Jaeger-LeCoultre’s Duometre Chronograph Moon is a Double-Barrelled Dynamo

If there is one brand we sit in eager anticipation for each Watches & Wonders, it is undoubtedly Jaeger-LeCoultre. The grand maison has made a habit of using the event to unveil impossibly intricate and unexpected timepieces that best embody the art of fine watchmaking, just look at last year’s Reverso Hybris Artistica Calibre 179 or 2022’s remarkable Rendez-Vous Star. At this year’s event, Jaeger-LeCoultre continued the trend, unveiling a swathe of high-complication pieces, not the least of which being the seemingly infallible Duometre Chronograph Moon.

Jaeger-LeCoultre Duometre Chronograph Moon | Image: Jaeger-LeCoultre

Presented in two variations: a platinum case with a copper-coloured dial and a pink gold case with a silver dial, the new chronograph introduces Jaeger-LeCoultre’s highly-revered Duometre mechanism to a celestial complication for the first time. First conceived in 2007, the dual-barrel complication features two independent gear trains – one to drive the escapement and one to power the complication. However, unlike other releases, both gear trains are integrated into a single calibre and linked to a single escapement. While that might sound overly complicated (pun intended), it serves an important purpose.

In the past, complex mechanical watches encountered the issue of power supplementation. In essence, if you wanted the complication to actually work, you would invariably have to draw on some of the power provided by the barrel. Less power to the escapement meant less accurate timekeeping, which is, to borrow some technical watchmaking lingo, a bit of a bummer.

The Duometre was conceived to solve this very issue but when the designers sat down to work on the task, they found it had, in part, already been solved by none other than the LeCoultre Calibre 19/20RMSMI, a pocket watch movement developed more than 120 years earlier that featured a twin-barrel design. Turns out when it comes to innovation, even Jaeger-LeCoultre can’t beat Jaeger-LeCoultre.

Jaeger-LeCoultre Duometre Chronograph Moon | Image: Jaeger-LeCoultre

Admittedly, the new 42.5mm Duometre Chronograph Moon takes things up a notch by introducing the Calibre 391. Specifically designed for the new release, the integrated movement combines a manually wound mono-pusher chronograph with moon phase and night-day complications. It also features two power reserve indicators and a seconde foudroyante (flying second) display.

“When the chronograph mechanism is activated, the foudroyante hand begins its whirling dance, making a complete rotation in one second, during which it beats six times – stopping instantaneously when the chronograph timer is stopped and thus providing a reading accurate to 1/6th of a second,” Jaeger-LeCoultre said in a press release.

Jaeger-LeCoultre Duometre Chronograph Moon | Image: Jaeger-LeCoultre

From a visual perspective, the Duometre Chronograph Moon is a remarkable feat of ingenuity. The twin open-worked sections on the dial allow you to see the Calibre 391 in action, providing a glimpse at the individually decorated bridges, which appear to be almost floating in the design. The moon phase display is integrated into the chronograph hours and minutes sub-dial, which is set at 3 o’clock, and the blue background is visually balanced by the Night and Day display. Throw in a tachymeter scale marked around the periphery of the dial, the seconde foudroyante sub-dial at 6 o’clock and two power reserve indicators and you start to get a little overwhelmed. It’s almost unfathomable to believe you could stuff so many functions into one dial without things appearing chaotic, and yet somehow, Jaeger-LeCoultre has done it.

The Jaeger-LeCoultre Duometre Chronograph Moon was unveiled at Watches & Wonders 2024 and is available in Pink Gold 750/100 or 950 Platinum. Both pieces are presented on an alligator strap with small-scale alligator lining and are powered by the new manually wound Jaeger-LeCoultre Calibre 391, an innovative addition that provides 50 hours of power reserve. Jaeger-LeCoultre has not confirmed pricing or availability at this stage, but I am willing to bet the Grand Maison’s new release will be out of my price range. Too bad.

Jaeger-LeCoultre Duometre Chronograph Moon | Image: Jaeger-LeCoultre

Jaeger-LeCoultre Duometre Chronograph Moon

• Brand: Jaeger-LeCoultre
• Model: Duometre Chronograph Moon
• Reference: Ref. Q622252J (Pink Gold) / Ref. Q622656J (Platinum)
• Diameter: 42.5mm
• Calibre: Manually wound Jaeger-LeCoultre Calibre 391
• Water-Resistance:  50m
• Power Reserve: 50 hours