This watch was produced between 2003 and 2005
Octa Lune helps us reach for the stars and reminds us of ancient times when people had to wait for a full moon in order to move around, since it alone reflected the light need for nocturnal wanderings.
Although today we tend to no longer pay any attention to the movements of this mythical celestial body, the moon-phase indication is still one of the most poetic horological complications.
The 18-carat moon and stars against a blue background have been crafted with particular care and make a perfect match with the blued hands of chronometers by F.P.Journe – Invenit et Fecit –.
Moreover, this model displays the power reserve on the left, the date at 12 o’clock and the hour, minute and seconds indications in guilloché silver subdials secured to the 18-carat gold dial by steel rings.
A horological ideal
“The construction of the Octa calibre has less powerful ties with horological history than do the constant-force device or resonance models, but it symbolises an horological ideal of giving timekeepers the highest possible degree of precision and autonomy!
One can indeed note the fact that if church clocks are placed so high, in addition to enhancing visibility, it was mostly because it often took an entire month for the driving-weights to drop the length of their cords. Numerous systems were invented to increase the operating duration of timekeeping devices, meeting with various degrees of success. Given the small volume of a wristwatch, the size of the mainspring was automatically limited. Watchmakers therefore discovered the trick of adding an extra wheel to the customary geartrain in order to extend the duration of its development. Unfortunately, actually using this system, even with a stronger spring, led them to observe that the level of energy actually reaching the balance remained low. To compensate for this, they fitted a smaller balance using less energy, but which was also less stable. It is therefore not unusual to find that some watches able to run for several days display an extremely unpredictable level of precision.
This challenge was a powerful source of motivation! I then imagined that the best and the most obvious means of extending the running duration would be to extend the capacity of the spring development. The difficulty lay in integrating it on the same level as the gear-train and the escapement, given its stability: 1 metre and 1 millimetre thick. Thanks to the low torque of this spring, I could achieve extremely fast automatic winding (one and a half hours on a Chappuis cyclotest for over 5 days’ running).
Once the challenge of autonomy was thus successfully met with this automatic winding calibre, I knuckled down to the second challenge of managing to insert various complications into that same movement: power reserve with large date display, fly-back chronograph with large date display, retrograde annual calendar, etc… and of doing so while maintaining an identical size for all models.
Three years of research and development were required before this automatic winding movement that is unique in the world could be presented to the public.”