Astro-Databank:Handbook chapter 11

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11. Calendar Changes

A calendar is a system for fixing the beginning, length, divisions of the civil year in a definite order. The Roman calendar system, taken from the Egyptians, was introduced in Rome during the reign of Julius Caesar. Historic beginning points may seem arbitrary in retrospect though they certainly had some reasonable basis at the time. The year 2,000, for example, is the year 4,698 for the Chinese, 5,761 for Jews and 1,422 A.H. for Muslims.

Julius Caesar added 90 days to the year 46 BC on the advice of the astronomer Sosigenes in order that the calendar might better conform to the changing seasons, establishing a 12-month year of 365 days with each fourth year having 366 days.

Pope Gregory XIII introduced the Gregorian Calendar in 1582 as a revision of the Julian calendar. He "suppressed" ten days because, by that time, spring was arriving on March 11th instead of the 21st, the time of the vernal equinox. Because the mean solar year is approximately 11 minutes shorter than 365 ¼ days, the Julian leap-year rule of "one extra day every 4th year" created three leap years too many in every 400-year period.

To prevent future misalignments to the calendar, the Gregorian revised leap-year rule was "one extra day in the years divisible by four, expect in the years that end in zero-zero. These years had to be divisible by 400." Thus, for example, the year 1600 would be a leap year but years 1700, 1800 and 1900 would not, which eliminated three leap years in the 400-year period. In today's world, we label a calendar year as one that begins on January 1st and concludes on December 31st. This demarcation was not always in use. The designation of the first day of the New Year, called the Date Style, has been named as a number of different days through the year.

The Gregorian calendar altered the year by omitting ten days as well as declaring the first day of the year to be January 1st. Prior to then, the first day of the year had been named as various days, most commonly March 25. The Gregorian calendar was not fully adopted in Great Britain until 1752 because of religious differences. Where the Roman Catholic countries were quick to adopt the new calendar, it was initially rejected by Protestant states. Eastern Orthodox churches rejected the new calendar and continued to use the Julian calendar with traditional lunar tables for calculating Easter. Because the purpose of the Gregorian calendar was to regulate the cycle of Christian holidays, its acceptance in the non-Christian world was initially not an issue. But as international trade and communication increased, the civil rules of the Gregorian calendar were gradually adopted around the world.

The Gregorian Calendar was not fully adopted in Great Britain until 1752 although it had been practically universal on the Continent for over a century. Because of the difference between English and Continental dates during 1582 and 1751, care must be taken with these dates. As long as Great Britain used the Julian Calendar, they continued to commence their New Year's Day on March 25th.

By the time that Great Britain converted to the Gregorian Calendar, the discrepancy between the reformed and the old (Julian) Calendar had then grown to 11 days, and students of history remember how the ignorant classes made public protest, afraid that they had been deprived of 11 days of their lives. By the time that the last countries left the Julian Calendar in the 20th century, the discrepancy had accumulated to 13 days.

The Florentine Calendar was used in Italy in the middle ages. In this system, the new day begins at sunset and continues until the following day. When the reference of a birth was, for example, "two hours into the day," this meant two hours after sunset. If this reference was considered to be, for example, August 12th, by modern reckoning we would still consider this to be August 11th, civil time.

Conversion Dates by Country: Old-Style (Julian) to New-Style (Gregorian) Calendars

The recommendations of Pope Gregory's calendar commission were instituted by the papal bull, "Inter Gravissimus," signed on February 24, 1582. Ten days were omitted from the calendar and the day following Thursday, October 4, 1582, became Friday, October 15, 1582. Along with the change of calendar style, the first day of the year, New Year's Day, was designated as January 1st. Prior to this, New years had been celebrated as the beginning of the year on various days (See New Year's Day, following).

Though we may note the calendar change as 1582, in actual practice, the people continued to use the Julian calendar long after. We even have an American president, George Washington, born in 1731/32, with a birth recorded as O.S. in Virginia, U.S.A. In Europe, for several centuries, Old Style and New Style were used side-by-side in different countries and by different cultures or even different families.

The logistics of War were further complicated by the fact that during World War I, England and Germany shared the same dates but Russia and Turkey had dates that were 14 days different. In certain areas of Greece, the Gregorian calendar was not adopted until 1924.

