Resonance is a term that for us watchmaking lovers evokes wonderful watches, mostly refined mechanical and stylistic creations brought to light by that genius who bears the name François-Paul Journe. 

But what does Résonance or Resonance mean for us Italians? Is it a term linked exclusively to marketing, or does it find its concrete reason, aimed at seeking the best performance of a mechanical watch? Let's start with the definition of this phenomenon:

Resonance is a physical condition that occurs when a forced oscillating system is subjected to periodic stress of a frequency equal to the oscillation of the system itself.

The first to study this phenomenon in the 17th century was the Dutch Christian Huygens, mathematician, physicist, watchmaker and author of one of the most important scientific books of that period, the Horologium OscillatoriumHe was responsible for the invention of the pendulum clock in 1656, built for the watchmaker Solomon Coster and inspired by the studies of Galileo Galilei begun in 1602, the first to understand the property that makes the pendulum a great timepiece: isochronism. In February 1665 Huygens made a discovery: two pendulum clocks hanging from a common wooden beam supported by two chairs demonstrated a strange phenomenon: the pendulums rotate in the opposite direction, maintaining an identical period of oscillations with respect to each other.

It was the French watchmaker who put this principle into practice Antide Janvier who had the idea of ​​building two complete movements, with two escapements, placed side by side and suspended from a common structure protected from the outside; thus remedying the possible interference generated by the vibrations of the mass of the pendulum, which could have led to the arrest of the pendulum itself. Around 1780 he built three precision resonant regulators, one of which is exhibited at Montres Journe SA Museum.

The ingenious French watchmaker, however, was not as skilled in managing his finances, so much so that he was forced to sell, in addition to his assets, also the work equipment, his movements, the books and the technical drawings of his masterpieces. Abraham Louis Breguet.

And it was the latter who sold to Louis XVIII, king of France, a resonance regulator, which today is part of the collection of the Musée des Arts et Métiers in Paris, while to the king of England George IV (1762-1830), a second example which is now kept in Buckingham Palace. He also created the only Resonance-based pocket model for these two rulers. A third model from the collection of Henry Graves Jr and his grandson Pete Fullerton was sold by Christie's in 2012 for $ 4,600,000.

The transition from a mechanical solution designed for a pocket watch to a wrist watch, as many will know, is far from simple. The only one to translate what Breguet has created into a modern key and make it a real trademark is Monsieur Francois-Paul Journe. The search for precision and mechanical perfection took several years, during which Journe gave life to numerous prototypes that did not always turn out to be up to his expectations.

FP Journe prototype from 1983

Up to the first Chronometre à resonance by FP Journe, which debuted exactly twenty years ago. The result of a long work that led him to win one of the greatest challenges in the world of watchmaking.

In the case of the Chronomètre à Résonance, both rockers offset by 180 degrees respectively, and are mounted on the main platen with two separate but very close bridges. This proximity allows the waves - or vibrations - generated by the movement of the rocker arms to move through the metal of the main plate and affect each other's oscillation by shifting its period. Two resonant balance wheels tend to correct any change in gear thanks to the change of pace of one of the two, compared to the slowdown of the other. After that, the two rockers go back to looking for their point of harmony.

Compared to what Breguet noted in his pocket watch, where the difference should not exceed 20 seconds per day in order not to affect the resonance, the Chronomètre of FP Journe must be set within five seconds a day in all six positions of gear. Obviously, the spirals of the balance wheels are free spirals, i.e. without the gear adjustment racket, in order not to influence the transfer of energy and therefore the effect of the resonance. 

20 years later, FPJourne celebrates its revolutionary timepiece with the new one FPJourne Chronomètre à Résonance introducing a number of innovations and variations to its Caliber 1499.3 with the new 1520 caliber, raising the bar once again.

How did Journe perfect his Résonance?

As mentioned, Caliber 1520 is the latest addition to Journe, so let's examine the principles and solutions that guide this spectacular movement. It is evident that compared to the previous caliber, there is only one barrel and not two, with the winding crown moved from 12 to 2 o'clock. The crown at 5 o'clock will be used to reset the seconds.

The resonance, combined with the help of the Winder byegalite (Fig. 1) and del differential (Fig. 2) placed under the center wheel, they contribute not only to better precision but also to have fewer variations in gear, thanks to the constant maintenance of amplitude.  

While the differential uniformly distributes the energy released by the barrel to the two sets of wheels, the remontoir d'egalite distributes the received energy with a constant force to the escapement (hence egalité). The remontoir is nothing more than a small additional spring which is loaded at regular intervals by the main spring.

This mechanism runs for approximately 28 hours of the 42 power reserve. Once deactivated, the bars will swing wider and more stable amplitude due to the effect of resonance than a single bar movement. If you want to bring it back to "maximum performance" you will have to manually load it every 24 hours.