Genealogy Calendar Info - Part 1

The Jewish, Julian, and Gregorian Calendars Demystified

The Jewish Calendar

Various calendars have been developed throughout history to mark the passage of time and are commonly based on the solar calendar (the secular calendar), the lunar calendar (the Muslim calendar), or a combination of the two (the Jewish calendar).

Molad, the new moon, defines the start of the new month. A lunar month lasts 29 days, 12 hours, 44 minutes, and 3 1/3 seconds, or 29 days, 12 hours, 793 halaqim. There are between 12 and 13 lunar months in a solar year.

Because 19 years encompass almost exactly 235 months, the Jewish calendar employs a cycle of 19 years, as do the Chinese calendar and the Ancient Greek calendar. In a cycle of 19 years, the Jewish calendar includes 12 common years of 12 months, and 7 leap years of 13 months. Leap years occur in years 3, 6, 8, 11, 14, 17, and 19 of each 19-year cycle.

The months in the Jewish calendar are:

Tishri -30 days

Heshvan – 29 days

Kislev – 30 days

Tevret – 29 days

Shevat – 30 days

Adar 1 – 30 days (Adar 1 occurs only in leap years)

Adar 2 – 29 days

Nisan – 30 days

Iyyar – 29 days

Sivan – 30 days

Tamuz – 29 days

Ab – 30 days

Elul – 29 days

However, a common year is 8 hours, 876 halaqim too short and a leap year is 2 hours, 491 halaqim too long.

Thus, the first day of Tishri will drift from the molad of Tishri (the new moon that marks the beginning of the month of Tishri). If the molad falls on the first day of Tishri, everything is fine. If the first of Tishri arrives too soon, the Jewish calendar adds one day to the preceding month of Heshvan (this is called a complete year). If the first day of Tishri arrives too late, the Jewish calendar subtracts a day from the preceding month of Kislev (this is called a defective year).

In a defective year, Heshvan is 29 days, Kislev is 29 days, a common year is 353 days, and a leap year is 383 days.

In a normal year, Heshvan is 29 days, Kislev is 30 days, a common year is 354 days, and a leap year is 384 days.

In a complete year, Heshvan is 30 days, Kislev is 30 days, a common year is 355 days, and a leap year is 385 days.

But here is where things get more complicated. There are four rules that further govern the Jewish calendar.

If molad Tishri falls on a Sunday, Wednesday, or Friday, the first day of Tishri must be delayed by one day. If Tishri begins on a Wednesday or Friday, Yom Kippur would fall on a Friday or a Sunday, making it impossible to prepare food for the day after the Yom Kippur fast, due to Sabbath restrictions. if Tishri begins on a Sunday, the seventh day of Succoth would fall on the Sabbath.

If molad Tishri occurs at noon or later, the first day of Tishri must be delayed by one day in order to ensure that the new crescent moon is visible during the first day of the year.

If molad Tishri falls on a Tuesday at 3:11:20 AM or later, then the first of Tishri is delayed by one day, otherwise both rules 1 and 2 will be invoked, making the previous year too long (356 days).

If molad Tishri after a leap year falls on Monday at 9:32:43 1/3 AM or after, then the first of Tishri is delayed by one day, otherwise the previous leap year would have been delayed by both rules 1 and 2, making the previous leap year too short (382 days).

Biblical creation began on the 25th of Elul in year 1 and ended on the 1st of Tishri in year 2. Today, May 11, 2008 is the 6th of Iyyar in the year 5768. The conversion from the Gregorian calendar, which we use today to the Jewish calendar, can be computed for Jewish Calendar Conversions.

The Jewish calendar slowly creeps forward compared to the astronomical year since a year lasts 365.2422 days, but the Jewish calendar, on average, lasts 365.2468 days. Thus, the Jewish calendar will creep one day forward every 217 years. The Gregorian calendar which is in common use today is also subject to calendar creep, but the Gregorian calendar creeps forward only 1 day every 3333 years. By comparison, the Julian calendar, which was replaced by the Gregorian calendar, crept forward 1 day every 128 years.

The Julian Calendar

In 45 B.C Julius Caesar ordered a calendar consisting of twelve months based on a solar year. This calendar employed a cycle of three years of 365 days, followed by a year of 366 days (leap year). When first implemented, the "Julian Calendar" also moved the beginning of the year from March 1 to January 1. However, following the fall of the Roman Empire in the fifth century, the new year was gradually realigned to coincide with Christian festivals until by the seventh century, Christmas Day marked the beginning of the new year in many countries.

By the ninth century, parts of southern Europe began observing first day of the New Year on March 25 to coincide with Annunciation Day (the church holiday nine months prior to Christmas celebrating the Angel Gabriel's revelation to the Virgin Mary that she was to be the mother of the Messiah). The last day of the year was March 24. However, England did not adopt this change in the beginning of the New Year until late in the twelfth century.

Because the year began in March, records referring to the "first month" pertain to March; to the second month pertain to April, etc., so that "the 19th of the 12th month" would be February 19. In fact, in Latin, September means seventh month, October means eighth month, November means ninth month, and December means tenth month. Use of numbers, rather than names, of months was especially prevalent in Quaker records.

