Editing Old Style and New Style dates

{{Short description|Changes in calendar conventions}}
{{Redirect2|Old Style|New Style|other meanings of old style|Old Style (disambiguation)|other meanings of new style|The New Style (disambiguation){{!}}The New Style}}
{{about|the 18th-century changes in calendar conventions used by Great Britain and its colonies, together with a brief explanation of usage of the term in other contexts|a more general discussion of the equivalent transitions in other countries|Adoption of the Gregorian calendar}}
{{Use dmy dates|date=May 2021}}
[[File:The London Gazette 9198.djvu|thumb|Issue 9198 of ''[[The London Gazette]]'', covering the calendar change in Great Britain. The issue spans the changeover; the date heading reads: "From Tuesday September 1, O.S. to Saturday September 16, N.S. 1752".<ref>{{cite journal |journal=London Gazette |issue=9198 |page=1 |date=1 September 1752 |title= The London Gazette {{!}} From Tuesday September 1 O.S. to Saturday September 16 N.S. 1752 |url=https://www.thegazette.co.uk/London/issue/9198/page/1}}</ref>]]
'''Old Style''' ('''O.S.''') and '''New Style''' ('''N.S.''') indicate dating systems before and after a calendar change, respectively. Usually, they refer to the change from the [[Julian calendar]] to the [[Gregorian calendar]] as enacted in various [[Europe|European]] countries between 1582 and 1923. <!-- Similar notations in Asia are outside the scope of this article. -->

In [[England]], [[Wales]], [[Ireland]] and [[British America|Britain's American colonies]], there were two calendar changes, both in 1752. The first adjusted the start of a new year from 25 March ([[Lady Day]], the [[Feast of the Annunciation]]) to 1 January, a change which [[Scotland]] had made in 1600. The second discarded the Julian calendar in favour of the Gregorian calendar, skipping 11 days in the month of September to do so.{{sfn|Poole|1995 |pages=95–139}}<ref name="MS2">{{cite web |last=Spathaky |first=Mike |url=https://www.cree.name/genuki/dates.htm |title=Old Style and New Style Dates and the change to the Gregorian Calendar |access-date=19 August 2023}}. "Before 1752, parish registers, in addition to a new year heading after 24th March showing, for example '1733', had another heading at the end of the following December indicating '1733/4'. This showed where the Historical Year 1734 started even though the Civil Year 1733 continued until 24th March. ... We as historians have no excuse for creating ambiguity and must keep to the notation described above in one of its forms. It is no good writing simply 20th January 1745, for a reader is left wondering whether we have used the Civil or the Historical Year. The date should either be written 20th January 1745 OS (if indeed it was Old Style) or as 20th January 1745/6. The hyphen (1745-6) is best avoided as it can be interpreted as indicating a period of time."</ref>  To accommodate the two calendar changes, writers used [[dual dating]] to identify a given day by giving its date according to both styles of dating.

For countries such as [[Russia]] where no start-of-year adjustment took place,{{efn|By decrees (1735, 1736) of [[Peter the Great]] in December 1699 (with effect from 1 January 1700), Russia changed its start of year from September to January and adopted the AD era in place of [[Anno Mundi]].<ref>{{cite book |title=Полное собрание законов Российской империи. Том III |trans-title=Complete Collection of Laws of the Russian Empire. Volume III. |page=682  |entry=Ukase No. 1735 |entry-url=https://viewer.rsl.ru/ru/rsl01003821638?page=682&rotate=0&theme=white |date=10 December 1699 }}</ref><ref name="Ukase 1736">{{cite book |title=Полное собрание законов Российской империи. Том III |trans-title=Complete Collection of Laws of the Russian Empire. Volume III. |page=683  |entry=Ukase No. 1736 |entry-url=https://viewer.rsl.ru/ru/rsl01003821638?page=683&rotate=0&theme=white |date=20 December 1699 }}</ref>}} O.S. and N.S. simply indicate the Julian and Gregorian dating systems respectively.

