The calendar that was used in the Christian world up to the 1500s' was called the Julian Calendar or the Old Style (O.S.) calendar. The problem with this calendar was its lack of accuracy. This inaccuracy caused the calendar dates of the seasons to regress about ¾ of a day per century.
The Julian Calendar
The Julian Calendar was introduced by Emperor Julius Caesar in 46 BC. In that year Julius Caesar inserted 90 days to bring the months of the Roman calendar back to their traditional place with respect to the seasons.The Julian calendar was a pure solar calendar with twelve months of fixed lengths. The length of the Julian year was set to 365¼ days. This was the time it took the Earth to revolve once around the Sun, as it was known at the time. In order to get a integral number of days per year (365 days) it was decided that for each period of three years there will be a fourth year of 366 days, the leap year.The difference in length between the Julian year and the tropical year was 1 day (24 hours) per 128 years. The tropical year is defined as the mean interval between vernal equinoxes; it corresponds to the cycle of seasons. A solar calendar is designed to maintain synchrony with the tropical year.The Julian calendar year was too long causing an error of 11 minutes 14 seconds per year. This error amounted to almost one and a half days in 200 years and seven days in 1000 year. Once again the calendar became out of phase with the seasons.
The Gregorian Calendar
In 1582 Pope Gregory XIII decided to correct the calendar. The papal bull ”Inter Gravissimus” signed, on February 24 1582 (O.S.), instituted the recommendations of the pope’s Calendar Commission. The difference between the tropical year and the Julian year was then 10 days. The vernal equinox, which was used in determining Easter had moved 10 days from its proper date.In October 5, 1582 the calendar was put forward to October 15 in order to correct the calendar. In other words, that year was made 10 days shorter. This caused the vernal equinox of 1583 and subsequent years to occur about March 21. Therefore a new table of New Moons and Full Moons was introduced for determining the date of Easter.This correction was adopted by most of the Catholic countries that year. This new calendar was called the Gregorian Calendar (or the New Style, N.S.) after Pope Gregory.The Julian calendar had then been in use for about 1600 years.The difference between the Gregorian Calendar and the Julian Calendar was the length of the year and how leap years was determined. In the Julian calendar there was a leap year every fourth year. In the Gregorian Calendar there is no leap year in the last year of a new century that is not evenly divisible by 400. The average length of a Gregorian year will then be 365.2425 days. This will only accumulate an error of one day in about 2500 years.
The leap years are determined according to the following rule:
Every year that is exactly divisible by 4 is a leap year, except for years that are exactly divisible by 100; These centurial years are leap years only if they are exactly divisible by 400.The Gregorian Calendar is thus based on a cycle of 400 years or 146.097 days. Since 146.097 is evenly divisible by 7, the Gregorian Calendar repeats after 400 years.
Adoption of the Gregorian Calendar:
In France, Italy, Luxembourg, Portugal and Spain the New Style (N.S.) calendar was adopted in 1582. It was in use by most of the Catholic states in Germany as well as by Belgium and part of the Netherlands by 1584. Switzerland did a gradual change beginning in 1583 and completed first in 1812. Hungary adopted the New Style in 1587, but then the adoption came to a pause of more than a century before the first Protestant countries adopted the New Style. Denmark/Norway, the Netherlands and the Protestant states of Germany adopted the Gregorian Calendar in March 1, 1700 (O.S.). But the German Protestant states declined to adopt the rules laid down for determining Easter. Instead they preferred to rely on the astronomical tables. But in 1776 they acceded to the Gregorian calendar rules for Easter.In 1752 Great Britain and the British Empire adopted the New Style. In that year, September 2 was then brought forward to September 14. Use of the Gregorian Calendar in the United States stems from a British Act in 1751 which specified the use of the Gregorian Calendar in England and its colonies. The Alaskan territory retained the Old Style calendar until 1867, when it was transferred from Russia to the USA.SwedenIn November 1699 Sweden decided to adopt the new calendar the following year, 1700. But instead of doing the correction of the calendar at the same time, Sweden decided to do it gradually during the following 11 years by reducing one day per year during that time period. In 1700 the leap day was reduced. But no further reduction of days was being made during the following years.In January 1711 King Karl XII abolished the corrections to the calendar. Sweden then switched back to the Julian Calendar. Between 1700 and 1711 Sweden and Finland had their own calendar, Old Style + 1 day. That made foreign contacts very difficult.The return to the Julian Calendar was carried out by adding one day to February (in total 30 days) in the leap year of 1712. In 1740 Sweden followed the German Protestants using their astronomical methods for determining Easter. Not until 1844 did the Swedes