Part 2 of 2 parts >> From uia.ac.be!donche2 Thu Mar 3 02:11:16 1994 >> From: "PieterAV.Donche" >> Subject: Re: Julian vs. Gregorian Calendar > Could this text be included in the ROOTS-L archive for other > ROOTS-L/soc.roots users? ---------------------------------------------------------------- ____ Pieter Donche E-mail: donche@uia.ac.be // /// \ Univ. Inst. Antwerpen /\ _/~ Rekencentrum A2.23 Voice: +32 (0)3.820.22.02 ~~/` EU Universiteitsplein 1, Fax : +32 (0)3.820.22.44 __\_ _ B 2610 Wilrijk /_/ \\\_/ Belgium (`) EUROPE =~ = This text is a copy from what can be found in the Encyclopedia Britannica about European and Middle-East calendars. A few ** NOTES have been added and a minor error corrected. ENCYCLOPAEDIA BRITANNICA: Early Calendar systems; Jewish and Muslim calendar -------------------------------------------------------------------------------- Part 2 of 2 parts. In the latter, the commencement of the month was determined by the observation of the crescent New Moon, and the date of the Passover was tied in with ripening of barley. The actual witnessing of the New Moon and observing of the stand of crops in Judaea were required for the functioning of the religious calendar. The Jews of the Diaspora, who generally used the civil calendar of their respective countries, were informed by messengers from Palestine about the coming festivals. This practice is already attested for 143 BC. After the destruction of the Temple in AD 70, rabbinic leaders took over from the priests the fixing of the religious calendar. Visual observation of the New Moon was supplemented and towards AD 200, in fact, supplanted by secret astronomical calculation. But the Diaspora, or Dispersion, was often reluctant to wait for the arbitrary decision of the calendar makers in the Holy Land. Thus, in Syrian Antioch in AD 328-342, the Passover was always celebrated in (Julian) March, the month of the spring equinox, without regard to the Palestinian rules and rulings. To preserve the unity of Israel, the patriarch Hilel II, in 358/359, published the "secret" of calendar making, which essentially consisted of the use of the Babylonian 19-year cycle with some modifications required by the Jewish ritual. The application of these principles occasioned controversies as late as the 10th century AD. In the 8th century, the Karaites, following Muslim practice, returned to the actual observation of the crescent New Moon and of the stand of barley in Judaea. But some centuries later they also had to use a precalculated calendar. The Samaritans, likewise, used a computed calendar. Because of the importance of the sabbath as a time divider, the seven-day week served as a time unit in Jewish worship and life. As long as the length of a year and of every month remained unpredictable, it was convenient to count weeks. The origin of the biblical septenary, or seven-day, week remains unknown; its days were counted from Sunday on. A visionary, probably writing in the Persian or early Hellenistic age under the name of the prediluvian Enoch, suggested the religious calendar of 364 days, or 52 weeks, based on the week, in which all festivals always fell on the same weekday. His idea was later taken up by the Dead Sea Scrolls people. THE MUSLIM CALENDAR ------------------- The Muslim Era is computed from the starting point of the year of the emigration (Hegira); that is, from the year in which Muhammad, the prophet of Islam, migrated from Mecca to Medina, 622 AD. The second caliph, Umar I, who reigned 634-644, set the first day of the month Muharram as the beginning of the year (see table of months and days); days days Muharram 30 Rajab 30 Safar 29 Sha'ban 29 Rabi I 30 Ramadan 30 Rabi II 29 Shawwal 29 Jumada I 30 Dhu al-Qa'dah 30 Jumada II 29 Dhu al-Hijjah 29 that is, July 16, 622 which had already been fixed by the Quran as the first day of the year. The years of the Muslim calendar are lunar and always consist of 12 lunar months alternately 30 and 29 days long, beginning with the approximate New Moon. The year has 354 days, but the last month (Dhu al-Hijjah) sometimes has an intercalated day, bringing it up to 30 days and making a total of 355 days for that year. ** NOTE: In a 30-year cycle, the years 2, 5, 7, 10, 13, 16, 18, 21, 14, 26 and 29 are leap years. The Turks used an eight year cycle, with leap years in the years 2, 5 and 7. The months do not keep to the same seasons in relation to the Sun, because there are no intercalations of months. The months regress through all the seasons every 32 1/2 years. The names of the months and the number of days in each are given in the accompanying table. Ramadan, the ninth month, is observed throughout the Muslim world as a month of fasting. According to the Quran, Muslims must