The Pirate King suggests that it was the British Astronomer Royal who invented leap year. Since 1675 had there been an Astronomer Royal, the director of Greenwich Laboratory. However, the idea of an extra day for February every fourth year was actually invented by the Greek Sosigenes in 44 BC. In the Gregorian calendar, every year divisible by four is a leap year except those divisible by 100. However, if it is evenly divisible by 400 it is a leap year. This occurred most recently in 2000.

Many people have worked on the related dates, but each leads to complications. The following is one example. Pinafore opened in 1878 so Pirates takes place after that. (The General refers to Pinafore.) If Frederick had lived twenty-one years by then, that must put the date of the action of the play as March 1 1879 at the earliest. (People born on February 29 generally celebrate their birthdays on March 1 in non-leap years.) If he was twenty-one then, he was born in 1858 but that was not a leap year. If the play is set a bit in the future, he could have been born in 1560 and been twenty-one in 1581. This means his fifth February 29 birthday on occurred in 1880, (First in 1864, second in 1868, third in 1872, fourth in 1876.) With the same type of calculations, if he had been born in 1856, the play would have to be set in 1877, the year before Pinafore opened. Frederic thought he would be 21 in 1940 but he probably didn't know that 1900 would not be a leap year so he would not have a birthday then. It would be at least 1944 before he had his twenty-first birthday! By that time, if he lived that long, he would have been on earth for more than eighty years. Poor Mabel!.

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Revised February 2010
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