The Calendar

Our calendar is like an old friend, always steady; always reliable. The year always begins on 1 January, and it ends on 31 December. There are twelve months. The day after 2 September is 3 September. Always. Right?


The Julian Calendar

Not long after humans began to notice the regular cycles of the sun and the moon, they began counting the days. The regular changes of the seasons defined the course of a year. In 535 B.C. the Romans introduced a calendar that was ten months in length and contained 304 days in a year. Their calendar began in March. It made perfect sense that the year should begin in the spring, when the crops were planted.

Several hundred years later, in 46 B.C., Julius Caesar adjusted the Roman calendar to contain twelve months and the year to contain 365¼ days. The quarter-day gave rise to the concept of a leap year, with an extra day every fourth year. Another Roman emperor, Constantine, created the seven-day week and introduced Sunday as a holy day in 325 A.D.

While these changes to the calendar were a great improvement over the earlier attempts to mark the cycle of the year, they were still not quite right. So, after many centuries, important events (like the seasons) continued to shift earlier and earlier each year. In the 1500s the Vatican ordered another reform to the calendar, and the Gregorian calendar was developed under the orders of Pope Gregory XIII in 1582. In that year, Thursday, 4 October 1582 was the final day of the old Julian calendar. The next day was Friday, 15 October 1582, shifting the date forward by eleven days as the first day of the new Gregorian calendar.

Pope Gregory’s calendar solved a host of problems for Catholic nations. But many parts of the world—especially Protestant countries, including England and its colonies—were certainly not going to adopt a calendar that was the creation of the Pope. Germany and the Netherlands held out until 1698. Britain didn’t make the change until 1752. Russia and China waited until the twentieth century to conform.

1752: The Year the British Calendar Changed

Changing the calendar for a country (and all of its dominions) is not a simple task. There are many details to be accounted for. When do the holidays occur? What happens to date-dependent contracts? When is the rent due? When do minors reach the age of 21? For that matter, what happens to my birthday? All of these issues were addressed in the British Calendar Act of 1751, enacted by the British parliament under King George II.

Under the old Julian calendar, the year began on 25 March. The British Calendar Act declared that the year 1752 would begin on 1 January. It also decreed that the day following 2 September 1752, would not be 3 September, but instead would be 14 September. Finally, it (almost) corrected the inaccuracy in Caesar’s leap year calculation by declaring that any year divisible by 100 (e.g., 1800, 1900) will not be a leap year, unless the year is also divisible by 400 (e.g., 2000, 2400), in which case it will be a leap year.

People did not take kindly to these changes. Many people rioted, feeling that the government had “robbed them” of eleven days. Also, since Roman times the new year was often celebrated with a week of partying, ending on 1 April. Some people continued to observe the new year on 1 April. These people were often called “April fools,” and many believe that this forms the source for our April Fool’s Day holiday.


No, we’re not talking about two couples going out for ice cream. We’re talking about how to deal with those dates that fall between 1 January and 25 March for all events in England and its colonies prior to 1752.

For example, the old Julian calendar was still in force when George Washington was born in Virginia on 11 February 1731. (Remember, February was one of the last months in the year 1731, since the new year—1732—didn’t begin until 25 March, over a month after Washington’s birth.) With the change in the beginning of the year and the shift in eleven days after the British Calendar Act of 1752, Washington’s birthday is now reckoned (in the Gregorian calendar) as 22 February 1732.

The entry for George Washington’s birth in the family Bible actually reads, “George Washington, son to Augustine and Mary his wife, was born ye 11th day of February 1731/32…” That reckoning reflects the common practice of “double-dating” events that occur within these first three months of the year, because so many countries (other than England and its colonies) used the Gregorian calendar which began on 1 January. It shows that his birthday occurred in what used to be called 1731 but is currently called 1732. The key to interpreting these double-dates is that it is always the second year that reflects how we would register the date in our current (Gregorian) calendar.

After England legislated the change to the Gregorian calendar in 1752, the need for double-dating events ceased, as the British calendar was now in agreement with most of the rest of the world. Still, you may well find that as you record dates for the events in the lives of your American or British ancestors prior to 1752, you will need to record and understand these double-dates.

What date was last Tuesday?

Often genealogists find a newspaper obituary or other document that refers to an earlier event by the day of the week. For example, an obituary might read, “John Wilson passed away Tuesday evening.” A wedding announcement might state, “Tom and Mary were joined in matrimony at the bride’s home on Thursday.”

To help you determine on what date events such as these occurred, the Society has prepared a free perpetual calendar. This is a one-page PDF document which you can download and print using Adobe Acrobat Reader. Download the pdf file below.

Perhaps unfamiliar abbreviations that may also be encountered in newspaper items are the terms “inst.” and “ult.” For example, an obituary dated 15 April might read, “James Miller died on the 12th inst.” Similarly, an obituary dated 2 April could state, “Barbara Jones died on the 29th ult.” The abbreviation “inst.” stands for instant, which means a prior date in the current month, while “ult.” is an abbreviation for unliumo, meaning a date in the prior month. (Just for completeness, “prox.” abbreviates proximo, meaning a date in the following month. Unless there is a clairvoyant in the family, however, this term is likely not to be encountered in genealogical materials.)

Other Calendars

Throughout history, other parts of the world have also defined their own calendars. During the years following the French Revolution in 1793, the First Republic created a French Revolutionary Calendar (or Republican Calendar). The year was 365 or 366 days long and consisted of twelve months of thirty days each, with five or six additional days at the end of each year. Each month was divided not into seven-day weeks but into ten-day decades. This calendar lasted from 24 October 1793 until 1 January 1806, when it was abolished by Emperor Napoleon I.

In the Muslim world, the Islamic calendar is a lunar calendar, in which the first year was that of the Hijra, when Muhammad traveled from Mecca to Medina. It contains 354 days in twelve lunar months.

The Hebrew calendar is a complex combination of a solar year and lunar months. Ordinary years may have 353, 354, or 355 days. A leap year may have 383, 384, or 385 days. Each month starts (roughly) on the day of a new moon. An ordinary year has twelve months; a leap year has thirteen months. Year one for the Jewish calendar is the presumed creation of the world; the current year (in 2007) is the year 5767 in the Jewish calendar.

Although the Chinese adopted the Gregorian calendar for official purposes in 1929, they continue to use a traditional Chinese calendar to determine festivals, the most significant of which is the traditional Chinese New Year. The Chinese calendar is very similar to the Hebrew calendar described above. Unique to the Chinese, however, is that their years are not numbered. Rather, they are given a sequence of names which repeats every sixty years.


Dates are not as simple as we might first expect, and, like spelling, need some understanding of context to be property interpreted. It’s no wonder our ancestors didn’t always know when they were born!

Last modified: 04-Jul-2016 12:09