see the New Moon with the naked eye before they can begin their fast. It has become usual for Middle Eastern Arab countries to accept, with reservations, the verdict of Cairo. Should the New Moon prove to be invisible, then the month Shaban, immediatly preceding Ramadan, will be reckoned as 30 days in length, and the fast will begin on the day following the last day of this month. The end of the fast follows the same procedure. The era of the Hegira is the official era in Saudi Arabia, Yemen, and the principalities of the Persian Gulf, Egypt, Syria, Jordan, and Morocco use both the Muslim and the Christian eras. In all Muslim countries, people use the Muslim Era in private, even though the Christian Era may be in official use. Some Muslim countries have made a compromise on this matter. Turkey, as early as 1088 AH (AD 1677), took over the solar (Julian) year with its month names but kept the Muslim Era. March 1 was taken as the beginning of the year (commonly called marti year, after the Turkish word mart, for March). Late in the 19th century, the Gregorian calendar was adopted. In the 20th century, Pres. Mustafa Kemal Ataturk ordered a complete change to the Christian era. Iran, under Reza Shah Pahlavi (reigned 1925-41), also adopted the solar year but with Persian names for the months and keeping the Muslim Era. March 21 is the beginning of the Iranians year. Thus, the Iranian year 1349 began on March 21, 1970. ENCYCLOPAEDIA BRITANNICA: Julian and Gregorian calendar -------------------------------------------------------------------------------- I. Early calendar systems Standard units and cycles Time determination by stars, sun, and moon Complex cycles The early Roman calendar The Jewish calendar The Muslim calendar II. The western calendar The Julian calendar The Gregorian calendar II. THE WESTERN CALENDAR ======================== The calendar now in general worldwise use had its origin in the desire for a solar calendar that kept in step with the seasons and possessed fixed rules of intercalation. Because it developped in Western Christendom, it had also to provide a method for dating movable religious feasts, the timing of which had been based on a lunar reckoning. To reconcile the lunar and solar schemes, features of the Roman Republican calendar and the Egyptian calendar were combined. The Roman Republican calendar was basically a lunar reckoning and became increasingly out of phase with the seasons as time passed. By about 50 BC the vernal equinox that should have fallen late in March fell on the Ides of May, some eight weeks later, and it was plain that this error would continue to increase. Moreover, the behaviour of the Pontifices made it necessary to seek a fixed rule of intercalation in order to put an end to arbitrariness in inserting months. In addition to the problem of intercalation, it was clear that the average Roman Republican year of 366.25 days would always show a continually increasing disparity with the seasons, amounting to one month every 30 years, or three months a century. But the great difficulty facing any reformer was there seemed to be no way of effecting a change that would still allow the months to remain in step with the phases of the Moon and the year with the seasons. It was necessarry to make a fundamental break with traditional reckoning to devise an efficient seasonal calendar. THE JULIAN CALENDAR ------------------- In the mid-1st century BC Julius Caesar invited Sosigenes, an Alexandrian astronomer, to advise him about the reform of the calendar, and Sosigenes decided that the only practical step was to abandon the lunar calendar altogether. Months must be arranged on a seasonal basis, and a tropical (solar) year used, as in the Egyptian calendar, but with its length taken as 365 1/4 days, a value more accurate than the Egyptians' 365. To remove the immense discrepancy between calendar date and equinox, it was decided that the year known in modern times as 46 BC should have two intercalations. The first was the customary intercalation of the Roman Republican calendar due that year, the insertion of 23 days following February 23. The second intercalation, to bring the calendar in step with the equinoxes, was achieved by inserting two additonal months between the end of November and the beginning of December. This insertion amounted to an addition of 67 days, making a total intercalation for the year of 90 days, and causing the beginning of March, 45 BC in the Roman Republican calendar, to fall on what is still called the January 1 of the Julian calendar. Previous errors having been corrected, the next step was to prevent their recurrence. Here Sosigenes' suggestion about a tropical year was adopted and any pretence to a lunar calendar