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Julian and Gregorian Calendars - Effect on Church and Civil Records


Cliff Lamere    10 Nov 1999, revised 5-8 Oct 2001, revised 9 Mar 2002




As many of us know, 'sept' means seven, but it is the 9th month of our year.  'Octo' means eight, as in octagon, an eight sided figure, but October is our 10th month.  'Dece' mean ten, but December is the 12th month.  Why?

Calendars have changed throughout time as they have tried to fit months, weeks, and days into a year that is approximately 365 1/4 days in length (actually 365.2422 days).  The extra 1/4 day makes the task very difficult.  


Early Roman Calendar


An early Roman calendar was 10 months in length.  The months were named Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, Septembris, Octobris, Novembris and Decembris.  The last six months were named after the numbers 5, 6, 7, 8, 9, and 10.  Notice that March (named after the god Mars) was the first month of the year at that time.  Later, the months of Januarius and Februarius were added to the end of the year as the 11th and 12th months.   


Julian Calendar


By 45 BC, the seasons were not occuring at their proper times.  That year, Julius Caesar developed the Julian Calendar of 365 days so that the seasons would occur in the same months each year.  This made it easier for farmers to know when to plant their crops.  He instituted the idea of a leap year every four years.  The leap year contained one extra day so that celestial events would occur on the same day each year (otherwise, due to the extra day each celestial year, everything would be off by a calendar day at the end of four years, and off by 10 days at the end of forty years, and so on).  


Strangely, March was both the first and last month of the year because the year ended on March 24, and the new year began on March 25.  This resulted from the fact that in 45 BC the spring (vernal) equinox fell on March 25 and that celestial event was chosen as the first day of the year.


Gregorian Calendar


The Julian calendar worked quite well, but wasn't perfect.  It contained an extra 11 minutes and 14 seconds each year.  As the centuries passed, that discrepancy accumulated into a significant error and pushed celestial events earlier and earlier in the calendar.  The error was as much as 10 days by 1582, the year that the Gregorian calendar was proposed by Pope Gregory XIII (in a papal bull).  The reason for concern was that the Julian calendar was throwing off Christian religious holidays such as Easter.  The date of Easter was based on the spring (vernal) equinox which fell on March 25 during the time of Julius Caesar, but had shifted to March 21 by the year 325 when the Catholic Church defined the day on which Easter should fall.  By 1582 it was occuring ten days early by the calendar.  Since the occurence of many other religious holidays was based on Easter, they were also thrown off.


To adopt the new calendar, 10 days had to be dropped in order to get the spring equinox back to its 325 calendar date.  To compensate for the extra 11 minutes and 14 seconds difference each year, the Gregorian calendar dropped the leap year from all century years that were not divisible by 400.  As an example, the year 2000 had a leap year, but the years 1700, 1800, and 1900 did not.  Another change which occurred was that the Gregorian year began on January 1 instead of March 25.


Gregorian Calendar Was First Adopted by Catholic Countries and Provinces


Since the pope was Catholic, Catholic countries adopted the new calendar rather quickly, while Protestant nations did not.  Italy, Spain, Portugal, Poland, France and the Spanish Netherlands all accepted the calendar in 1582, the year it was proposed.  In the Netherlands, the provinces of Holland and North Brabant also changed that year.  The remaining parts of the Netherlands switched in 1700-1701.  The Catholic portions of Germany adopted the new calendar in 1583, but some of the Protestant parts of Germany waited until 1700.  Great Britain did not change until 1752, and the English colonies in America switched at the same time.  Russia did not change until 1918.


Gregorian Calendar Adopted by Great Britain and American Colonies

By 1752 when the Gregorian calendar was adopted in Great Britain and its American colonies, an 11-day correction was needed because the Julian calendar observed a leap year in 1700 which the Gregorian calendar ignored.  The day after September 2, 1752 (which would have been September 3) became September 14, 1752.  The British also adopted January 1 as the day when a new year begins.  That changed September, October, and December to months 9, 10, and 12.  Previously, these months had sometimes been abbreviated as 7ber, 8ber and 10ber or possibly 7bre, 8bre, and 10bre.  Even after 1752, the abbreviations persisted for a time.


