England was among the last countries in the world to accept that they actually use the calendar disabilities. The Julian calendar - named after Julius Caesar, who adopted it around 45 BC - declared March 25 New Year's Day and added that the year will be 365 days and 6 hours long. The Council of Nicaea adopted the official calendar in 325 AD As it becomes possible to measure the length of the solar year is more accurate, astronomers discovered that the system exceeds the Julian solar year by 11 minutes, or 24 hours every 131 years, and three days every 400 years. Excess amounts to 10 days between 325 BC and 1582 AD
Pope Gregory XIII ordered a new calendar, called the Gregorian calendar in 1582, when most of the world leap forward with 10 days on October 5, thus restoring the vernal equinox, March 21. To prevent a recurrence of this error, he ordered that, within every 400 years, an extra day of leap year should be eliminated three times. To achieve this on a regular basis, he was eliminated last day of February in the year one hundred and first two digits is not divisible by four without a remainder. So, it was eliminated in 1700, 1800, and 1900, but will not be eliminated in 2000.
All Catholic countries, following the orders of the Pope, to implement the new system. But Britain, then in trouble with the Church of Rome, refused to join the new calendar until the mid 18th century and then the difference has grown to 11 days. All land except UK Scotland, who changed the calendar 100 years earlier, now celebrating New Year's Day on January 1. In Russia, the Julian calendar remained in use.
Although the official calendar, the people in England and the colonies began using the Gregorian system in the early 16th century. Thus, many early colonial records including double date, written as "February 12, 1661/1662," shows that, although officially in 1661, some consider it to be 1662.
Genealogists, especially those just starting their search for ancestors, need to check the date found in the English-speaking countries between 1582 and 1752. Is this the date shown as the OS (Old Style) or NS (New Style)? If no date is listed as 1750/51? That means it would have probably been between January 1 and March 24, which means that the 1750 is an old-style notation and in 1751, the new. Double those dates only occur in January, February and March - never in the other months and never after 1752.
Additionally, the dates in the 17th century often had months indicated by numbers and not names. This is because most months have Roman or "infidels" and the name of the Puritans and Quakers do not like them. Since March is considered as the first month of the year before 1752, the date before which might read like this: "13, 2 mo: 1683." This is a "13 April 1683." In general, that day arrived first and second months, but to be sure, genealogists verify by comparing dates with other people in the same record.
Often, a change in the calendar would explain the birth of two children appeared to be too short a period. So, if a researcher finds that Joshua and Rachel Smith had a daughter Mary, born March 22, 1638, and from recording a son, Henry, born February 27, 1639, it would seem that they were born 28 days apart, but actually was born 11 months separately, according to the old and new-style
