Equipped with twin power sources, one for the time and the other for the multiple displays, the Duomètre à Quantième Lunaire is a complicated watch with an unusual combination of functions, including a moon phase and a 1/6th of a second counter.

Rather than a single major complication, the Duomètre à Quantième Lunaire features several minor ones that together make it interesting; the whole is greater than the sum of its parts. The Duomètre à Quantième Lunaire features a moon phase, date, twin power reserve displays, and a lightning seconds, powered by what Jaeger-Lecoultre terms a “dual wing” movement with twin barrels and gear trains.

The origins of “dual wing”

Originally devised for the grande and petite sonnerie, which required twin barrels to power the timekeeping mechanism and the automated striking mechanism, the “dual wing” concept has been appropriated by Jaeger-LeCoultre for an entire line of watches known as the Duometre.

The Duometre collection began with a chronograph, then continued on with Spherotourbillon, which used one mainspring to power the tourbillon and the other for the flyback seconds. Likewise, the Duomètre à Quantième Lunaire has one barrel that drives the timekeeping portion of the movement, meaning it powers the escapement and time display. All the other indications – the moon phase, lightning seconds and date – are powered by the second barrel.

Segregating the power source and transmission is meant to improve timekeeping by ensuring that the regulator has a consistent and uninterrupted supply of energy. In an ordinary movement, the energy transmitted to the regulator drops every so slightly when the date changes, because a sliver of energy is required to advance the date display. This is one reason why constant force mechanisms were invented.

A new face

While the Duomètre à Quantième Lunaire was originally introduced several years ago, it was face-lifted this year. The latest version features an open-worked dial, with twin apertures on either side of the 1/6th of a second counter. Each aperture reveals the fan-shaped power reserve gear that indicates the remaining energy in each barrel. Beyond the apertures, the look is the same as the other Duometre models, with an eggshell-textured dial.

While the 1/6th of a second counter runs constantly, the central seconds hand is linked to the time-setting mechanism and resets to zero when the crown is pulled out to set the time. Only when the crown is pushed back in does it resume its motion, ensuring that the time can be synchronised precisely.

The calibre 381

Like the other Duometre movements, the Quantième Lunaire has the twin barrels on the top half of the movement, each with grand sonnerie style winding ratchets that allow for winding of each barrel by turning the crown in opposing directions.

All the bridges and base plate are made of unplated German silver, hence the characteristic subdued silver tone

The grande sonnerie-style winding ratchet

The look is lavish in appearance and engaging, with radial striping on the bridges and blued steels screws. Though the movement is carefully done and nothing appears amiss, the decoration is mostly done mechanically. The bevelling of the bridges for example is clearly done with an electric tool that resembles a dentist’s drill. The result is typical of Jaeger-LeCoultre’s unique approach that blends industrial production and high horology.

The rounded lines of the bridges characteristic of bevelling done with an electric tool

The verdict

This is an good-looking and interesting watch. The combination of complications is unusual and unique, however, it is not a logical or intuitive union as it is in a chronograph or grande sonnerie. An unkind conclusion would be that it was conceived just to put the Duometre concept to good use.

Few other brands can produce watches like Jaeger-LeCoultre, blending complications, attractive finishing and competitive pricing. The Duomètre à Quantième Lunaire is available in pink gold, with a case diameter of 42mm. It is priced at US$39,200 or S$55,500.

Breguet: Art and Innovation in Watchmaking is a comprehensive showcase of the work of the great Abraham-Louis Breguet. Comprising over 70 timepieces, it takes place in San Francisco from September 19, 2015 to January 10, 2016.

Breguet no. 3066, a repeating pocket watch with oversized moon phase, sold in 1818

Abraham-Louis Breguet was one of the preeminent watchmakers of his time, responsible for inventions including the tourbillon regulator, with clients like Marie-Antoinette and Napoleon. Not only did he was he responsible for complications, Breguet also had his own distinctive aesthetic, one that still appeals three centuries later. The largest ever Breguet exhibition in the United States, Breguet: Art and Innovation in Watchmaking celebrates his work, as well as that of the company bearing his name. Over 70 timepieces, including many originals from his lifetime, will be on show at the California Palace of the Legion of Honor in San Francisco starting September 19, 2015. The exhibition is organised into 15 sections, each dedicated to a particular complication or style that is significant in Breguet’s body of work. One such section covers subscription watches, simple timekeepers with only an hour hand that Breguet invented in 1797 and sold on a subscription basis. More affordable than most watches at the time, they helped Breguet grow his client base.

Breguet no. 3424 subscription watch

Many of the timepieces on show once belonged to key historical figures whom Breguet counted amongst his clients, a list that included practically all of the heads of state of major European countries. Breguet timepieces are intimately intertwined with European history of the 18th and 19th centuries. 

A quarter repeating travel clock sold in 1798 to Napoleon Bonaparte days before he departed for Egypt on his campaign against the British

Another Breguet invention, the montre a tact that indicates the time in a tactile manner with the arrow-shaped pointer, this one sold in 1800 to Empress Josephine, wife of Napoleon

A pocket watch with moon phase sold in 1813 to Empress Marie-Louise, the second wife of Napoleon

Marine chronometers, or precision, gimballed clocks, made for navigation and supplied to the French navy are also a key part of the exhibition, so are watches made for the Turkish market, distinguished by their enamelled cases and Arabic numerals.

Marine chronometer, sold in 1841 to the French navy

Quarter repeater with grande and petite sonnerie made for the Turkish market, sold in 1808

Breguet also worked on various precision watches, including those he terms garde-temps. Many were scientific instruments but some were also created for civilian clients.

A precision wristwatch that was the personal watch of Abraham-Louis Breguet’s son Antoine-Louis

And Breguet’s work also encompasses various complications, ranging from the well known, like the minute repeater, to the esoteric, like this resonance-type pocket watch.

A pocket watch with two movements designed to operate on the principle of resonance, sold in 1814

Chronographs also feature prominently, with Breguet having made several pocket watches a seconds hand that could be stopped and started.

A split-seconds chronograph pocket watch sold in 1825

And of course the tourbillon regulator has a section all to itself, being Breguet’s most famous invention. Conceived to average out timekeeping errors due to gravity, Breguet patented the tourbillon in 1801.

Pocket watch with four minute tourbillon regulator, sold in 1809 to Count Stanislas Potocki of Poland

Clocks are also a key part of the exhibition, amongst them an Art Deco clock from 1921, by which time the Breguet family had sold the company to English watchmaker Edward Brown.

A pyramid clock with constant force escapement with passing hour and quarter strike, sold in 1827

An Art Deco minute repeating clock with an enamelled case from 1921

Breguet: Art and Innovation in Watchmaking opens on September 19, 2015 and runs until January 10, 2016. It’s open Tuesdays through Sundays from 9:30 am to 5:15 pm. On December 24 and 31 opening hours are 9:30 am to 4:00 pm. It’s located at Rosekrans Court, Special Exhibition Galleries 20B-C, inside the California Palace of the Legion of Honor, located at: Lincoln Park 34th Avenue and Clement Street,  San Francisco, CA 94121 USA Tickets can be purchased online from the Legion of Honor.