Why was there a need for a calendar reform? It was because of leap year and the length of the year. The old Julian calendar had leap year every four years which gave an average year length of 365.25 days. But the yearly orbit around the sun took "only" 365.2422 days. During the course of the centuries the little errors added up to entire days: 3 days in 400 years.
This meant that seasons and holidays slowly moved through the calendar. In the 1500s when Pope Gregorius decided to rectify the situation, the spring equinox fell on 11 March rahter than the 21st. And this was a serious matter as the date of Easter was to be calculated from the spring equinox. If this had been allowed to continue we would gradually have had summer in March-April and celebrated Christmas in the warmth of spring.
In 1582 this was corrected in all the Catholic countries. To get the spring equinox back to the "correct" date (i.e. the original placement of Easter which was decided upon at the council of Nicaea ), they simply skipped 10 days 4 October 1852 was followed by 15 October. In order to avoid having a future problem, they created a rule that a leap year couldnt occur every fouth year. Even-numbered centuries are leap years only when evenly divisible by 400, i.e. years 1600 and 2000, but not 1800 and 1900. This is what is called the Gregorian calendar. The beauty of it is that it is better than the other calendar, with the "correct" length of the year.
The change appeared only in the countries faithful to the Pope. Sweden (with Finland) as well as other protestant countries kept the old time calculation. But people began to tire of the impracticality of having different dates in different countries, and around 1700 the countries changed to the new calendar. Most of them referred to it as the "new style" calendar to escape being linked to a pope.
In 1700 Sweden took the first step to skip one leap day (in the Gregorian manner) but without eliminating the extra 10 days. As a result they had their own time calculation compared to the countries that still held firmly to the old law.
Because of king Karl XIIs perseverence in making war it never happened that those extra days were eliminated. So, in order not to be different from all other countries it became necessary to acquire the extra days. In 1712 it was decided to return to the old calendar. To keep pace with the Julian calendar it was necessary to add an extra day. February received 2 leap days and in that year there actually was a day called 30 February. In order not to be different from all other countries, in 1712 it was decided to return to the old calendar. To keep pace with the Julian calendar it was necessary to add an extra day. February received 2 leap days and in that year there actually was a day called 30 February.
In 1753 it was felt that the time was ripe for the new calendar. Once more it was February that was effected, as we went directly from 17 February to 1 March.
And one more thing: If perchance you should be one of those people feeling pity for all children born on 29 February (who could only have a birthday every fourth year), you could just think about the poor wretch who got caught being born 30 February 1712!
Written by Folke A. Nettelblad, Hufvudstadsbladet, 9 March 2003.
Translated to English by June Pelo