Alaska 1867, October 18, when transferred to the U.S.
Albania 1912, December, for civil purposes
Austria Different religions have different dates
Brixen, Salzzburg, Tyrol 1583, October5/16
Carintha, Syria 1583, December 14/25
(See also Hungary, Czechslovakia)
Belgium 1582, December 22 /January 1, 1583
Some provinces 1582, December 14/25
Bulgaria 1915, November 13 and 14 both given
1916, March 18 / April 1 given by some sources
1916, March 31 / April 14 given by other sources
1920, September 3/17 in some areas
Canada Different regions followed changes in U.K and France
Chinese Republic 1911, December 18 / 1912, January 1, however, both Gregorian and the Chinese calendars were given in official documents during 1912 - 1928
1928, December 18 / January 1, 1929 given by some authorities
Croatia 1918, January 18 or the Republic, 1912, February 12
Bohemia, Moravia 1584, January 6/17
The date of the founding of the Republic also given
Denmark and Norway 1700, February 19 / March 1
Egypt 1875 for civil purposes
Estonia 1918, January
Finland (part of Sweden) 1753, February 18 / March 1. Finland later became part of Russia which was on Julian. The Gregorian calendar remained official but also some use of the Julian 1918, January 14 also given
France Gregorian exchanged in 1793, October 5, for the Republican Calendar, then Gregorian re-adopted in 1806
Alsace 1648, after the Peace of Munster
Loraine 1582, December 9/20: 1760, Feb 16 given in other reference
Strasbourg (city) 1682, February 4/16
Strassurg (bishopric) 1583, November 12/22: in some areas November 17/27
Germany Under Frederick the Great, Gregorian reckoning was adopted in 1775 under the name of "improved calendar."
Aachen 1583, November 4/14
Augsburg 1583, February 14/24
Baden (marquisate) 1583, November 17/27
Bavaria 1583, October 6/16
Cologne (city) 1583, November 4/14
Eichstadt, Freising 1583, October 6/16
Hildesheim (bishopric) 1631, March 16/26
Julich 1583, November 3/13
Lausitz 1584, January 7/17
Mainz (bishopric) 1583, November 12/22
Munster (city and country) 1583, November 17/27
Neuburg Palatinate 1615, December 14/24
Osnabruck (city) 1624
Paderborn (bishopric) 1585, June 17/27
Prussia (duchy) 1610, August 23 / September 2
Regensburg 1583, October 6/16
Silesia 1584, January 13/23
Trier (archbishopric) 1583, October 5/15
Westphalia (duchy) 1584, July 2/12
Wurzburg (bishopric) 1583, November 5/15
Kaiser and Parliament 1584, January 7/17
Protestant states 1700, February 19 / March 1
Great Britain and Dominions 1752, September 03/14, by Act of Parliament passed 1751, March 18. At the same time, the beginning of the year was changed from March 25 to January 1, commencing with 1752
Greece "*" 1924, March 10/23, a modified form of the Gregorian calendar
Hungary 1587, October 22 / November 1
Ireland 1788 (according to Wemyss)
Italy 1582, October 4/15
Japan 1872, December 19 / 1873, January 1

Also given is 1892, December 19 / 1873, January 1 Also given is 1918, December 18 / 1919, January 1

Latvia 1915 to 1918, February 15, a gradual change
Lithuania 1915 by the Catholic church: 1918, February 15 civil
Luxemburg 1582, December 14/35
Catholic states 1582, December 21/ 1583, January 1: sources disagree of dates
Protestant states 1700-1701, sources disagree as to dates
Holland, in part 1583, January 1/12
Groningen 1583, February 28 / March 11, then back to Julian summer of 1584, then 1700, December 13 / 1701, January 12
Gelderland 1700, June 30 / July 12
Utrecht, Overijssel 1700, November 30 / December 12
Poland 1582, October 4/15
Poland Russian section 1915, March 21, Gregorian calendar introduced by German occupation. Other sources give 1914, January 14
Portugal 1582, October 4/15
Romania 1919, March 31 / April 14. Also 1918, March 18 is given / Also suggested that Catholic Romania adopted Gregorian In 1918, March 18, and Orthodox Romania in 1920, March 18. (Greek Orthodox part of the country may have changed later)
Russia 1918, January 31 / February 14. The Russian Orthodox Church kept the Julian calendar
Scotland 1600, January 1 adopted as New Year, still on Julian calendar
Serbia 1919, January 18
Spain 1582, October 4/15
Sweden (and Finland)"**" 1753, February 17 / March 1
Switzerland "***" 1584, January 12 to 1701, January 12, 1701 in various locations
Turkey 1927, January 1. Other sources give 1917, November 13
European Turkey 1908
Asian Turkey 1914
United States 1752, September 3/14
U.S.S.R. 1918, February 1/14 for civil purposes.
Western Soviet 1914, January 14
Estonia, Latvia, Lithuania 1918, February 15
Soviet: entire 1929, instituted five-day week, changed calendar. In 1932, had a six-day week, changed calendar: 1940, June 27 resumed N.S.
Yugoslavia (Serbia, Croatia, Slovenia) 1919, February 1; March 18 also given

