Happy 2016… a leap year!
Leap year were introduced by Julius Caesar in his Calendar on 46 B.C.: it appeared to be necessary to add one day to the 365 days calendar, once each 4 years, in order to keep the season flow aligned with the calendar.
Since Earth needs not only 365 days, but 365 days, 5 hours, 48 minutes and 49 seconds to rotate around the Sun, also the still current Gregorian Calendar includes leap years. But it added a new exception, defined thanks to the improved astronomical measurements: centenary years, divisible by 100, will not be leap year unless they are divisible by 400. The year 2000 was a leap year, but given this rule the following centenary years (2100, 2200, 2300) will not.
2016 will thus be a leap year. Divisible by 4, but not by 100. Watches with a perpetual calendar mechanism can be set on the number “4” of the leap year cycle (sometimes indicated by an “L”, standing for leap year). This year, lucky perpetual calendar watch owners will be pleased to read on the dial of their precious watch the date of February, the 29th!