The perpetual calendar is one of the best known complications in watchmaking and one of the most useful: it’s a miniature computer that automatically corrects the date at the end of each month, since some months (as the children’s rhyme reminds us) are 30 days long, and some 31.  The odd man out is February: 28 days long except in a leap year, when an extra day is added to correct for the fact that a standard year is actually about 365 and a quarter days long.  (The whole story is much more complicated than that but we can leave that to the astronomers.)

It’s a fantastically useful but also fantastically complicated mechanism and most perpetual calendars are rather more delicate than not –and, they are usually quite difficult to set, requiring the correct operation of four different correctors set into the case of the watch.  Not only that, they’re notoriously intolerant of rough handling.  To fill the gap, the annual calendar was developed; the annual calendar doesn’t automatically correct for February but it does for all the other months, and in exchange for the negligible trouble of setting the watch from the 28th of February to the 1st of March by hand once per year, it does exactly what the perpetual calendar does.

Thanks to the ease of owning one (both technically and in terms of cost, they’re easier on the owner than the perpetual calendar) they’ve become one of modern watchmaking’s most sought after complication, especially appreciated by owners who admire the poetic beauty of a self-correcting calendar but who also appreciate the greater robustness and practicality of the annual calendar.  One of the most distinctively styled that we’ve seen this year comes from the new 2012 collection of Parmigiani Fleurier, one of the most accomplished haute horlogerie firms which not only makes and hand-finishes all its own movements, but also cases and dials as well (components most other manufactures source from outside suppliers.)  The artisanal, small-batch approach to watchmaking embraced by Parmigiani produces very uniquely constructed and delightfully different watches.

The round Tonda case (in rose or white gold) houses a manufacture (watchspeak for “made in-house”) annual calendar movement, the automatic PF 339 Annual Calendar, which features a large, easy to read retrograde date display, as well as an indication of the month and also one for the day of the week.  The subtly asymmetric hour track embraces a display showing the age and phase of the moon, as well; the lunar disks are done in rose gold, and both the Northern and Southern hemispheres are displayed (just the thing if you’re a traveler who happens to be crossing the equator.)

The moon display is an especially pleasing addition; self-correcting calendars are often thought of as astronomical complications, since the length of the solar year is determined by the Earth’s orbit around the sun, and the addition of a display for the phases of the moon underscores the connection to the cosmos of the mechanical computer on your wrist.  (The moonphase display is accurate to within one day’s error every 120 years as well.)  The Tonda Annual Calendar is a beautifully elegant demonstration that practicality and poetry can make the happiest of marriages –a pleasant horological example of being able to have your cake and eat it too.

The Parmigiani Fleurier Annual Calendar is available in rose or white gold, with a matching buckle and strap by Hermes for Parmigiani Fleurier.  As part of the Parmigiani Fleurier 2012 collection, expect final pricing information after the official launch of the watch at the Salon International Haute Horlogerie in Geneva, in January of 2012.

Jack Forster is the Editor in Chief of Revolution Magazine, a quarterly publication celebrating the world of fine watchmaking, and he also manages Revolution Online the foremost information and discussion site on the internet for watch enthusiasts.

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