Perpetual calendar

A perpetual calendar is a calendar which is good for a span of many years.

For the Gregorian calendar, a perpetual calendar often consists of 14 one-year calendars, plus a table to show which one-year calendar is to be used for any given year. Note that such a perpetual calendar fails to indicate the dates of moveable feasts such as Easter.

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The International Perpetual calendar (also known as the International Fixed calendar, the Cotsworth plan, the Eastman plan, the 13 Month calendar or the Equal Month calendar) is a proposal for calendar reform providing for a year of 13 months of 28 days each, with one day at the end of each year belonging to no month or week. The thirteenth month is inserted between June and July and called Sol or Midi. In leap years, two days are added to the end of the year instead of one, again belonging to no month or week. Regular years are 365 days long; leap years are 366 days long.

The International Fixed Calendar League, with offices in London and in Rochester, New York, ceased activities in the 1930s. In recent years there have been attempts to revive the plan.

The International Perpetual calendar is based on the Positivist Calendar published in 1849 by French philosopher Auguste Comte (1798-1857). Compte based his calendar on Polynesian calendars. The main difference between the International Perpetual calendar and the Positivist calendar is the names Compte gave to months and days. The months in the Positivist calendar were, in order: Moses, Homer, Aristotle, Archimedes, Caesar, St. Paul, Charlemagne, Dante, Gutenburg, Shakespeare, Descartes, Frederick II and Bichat. Every day of the year was likewise named.

External link

• Article on the International Fixed Calendar League at the International Institute of Social History Archives.