==Differences between Julian and Gregorian dates==
{{Main article|Gregorian calendar#Difference between Gregorian and Julian calendar dates}}
The need to correct the calendar arose from the realisation that the correct figure for the number of days in a year is not 365.25 (365 days 6 hours) as assumed by the Julian calendar but [[Tropical year#Mean tropical year current value|slightly less]] (c. 365.242 days). The Julian calendar therefore has too many [[leap year]]s. The consequence was that the basis for the calculation of the [[date of Easter]], as [[Easter controversy|decided in the 4th century]], had drifted from [[March equinox|reality]]. The Gregorian calendar reform also dealt with the accumulated difference between these figures, between the years 325 and 1582, by skipping 10 days to set the [[Ecclesiastical equinox|ecclesiastical date of the equinox]] to be 21&nbsp;March, the median date of its occurrence at the time of the [[First Council of Nicea]] in 325.

Countries that adopted the Gregorian calendar after 1699 needed to skip an additional day for each subsequent new century that the Julian calendar had added since then. When the British Empire did so in 1752, the gap had grown to eleven days;{{efn|Because 1600 was a leap year in both calendars, only one extra Julian leap day (in 1700) needed to be taken into account.}}  when Russia did so (as its [[civil calendar]]) in 1918, thirteen days needed to be skipped.{{efn|Because 1600 was a leap year in both calendars, three extra Julian leap days (in 1700, 1800 and 1900) needed to be taken into account.}}

==Britain and its colonies or possessions==
[[File:Memorial to John Etty (18373251064).jpg|thumb|Memorial plaque to John Etty in [[All Saints' Church, North Street, York]], recording his date of death as "28 of Jan: {{sfrac|170|8|9}}"]]
In the [[Kingdom of Great Britain]] and its possessions, the [[Calendar (New Style) Act 1750]] introduced two concurrent changes to the calendar. The first, which applied to England, Wales, Ireland and the British colonies, changed the start of the year from 25 March to 1 January, with effect from "the day after 31 December 1751".{{sfn|Bond|1875|loc=[https://archive.org/details/handybookofrules00bond/page/91/mode/1up page 91]}}{{efn|The act has to use this formulation since "1 January 1752" was still ambiguous.}} (Scotland had already made this aspect of the changes, on 1 January 1600.){{sfn|Steele|2000|page=4}}{{sfn|Bond|1875|loc=[https://archive.org/details/handybookofrules00bond/page/n20/mode/1up xvii]–xviii: original text of the Scottish decree}} The second (in effect{{efn|The Calendar Act does not mention Pope Gregory}}) adopted the Gregorian calendar in place of the Julian calendar. Thus "New Style" can refer to the [[#Differences in the start of the year|start-of-year adjustment]], to the [[adoption of the Gregorian calendar]], or to the combination of the two. It was through their use in the Calendar Act 1750 that the notations "Old Style" and "New Style" came into common usage.

=== {{anchor|Differences in the start of the year}}Start-of-year adjustment ===
{{Further|Julian calendar#New Year's Day|Regnal year|Calendar (New Style) Act 1750#New Year's Day}}
When recording British history, it is usual to quote the date as originally recorded at the time of the event, but with the year number adjusted to start on 1 January.<ref name="woolf">e.g. {{cite book |first=Daniel |last=Woolf |author-link=Daniel Woolf |title=The Social Circulation of the Past: English Historical Culture 1500–1730 |location=Oxford |publisher=Oxford University Press |year=2003 |isbn=0-19-925778-7 |page=xiii |quote=Dates are Old Style, but the year is calculated from 1 January. On occasion, where clarity requires it, dates are written 1687/8.}}</ref> The latter adjustment may be needed because the start of the [[civil calendar]] year had not always been 1 January and was altered at different times in different countries.{{efn|British official legal documents of the 16th and 17th centuries were usually dated by the [[regnal years of English monarchs|regnal year]] of the monarch. As these commence on the day and date of the monarch's accession, they normally span two consecutive calendar years and have to be calculated accordingly, but the resultant dates should be unambiguous.}} From 1155 to 1752, the civil or legal year in England began on 25 March ([[Lady Day]]);<ref>Nørby, Toke. [http://www.norbyhus.dk/calendar.php#England The Perpetual Calendar: What about England?] Version 29 February 2000.</ref>{{sfn|Gerard|1908}} so for example, the execution of [[Charles I of England|Charles I]] was recorded at the time in Parliament as happening on 30 January 164'''8''' (Old Style).<ref name=regicides>{{cite web|url= http://www.british-history.ac.uk/report.asp?compid=26211#s5|title= House of Commons Journal Volume 8, 9 June 1660 (Regicides)|publisher= British History Online|access-date= 18 March 2007}}</ref> In newer English-language texts, this date is usually shown as "30 January 164'''9'''" (New Style).<ref name="EC-NA">[http://www.nationalarchives.gov.uk/pathways/citizenship/rise_parliament/docs/charles_warrant.htm Death warrant of Charles I] web page of the [http://www.nationalarchives.gov.uk/ UK National Archives]. A demonstration of New Style, meaning Julian calendar with a start of year adjustment.</ref> The corresponding date in the Gregorian calendar is 9 February 1649, the date by which his contemporaries in some parts of continental Europe would have recorded his execution.

