There’s something special about 2020 – and it’s not just those satisfying duplicated digits or their association with perfect vision and long-range foresight. It’s because it’s a leap year, meaning it has 366 instead of 365 days. To mark the occasion, we explore one of the most revered of all horological complications – an ingenious type of watch that’s highly sought after among collectors because it’s capable of accounting for that extra day. We’re talking about the perpetual calendar.
But first, what makes a leap year?
In our busy modern lives, we all rely on our calendars – whether on our kitchen wall, our desk or, increasingly, our smartphone – to keep abreast of our schedule. And, without realising it, many of us will be using a version that originated back in 1582.
It typically takes the Earth 365 days, five hours, 49 minutes and 16 seconds to orbit the Sun from equinox to equinox. To accommodate those ‘spare’ hours, minutes and seconds, and keep the year aligned with the equinoxes, an extra ‘leap day’ was introduced every four years, on 29 February. The instigator of this radical reform was Pope Gregory XIII. He decreed that Christianity’s ‘moveable feasts’, such as Easter, which follow the cycle of the sun and the seasons, had drifted too far from the date of their original celebration. While the Gregorian calendar was a European invention, by the 20th century, thanks to globalisation, the entire world was using it for civil purposes.
But, obviously, all of those instances of 29 February eventually add up. Every 400 years, therefore, there are three extra days. To redress that, Aloysus Lilius, the Italian scientist who developed the new calendar, added leap days only in years divisible by four, unless the year was also divisible by 100. That means 2400 will be a leap year, but 2100 will not.
That might sound complex, but it didn’t faze English watchmaker Thomas Mudge, who, in 1762, succeeded in inventing a mechanism that could account for these quirks. The perpetual-calendar complication he devised first appeared in a wristwatch in 1925, having been adapted by Patek Philippe from a movement made in 1898 for a ladies’ pendant timepiece. As you’d expect from a mechanism featuring gears used only every four years, it takes even the most skilled of horologists months to assemble such a watch, adding to its appeal. More attractive still, using the above calculation, a perpetual calendar created in 2020 will not need to be adjusted for 80 years.
Few brands create perpetual calendars quite like Patek Philippe. This stunning Ref 7140G for ladies will adjust itself to the leap year this 29 February (£72,400)
Mastering the art: Patek Philippe Ref 7140G
Today, Patek Philippe is still the master of the complication, and we are especially enamoured of Ref 7140G. This ultra-thin watch is the first perpetual-calendar timepiece for women in the brand’s collection. It comes in a beautiful 18-carat white-gold 35.1mm case featuring a bezel set with 68 shimmering diamonds and a prong buckle glistening with a further 27.
Beneath the Ladies First’s silvery sunburst dial ticks the automatic calibre 240 Q, which powers a perpetual-calendar mechanism. That means it displays the hour, day, date, month and moon phase, and will adjust itself on the leap year from 28 February to 29 February and 1 March. Incredibly, this movement is a mere 3.8mm thick, which makes for a svelte dress watch that’s just 8.7mm in profile. Throw in an elegant alligator-leather strap and you’ve got yourself an exquisite perpetual-calendar example (£72,400).
As its name suggests, the Vacheron Constantin Patrimony Perpetual Calendar Ultra-Thin is just 8.96mm thick – incredible, given the intricate complex movement within (£68,600)
Style and substance: Vacheron Constantin Patrimony Perpetual Calendar Ultra-Thin
Another venerable brand known for having a handle on the perpetual-calendar mechanism is Vacheron Constantin. The Patrimony Perpetual Calendar Ultra-Thin houses the super-slim calibre 1120 QP, which drives the month display sub-dial, in which the leap year appears in its own quadrant at 12 o’clock. It also powers the day, date and moon-phase displays, as well as the hour and minutes – all while offering a 40-hour power reserve.
The watch has a 41mm case cast in warm 18-carat pink-gold with a transparent case back, a silver dial and a brown alligator-leather strap. At just 8.96mm thick, it boasts an impressively slender profile, given the complex perpetual-calendar movement inside (£68,600).
A. Lange & Söhne’s Datograph Perpetual Tourbillon not only features a perpetual-calendar complication, but also a flyback chronograph and a stop-seconds tourbillon (£255,000)
Pushing the envelope: A. Lange & Söhne Datograph Perpetual Tourbillon
One of the most outstanding perpetual-calendar timepieces is that by the revered German brand A. Lange & Söhne. Its Datograph Perpetual Tourbillon, which first launched in 2016, combines a flyback chonograph, a stop-seconds tourbillon and a perpetual-calendar mechanism with a moon-phase display. This model from 2019 is cast in 18-carat white-gold for the first time. Its calendar is designed to remain accurate for 122.6 years, meaning it will still be ticking smoothly when you hand it down.
The high-end timepiece is powered by the calibre L952.2 movement, made up of a whopping 729 parts, each hand-finished down to the last detail. It powers the outsized date window just under the 12 o’clock position and the romantic moon-phase display at 6 o’clock, and its remaining juice is indicated by the power-reserve indicator at 11 o’clock around the edge of the dial. Its 41.5mm case is cast in elegant 18-carat white-gold and features a symmetrical pink-gold dial. This handsome watch is limited to just 100 pieces worldwide (£255,000).
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