Patek Philippe Perpetual Calendar

Patek Philippe built the first perpetual calendar wristwatch in 1925, on a movement made in 1898 for a pendant watch, and brought the complication into series production in 1941 with the reference 1518 perpetual calendar chronograph. The mechanism carries the long and short months and the leap year cycle, and Patek states that it needs no correction until 2100. One layout recurs across the family, with day and month in apertures below 12 and the date read by a hand around a moon phase at 6, while other references set the calendar out in subdials read by hands, run it in a single line across the dial, or sweep the date on a retrograde hand. They sit under Grand Complications in the catalogue, in round gold and platinum cases.