The O.S./N.S. designation is particularly relevant for dates which fall between the start of the "historical year" (1 January) and the legal start date, where different. This was 25 March in England, Wales, Ireland and the colonies until 1752, and until 1600 in Scotland.

In Britain, 1 January was celebrated as the New Year festival from as early as the 13th century, despite the recorded (civil) year not incrementing until 25&nbsp;March,<ref>{{Cite journal |date=1940 |title=New Year's Day and Leap Year in English History |url=https://www.jstor.org/stable/553864 |url-status=live |journal=The English Historical Review |publisher=[[Oxford University Press]] |volume=55 |pages=180–185 |doi=10.1093/ehr/lv.ccxviii.177 |jstor=553864 |archive-url=https://web.archive.org/web/20210202193510/https://www.jstor.org/stable/553864 |archive-date=2 February 2021 |last1=Pollard |author-first1=A. F. |author1-link=Albert Pollard |issue=218}}</ref>{{efn|name=Pepys|For example, see the [[Diary of Samuel Pepys]] for 31{{nbsp}}December 1661: "I sat down to end my {{notatypo|journell}} for this year, ...",<ref>{{Cite web |last=Pepys |first=Samuel |title=Tuesday 31 December 1661 |url=https://www.pepysdiary.com/diary/1661/12/31/ |website=www.pepysdiary.com |date=31 December 2004 |archive-url=https://web.archive.org/web/20211124225143/https://www.pepysdiary.com/diary/1661/12/31/ |archive-date=24 November 2021}}</ref> which is immediately followed by an entry dated "1{{nbsp}}January 1661/62".<ref>{{Cite web |last=Pepys |first=Samuel |title=Wednesday 1 January 1661/62 |url=https://www.pepysdiary.com/diary/1662/01/01/ |website=www.pepysdiary.com |date=January 2005 |archive-url=https://web.archive.org/web/20211124225147/https://www.pepysdiary.com/diary/1662/01/01/ |archive-date=24 November 2021}}</ref> This is an example of the [[dual dating]] system which had become common at the time.}} but the "year starting 25th March was called the Civil or Legal Year, although the phrase Old Style was more commonly used".<ref name="MS2"/> To reduce misunderstandings about the date, it was normal even in semi-official documents such as parish registers to place a statutory new-year heading after 24 March (for example "1661") and another heading from the end of the following December, ''1661/62'', a form of [[dual dating]] to indicate that in the following twelve weeks or so, the year was 1661 Old Style but 1662 New Style.<ref name="MS-oblique-stroke">Spathaky, Mike [http://www.cree.name/genuki/dates.htm Old Style and New Style Dates and the change to the Gregorian Calendar]. "An [[slash (punctuation)|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, thus: <math>17\tfrac{33}{34}</math>. Very occasionally a hyphen is used, as {{notatypo|1733-34}}."</ref> Some more modern sources, often more academic ones (e.g. the [[History of Parliament]]) also use the ''1661/62'' style for the period between 1 January and 24 March for years before the introduction of the New Style calendar in England.<ref>See for example this biographical entry: {{cite book |last=Lancaster |first=Henry |year=2010 |chapter=Chocke, Alexander II (1593/4–1625), of Shalbourne, Wilts.; later of Hungerford Park, Berks |title=The History of Parliament: the House of Commons 1604–1629 |editor-first=Andrew |editor-last=Thrush |editor2-first=John P. |editor2-last=Ferris |publisher=Cambridge University Press |location=Cambridge |chapter-url=http://www.historyofparliamentonline.org/volume/1604-1629/member/chocke-alexander-ii-15934-1625}}</ref><ref name="woolf"/>

