You are here
In Pursuit Of Precision
THE idea is simple enough to grasp, but it's taken almost 300 years before someone figured how to make the "resonance" phenomenon work in a wristwatch. The watch is the Chronometre a Resonance, unveiled in 2000. Its birth marked a milestone in the horological world's constant search for precision in watchmaking and helped elevate the watchmaker, Francois-Paul Journe, to cult status today.
"After 15 years of work, I was able to adapt (the resonance) phenomenon to a wristwatch," recalls Mr Journe, who started the project in 1983. "I felt that this resonance system was particularly well-suited for the various wrist movements; especially the repeated shocks that can occur on the watch mechanism that are so detrimental to its smooth running."
The theory that underpins resonance timepieces is straightforward. You need only to place two oscillators with the same frequency close to one another. They will then begin to beat in sync, thanks to the exchange of rhythmical energy between them.
Active elements transmit vibrations to their environments and the resonance phenomenon is observed when an element picks up the vibration of another, absorbing its energy and starting to vibrate at the same frequency. This is demonstrated when looking for a channel on the radio. The radio crackles till the chosen wavelengths meet those of the transmitter. Only then do they harmonise and begin resonating together.
In MRI (magnetic resonance imaging) scan, a diagnostic procedure common in hospitals, the resonance of the protons in a patient's body is used to produce images.
The caveat is that the frequency of the two oscillators must be adjusted to be very close with one another for the resonance effect to occur. To do this in the tiny wristwatch would have been near impossible.
Christiaan Huygens, a Dutch scientist in the 17th century, was the first to notice the natural resonance phenomenon. It was only 100 years later that watchmakers detected it and developed timepieces using the resonance principle.
The awakening came with the invention of the pendulum. Horologists witnessed that when the pendulum - which is a regulator of clock movements - swings, its rhythm often interfered with the environment - and it was not unusual for a pendulum clock to stop on its own when it entered into resonance with the driving-weight hanging from the cords.
Antide Janvier, a French watchmaker born in 1751, was the first to see the potential of turning this advantage into an asset.
As recalled in a F P Journe pamphlet issued to mark the 20th anniversary of the Chronometre a Resonance this year, Janvier's idea was to build two complete movements with two precision escapements and place them close to each other, ensuring that the two pendulums were hanging from the same construction. Just as he imagined, the pendulums recovered the energy dissipated by one another and began to beat together, thus entering into resonance.
Functioning as such, the movements are protecting themselves from outside vibrations, considerably enhancing their precision. Around 1780, Janvier built three regulators, of which one was acquired by F P Journe in 2002. The other is preserved in the Paul-Dupuy museum in Toulouse.
A third regulator is kept in the Patek Philippe Museum in Geneva.
Thirty years subsequently, Abraham-Louis Breguet built a resonance regulator for Louis XVIII, King of France, which is now part of the collection of the Musee des Arts de Metiers in Paris. A second piece built for the King of England, George IV, is housed at the Buckingham Palace. Breguet also made a resonance pocket-watch each for the two kings.
Conceived and made to meet the demands of wrist-wear, as well as to provide chronometric performance driven to the extremes, the Chronometre a Resonance is a double-balance timepiece. When in motion, the two balances in the watch enter into harmony and begin to beat naturally in opposition - thanks to the resonance phenomenon. They then support one another, giving more inertia to their movement.
But this works only if the two balance are running within no more than a five-second per day difference in rate, cumulated in six positions. Setting their frequencies right is an extremely delicate task.
"Whereas an external disturbance affects the running of a traditional mechanical watch, the same disturbance, for the Chronometre a Resonance, produces an effect that accelerates one of the balances as much as it slows down the other," according to the F P Journe pamphlet.
"Little by little, the two balances come back towards each other to find their point of harmony, thus eliminating the disturbance, and beating in perfect synchronisation."
The hand-winding Chronometre a Resonance, which has appeared in several guises since 2000, has attracted a big following and the watch is hotly sought-after. One of the first 22 pieces sold under "subscription" - made to order - was sold for over US$1 million at an auction in June in Geneva - 10 times above its high estimates of US$87,000-174,000.
The 10th anniversary model of the timepiece won the "Montre a Grande Complication" award at the Grande Prix d' Horlogerie de Geneve, the watch industry's equivalent of Hollywood's Academy Award.
To celebrate its 20th anniversary this year, F P Journe has rolled out a new version of the Chronometre a Resonance, complete with a totally new mechanical construction and redesigned case. Instead of two barrels as in the earlier watches, the latest model is fitted with only one to power not only two movements, but also two new "remontoirs d'egalite" constant force mechanisms. The power reserve remains at 42 hours, notwithstanding the changes.
The Remontoir d'Égalité serves in a way to compensate for the switch from a double barrel to a single barrel system and to help maintain rate stability when the balance amplitude drops with less and less energy transmitted to the balance, as the mainspring unwinds.
The case - buyers got a choice between a 40 and 42 millimetres-wide case - is also modified. The winding and time-setting crown is moved from 12 to 2 o'clock, making it easier to operate. The second-setting crown remains at 4 o'clock. In limited production, the 20th anniversary Chronometre a Resonance is priced at US$106,800 in 18k rose gold and US$110,600 in platinum.