The Perpetual Calendar: Degrees Of Complication

Found: The Watch So Perfect, It Inspires Meltdowns

Page 1 of 3

Remove the back of even the simplest mechanical timepiece and the mechanism you see inside looks impossibly complicated. This mechanism, known as the movement, is typically made up of 200 or more individual parts, most assembled manually in a workshop by someone with very steady hands. Over the next week, we'll be looking at the six complications that represent the height of the horological craft.

The Complications

May 30th - The chronograph, which stops time.

May 31st - The power reserve, which tells you how long it will stay running.

June 1st - The repeater, which chimes the time.

Today - The perpetual calendar, which never needs setting.

June 3rd - The moon phase, which tracks the lunar cycle.

June 4th - The tourbillon, which defies gravity in a quest for precision.



While most of the time we celebrate human interaction with a mechanical watch — winding it or operating a chronograph — in one respect, interaction can be a mundane chore. That respect is setting the date. Our beloved calendar, with its irregular months and leap years, requires the watch owner to aid his ingenious yet dumb timepiece in keeping up with the short months and long years. The conventional wristwatch with a date function dutifully marches off 31 24-hour cycles before starting all over again. The concept of building a watch that could “know” when it was a month with only 30 days (or 28) or a leap year was one of the classic challenges facing the world of horology. But as we’ve seen thus far, watchmakers never back down from a challenge. And in 1925, that challenge was met, and the perpetual calendar wristwatch was born.

As the name implies, a perpetual calendar wristwatch is one that never needs resetting, other than maybe for daylight-savings adjustments twice a year (depending on where you live, that may not even be necessary). The dial of the watch will tell you the time, the date, and sometimes the day as well as the month. But the real key is that the watch movement knows the year. There is a lesser complication called the annual calendar that will go so far as knowing short months from long but will still need resetting in leap years. A perpetual calendar watch will dutifully and accurately keep time long after you pass it down to your next of kin.



By Imperial decree

As with many things, like candles, umbrellas and aqueducts, we have the ancient Romans to thank for our modern calendar. The names of the months bear witness: January, named for the god Janus, and March for the god Mars. In the early days of the Roman calendar, it followed a lunar cycle and there were 10 months. This is why the months September ("seventh") through December ("tenth") are now strangely misnamed. When the solar calendar added months during the reign of Caesar Augustus, so too were months honoring the Caesar dynasty — Augustus and Julius. Naturally, the months then had to have the most days, 31, as well as October (Caesar Octavius). So while the calendar approximated the sun’s travel across the heavens, these imperially designated long months threw a wrench in the works for future watchmakers.

Similarly, the concept of the leap year was the result of a political, or rather, religious decree. Pope Gregory wanted to make sure that Easter fell as close to the spring equinox as possible every year, so he determined that every fourth February should get an extra day to keep the calendar synchronized to the seasons. This "Gregorian" calendar compensates for the fact that our 365-day year is six hours shorter than a solar year and thus "resets" it every four years. As if the Roman calendar wasn’t enough to have to deal with, the Gregorian added yet more complexity for horologists.

Rolex gave Patek a run for its money during the development of the perpetual calendar...