==Other notations==<!-- This article is about the notation used to disambiguate dates near conversion day. Please do not add material about the adoption itself, that belongs at [[Adoption of the Gregorian Calaendar]]. -->
{{More|Adoption of the Gregorian calendar|List of adoption dates of the Gregorian calendar by country}}
<!-- Greece: can anyone add some material that shows what  notation is used in Greece or in Greek to disambiguate a date? (Please do not duplicate the material at [[Adoption of the Gregorian calendar]] but of course it will be essential to summarise it briefly to explain the need for disambiguation, especially since the Church is still using Julian but the state is using Gregorian.  -->

===Russia===
{{more|Adoption of the Gregorian calendar#Russia}}
The Gregorian calendar was implemented in Russia on {{nowrap|14 February 1918}} by dropping the [[Julian calendar|Julian]] dates of {{nowrap|1–13 February 1918}},{{efn|The Julian calendar had by that time drifted by another three days since 1582 (in 1700, 1800 and 1900, see [[Century leap year]]) from astronomical reality, so thirteen days needed to be elided.}} pursuant to a [[Sovnarkom]] decree signed {{nowrap|24 January 1918}} (Julian) by [[Vladimir Lenin]]. The decree required that the Julian date was to be written in parentheses after the Gregorian date, until {{nowrap|1 July 1918.<ref name=Grigorenko>[http://grigam.narod.ru/kalend/kalen19.htm История календаря в России и в СССР (Calendar history in Russia and the USSR)] {{Webarchive|url=https://web.archive.org/web/20091017163723/http://grigam.narod.ru/kalend/kalen19.htm |date=17 October 2009 }}, chapter 19 in История календаря и хронология by Селешников (History of the calendar and chronology by Seleschnikov) {{in lang|ru}}. [http://www.niv.ru/library/006/001.htm ДЕКРЕТ "О ВВЕДЕНИИ ЗАПАДНО-ЕВРОПЕЙСКОГО КАЛЕНДАРЯ" (Decree "On the introduction of the Western European calendar")] {{webarchive|url=https://web.archive.org/web/20070121144021/http://www.niv.ru/library/006/001.htm |date=21 January 2007 }} contains the full text of the decree {{in lang|ru}}.</ref>}}

It is common in English-language publications to use the familiar Old Style or New Style terms to discuss events and personalities in other countries, especially with reference to the [[Russian Empire]] and the very beginning of [[Russian Soviet Federative Socialist Republic|Soviet Russia]]. For example, in the article "The October (November) Revolution", the ''[[Encyclopædia Britannica]]'' uses the format of "25 October (7 November, New Style)" to describe the date of the start of the revolution.{{sfn|EB online|2017}}

===Latin notation: st.v. and st.n.===
The Latin equivalents, which are used in many languages, are, on the one hand, ''stili veteris'' (genitive) or ''stilo vetere'' (ablative), abbreviated ''st.v.'', and meaning {{nowrap|"(of/in) old style"}}; and, on the other, ''stili novi'' or ''stilo novo'', abbreviated ''st.n.'' and meaning {{nowrap|"(of/in) new style".}}<ref name=Lenz210>{{cite book|last=Lenz|first=Rudolf|author2=Uwe Bredehorn |author3=Marek Winiarczyk |title=Abkürzungen aus Personalschriften des XVI. bis XVIII. Jahrhunderts |publisher=Franz Steiner Verlag|year=2002|edition=3|page=210|isbn=3-515-08152-6}}</ref> The Latin abbreviations may be capitalised differently by different users, e.g., ''St.n.'' or ''St.N.'' for ''stili novi''.<ref name=Lenz210/> There are equivalents for these terms in other languages as well, such as the German ''a.St.'' ("''alter Stil''" for O.S.).
==Transposition of historical event dates and possible date conflicts==
[[File:Thomas Jefferson's Grave Site.jpg|right|thumb|[[Thomas Jefferson]]'s tombstone. Written below the [[epitaph]] is "Born April 2. 1743. O.S. Died July 4. 1826."<!-- Punctuation transcribed from image – ignore MOS here -->]]
Usually, the mapping of New Style dates onto Old Style dates with a start-of-year adjustment works well with little confusion for events before the introduction of the Gregorian calendar. For example, the [[Battle of Agincourt]] is well known to have been fought on 25 October 1415, which is [[Saint Crispin's Day]]. However, for the period between the first introduction of the Gregorian calendar on 15 October 1582 and its introduction in Britain on 14 September 1752, there can be considerable confusion between events in Continental Western Europe and in British domains. Events in Continental Western Europe are usually reported in English-language histories by using the Gregorian calendar. For example, the [[Battle of Blenheim]] is always given as 13 August 1704. However, confusion occurs when an event involves both. For example, [[William III of England]] arrived at [[Brixham]] in England on 5 November (Julian calendar), after he had set sail from the Netherlands on 11 November (Gregorian calendar) 1688.<ref name="C&J19">{{harvnb|Cheney|Jones|2000|p=19}}.</ref>

