The Odd Sympathy
Resonance is mechanical watchmaking’s most intellectually seductive idea. Examining how different makers pursue it reveals more about the politics of innovation than about timekeeping.
In 1665, the Dutch physicist Christiaan Huygens lay ill in bed and noticed something peculiar about two pendulum clocks hanging from a shared wooden beam. They had synchronised. Their pendulums swung in perfect opposition—same period, same amplitude, mirrored direction—and returned to this pattern even when disturbed. He called it an “odd kind of sympathy.” Three and a half centuries later, that sympathy remains one of the rarest and most debated phenomena in mechanical watchmaking. Fewer than half a dozen makers have ever attempted to harness it in a wristwatch. Each claims a different inheritance. None agrees on what, exactly, they are doing.
The history fits on a single page. Huygens observed the effect but lacked the mathematics to model it. The French clockmaker Antide Janvier built double-pendulum clocks exploiting the principle in the late eighteenth century. Abraham-Louis Breguet miniaturised paired oscillators into a handful of experimental pocket watches—perhaps three survive—and concluded that coupling depended on vibration through the movement plate rather than proximity or air turbulence. He even tested one in a vacuum. Then silence. For nearly two centuries, nobody touched it.
François-Paul Journe broke that silence in 2000 with the Chronomètre à Résonance, the first wristwatch to employ coupled oscillators without any mechanical linkage between them. Two independent balance wheels, two complete gear trains, one shared mainplate. No spring connecting them, no physical bridge—just micro-vibrations transmitted through rigid metal. The balances must be regulated within five seconds per day of each other for the effect to occur. If that sounds exacting, it is. Journe first attempted a resonance pocket watch in 1983. It took him seventeen years to get a wristwatch to work.
The 2020 revision, housing the calibre 1520, represents a significant mechanical evolution: a single barrel feeding a differential that splits energy equally to two going trains, each equipped with a remontoir d’égalité. The constant-force devices maintain stable amplitude for twenty-eight hours, addressing the original movement’s tendency toward amplitude decay as the power reserve diminished. It is sophisticated engineering in service of an essentially eighteenth-century idea. Journe is explicit about this lineage. His is the only wristwatch, he maintains, that uses “natural physical resonance without any mechanical transmission.” The purity is the point.
Armin Strom, from their manufacture in Biel, took a fundamentally different approach. Their patented clutch spring, introduced in 2016, is a flexible steel element connecting the hairspring studs of both balances—a deliberate, engineered coupling. Where Journe relies on the whisper of energy through a rigid plate, Armin Strom builds a dedicated channel. The clutch spring acts, in their language, as a “third oscillator,” absorbing excess energy from whichever balance is running ahead and feeding it to whichever is lagging. Synchronisation occurs within minutes, even if the balances’ daily rates differ by up to 250 seconds. That tolerance is fifty times wider than Journe’s. The system is robust, forgiving, and visually mesmerising—the sinuous spring oscillating between two exposed balances on the dial side invites sustained contemplation. Whether it constitutes resonance in the Breguet-Huygens tradition, or a different beast entirely, is the sort of question that generates heat in horological circles.
Beat Haldimann, working by hand in Thun without CNC machines, offered yet another architecture with his H2 Flying Resonance: two balance wheels sharing a coupling spring inside a single tourbillon cage, rotating at the centre of the dial. Vianney Halter pushed further still. His Deep Space Resonance places two acoustically coupled balances—hairsprings fixed to opposite sides of a shared wheel—inside a triple-axis tourbillon. No clutch spring, no mechanical linkage. Halter tested his prototype in a vacuum to confirm the coupling was structural, not aerodynamic. The watch is a conceptual proposition as much as a timekeeping instrument: one piece every three years, CHF 1.1 million, inspired by the 2016 detection of gravitational waves from colliding black holes. It exists at the frontier where horology becomes experimental physics made portable.
Here is the uncomfortable question that the trade press tends to avoid. Does any of this actually matter for timekeeping? A well-adjusted modern single-oscillator wristwatch can achieve a daily rate variation of a few seconds. The chronometric advantage of coupled oscillators—their supposed self-correcting property, where one balance compensates for disturbances to the other—has never been rigorously quantified by independent testing across the various systems. No comparative data exist in the public domain. The theoretical benefit is real in physics; whether it is meaningful on the wrist, at scales of a few seconds per day, remains an article of faith rather than demonstrated fact.
There is an even sharper terminological point. As a recent technical analysis in SJX Watches carefully argued, calling these “resonance watches” is, strictly speaking, a misnomer. In physics, resonance describes a system oscillating at greater amplitude when driven at its natural frequency. What these watches actually demonstrate is the synchronisation of coupled oscillators—each with its own motor source, merely locking in phase. The industry uses “resonance” because it is evocative and marketable. Precision of language has never been the luxury sector’s strongest suit.
So which approach represents genuine innovation, and which refines an old method? The answer depends on what you value. Journe’s system is the direct descendant of Breguet’s experiments—philosophically pure, historically grounded, and demanding extreme precision in manufacture and regulation. The 2020 remontoir upgrade is a brilliant engineering refinement of a centuries-old principle. Armin Strom’s clutch spring, by contrast, has no historical antecedent. It is a purpose-built mechanism that solves the fundamental fragility of natural coupling through modern engineering. If innovation means creating something with no precedent to address a known limitation, the clutch spring is the stronger claim. If innovation means pursuing an idea to its logical extreme without compromise, Journe’s refusal of mechanical linkage is the purer position. Halter, characteristically, transcends the debate entirely—his is watchmaking as cosmological metaphor.
What unites all of them is something the chronometric argument misses. Resonance—or coupled oscillation, if we are being rigorous—is one of the vanishingly few areas where independent watchmakers are conducting genuine mechanical research rather than elaborating on established complications. It is not a tourbillon, endlessly replicated. It is not a perpetual calendar, solved a century ago. It is a phenomenon still imperfectly understood at the scale of a wristwatch, still yielding different solutions from different minds, still capable of surprise. That may matter more than any rate variation measured in seconds per day.
About the Author
Sergio Galanti is an independent brand strategist and writer in the luxury watch industry. He is the editor of WatchDossier, a publication devoted to the cultural and philosophical undercurrents of modern horology.
No compensation or brand affiliation influenced this essay. Opinions are the author’s own.
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