rejected. The figure of 365.25 days was accepted for the tropical year, and to achieve this by a simple civil reckoning, Caesar directed that a calendar year of 365 days be adopted and that an extra day be intercalated between February 23 and 24 every fourth year. Since February ordinarily had 28 days, February 23 was the sixth day before the Kalendae, or beginning of March, and known as the sexto-kalendae; the intercalary day, when it appeared, came the day after, and was therefore called the bis-sexto- kalendae. This practice led to the term bissextile being used to refer to such a leap year. The name leap year is a later connotation, probably derived from the Old Norse hlaupa ("to leap") and used because, in a bissextile year, any fixed festival after February leaps forward, failing on the next weekday but one to that on which it fell the previous year, not on the next weekday as it would to in an ordinary year. In Caesar's edict, the intercalary day was known as a punctum temporis (point of time), and anyone born that day had subsequent birthdays on February 23 (the day before); but lawyers then and in medieval times raised a number of arguments about its precise interpretation. Also, the Pontifices misinterpreted the edict and inserted the intercalation too frequently. The error arose because of the Roman practice of inclusive numbering, so that an intercalation once every fourth year meant to them intercalating every three years, because a bissextile year was counted as the first year on the next four year period. This error continued undetected for 36 years, during which period 12 days instead of nine were added. The emperor Augustus made a correction by omitting intercalary days between 8 BC and AD 4. In consequence it was not until 48 years after 45 BC that the Julian calendar came into proper operation, a fact that is important in chronology but is often forgotten. It seems that the months of the Julian calendar were taken over from the Roman Republican calendar but were slightly modified to give a more even pattern of numbering. The Republican calendar months of March, May, and Quintilis (July), which had each possessed 31 days, were retained unaltered. Although there is doubt about the details, changes seem probably to have occurred as follows. Except for October, all the months that had previously had only 29 days had either one or two days added. January, September, and November received two days, bringing their totals to 31, while April, June, Sextilis (August), and December received one day each, bringing their totals to 30. October was reduced by one day to a total of 30 days, and February increased to 29 days, or 30 in a bissextile year. With the exception of February, the scheme resulted in months having 30 or 31 days alternately throughout the year. And in order to help farmers, Caesar issued an almanac showing on which dates of his new calendar various seasonal astronomical phenomena would occur. These arrangements for the months can only have remained in force for a short time, because in 8 BC changes were made by Augustus. In 44 BC, the second year of the Julian calendar, the Senate had decided to alter the name of the month Quintilis to Julius (July), in honour of Julius Caesar, and in 8 BC Augustus prevailed upon them to change the name of Sextilis to Augustus (August), in his honour. Perhaps because Augustus felt that his month must have at least as many days as Julius Caesar's, February was reduced to 28 days and August increased to 31. But because this made three 31 day months (July, August, and September) appear in succession, Augustus is supposed to have reduced September to 30 days, added a day to October to make it 31 days, reduced November from 30 to 31 days, giving the months the lengths they have today. ** NOTE: The story that Augustus took one day from February to increase August, first appeared in the Encyclopaedia Britannica in 1820. It is untrue. Already under Numa Pompilius (715-672 BC) February had 28 days. During the calendar reform of Julius Caesar the length of the months changed to their present values. The name of the month Sextilis was changed to August in honour of Augustus, for having corrected in 8 BC the error in the insertion of the leap day. The Julian calendar retained the Roman Republican calendar method of numbering the days of the month. Compared with the present system, the Roman numbering seems to run backward, for the first day of the month was known as the Kalendae, but subsequent days were not enumerated as so many after the Kalendae but as so many before the following Nonae ("nones"), the day called nonae being the ninth day before the Ides (from iduare, meaning "to divide"), which occured in the middle of the month and