Well, we all know that February has 29 days every four years, barring those century years not evenly divisible by 400, but once in history (at least), it had 30 days. Yes, children, it did! I am not making this up. This engaging version of the circumstances surrounding such an aberration was sent me by a learned colleague:
“No place on earth had a more difficult transition to the Gregorian calendar than Sweden. At the end of the 17th century, the King and parliament had finally agreed they would switch, but they decided to implement a gradual system instead of the shock of dropping eleven days at once. The plan was to eliminate the leap years between 1700 and 1740 by which time the calendar would be in sync with the Gregorian nations. (This phased-in approach had been considered, but rejected by the Pope in the 1500's).”
“The drawback, of course, was that as of March 1, 1700, Sweden was truly on its own – with a calendar that didn't match any other part of the world. Worse, for some murky reasons (war? politics? an abundance of glögg?) they forgot their bargain and did have a leap year in both 1704 and 1708.
[My bet would be on the abundance of glögg, but other sources say that it was war and rumors of war.]
“Now Sweden was not only out of step with the world, but not even gaining the benefits of their plan. King Karl XII scrapped the experiment in 1712, so far as I know the only country ever to return to the Julian calendar after leaving it. Two leap days were added for that year, and so, three hundred years ago, Sweden had a February 30th, maybe the only one in history! (Sweden eventually adopted the Gregorian calendar in 1753, using the "all-at-once" dropping of days).”
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There are two images on a very informative webpage about the Gregorian calendar which show this extra leap day in 1712. One is the Swedish almanac for February of that year. The more interesting image shows an entry in a church registry book for a marriage which took place on the 30th of February.
Now there’s one guy who didn’t have to worry about missing an anniversary and the fall-out that generally ensues thereafter!