Genealogy Calendar Info - Part II

The Gregorian Calendar

During the middle ages, it began to become apparent that the Julian leap year formula had overcompensated for the actual length of a solar year, having added an extra day every 128 years. However, no adjustments were made to compensate. By 1582, seasonal equinoxes were falling 10 days "too early," and some church holidays, such as Easter, did not always fall in the proper seasons. In that year, Pope Gregory XIII authorized, and most Roman Catholic countries adopted, the "Gregorian" or "New Style" Calendar." As part of the change, ten days were dropped from the month of October, and the formula for determining leap years was revised so that only years divisible by 400 (e.g., 1600, 2000) at the end of a century would be leap years. January 1 was established as the first day of the New Year. Protestant countries, including England and its colonies, not recognizing the authority of the Pope, continued to use the Julian calendar.

Double Dating

Between 1582 and 1752, not only were two calendars in use in Europe (and in European colonies), but also two different starts of the year were in use in England. Although the "Legal" year began on March 25, the use of the Gregorian calendar by other European countries led to January 1 becoming commonly celebrated as "New Year's Day" and given as the first day of the year in almanacs.

To avoid misinterpretation, both the "Old Style" and "New Style" year was often used in English and colonial records for dates falling between the New Year (January 1) and old New Year (March 25), a system known as "double dating." Such dates are usually identified by a slash mark [/] breaking the "Old Style" and "New Style" year, for example, March 19, 1631/2. Occasionally, writers would express the double date with a hyphen, for example, March 19, 1631-32. In general, double dating was more common in civil than church and ecclesiastical records.

The Changes Of 1752

In accordance with a 1750 Act of Parliament England and its colonies changed calendars in 1752. By that time, the discrepancy between a solar year and the Julian calendar had grown by an additional day, so that the calendar used in England and its colonies was 11 days out-of-sync with the Gregorian calendar in use in most other parts of Europe.

England's calendar change included three major components. The Gregorian calendar, changing the formula for calculating leap years, replaced the Julian calendar. The beginning of the legal New Year was moved from March 25 to January 1. Finally, 11 days were dropped from the month of September 1752.

The changeover involved a series of steps:

December 31, 1750 was followed by January 1, 1750 (under the "Old Style" calendar, December was the 10th month and January the 11th

March 24, 1750 was followed by March 25, 1751 (March 25 was the first day of the "Old Style" year)

December 31, 1751 was followed by January 1, 1752 (the switch from March 25 to January 1 as the first day of the year)

September 2, 1752 was followed by September 14, 1752 (drop of 11 days to conform to the Gregorian calendar)

Which Calendar Is It?

Out of context, it is sometimes hard to determine whether information in colonial records was entered "Old Style" or "New Style." Some examples:

In the Public Records of the Colony of Connecticut, “A Corte at New Towne, Hartford, CT 27 December 1636” is immediately followed by a court held “21 February 1636” which is followed, in turn, by “A Cort at Hartford, CT, 28 March 1637. Although it may first appear that the February session was entered out of sequence, the arrangement is actually correct. Under the "Old Style" calendar and legal New Year, 1636 began on March 25. December 1636 was followed by January 1636 and February 1636, and 1636 continued through March 24.

The “Warwick Patent” is dated the "Nineteenth day of March in the Seventh/ year of ye reigned of our Sovergne Lord Charles by ye grace of God / King of England, Scotland, France, and Ireland defender of ye faith & Anno Dom/ 1631." Although not double dated, the historical context indicates that the date as recorded was "Old Style." If double dated, it would have been recorded as March 19, 1631/2; if recorded "New Style," it would be March 19, 1632.

John and Joanne Carrington, accused of "familiarity with Satan the great Enemy of God and mankind" were indicted by Connecticut's Particular Court on "6 March 1650/1." In his "diary" or notebook, Matthew Grant records that they were executed "mar. 19.50." Although Grant did not employ the double date, had he done so it would have been recorded as March 19, 1650/1.

Although current historical scholarship calls for retention of Old Style dates in transcriptions, historians and genealogists need to be aware that some people living at the time converted the date of an event, such as a birthday, from Old Style to New Style. George Washington, for example, was born on February 11, 1731 under the Julian Calendar, but changed the date to February 22, 1732 to reflect the Gregorian Calendar.

Today, Americans are used to a calendar with a "year" based the earth's rotation around the sun, with "months" having no relationship to the cycles of the moon and New Years Day falling on January 1. However, that system was not adopted in England and its colonies until 1752. The changes implemented that year have created challenges for historians and genealogists working with early colonial records, since it is sometimes hard to determine whether information was entered according to the then-current English calendar or the "New Style" calendar we use today.

Throughout history there have been numerous attempts to convey time in relation to the sun and moon. Even now the Chinese and Islamic calendars are based on the motion of the moon around the earth, rather than the motion of the earth in relation to the sun, and the Jewish calendar links years to the cycle of the sun and months to the cycle of the moon.