There is a very special and secret phrasebook that is spoken of only in whispers, a phrasebook that belongs to the world of watch lovers. This is not a book that has ever been published — you will not find it in your local library and you definitely cannot pre-order it on Amazon. It exists only in the collective consciousness of everyone who has ever felt a moment of mad, hopeless passion in the presence of horological greatness. With any one of the terms plucked from this phrasebook, you will awaken the dormant fanatic in members of this hidden tribe. They might look like a regular person; they behave like regular people with regular lives. But all it takes is the right combination of syllables, and you will see a dangerous gleam ignite in their eyes. The words in this book have power; in the right people, they strike a note that cannot be unstruck and drive their intended subjects to unpredictable ends. Among the most potent of them all is a word that can rouse even the most jaded elders of the horological community, though it means nothing to those who have never visited the realm of fine watchmaking or heard its language. That word is “Duomètre”.
The etymology of this word is complex, but fortunately it is a relatively short history to relate. The first instance of the word “Duomètre” appearing in public record was in 2007, when Jaeger-LeCoultre released a chronograph unlike any other chronograph made before. In terms of nomenclature, Jaeger-LeCoultre borrowed from its patrimonial lexicon, echoing the milestone Duoplan of 1925. This was a watch with a double-level (Duo = two; plan = plane) movement construction, proving that precision could be achieved even in smaller movements, thus easing the transition from pocket watches to wristwatches.
When Jaeger-LeCoultre took their exploration of chronometric precision to the next level, they therefore named it Duomètre to convey the sense of increased timing accuracy (Duo = two; mètre = measure). The Duomètre system is simple in theory: there are two separate mainspring barrels, with one dedicated to the regulating organ and another providing the energy required to drive the other functions and complications of the movement.
In 2007, this idea of splitting the power distribution was not new. In fact, it is the accepted construction for chiming watches, which are thusly built because of how voraciously the chiming mechanism consumes energy. Assigning a separate mainspring barrel to the chiming mechanism stops it from siphoning torque away from the balance, which makes it more prone to error. Until the Duomètre à Chronographe, however, this system did not apply to other timekeeping functions apart from the sonnerie group of complications. (There’s a reason for this, but now is not the time to go into it.)
Since then, the Jaeger-LeCoultre Duomètre has become synonymous with the concept of isolating the watch movement’s balance and escapement from its associated complications, with the term itself taking on unique resonance as a kind of horological shorthand for chronometric excellence.
This year, La Grande Maison, as Jaeger-LeCoultre is alternately known, goes all in on the Duomètre with a number of new models and new calibres associated with this collection. Each of them could easily lead the 2024 armada of new Watches and Wonders launches from Jaeger-LeCoultre — either the Duomètre Quantième Lunaire or the Duomètre Chronograph Moon alone, for example, is a virtuoso work of watchmaking that would instantly define the watchmaking year for most other brands. It is the Duomètre Heliotourbillon Perpetual, however, that is inarguably the one watch to rule them all, the star at the gravitational centre of Jaeger-LeCoultre’s universe in 2024.
This horological behemoth unites two of the brand’s most well-regarded expertises — multi-axis tourbillons and perpetual calendars. As I mentioned before, any year may be a good year to launch a perpetual calendar, but a leap year is particularly relevant, with its focus on the idiosyncrasies and complexities of our calendrical system. Jaeger-LeCoultre have even improved upon the utilitarian aspect of the perpetual calendar (“utilitarian” is not a word you hear very often in context of haute horlogerie complications, so this is truly a refreshing situation) by implementing a simple and intuitive way of displaying the leap year. Whilst the majority of other perpetual calendars will opt for a disc, printed with the digits 1 through 4, rotating behind a small dial cutout to indicate where we are in the four-year leap cycle, the Duomètre Heliotourbillon Perpetual instead integrates this indication within the display of the year itself. During leap years, the final digit of the year appears in red, a solution so practical and straightforward that you immediately wonder why this isn’t the standard way to indicate a leap year in mechanical watchmaking.
The showstopper in this watch is, of course, the eponymous Heliotourbillon. It feels like forever that Jaeger-LeCoultre has possessed the dominant mindshare in multi-axis tourbillons — certainly they were the first to bring it to general awareness, and they are currently still the brand with the most number of mechanical distinct variations of this concept. With the Heliotourbillon, Jaeger-LeCoultre have taken the objective of spatial efficiency, which they first broached with the 2012 Duomètre à Sphérotourbillon, and brought it to the next stage of evolution. The Duomètre à Sphérotoubillon theorised that it was not necessary to rotate through a full 360° in all dimensions in order to attain an optimal level of timing stability, and it would therefore also be possible to create a smaller mechanism. This is a paramount consideration in a wristwatch, and the Jaeger-LeCoultre Duomètre Heliotourbillon Perpetual adds a new form of positional displacement — a controlled semi-orbital arc that resembles the motion of a very well-regulated rocking cradle — to the full rotations that already define the family of multi-axis tourbillons as we know it from Jaeger-LeCoultre.
And speaking of spatial efficiency, the Duomètre collection has undergone a general aesthetic redesign, incorporating smoother angles and curves for greater tactility and a more compact appearance, adding even more allure to this already irresistible model. You wouldn’t think that Jaeger-LeCoultre would have been able to increase the magnetic appeal of the Duomètre, but with this year’s new launches, that’s what they’ve done.