were supposed to coincide with the full moon. Days after the Nonae and before the Ides were numbered as so many before the Ides, and those after the Ides as so many before the Kalendae of the next month. There were no weeks in the original Julian calendar, but days were designated either dies fasti or dies nefasti, the former being business days and days on which the courts were open: this had been the practice in the Roman Republican calendar. Julius Caesar designated his additional days all as dies fasti, and they were added at the end of the month, so that there was no interference with the dates traditionally fixed for dies comitales (days when public assemblies might be convened) and dies festi and dies feriae (religious festivals and holy days). Originally, then, the Julian calendar had a permanent set of dates for administrative matters. The official introduction of the seven-day week by the Emperor Constantine I in the 4th century AD disrupted this arrangement. It appears, from the date of insertion of the intercalary month in the Roman Republican calendar and the habit of designating years by the names or the consuls, that the calendar year had originally commenced in March, which was the date when the new consul took office. In 222 BC the date of assuming duties was fixed as March 15, but in 153 BC it was transferred to the Kalendae of January, and there it remained. January therefore became the first month ot the year, and in the western region of the Roman Empire, this practice was carried over into the Julian calendar. In the eastern provinces, however, years were often reckoned from the accession of the reigning emperor, the second beginning on the first new year's day after the accession; and the date on which this occurred varied from one province to another. THE GREGORIAN CALENDAR ---------------------- The Julian calendar year of 365.25 days was too long, since the correct value for the tropical year is 365.242199 days. This error of 11 minutes 14 seconds per year amounted to almost one and a half days in two centuries, and seven days in 1,000 years. ** NOTE: The following table gives the number of days to add to a date of the Julian calendar to find the Gregorian date. If the Gregorian Calendar would have been introduced between 200-300 AD, no skipping of days would have been necessary. The notation 200-300 means: from leap day of Julian year 200 to the day before the leap-day of Julian year 300, and so on. 200 - 300: +0 900 - 1000: +5 1500 - 1700: +10 300 - 500: +1 1000 - 1100: +6 1700 - 1800: +11 500 - 600: +2 1100 - 1300: +7 1800 - 1900: +10 600 - 700: +3 1300 - 1400: +8 1900 - 2000: +13 700 - 900: +4 1400 - 1500: +9 Once again the calendar became increasingly out of phase with the seasons. From time to time, the problem was placed before church councils, but no action was taken because the astronomers who were consulted doubted whether enough precise information was available for a really accurate value of the tropical year to be obtained. By 1545, however, the vernal equinox, which was used in determining Easter, had moved ten days from its proper date; and in December, when the Council of Trent met for the first of its sessions, it authorized Pope Paul III to take action to correct the error. Correction required a solution, however, that neither Paul III nor his successors were able to obtain in satisfactory from until nearly 1572, the year of election of Pope Gregory XIII. Gregory found various proposals awaiting him and agreed to issue a bull that the Jesuit astronomer Christopher Clavius (1537-1612) began to draw up, using suggestions made by the astronomer and physician Luigi Lilio (also known as Aloysius Lilius; died 1576). The papal bull appeared in February 1582. First, in order to bring the vernal equinox back to March 21, the day following the Feast of St.Francis (that is, October 5) was to become October 15, thus omitting ten days. Second, to bring the year closer to the true tropical year, a value of 365.2422 days was accepted. This value differed by 0.0078 days per year from the Julian calendar reckoning, amounting to 0.78 days per century, or 3.12 days every 400 years. It was therefore promulgated that three out of every four centennial years should be common years, that is, not leap years; and this practice led to the rule that no centennial years should be leap years unless exactly divisible by 400. Thus, 1700, 1800 and 1900 were not leap years, as they would have been in the Julian calendar, but the year 2000 will be. The bull also laid down rules for calculating the date of Easter. The date of Easter; epacts. Easter was the most important feast of the Christian Church, and its place in the calendar determined the position of the rest of