*** In England and British colonial America (including New York after 1664), if a birth record for a Sarah says that she was born Oct 10, 1750, then she would really have been born on Oct 21, 1750 by the Gregorian calendar which we now use.  And if the record said that she was born Nov 20, 1750, she must have been born Dec 1, 1750 by our present reckoning.  That would change the month.  Finally, if she was born Jan 31, 1750, we would consider her to have been born Feb 11, 1751 (seemingly 12 months later!!).


Double Dates


In the time of Julius Caesar, January and February were the last full months at the END of the year.  The Julian year ended on March 24, allowing each year to begin on the vernal equinox, which occurred on March 25 at that time.  


The Gregorian New Year was on January 1.   So, a Great Britain church record for Jan 1650 was actually Jan 1651 according to the Gregorian calendar.  This resulted in what is called Double Dates.  You may have seen a date like 15 Feb 1688/89.  Now you know the reason.  January, February and March 1-24 were either at the end of 1688 or at the beginning of 1689 depending on the calendar a person was using.  


In Great Britain and colonial British America, double dates were often used in records for dates between January 1 and March 24 of each year from 1582-1752.


If you don't use double dates in your genealogy program, then you would record the latter of the two years.  Use the date that it would be in the system we use today, rather than what it would have been then.  If you don't use a genealogy program, then I recommend that you either keep the double date if it is shown on a record, or at least make a note of it.

New Netherland


The Dutch colony of New Netherland observed the laws and customs of the Netherlands province of Holland, which had been using the Gregorian calendar since 1582.  Therefore, the early records of the colony and its churches were written according to the same calendar that is in effect today.  The year began with Jan 1, the dates were the same, and there were no double dates.


In 1664, the English conquered New Netherland, renaming it New York.  The Julian calendar became required in official documents.  Ten days had to be added to their calendar.  However, many of the Dutch continued using the Gregorian calendar in their church and family records. 

In 1752, 11 days had to be dropped from the calendar (see above) when Great Britain and its colonies, including New York, finally adopted the Gregorian calendar.


Since the pre-1664 NY Dutch in New Netherland were using the Gregorian calendar, their calendar was different from the one used by nearby New England.  Therefore, two people born on the same calendar date, one in NY and one in New England, were born 10 days apart (the Gregorian calendar before the year 1700 was only 10 days different).  Conversely, two people born on the same actual day may not even have been born in the same calendar year in the two places.  This can be important for a family that moves from one calendar area to the other or has children baptized in churches using different calendars (in the same or different colonies).  Children who seem to be born too close together to fit into a particular family, may not present a problem at all after the calendar problem is considered.


What about the immigrant Palatines who arrived about 1710?  They had switched to Gregorian before they arrived here.  Did they maintain their records using the dates with which they were familiar or did they switch back to Julian right away?


How Should You Use This Information?


Should a transcriber of records change Julian dates to Gregorian?  No.  That would only create confusion.  Other people will have recorded the same records using unaltered dates.  Records should be transcribed as they appear.  Let later researchers make the adjustments if they so wish.  Guidance can be given to the researchers by including bracketed remarks, but the records should be reported as close to the original as possible.  If double dates appear in the record, they should not be adjusted by a transcriber.  The use of double dates gives us a clue as to which calendar the church was using at a particular time.   


Should you change the dates when adding old records to your own personal database?  I think not.  First, we cannot be certain about which calendar was being used at each church during different periods.  Second, even if we knew, private records get shared with other people and will cause those people eventual confusion.  It is better to use the same date as in the original church records and make a written or mental note that the day may have been off by 10-11 days (and possibly the year) because of calendar differences.


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