The [[Battle of the Boyne]] in Ireland took place a few months later on 1 July 1690 (Julian calendar). That maps to 11 July (Gregorian calendar), conveniently close to the Julian date of the subsequent (and more decisive) [[Battle of Aughrim]] on 12 July 1691 (Julian). The latter battle was commemorated annually throughout the 18th century on 12 July,<ref name=Lenihan>{{cite book |last=Lenihan |first=Pádraig |title=1690 Battle of the Boyne |year=2003 |location=Stroud, Gloucestershire |publisher=Tempus |pages=258–259 |isbn=0-7524-2597-8 }}</ref> following the usual historical convention of commemorating events of that period within Great Britain and Ireland by mapping the Julian date directly onto the modern Gregorian calendar date (as happens, for example, with [[Guy Fawkes Night]] on 5 November). The Battle of the Boyne was commemorated with smaller parades on 1 July. However, both events were combined in the late 18th century,<ref name="Lenihan"/> and continue to be celebrated as "[[The Twelfth]]".

Because of the differences, British writers and their correspondents often employed two dates, a practice called [[dual dating]], more or less automatically. Letters concerning diplomacy and international trade thus sometimes bore both Julian and Gregorian dates to prevent confusion. For example, Sir [[William Boswell]] wrote to Sir [[John Coke]] from [[The Hague]] a letter dated "12/22 Dec. 1635".<ref name="C&J19"/> In his biography of [[John Dee (mathematician)|John Dee]], ''The Queen's Conjurer'', Benjamin Woolley surmises that because Dee fought unsuccessfully for England to embrace the 1583/84 date set for the change, "England remained outside the Gregorian system for a further 170 years, communications during that period customarily carrying two dates".<ref>{{cite web |first=John |last=Baker |url=http://www2.localaccess.com/marlowe/bacon6.htm |title=Why Bacon, Oxford and Other's Weren't Shakespeare |archive-url=https://web.archive.org/web/20050404085408/http://www2.localaccess.com/marlowe/bacon6.htm |archive-date=4 April 2005}}) uses the quote by Benjamin Woolley and cites ''The Queen's Conjurer, The Science and Magic of Dr. John Dee, Adviser to Queen Elizabeth I'', page 173.</ref> In contrast, [[Thomas Jefferson]], who lived while the British Isles and colonies converted to the Gregorian calendar, instructed that his tombstone bear his date of birth by using the Julian calendar (notated O.S. for Old Style) and his date of death by using the Gregorian calendar.<ref>{{cite web |date=June 1995 |url=http://www.monticello.org/site/research-and-collections/old-style|title=Old Style (O.S.)|publisher=monticello.org|access-date=6 May 2017}}</ref> At Jefferson's birth, the difference was eleven days between the Julian and Gregorian calendars and so his birthday of 2 April in the Julian calendar is 13 April in the Gregorian calendar. Similarly, [[George Washington]] is now officially reported as having been born on 22 February 1732, rather than on 11 February 1731/32 (Julian calendar).<ref>{{cite journal|url=http://www.slate.com/id/2134455/|title=What's Benjamin Franklin's Birthday?|first=Daniel|last=Engber|date=18 January 2006|journal=[[Slate (magazine)|Slate]]|access-date=8 February 2013}} (Both Franklin's and Washington's confusing birth dates are clearly explained.)</ref> The philosopher [[Jeremy Bentham]], born on 4 February 1747/8 (Julian calendar), in later life celebrated his birthday on 15 February.<ref>{{cite book |editor-first=Timothy L. S. |editor-last=Sprigge |editor-link=Timothy Sprigge |title=The Correspondence of Jeremy Bentham: Volume I: 1752–76 |location=London |publisher=UCL Press |year=2017 |orig-year=1968 |isbn=978-1-911576-05-1 |page=294 |chapter=Jeremy Bentham to [[Samuel Bentham]], 15 Feb. 1776 |quote=God's-daddikins! it is my birthday – say something pretty to me on the occasion. |url=https://discovery.ucl.ac.uk/id/eprint/1558740/1/The-Correspondence-of-Jeremy-Bentham-Volume-1.pdf }}</ref>

