Pax Calendar

The Pax calendar was invented by James A. Colligan, SJ in 1930 as a perennializing reform of the annualized Gregorian calendar.

Unlike other perennial calendar reform proposals, such as the International Fixed Calendar and the World Calendar, it preserves the 7-day week by periodically intercalating an extra seven days to a common year of 52 weeks = 364 days.

The common year is divided into 13 months of 28 days each, whose names are the same as in the Gregorian calendar, except that a month called Columbus occurs between November and December. The first day of every week, month and year would be Sunday.

In leap years, a one-week month called Pax would be inserted after Columbus.

To get the same mean year as the Gregorian Calendar it adds a leap week to 71 out of 400 years. It does so by adding the leap week Pax to every year whose last two digits make up a number that is divisible by six or are 99. Years ending with 00 have Pax, unless the year number is divisible by 400.

The Pax Calendar proposal is mentioned in the book "Marking Time: The Epic Quest to Invent the Perfect Calendar" (by Duncan Steel, John Wiley & Sons, Inc., 2000, page 288):

Colligan's original 1930 proposal is reprinted on Rick McCarty's Website on Calendar reform.

Unlike the International Fixed Calendar, the Pax calendar has a new year day that differs from the Gregorian New Year's Day. This is a necessary consequence of it intercalating a week rather than a day.

The following tables show that Gregorian dates of some Pax Calendar New Year Days. NB: Those dates that occur in December occur in the preceding Gregorian year.

The next table shows what happens around a typical turn of the century and also the full range (18 Dec to 6 Jan) of 19 days that the Pax Calendar New Year Day varies against the Gregorian calendar.

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