the Church's moveable feasts. Because its timing depended on both the Moon's phases and the vernal equinox, ecclesiastical authorities had to seek some way of reconciling lunar and solar calendars. Some simple form of computation, usable by non- astronomers in remote places, was desirable. There was no easy or obvious solution, and to make things more difficult there was no unanimous agreement on the way in which Easter should be calculated, even on a lunar calendar. Easter, being the festival of the Resurrection, had to depend on the dating of the Crucifixion, which occured three days earlier and just before the Jewish Passover. The Passover was celebrated in the 14th day of Nisan, the first month in the Jewish religious year - that is, the lunar month the 14th day of which falls on or next after the vernal equinox. The Christian churches in the eastern Mediterranean area celebrated Easter on the 14th of Nisan on whatever day of the week it might fall, but the rest of Christendom adopted a more elaborate reckoning to ensure that it was celebrated on a Sunday in the Passover week. To determine precisely how the Resurrection and Easter Day should be dated, reference was made to the Gospels; but even as early as the 2nd century AD, difficulties had arisen the synoptic Gospels (Matthew, Mark, and Luke) appeared to give a different date from the Gospel according to John for the Crucifixion. This difference led to controversy that was later exacerbated by another difficulty caused by the Jewish reckoning of a day from sunset to sunset. The question arose of how the evening of the 14th day should be calculated, and some - the quintadecimans - claimed that it meant one particular evening, but others - the quartadecimans - claimed that it meant the evening before, since sunset heralded a new day. Both sides had their protagonists, the eastern churches supporting the quartadecimans, the western churches the quintadecimans. The question was finally decided at the council of Nicaea, in 325, in favour of the quintadecimans, and the Western church agreed. The Eastern churches decided to retain the quartadeciman position, and the church in England, which had few links with the European churches at this time, retained the quartadeciman position until Roman missionaries arrived in the 6th century, when a change was made. The dating of Easter in the Gregorian calendar was based on the decision of the Council of Nicaea, which decreed that Easter should be celebrated on the Sunday immediatly following the Full Moon that fell on or after the vernal equinox, which they took as March 21. The Council also ordered that if this Sunday either coincided with the Jewish Passover or with the Easter Day of the quartadecimans, the festival should be held seven days later. With these provisions in mind, the problem could be broken down into two parts: first, devising a simple but effective way of calculating the days of the week for any date in the year and, second, determining the date of the Full Moons in any year. The first part was solved by the use of a letter code derived from a similar Roman system adopted for determining market days. For ecclesiastical use, the code gave what was known as the Sunday, or dominical, letter. The seven letters A through G are each assigned to a day, consecutively from January 1 so that January 1 appears as A, January 2 as B, to January 7 which appears as G, the cycle then continuing with January 8 as A, January 9 as B, and so on. Then in any year the first Sunday is bound to be assigned to one of the letters A-G in the first cycle, and all Sundays in the year possess that dominical letter. For example, if the first Sunday falls on January 3, C will be the dominical letter for the whole year. No dominical letter is placed against the intercalary day, February 29, but since it is still counted as a weekday and given a name, the series of letters moves back one day every leap year after intercalation. Thus, a leap year beginning with the dominical letter C will change to a year with the dominical letter D on March 1; and in lists of dominical letters, all leap years are given a double letter notation, in the example just quoted, CD. It is not difficult to see what dominical letter of letters apply to any particular year, and it is also a comparatively simple matter to draw up a table of dominical letters for use in determining Easter Sunday. The possible dates on which Easter Sunday can fall are written down - they run from March 22 to April 25 - and against them the dominical letters for a cycle of seven years. Once the dominical letter for a year is known, the possible Sundays for celebrating Easter can be read directly from the table. This system does not, of course, completely