There is some evidence that the calendar change was not easily accepted. Many British people continued to celebrate their holidays "Old Style" well into the 19th century,{{efn|See also [[Little Christmas]].}} a practice that the author Karen Bellenir considered to reveal a deep emotional resistance to calendar reform.<ref>{{cite book |last=Bellenir |first=Karen |title=Religious Holidays and Calendars |publisher=Omnigraphics |year=2004 |location=Detroit |page=33}}</ref>

== See also ==
* {{annotated link|Dual dating}}
* [[Gregorian calendar#Difference between Gregorian and Julian calendar dates|Difference between Gregorian and Julian calendar dates]] (ready-reckoner)
* {{annotated link|Old New Year}}
* {{annotated link|Little Christmas}} ("Old Christmas")

== Notes ==
{{Notelist}}

==References==
{{reflist}}

==Sources==
{{refbegin|40em}}
*{{cite book |author-last1=Bond |author-first1=John James |author-link=John James Bond |year=1875 |url=https://archive.org/details/handybookofrules00bond/page/n4/mode/1up |title=Handy Book of Rules and Tables for Verifying Dates With the Christian Era Giving an Account of the Chief Eras and Systems Used by Various Nations...' |location=London |publisher=George Bell & Sons |access-date=13 March 2016 |archive-date=21 November 2020 |archive-url=https://web.archive.org/web/20201121133435/https://books.google.com/books?id=b2wBAAAAQAAJ |url-status=live }}
*{{cite book|editor1-last=Cheney |editor1-first=C. R. |editor1-link=C. R. Cheney |editor2-first=Michael |editor2-last=Jones |editor2-link=Michael Jones (historian) |title=A Handbook of Dates for Students of British History |series=[[Royal Historical Society]] Guides and Handbooks |volume=4 |place=Cambridge |publisher=Cambridge University Press |edition=Revised |year=2000 |pages=17–20 |isbn=978-0-521-77095-8 |url=http://catdir.loc.gov/catdir/samples/cam032/99027383.pdf}}
*{{cite CE1913|last=Gerard  |first=John |wstitle=General Chronology#Beginning of the year |display=General Chronology § Beginning of the year |volume=3}}
*{{cite book|ref={{sfnRef|EB online|2017}} |url=https://www.britannica.com/eb/article-38556/Russia |title=Russia: the October (November) Revolution |publisher=Encyclopædia Britannica |edition=Online |year=2007 |access-date=18 March 2007}}
*{{cite book|last1 = Steele |first1=Duncan |title=Marking Time: the epic quest to invent the perfect calendar |date=2000 |publisher=John Wiley & Sons |location=New York |isbn=978-0471404217}}
* {{cite journal|last=Poole |first=Robert |date=1995 |url=https://www.academia.edu/2342015 |title='Give us our eleven days!': calendar reform in eighteenth-century England |journal=Past & Present |issue=149 |pages=95–139 | publisher = [[Oxford Academic]] |archive-url=https://web.archive.org/web/20141205220427/http://www.academia.edu/2342015/Give_us_our_eleven_days_ |archive-date=5 December 2014 |url-status=live|doi=10.1093/past/149.1.95  }}
{{refend}}

==External links==
{{wikisource|British Calendar Act of 1751}}
*[https://www.folger.edu/blogs/collation/untangling-dating/ Untangling Lady Day dating and the Julian Calendar] by Erin Blake (Folger Library)
*[http://www.norbyhus.dk/calendar.php The Perpetual Calendar] by Toke Nørby - Details of conversion for many countries
*[http://5ko.free.fr/en/jul.php Side-by-side Old style–New style reference] by Petko Yotov
*[http://www.fourmilab.ch/documents/calendar/ Calendar Converter] by [[John Walker (programmer)|John Walker]]

{{Chronology}}

{{DEFAULTSORT:Old Style And New Style Dates}}
[[Category:Gregorian calendar]]
[[Category:Julian calendar]]
[[Category:Time]]