Gregorian calendar or are permitted to observe
the Nativity according to it. The Armenian Apostolic Orthodox Church
celebrates the Nativity as part of the Feast of Theophany according to
its traditional calendar.
Conversion between Julian and Gregorian calendars
Julian year (astronomy)
* List of adoption dates of the
Gregorian calendar per country
Proleptic Julian calendar
Revised Julian calendar
Revised Julian calendar
* ^ Richards 2013 , p. 595.
* ^ Using value from Richards (2013, p. 587) for tropical year in
mean solar days, the calculation is 1/(365.2425-365.24217)
* ^ Introduction to Calendars. (15
United States Naval
* ^ Social Security Administration publication GN 00307.180 -
* ^ Social Security Administration (26
August 2005). "GN 00307.180
Gregorian/Julian calendar". Retrieved 27
July 2016. Although the
Russian authorities officially changed calendars in 1918, individual
registrars particularly in remote areas continued to use the old
calendar for as long as ten years.
* ^ Towards a Common Date of Easter. (5–10 March). World Council
of Churches/Middle East Council of Churches Consultation, Aleppo,
* ^ Oxby, Clare (1998). "The manipulation of time: Calendars and
power in the Sahara". Nomadic Peoples, New Series. 2 (1/2): 137–149.
JSTOR 43123542 .
* ^ A B C The letter J was not invented until the 16th century.
* ^ Censorinus, The Natal Day, 20.28, tr. William Maude, New York
1900, available at and Macrobius, Saturnalia, 1.13.12, 1.13.15 tr.
Percival Vaughan Davies, New York 1969,
Latin text at say that an
intercalary month of 22 or 23 days was inserted at or near the end of
February. Varro, On the
Latin Language, 6.13, tr. Roland Kent, London
1938, available at says that in intercalary years the last five days
February were dropped. They were re – added at the end of the
intercalary month and formed part of it.
* ^ An intercalary day was sometimes inserted after
prevent the nones and ides of
March falling on a nundine. See
Macrobius, Saturnalia, 1.13.16-1.13.19 tr. Percival Vaughan Davies,
New York 1969,
Latin text at . Those who say the length of
Intercalaris was fixed also say that the intercalary day was sometimes
February and Intercalaris even when no
nones/ides/nundine clash would otherwise have occurred. See Mrs A K
Calendar of the Roman Republic, Princeton 1967.
* ^ The spelling Quinctilis is also attested; see page 669 of The
Oxford Companion to the Year.
* ^ T H Key, "A Dictionary of Greek and Roman Antiquities" (article
Calendarium), London, 1875, available at .
* ^ Blackburn, B & Holford-Strevens, L The Oxford Companion to the
Year, Oxford University Press, 1999, reprinted with corrections, 2003,
* ^ Censorinus, De die natali 20.7 (Latin)
* ^ A B Varro, On Agriculture I.1.28.
* ^ Pliny, Natural History: (Book 18, LIX / LXVI / LXVIII / LXXIV).
* ^ Parker, R. A. (
May 1974). "Ancient Egyptian Astronomy".
Philosophical Transactions of the Royal Society of London. Series A,
Mathematical and Physical Sciences. 276 (1257): 51–65.
JSTOR 74274 .
* ^ Hartner, Willy. "The young Avestan and Babylonian calendars and
the antecedents of precession." Journal for the
History of Astronomy
10 (1979): 1. pp. 1–22. doi:10.1177/002182867901000102
* ^ Stern, Sacha. Calendars in antiquity: Empires, states, and
societies. Oxford University Press, 2012., p. 178.
* ^ A B Lucan,
Pharsalia : Book 10.
* ^ Émile Biémont, Rythmes du temps, astronomie et calendriers,
éd. De Boeck (Bruxelles), 2000 (ISBN 2-8041-3287-0 ), p. 224.
* ^ Suetonius, Caesar 52.1.
* ^ Plutarch, Lives of the Noble Grecians and Romans: Caesar 59.
* ^ Pliny, Natural History: (Book 18, LVII).
* ^ Encyclopædia Britannica Sosigenes of Alexandria.
* ^ Macrobius, Saturnalia I.14.2 (Latin).
* ^ It is not known why he decided that 67 was the correct number
of days to add, nor whether he intended to align the calendar to a
specific astronomical event such as the winter solstice. Ideler
suggested (Handbuch der mathematischen und technischen Chronologie II
123–125) that he intended to align the winter solstice to a
supposedly traditional date of 25 December. The number may compensate
for three omitted intercalary months (67 = 22+23+22). It also made the
distance from 1
March 46 BC, the original New Years
Day in the Roman
calendar, to 1
January 45 BC 365 days.