determine Easter; to do so, additional information is required. This must provide dates for Full Moons throughout the year, and for this a lunar cycle like the Metonic cycle was originally used. Tables were prepared, again using the range of dates on which Easter Sunday could appear, and against each date a number from 1 through to 19 was placed. This number indicated which of the 19 years of the lunar cycle would give a Full Moon on that day. From medieval times these were known as golden numbers, possibly from a name used by the Greeks for the numbers of the Metonic cycle or because gold is the colour used for them in manuscript calendars. The system of golden numbers was introduced in 530, but they were arranged as they should have been if adopted at the Council of Nicaea two centuries earlier; and the cycle was taken to begin in a year when the New Moon fell on January 1. Working backward, this date was found to have occured in the year preceding AD 1, and therefore the golden number for any year is found by dividing the year by 19, then adding one to the remainder. If the result is zero, the golden number for the year is 19. To compute the date of Easter, the medieval chronologer computed the golden number for the year and then consulted his table to see by which date this numer lay. Having found this date, that of the first Full Moon after March 20, he consulted his table of dominical letters for that year appeared; this was the Sunday to be designated Easter. The method, modified for dropping centennial leap years as practiced in the Gregorian calendar, is still given in the English prayer book, although it was officially discarded when the Gregorian calendar was introduced. The system of golden numbers was eventually rejected because the astronomical Full Moon could differ by as much as two days from the date they indicated. It was Lilius who had proposed a more accurate system based on one that had already been in use unofficially while the Julian calendar was still in force. Called the epact - the word is derived from the Greek epagein, meaning "to intercalate" - this was again a system of numbers concerned with the Moon's phases, but now indicating the age of the moon on the first day of the year, and from which the age of the Moon on any day of the year may be found, at least approximately, by counting, using alternately months of 29 and 30 days. The epact as previously used was not, however, completely accurate because, like the golden number, it had been based on the Metonic cycle. This cycle occupied a period of 6,939.75 days, whereas it should have lasted for 6,939.9 days; and although the difference is small, it does amount to one day in a little over 307 years, so that after this period, New Moons occur one day earlier than indicated. When the Gregorian calendar was adopted, this difference was taken into account. It was for convenience, that the error of one day could be said to occur once every 312 1/2 years, so that an eight-day error appeared once every 2,500 years. A one-day change on certain centennial years was then instituted by making the computed age of the Moon one day later seven times, at 300-years intervals, and an eighth time after a subsequent 400 years. This operation was known as the lunar correction, but it was not the only correction required; there was another. Because the Gregorian calendar used a more accurate value for the tropical year than the Julian calendar and achieved this by omitting most centennial leap years, Clavius decided that when the cycle of epacts reached an ordinary centennial year, the number of the epact should be reduced by one; this reduction became known at the solar correction. One advantage of the epact number was that it showed the age of the Moon on January 1 and so permitted a simple calculation of the dates of new Moon and Full Moon for the ensuing year. Another was that it lent itself to the construction of cycles of 30 epact numbers, each diminishing by one from the previous cycle, so that when it became necessary at certain centennial years to shift from one cycle to another, there would still be a cycle ready that retained a correct relationship between dates and New Moons. For determining Easter, a table was prepared of the golden numbers, 1 through 19, and below them the cycles of epacts for about 7,000 years; after this time, all the epact cycles are repeated. A second table was then drawn up, giving the dates of Easter full Moons for different epact numbers. Once the epact for the year was known, the date of the Easter Full Moon could be immediately obtained, while consultation of a table of dominical letters showed which was the next Sunday. Thus, the Gregorian system of epacts, while more accurate