Leap year most years that are multiples of 4 are leap years. In each leap year, the month of February has 29 days instead of 28. Adding one extra day in the calendar every four years compensates for the fact that a period of 365 days is shorter than a tropical year by almost 6 hours. Some exceptions to this basic rule are required since the duration of a tropical year is slightly less than 365.25 days. The Gregorian reform modified the Julian calendar's scheme of leap years as follows: Over a period of four centuries, the accumulated error of adding a
Pax Calendar to 48 hours or making Pax a month of 28 or 21 days to be added 18 times in 400 years. Pax Calendar The Pax calendar was invented by James A. Colligan, SJ in 1930 as a perennializing reform of the annualized Gregorian calendar. 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. Unlike other perennial calendar reform proposals, such as the International Fixed