* ^ e.g., "... we have a sidelight on what was involved in "the
year of confusion" as it was called. According to Dion Cassius, the
historian, there was a governor in Gaul who insisted that, in the
lengthened year, two months' extra taxes should be paid. The extra
months were called
Undecimber and Duodecimber." (P. W. Wilson, The
romance of the calendar (New York, 1937), 112). The eponymous dating
of the cited passage (Dio Cassius 54.21) shows that it actually refers
to an event of 15 BC, not 46 BC.
* ^ J. Rüpke, The Roman
Calendar from Numa to Constantine: Time,
History and the Fasti, 117f., suggests, based on the ritual structures
of the calendar, that 5 days were added to
November and that the two
intercalary months each had 31 days, with Nones and Ides on the 7th
* ^ William Smith ,
Dictionary of Greek and Roman Antiquities :
Year of Julius Caesar), following
Ideler , interprets Macrobius,
Saturnalia 1.14.13 (Latin) to mean that Caesar decreed that the first
day of the new calendar began with the new moon which fell on the
night of 1/2
January 45 BC. (The new moon was on 2
January 45 BC (in
Proleptic Julian calendar ) at 00:21 UTC, according to IMCCE (a
branch of the
Paris Observatory ): Phases of the moon (between −4000
and +2500).) However, more recent studies of the manuscripts have
shown that the word on which this is based, which was formerly read as
lunam, should be read as linam, meaning that
Macrobius was simply
stating that Caesar published an edict giving the revised calendar —
see e.g., p.99 in the translation of
Macrobius by P. Davies. Smith
gives no source or justification for his other speculation that Caesar
originally intended to commence the year precisely with the winter
* ^ Macrobius, Saturnalia 1.14.9 (Latin). Exceptionally, the extra
April was inserted as the 26th, a.d. VI Kal. Mai. in the Julian
calendar, in order to avoid adding a day to the
Floralia , which ran
from a.d. IV Kal. Mai. (27
April in the pre-Julian calendar) to a.d. V
* ^ Macrobius, Saturnalia 1.14.12 (Latin).
* ^ A. K. Michels, The
Calendar of the
Roman Republic Appendix II;
J. Rüpke, The Roman
Calendar from Numa to Constantine 113–114,
* ^ W. Sternkopf, "Das Bissextum", (JCP 41 (1895) 718–733).
* ^ Justinian, Digest 50.16.98.
* ^ Dio Cassius 48.33.4, 60.24.7; C. J. Bennett, "The Imperial
Nundinal Cycle", Zeitschrift für Papyrologie und Epigraphik 147
* ^ Roscoe Lamont, "The
Roman calendar and its reformation by
Julius Caesar", Popular
Astronomy 27 (1919) 583–595. Sacrobosco's
theory is discussed on pages 585–587.
* ^ Roman Republican calendar.
* ^ Macrobius, Saturnalia 1.13.7 and 1.14.7–8 (Latin),
Censorinus, De die natali 20.10 (Latin), (English).
* ^ Censorinus, De die natali 20.9 (Latin), (English)
* ^ Macrobius, Saturnalia 1.14.7 (Latin)
* ^ A B C Alexander Jones, Calendrica II: Date Equations from the
Reign of Augustus, Zeitschrift fűr Papyrologie und Epigraphik 129
(2000) 159–166, available at .
* ^ A. Degrassi, Inscriptiones Italiae XIII:
Fasti et Elogia 2:
Fasti Anni Numani et Iuliani; Accedunt Feralia, Menologia Rustica,
Parapegmata (Rome, 1963) 66 (Latin)
* ^ This section is based on S. Stern, Calendars in Antiquity (OUP
2012) pp. 259–297.
* ^ Studied in detail in W. Kubitschek, Die Kalendarbücher von
Florenz, Rom und Leyden (Vienna, 1915).
* ^ Gaius Julius Solinus, De mirabilibus mundi, c.3, available at .
* ^ Gaius Plinius Secundus, Natural History, Vol. 2, 18.57, tr. J
Bostock and H T Riley, London 1855, available at .
* ^ The Roman
History of Ammianus Marcellinus, 26.10, Loeb
Classical Library vol. II, Harvard 1940, available at .
* ^ Gaius
Suetonius Tranquillus, Life of Julius Caesar, 40.1, Loeb
Classical Library, Harvard 1913, available at .
* ^ Censorinus, The Natal Day, 20.30, tr. William Maude, New York
1900 available at .
Macrobius Ambrosius Theodosius, Saturnalia, 1.14.13–1.14.14,
tr. Percival Vaughan Davies, New York 1969,
Latin text at
* ^ Marcus Terentius Varro, On the
Latin Language, 6.13, tr. Roland
Kent, London 1938 available at .