than the old golden numbers, still forced the chronologer to consult complex astronomical tables. Adoption is various countries. The derivation of the term style for a type of calendar seems to have originated some time after the 6th century as a result of developments in calendar computation in the previous 200 years. in AD 463, Victorius (or Victorinus) of Aquitaine, who had been appointed by Pope Hilarius to undertake calendar revision, devised the Great Paschal (i.e., Passover) period, sometimes later referred to as the Victorian Period. It was a combination of the solar cycle of 28 years and the Metonic 19-year cycle, bringing the Full Moon back to the same day of the month, and amounted to 28 x 19, or 532 years. In the 6th century, this period was used by Dionysius Exiguus (Denis the Little) in computing the date of Easter, because it gave the day of the week for any day in the year, and so it also became known as the Dionysian period. Dionysius took the year now called AD 532 as the first year of a new Great Paschal period and the year now designated 1 BC as the beginning of the previous cycle. In the 6th century it was the general belief that this was the year of Christ's birth, and because of this Dionysius introduced the concept of numbering years consecutively through the Christian era. The method was adopted by some scholars but seems to have become widely used after its popularization by the Venerable Bede of Jarrow (?673-735), whose reputation for scholarship was very high in Western Christendom in the 8th century. This system of BC/AD numbering threw into relief the different practices, or styles, of reckoning the beginning of the year then in use. When the Gregorian calendar firmly established January 1 as the beginning of its year, it was widely referred to as the New Style calendar, with the Julian the Old Style calendar. In Britain, under the Julian calendar, the year had first begun on December 25 and then, from the 14th century onward, on March 25. Because of the division of the Eastern and Western Christian churches and of Protestants and Roman catholics, the obvious advantages of the Gregorian calendar were not accepted everywhere, and in some places adoption was extremely slow. In France, Italy, Luxembourg, Portugal, and Spain, the New Style was adopted in 1582, and by most of the German Roman Catholic states as well as by Belgium and part of the Netherlands by 1584. Switzerland's change was gradual, beginning in 1583 and being completed only in 1812. Hungary adopted the New Style in 1587, and then there was a pause of more than a century before the first Protestant countries moved over from the Old Style calendar. In 1699-1700, Denmark and the Dutch and German Protestant states embraced the New Style, although the Germans declined to adopt the rules laid down for determining Easter, preferring to rely on astronomical tables and specifying the use of the Tabulae Rudolphinae (Rudolphine Tables), based on the 16th century observations of Tycho Brahe. They acceded to the Gregorian calendar rules for Easter only in 1776. Britain adopted the New Style in 1752 and Sweden in 1753, although, because the Swedes had in 1740 followed the German Protestants in using their astronomical methods for determining Easter, they declined to adopt the Gregorian calendar rules until 1844. ** NOTE: these are the Easter Dates not according to standard Julian or Gregorian calculations: De: Denmark and Norway Ne: the Northern Netherlands provinces Gelderland, Utrecht, Overijssel, Friesland, Groningen Zw: the Swiss cantons Zurich, Bern, Basel, Schaffhausen, Geneva, Muhlhausen, Biel Sw: Sweden and Finland Ge: the German Protestant States 1700: April 11 (De, Ne, Zw, Ge) 1745: April 7 (Sw) 1704: April 20 (De, Ne, Zw, Ge) 1746: March 30 (Sw) 1705: April 2 (Sw) 1747: March 33 (Sw) 1709: April 18 (Sw) 1748: April 3 (Sw) 1711: April 26 (Sw) 1749: March 26 (Sw) 1724: April 20 (Ne, Ge) 1750: March 18 (Sw) April 16 (De) 1751: March 31 (Sw) 1740: April 6 (Sw) 1752: March 22 (Sw) 1741: March 22 (Sw) 1802: April 25 (Sw) 1742: March 14 (Sw) 1805: April 21 (Sw) 1743: April 3 (Sw) 1818: March 29 (Sw) 1744: March 29 (De, Ne, Ge) March 18 (Sw) Japan adopted the New Style in 1873; Egypt in 1875; and between 1912 and 1917 it was accepted by Albania, Bulgaria, China, Estonia, Latvia, Lithuania, Romania, Turkey, and Yuguslavia. Soviet Russia adopted the New Style in 1918; Greece in 1923. In Britain and the British dominions, the change was made when the difference between the New and Old Style calendars amounted to 11 days, bu naming the day after September 2, 1752, as September 14, 1752; but there was much public misunderstanding, and in Britain rioters demanded "give us back our 11 days," even though