"*"Greece: Some parts of Greece adopted the Gregorian calendar as early as 1846 although the Orthodox Church continued to use the Julian calendar. The Easters Orthodox Church officially adopted a modified form of the Gregorian calendar in 1923, October 1/14; 1916, July 28; and 1920, March 18 also given, the latter for Greek, Serbian, Russian and Rumanian churches.

"* *"Sweden and Finland decided in 1753 to make a gradual change from Julian to Gregorian. By dropping every leap year from 1700 through 1740, the eleven superfluous days would be omitted and from 1740, March 1, they would be in sync with the Gregorian calendar. So 1700 (which should have been a leap year in the Julian calendar) was not a leap year in Sweden. However, by mistake, 1704 and 1708 became leap years. This left Sweden out of sync with both the Julian and Gregorian worlds. They decided to correct this by inserting an extra day in 1712, making that year a double leap year! In 1712, February had 30 days in Sweden. In 1753, Sweden changed to the Gregorian calendar by dropping 11 days and finally, after 53 years of having different dates from any other country, Sweden assumed a standard calendar system.

"* * *" Switzerland. Catholic cantons 1583, 1584 or 1597; Protestant cantons 1700, December 31 / 1800, January 12; Wallis 1656; Glarus St. Gallen 1724; Appenzell Ausser-Rhoden 1798; Graublinden, 1811; Bavaria, Austria, Salzburg, Tyrol, 1583, October 16; Julich, Cologne, Mainz, Munster, Trier, Strassburg, 1583, November 14 (Strasburg also given as 1682). Frieburg, Geldern, Gronnigen, Overssel, Utrecht, Zutphen, 1700, December 12. Basle, Berne, Biel, Genf, Nechatel, Sargans, Schaffhausen, Thurgan, Zurich, 1701, January 12. Appenzall, Flarus, St. Gallen, Toggenburg, 1724, January 1. Grabunden, 1798.

Some of these dates are still questionable, as different reference sources may vary. Both calendars were widely used for a long period after the Gregorian calendar was first introduced, and it has been noted that, by the end of the 20th century, the Old Style calendar is still in traditional use in rural areas in some third world countries! The transition period is particularly fragile; it is often difficult to determine the accurate dates used in specific communities during those times. In England and her colonies the reformed, New Style Calendar was often well established in common use before the date that it was officially adopted, 1752, so great caution must be used in determining whether the date given is New or Old Style.

In the United States, Benjamin Franklin printed a pamphlet for the Society of Friends in 1751, commencing an act that the former date of 25th of March shall not be deemed the first day of the New Year, but the New Year shall commence on January 1, 1752.

The Conversion Dates are compiled up to the date of January 2000 with thanks to Kim Farnell for her contribution. Rodden data compiled over years from various sources.

Kim Farnell quotes her reference sources: 200 Year Ephemeris, Hugh MacCraig International Atlas, Thomas Shanks (It appears that the date of the first use of the Gregorian calendar is given, rather than the Julian date of change. Many dates are inconsistent with other sources) Reuters Greece, gave 1923 or 1924 for Greece Regimes Horaires: Henri Le Corre (French sources) More Notable Nativities: Alan Leo supplied information about Swiss/German cantons Information on year beginning from Michael Zeller Zeitaenderung in der Schweiz via Steinbrechr Branka Stamenkovic in Belgrade has verified the Serbian data from local sources.

Corrections and additions are welcomed.

The Calendar An excellent next step in your study of calendars.