* ^ Nautical Almanac Offices of the United Kingdom and the United
States. (1961). Explanatory Supplement to the Astronomical Ephemeris
and the American
Ephemeris and Nautical Almanac, London: Her Majesty's
Stationery Office. p. 410–11.
* ^ Pierre Brind'Amour, Le calendrier romain, Ottawa 1983, pp.
* ^ Dio Cassius 48.33.4, tr. Earnest Cary, Loeb Classical Library,
9 vol., Harvard 1914–1927, available at .
* ^ Refutation of Brind'Amour's theory by John Ward, Re:
Intercalation in 45BC to 8AD, East Carolina University Calendar
discussion List CALNDR-L,
* ^ C. J. Bennett, "The Early Augustan Calendars in
Egypt", Zeitschrift fűr Papyrologie und Epigraphik 142 (2003)
221–240 and "The Early Augustan Calendars in
Rome and Egypt: Addenda
et Corrigenda", Zeitschrift fűr Papyrologie und Epigraphik 147 (2004)
165–168; see also Chris Bennett, A.U.C. 730 = 24 B.C. (Egyptian
* ^ W. Soltau, Römische Chronologie (Freiburg, 1889) 170–173. He
accepted Matzat's phase of the triennial cycle but argued that it was
absurd to suppose that Caesar would have made the second Julian year a
leap year and that the 36 years had to be accounted from 45 BC.
* ^ H. Matzat, Römische Chronologie I (Berlin, 1883), 13–18. His
argument rested on Dio Cassius 48.33.4 which mentions a leap day
inserted in 41 BC, "contrary to the (i.e., Caesar's) rule", in order
to avoid having a market day on the first day of 40 BC. Dio stated
that this leap day was compensated for "later". Matzat proposed this
was done by omitting a scheduled leap day in 40 BC, rather than by
omitting a day from an ordinary year.
* ^ C. L. Ideler, Handbuch der mathematischen und technischen
Chronologie (Berlin, 1825) II 130–131. He argued that Caesar would
have enforced the bissextile day by introducing it in his first
reformed year. T. E. Mommsen, Die Römische Chronologie bis auf Caesar
(Berlin, 1859) 282–299, provided additional circumstantial
* ^ J. Kepler, De Vero Anno Quo Æternus Dei Filius Humanan Naturam
in Utero Benedictæ Virginis Mariæ Assumpsit (Frankfurt, 1614) Cap.
V, repub. in F. Hammer (ed.), Johannes Keplers Gesammelte Werke
(Berlin, 1938) V 28.
* ^ A B C D For the list of triennial leap years proposed by
Bünting, Christmann and Harriot, see Harriot\'s comparative table
reproduced by Simon Cassidy (Fig. 6). The table numbers years as
Julian years, where Julian year 1 = 45 BC. Thus, Scaliger and Clavius
(col. 7) resume intercalation in Julian year 53 = AD 8, while Bünting
(col. 8) and Harriot (col. 3) resume it in Julian year 49 = AD 4 and
Christmann (col. 9) in year 52 = AD 7.
* ^ J. Christmann Muhamedis Alfragani arabis chronologica et
astronomica elementa (Frankfurt, 1590), 173. His argument assumed that
the triennial cycle started in the third Julian year.
* ^ J. J. Scaliger, De emendatione temporum (Paris, 1583), 159,
* ^ Dieter Hagedorn, Zum aegyptischen Kalender unter Augustus,
Zeitschrift fűr Papyrologie und Epigraphik 100 (1994) 211–222,
available at .
* ^ OGIS 458 (Greek).
* ^ B A Buxton and R Hannah in Studies in
Latin Literature and
History (ed. C Deroux), XII 290.
* ^ U. Laffi, "Le iscrizioni relative all'introduzione nel 9 a.c.
del nuovo calendario della provincia d'Asia", Studi Classici e
Orientali 16 (1967) 5–99.
* ^ Suetonius, Caesar 76.1.
* ^ Suetonius,
Augustus 31.2; Macrobius, Saturnalia 1.12.35 (Latin)
* ^ Suetonius,
* ^ Tacitus, Annals 15.74, 16.12.
* ^ Suetonius,
* ^ Dio Cassius 73.15.3.
* ^ Historia Augusta,
Tacitus 13.6. On the chronology see R.
* ^ Surveyed in K. Scott, Honorific Months, Yale Classical Studies
2 (1931) 201–278.
* ^ Suetonius,
* ^ Historia Augusta,
Antoninus Pius 10.1.
* ^ Einhard, Life of Charlemagne, 29.