legislation authorizing the change had been framed to avoid injustice and financial hardship. Alaska retained the Old Style calendar until 1867, when it was transferred from Russia to the United States. CALENDAR REFORM SINCE THE MID-18TH CENTURY ------------------------------------------ The French Republican calendar. In late 18-th century France, with the approach of the French Revolution, demands began to be made for a radical change in the civil calendar that would divorce it completely from any ecclesiastical connections. The first attacks on the Gregorian calendar and proposals for reform came in 1785 and 1788, the changes being primarely designed to divest the calendar of all its Christian associations. After the storming of the Bastille in July 1789, demands became more vociferous, and a new calendar, to start from "the first year of liberty," was widely spoken about. In 1793 the National Convention appointed Charles-Gilbert Romme, president of the committee of public instruction, to take charge of the reform. Technical matters were entrusted to the mathematicians Joseph-Louis Lagrange and Gaspard Monge and the renaming of the months to the Paris deputy to the convention, Fabre d'Eglantine. The results of their deliberations were submitted to the convention in September of the same year and were immedialty accepted, it being promulgated that the new calendar should become law on October 5. The French Republican calendar, as it came to be known, was taken to have begun on September 22, 1792, the day of the proclamation of the Republic and, in that year, the date also of the autumnal equinox. All future years were to begin on the same date. The total number of days in the year was 365, the same as in the Julian and Gregorian calendars, and this was divided into 12 months of 30 days each, the remaining five days being devoted to festivals and vacations. These were to fall between September 17 and 22 and were specified, in order, to be festivals of virtue, genius, labour, opinion, and rewards. In a leap year an extra festival was to be added - the festival of the Revolution. ** NOTE: The five festival days were named sans-culottides (vertu, genie, travail, opinion, recompense). In a leap year, there was a sixth day: sans-culottide par excellence. The name sans-culottides was replaced by Jours Complementaires on 7 Fructidor III (24 August 1795). Leap years were retained at the same frequency as in the Gregorian calendar, but is was enacted that the first leap year should be year 3, not year 4 as it would have been of the Gregorian calendar had been followed precisely in this respect. Each four-year period was to be known as a Franciade. The seven-day week was abandonned, and each 30-day month was divided into three periods of ten days called decades, the last day of a decade being a rest day. It was also agreed that each day should be divided into decimal parts, but this was not popular in practice and was allowed to fall into disuse. The months themselves were renamed so that all previous associations should be lost, and Fabre d'Eglantine chose descriptive names as follows (the descriptive nature and Gregorian calendar dates for 1793-95 are given in parentheses): Vendemiaire ("vintage", September 11 to October 21), Brumaire ("mist", October 22 to November 20), Frimaire ("frost", November 21 to December 20), Nivose ("snow", December 21 to January 19), Pluviose, ("rain", January 20 to February 18), Ventose ("wind", February 19 to March 20), Germinal ("seedtime", March 21 to April 19), Floreal ("blossom", April 20 to May 19), Prairial ("meadow", May 20 to June 18), Messidor ("harvest", June 19 to July 18), Thermidor ("heat", July 19 to August 17), and Fructidor ("fruits", August 18 to September 16). The French Republican calendar was short-lived, for while it was satisfactory enough internally, it clearly made for difficulties in communication abroad because its months continually changed their relationship to dates in the Gregorian calendar. In September 1805, under the Napoleontic regime, the calendar was virtually abandonned, and on January 1, 1806, it was replaced by the Gregorian calendar. The lack of success of the French Republican calendar has no doubt decided other regimes against adopting any similar system, for when Soviet Russia undertook its calendar reform in February 1918, it merely moved from the Julian calendar to the Gregorian, with a loss of 13 days, so that February 1 became February 13. ** NOTE: February 13 should be February 14. After leap day 1900, the number of days to skip to adjust to the Gregorian calendar is 13. This means that February 14 should follow January 31. In 1929, a Revolutionary calendar was proposed for the U.S.S.R., but never put into use.