adopt the Gregorian rules for determining Easter.In 1753 Sweden (including Finland) was ready to adopt the Gregorian Calendar. That year Sweden made a correction of 11 days, by letting February 17 be followed by March 1.But everyone did not love the reform of calendars. Many people thought that they had been robbed of 11 days of their life. Japan adopted the New Style in 1873, Egypt in 1875 and between 1912 and 1917 Albania, Bulgaria, China, Estonia, Latvia, Lithuania, Romania and Turkey. Greece in 1923.Soviet Russia did not adopt the Gregorian Calendar until 1918 when February 1 became February 14. At that time the difference between the two calendars was 13 days. The October Revolution in 1917 was in fact in November according to the Gregorian Calendar.Example of differences of dates:•The Swedish King Gustav II Adolf was killed in action in Germany on November 6, 1632 according to the calendar Sweden was using at that time. But according to the calendar the Catholic countries were using he died in November 16.•The Swedish King Karl XII was killed in action in Norway on November 30, 1718 according to the calendar Sweden was using at that time. But according to the calendar Denmark/Norway used at that time he died in December 11 (The Gregorian Calendar).
Summary, Sweden
•The Middle Ages - February 28, 1700: The Julian Calendar (O.S.)•March 1, 1700 - February 30, 1712: A "Swedish" calendar (O.S. + 1 day)•March 1, 1712 - February 17, 1753: The Julian Calendar (O.S.)•March 1, 1753 - present days:The Gregorian Calendar (N.S. eller O.S. + 11 days))
Time zones in Sweden
Before 1879 also Sweden had different time zones. It could differ as much as 45 minutes between the most eastern and the most western part (Haparanda – Strömstad). The time difference between Stockholm and Göteborg was 24 minutes. This caused problems with timetables when the railroad started during the second half of the 1800’s. On January 1, 1879, a standard time zone was introduced for the entire of Sweden. Swedish standard time was set accordingly to the meridian half way between Stockholm on the east coast and Göteborg on the west coast.Top of page
The calendar that was used in the Christian world up to the 1500s' was called the Julian Calendar or the Old Style (O.S.) calendar. The problem with this calendar was its lack of accuracy. This inaccuracy caused the calendar dates of the seasons to regress about ¾ of a day per century.
The Julian Calendar
The Julian Calendar was introduced by Emperor Julius Caesar in 46 BC. In that year Julius Caesar inserted 90 days to bring the months of the Roman calendar back to their traditional place with respect to the seasons.The Julian calendar was a pure solar calendar with twelve months of fixed lengths. The length of the Julian year was set to 365¼ days. This was the time it took the Earth to revolve once around the Sun, as it was known at the time. In order to get a integral number of days per year (365 days) it was decided that for each period of three years there will be a fourth year of 366 days, the leap year.The difference in length between the Julian year and the tropical year was 1 day (24 hours) per 128 years. The tropical year is defined as the mean interval between vernal equinoxes; it corresponds to the cycle of seasons. A solar calendar is designed to maintain synchrony with the tropical year.The Julian calendar year was too long causing an error of 11 minutes 14 seconds per year. This error amounted to almost one and a half days in 200 years and seven days in 1000 year. Once again the calendar became out of phase with the seasons.
The Gregorian Calendar
In 1582 Pope Gregory XIII decided to correct the calendar. The papal bull ”Inter Gravissimus” signed, on February 24 1582 (O.S.), instituted the recommendations of the pope’s Calendar Commission. The difference between the tropical year and the Julian year was then 10 days. The vernal equinox, which was used in determining Easter had moved 10 days from its proper date.In October 5, 1582 the calendar was put forward to October 15 in order to correct the calendar. In other words, that year was made 10 days shorter. This caused the vernal equinox of 1583 and subsequent years to occur about March 21. Therefore a new table of New Moons and Full Moons was introduced for determining the date of Easter.This correction was adopted by most of the Catholic countries that year. This new calendar was called the Gregorian Calendar (or the New Style, N.S.) after Pope Gregory.The Julian calendar had then been in use for about 1600 years.The difference between the Gregorian Calendar and the Julian Calendar was the length of the year and how leap years was determined. In the Julian calendar there was a leap year every fourth year. In the Gregorian Calendar there is no leap year in the last year of a new century that is not evenly divisible by 400. The average length of a Gregorian year will then be 365.2425 days. This will only accumulate an error of one day in about 2500 years.The leap years are determined according to the following rule:Every year that is exactly divisible by 4 is a leap year, except for years that are exactly divisible by 100; These centurial years are leap years only if they are exactly divisible by 400.The Gregorian Calendar is thus based on a cycle of 400 years or 146.097 days. Since 146.097 is evenly divisible by 7, the Gregorian Calendar repeats after 400 years.
