Glossary of watchmaking

Leap year

Année bissextile | 閏年/ウルウドシ | 闰年

Introduced by Julius Caesar in 45 BC as part of the Julian calendar, the leap year was already found in certain Egyptian and Babylonian calendars. It has 366 days and generally occurs every four years to take into account the time taken for the Earth to make one complete revolution of the Sun, i.e. 365.2422 days.

See "Gregorian Calendar".