* ^ This name of February, the only name in the list without the
"month" suffix, is explained by König, Festschrift Bergmann (1997),
pp. 425 ff. as a collective of horn, taken to refer to the antlers
shed by red deer during this time. Older explanations compare the name
with Old Frisian horning (Anglo-Saxon hornung-sunu, Old Norse
hornungr) meaning "bastard, illegitimate son", taken to imply a
meaning of "disinherited" in reference to
February being the shortest
* ^ Chronography of AD 354.
Censorinus De die natali 21.6 (Latin). Because the festivities
associated with the
Parilia conflicted with the solemnity of
which was observed until the Saturday before
Easter Sunday, the early
Roman church did not celebrate
Easter after 21
April – Charles W.
Jones, "Development of the
Latin Ecclesiastical calendar", Bedae Opera
de Temporibus (1943), 1–122, p.28.
* ^ For a partial survey see A. E. Samuel, Greek and Roman
Chronology: calendars and years in classical antiquity (Munich, 1972),
245ff. Samuel introduces his survey by saying: "The number of eras
which came into use and then expired to be replaced by yet other eras
during Hellenistic and Roman times is probably not infinite, but I
have not been able to find the end of them." Anatolian eras are
exhaustively surveyed in W. Leschhorn, Antike Ären: Zeitrechnung,
Politik und Geschichte im Schwarzmeerraum und in Kleinasien nördlich
des Tauros (Stuttgart, 1993).
* ^ A. A. Mosshammer, The
Computus and the Origins of the
Era (Oxford, 2008) 27–29.
* ^ История календаря в России и в
Calendar history in
Russia and in the USSR).
* ^ M. L. R. Beaven, "The Regnal Dates of Alfred, Edward the Elder,
and Athelstan", English Historical Review 32 (1917) 517–531; idem,
"The Beginning of the
Year in the Alfredian
English Historical Review 33 (1918) 328–342.
* ^ Catholic Encyclopedia, General
Chronology (Beginning of the
* ^ Pepys Diary, "I sat down to end my journell for this year, ..."
* ^ Spathaky, Mike
Old Style and New Style dates and the change to
the Gregorian calendar.
* ^ Spathaky, Mike
Old Style and New Style dates and the change to
the Gregorian calendar. "An oblique stroke is by far the most usual
indicator, but sometimes the alternative final figures of the year are
written above and below a horizontal line, as in a fraction (a form
which cannot easily be reproduced here in ASCII text). Very
occasionally a hyphen is used, as 1733-34."
John James Bond , "Commencement of the Year", Handy-book of
rules and tables for verifying dates with the Christian era, (London:
* ^ Mike Spathaky Old Style and New Style Dates and the change to
the Gregorian Calendar: A summary for genealogists.
* ^ The source has Germany, whose current area during the sixteenth
century was a major part of the Holy Roman Empire, a religiously
divided confederation. The source is unclear as to whether all or only
parts of the country made the change. In general, Roman Catholic
countries made the change a few decades before Protestant countries
* ^ Sweden's conversion is complicated and took much of the first
half of the 18th century. See
Swedish calendar .
* ^ Per decree of 16
June 1575. Hermann Grotefend, "Osteranfang"
Easter beginning), Zeitrechnung de Deutschen Mittelalters und der
Chronology of the German
Middle Ages and modern times)
* ^ 1751 in England only lasted from 25
March to 31 December. The
January to 24
March which would have concluded 1751 under the
old calendar became part of 1752 when the beginning of the numbered
year was changed from 25
March to 1 January.
* ^ See
Rumi calendar for details. It is often stated that Turkey
Gregorian calendar in 1926 or 1927. This refers to the
adoption of the Anno domini era.
* ^ Richards 1998 , p. 216.
* ^ Walker 2009 .
* ^ "Estonian
Orthodox Church (Estonian Events)". Vancouveri Eesti
Apostliku Õigeusu Kirik. 2010.
* ^ Bishop Photius of Triaditsa, "The 70th Anniversary of the
Pan-Orthodox Congress, Part II of II"; "HELSINGIN SANOMAT
(International edition)". 21
* Bonnie Blackburn and Leofranc Holford-Strevens, The Oxford
Companion to the Year, Oxford University Press, reprinted with
* Brind'Amour, Pierre (1983). Le Calendrier romain: Recherches
chronologiques. Ottawa University Press.
* "Ethiopian Time". Washington D.C.: Embassy of Ethiopia. 2008.
* Feeney, Dennis (2007). Caesar's Calendar: Ancient
Time and the
Beginnings of History. Berkeley: University of California Press.
* Rüpke, Jörg (2011). The Roman