The Duality of Time: A Tale of Two Perpetual Calendars

The Duality of Time: A Tale of Two Perpetual Calendars

No civilization can live without tracking time, and not just hours and minutes, but days, months, years, the phases of the moon, and more. For that reason, horologists create a host of different types of calendar watches, the most complicated of which is the perpetual calendar.

By Roberta Naas
Special Correspondent

The intricate dance of timekeeping has been a fascination for humanity since the dawn of time. Among the many marvels of horology, the perpetual calendar complication stands as a testament to human ingenuity and precision engineering.

A deft blend of watchmaking, astronomy, and math, the perpetual calendar’s origins can be traced back to the mid-1700s when the English horologist Thomas Mudge pioneered the earliest known pocket watch with a perpetual calendar complication in 1762.

However, interestingly enough, clockmakers of the 1600s had also dabbled in calendar-like mechanisms, with Thomas Tompion creating a longcase Equation of Time clock as early as 1695. Additionally, George Graham, whom Mudge apprenticed with, also tinkered with calendar clocks.

Still, despite the progress made in the previous century, Mudge was the first to build a pocket watch with a perpetual calendar. In fact, he built two. One, Number 525, was sold at auction. The other, Number 574, is currently in the British Museum.

From Pocket to Wrist

Mudge’s creation marked the inception of a complication that would endure through the ages. However, its appearance in timepieces remained sporadic for about a century – most likely because of the extreme complexity and precision involved in its making.

In fact, it wasn’t until 1864 that renowned Swiss watchmaker Patek Philippe created a perpetual calendar pocket watch, taking another 25 years to patent the mechanism in 1889. In 1898, the brand created a woman’s perpetual calendar pendant watch.

Even still, it would be several decades later before this complication found its way into a wristwatch, the first being when Patek Philippe built the first perpetual calendar wristwatch in 1925, fueled by the patronage of Thomas Emery, a wealthy collector of Patek Philippe timepieces.

In the ensuing decades, other leading Swiss watch brands began developing perpetual calendar wristwatches, and today, they have evolved to the point where we have classic-looking pieces and sometimes crazy-looking pieces.

What is a Perpetual Calendar?

A perpetual calendar mechanism accurately displays the day, date, and year, accounting for leap years, varying lengths of months, and even moon phases. Its mechanism, comprised of hundreds of intricate mechanical parts, utilizes wheels, gears, and levers to calculate the passage of time with exceptional precision, accounting for 1,461 days (i.e., four years) and thus accommodating the complexities of our calendar system.

Most Gregorian perpetual calendar watches are accurate until 2100 before needing any adjustment. The reason for needing an adjustment is because the leap year that should take place in 2100 will be skipped in order to sync the Gregorian calendar with the sidereal year.

It is a complex mathematical formula that states that the turn-of-the-century year must be divisible by 400 exactly, with no leftover fraction. Rest assured, though, that as the ability to track time to the tiniest of fractions improves, the world’s finest watchmakers will find a way to track time far beyond 2100.

While all perpetual calendar watches have a wealth of information to display on the dial, some watch brands take a somewhat different approach to the layout and aesthetic, with some remaining extremely classic and others reaching for a more innovative approach.

A. Lange & Söhne Lange 1 Perpetual Calendar, Ref. 345.033 E

Crafted in 18-karat pink gold, this Lange 1 Perpetual Calendar watch, by German brand A. Lange & Söhne, is a study of timeless elegance. It also stands out in the world of perpetual calendars thanks to several of its technical aspects.

Easily one of this Lange 1’s most distinguishing features is the specially developed peripheral month ring that indicates the months on the outer portion of the dial to allow for a cleaner design. Furthermore, the watch boasts a range of additional complications, including Lange’s signature outsize date display, retrograde day-of-week indicator, leap-year display, and a moon-phase display with an integrated day/night indicator.

Meanwhile, the moonphase display features a white gold moon that rotates around its own axis once every 24 hours to track synodic orbit (29 days, 12 hours, 44 minutes, and 3 seconds). Moreover, it will be accurate for the next 122.6 years, and by then, it will need correcting by one day.

The watch is powered by an in-house-made mechanical calibre, the L021.3, consisting of 621 components, including a balance beating at 21,600 semi-oscillations per hour (3 Hz).

The movement, which goes through the assembly process twice, features a unidirectional winding rotor in 21-karat gold with a platinum mass – visible from the sapphire crystal caseback – and offers 50 hours of power reserve while also being water resistant to 30 meters. The use of untreated German silver, gold chatons, and hand-engraved balance cock with a whiplash spring further accentuates the brand’s commitment to excellence in every detail.

With a rich grey dial made of solid silver, the 41.9mm self-winding Lange 1 Perpetual Calendar (price given upon request) showcases the outsized date at 10:00, the offset hour and minute dial at 3:00, the leap year indication at 6:00, moonphase display and day/night indicator in the subsidiary seconds dial between 7:00 and 8:00.

MB&F Legacy Machine Perpetual Evo Blue

The newest rendition of MB&F’s Legacy Machine (LM) Perpetual Evo watch, which was first introduced in 2020, offers a bold three-dimensional design and sports an anything-but-classical look.

The original LM Perpetual watch, on which the LM Perpetual Evo line is based, was developed and unveiled in 2015. The movement was created by watchmaker Stephen McDonnell and showcased a new way to track the calendar.

You see, on most perpetual calendars, the days in the month are, traditionally, tracked using a 31-day wheel with notches in the disc that are shallowed or deepened so the wheel teeth can skip (or subtract) a day to achieve the 30-day months. February is no different; these mechanisms just skip enough notches to accommodate the 28- or 29-day month.

McDonnell’s invention reverses the process by working off of a 28-day month base and adding extra teeth in the wheel for months with more than 28 days, thus eliminating the need for “skipping” and offering a smoother transition. However, most importantly, it enabled the wearer to change the time or date without worrying about breakage.

The LM Perpetual Evo watches employ this same system but also provide a few “active lifestyle” features that the LM Perpetual does not. These include a FlexRing shock absorber, screwdown crown, and water resistance to 80 meters.

The newest LM Perpetual Evo Blue version, which retails for $191,400, is crafted in titanium and boasts black calendar rings and an offset hour/minutes dial at 12 o’clock – all against a spectacular ice blue background.

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