Adoption of the Gregorian Calendar:
In France, Italy, Luxembourg, Portugal and Spain the New Style (N.S.) calendar was adopted in 1582. It was in use by most of the Catholic states in Germany as well as by Belgium and part of the Netherlands by 1584. Switzerland did a gradual change beginning in 1583 and completed first in 1812. Hungary adopted the New Style in 1587, but then the adoption came to a pause of more than a century before the first Protestant countries adopted the New Style. Denmark/Norway, the Netherlands and the Protestant states of Germany adopted the Gregorian Calendar in March 1, 1700 (O.S.). But the German Protestant states declined to adopt the rules laid down for determining Easter. Instead they preferred to rely on the astronomical tables. But in 1776 they acceded to the Gregorian calendar rules for Easter.In 1752 Great Britain and the British Empire adopted the New Style. In that year, September 2 was then brought forward to September 14. Use of the Gregorian Calendar in the United States stems from a British Act in 1751 which specified the use of the Gregorian Calendar in England and its colonies. The Alaskan territory retained the Old Style calendar until 1867, when it was transferred from Russia to the USA.SwedenIn November 1699 Sweden decided to adopt the new calendar the following year, 1700. But instead of doing the correction of the calendar at the same time, Sweden decided to do it gradually during the following 11 years by reducing one day per year during that time period. In 1700 the leap day was reduced. But no further reduction of days was being made during the following years.In January 1711 King Karl XII abolished the corrections to the calendar. Sweden then switched back to the Julian Calendar. Between 1700 and 1711 Sweden and Finland had their own calendar, Old Style + 1 day. That made foreign contacts very difficult.The return to the Julian Calendar was carried out by adding one day to February (in total 30 days) in the leap year of 1712. In 1740 Sweden followed the German Protestants using their astronomical methods for determining Easter. Not until 1844 did the Swedes adopt the Gregorian rules for determining Easter.In 1753 Sweden (including Finland) was ready to adopt the Gregorian Calendar. That year Sweden made a correction of 11 days, by letting February 17 be followed by March 1.But everyone did not love the reform of calendars. Many people thought that they had been robbed of 11 days of their life. Japan adopted the New Style in 1873, Egypt in 1875 and between 1912 and 1917 Albania, Bulgaria, China, Estonia, Latvia, Lithuania, Romania and Turkey. Greece in 1923.Soviet Russia did not adopt the Gregorian Calendar until 1918 when February 1 became February 14. At that time the difference between the two calendars was 13 days. The October Revolution in 1917 was in fact in November according to the Gregorian Calendar.Example of differences of dates:•The Swedish King Gustav II Adolf was killed in action in Germany on November 6, 1632 according to the calendar Sweden was using at that time. But according to the calendar the Catholic countries were using he died in November 16.•The Swedish King Karl XII was killed in action in Norway on November 30, 1718 according to the calendar Sweden was using at that time. But according to the calendar Denmark/Norway used at that time he died in December 11 (The Gregorian Calendar).
Summary, Sweden
•The Middle Ages - February 28, 1700: The Julian Calendar (O.S.)•March 1, 1700 - February 30, 1712: A "Swedish" calendar (O.S. + 1 day)•March 1, 1712 - February 17, 1753: The Julian Calendar (O.S.)•March 1, 1753 - present days:The Gregorian Calendar (N.S. eller O.S. + 11 days))
Time zones in Sweden
Before 1879 also Sweden had different time zones. It could differ as much as 45 minutes between the most eastern and the most western part (Haparanda – Strömstad). The time difference between Stockholm and Göteborg was 24 minutes. This caused problems with timetables when the railroad started during the second half of the 1800’s. On January 1, 1879, a standard time zone was introduced for the entire of Sweden. Swedish standard time was set accordingly to the meridian half way between Stockholm on the east coast and Göteborg on the west coast.Top of page
