Audemars Piguet unveils the new Royal Oak Perpetual Calendar
Perpetual calendars are part of the DNA of Audemars Piguet, and in 2015 the Royal Oak Perpetual Calendar returns to center stage with four different versions (two in steel, and two in pink gold). Continuing the shift in watch case size that began in 2012, the new Royal Oak Perpetual Calendar is now 41 mm, yet still extremely thin.
Even watches from the mid-16th century began to feature astronomical complications, including day, date and phases of the moon, but it was not until the 17th century that better accuracy and reliability in mechanical horology could be achieved.
The calendar mechanisms of these early astronomical watches are generally referred to today as simple calendars or triple calendars (day, date and month). They usually feature moon phase displays but do not make the adjustment to the leap year, and the date does not automatically adjust to compensate for the varying number of days in each month.
On the other hand, a perpetual calendar watch is a complex micro-mechanical device that has been engineered to automatically adjust to the varying number of days in each month, and even to the leap year. The watch knows that February has 28 days for three consecutive years prior to the leap year when the 29th day is added. It is in many regards an analog computer as it calculates or computes the complexities of the calendar independently from the user, taking automatic account of months with 28, 29, 30 and 31 days.