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Julian – Gregorian Calendar – an explanation

A calendar has been used over the centuries in nearly every civilization. Its purpose is to provide a method of measuring time and to allow man to record and calculate dates and events. CalendarThe calendar has changed dramatically over the years, and family historians who research colonial records will soon realize that even as recently as 1750, the calendar was different. A basic knowledge of the 1752 calendar change during the colonial period of American history will help with family history research.

The Julian Calendar
To better understand the 1752 calendar change, it is beneficial to review the history of major calendars that led up to it, starting with the Romans. Following the advice of his astronomer and mathematician, Julius Caesar established a calendar in 45 B.C. This calendar is known as the Julian or Old Style (O.S.) calendar. It and had three common years containing 365 days, and one year (leap year) containing 366 days (every fourth year). This twelve-month calendar, based on a solar (tropical) year, served for many years in perpetual cycle.

Under this calendar, the first day of the year was March 25th (often known as Lady Day, Annunciation Day, or Feast of the Annunciation), and the last day of the year was March 24th. March was considered the first month.


Examples of the Julian Calendar

7ber     VIIber     September   7th month
8ber     VIIIber   October       8th month
9ber     IXber      November   9th month
10ber   Xber        December   10th month

Under the Julian calendar, four of the months
were written ending in “ber.”

The Gregorian Calendar
During the Middle Ages, astronomers and mathematicians observed that the calendar year was not completely accurate with matching solar years. Errors in the Julian calendar were noted by church officials and scholars because church holidays did not occur in their appropriate seasons.

In 1582, Pope Gregory XIII (1502–85), who was pope from 1572 to 1585, and his astronomer and mathematician created a new, reformed calendar known as the Gregorian or New Style (N.S.) calendar. It was adopted first in Roman Catholic countries. Protestant countries adopted the calendar during the eighteenth century.

In order to make the calendar adjustment in 1582, ten days were eliminated from October. Thus 4 October 1582 was followed by 15 October 1582.

England and its American colonies did not adopt the reformed Gregorian calendar until 1752. Scotland adopted it earlier, celebrating the New Year on 1 January 1600 and subsequently on January 1st of each year. Interestingly, Alaska did not change from the Julian calendar to the New Style Gregorian calendar until 1867 because, up to that point, it was part of Russia.

In order to make the calendar adjustment, eleven days were dropped from the month of September 1752. An eleven-day adjustment in 1752 was needed because one more day had been lost since the calendar was changed in 1582. The year 1751 began on 25 March and ended on 31 December 1751. The first day of the year was now January 1st and the last day was December 31st—the calendar we use today. Thus, 2 September 1752 was followed by 14 September 1752. In this way, the Julian calendar added one day between 1582 and 1752.


Summary of the 1752 Calendar Change

31 December 1750 was followed by 1 January 1750
24 March 1750 was followed by 25 March 1751
31 December 1751 was followed by 1 January 1752
2 September 1752 was followed by 14 September 1752
31 December 1752 was followed by 1 January 1753

Note that the 1752 calendar change occurred in a series of steps.

Just imagine your eighteenth-century ancestors going to bed on Wednesday, September 2nd and waking up on Thursday, September 14th. What would have been September 3rd was actually September 14th in the year 1752. They lost those eleven days from their lives. September 1752 had only nineteen days.

Other countries adopted the Gregorian calendar at different times. The standard reference source for a discussion of the 1752 calendar change is Handbook of Dates for Students of English History. It includes a list of rulers of England, Saints’ days and festivals used in dating, legal chronology, the Roman calendar, and other calendar details. A chart showing dates of changes from the Julian calendar to the Gregorian calendar in countries outside the British Empire is shown in Know Your Ancestors: A Guide to Genealogical Research.

Double Dating
Double dating was used in Great Britain, colonial British America, and British possessions to clarify dates occurring between 1 January and 24 March on years between 1582 and 1752. In the ecclesiastical or legal calendar, March 25th was recognized as the first day of the year and was not double dated.

Researchers of colonial American ancestors will often see double dating in older records. Double dates were identified with a slash mark (/) representing the Old and New Style calendars, e.g., 1690/1691. Even before 1752 in colonial America, some educated clerks knew of the calendar change in Europe and used double dating to distinguish between the calendars. This was especially true in civil records, but less so in church registers. Researchers will often see this type of double dating in New England town records, court records, church records, and wills, or on colonial gravestones or cemetery transcriptions. The system of double dating ended in 1752 in the American colonies with the adoption of the Gregorian calendar.


Double Dating Examples in Colonial Records

15 January 1690 or 15 January 1691
15 February 1745 or 15 February 1746
1 March 1749 or 1 March 1750
15 March 1700 or 15 March 1701

Some Calendar Sites: Learning


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