Lot 409

F.P. Journe

Octa Calendrier

A very rare and magnificent platinum wristwatch in almost mint condition, with retrograde annual calendar and 120 hours power reserve. The watch was serviced in September 2024

Sold

François-Paul Journe has once again demonstrated his ability to integrate a significant complication, namely a retrograde annual calendar, into his Octa automatic caliber, while maintaining the dimensions of the standard caliber with a diameter of 30 mm and a thickness of 5.76 mm. This is the third complication realised with the Octa automatic calibre, which has been recognised as an automatic movement with a power reserve of more than five days and a very high rate accuracy.
The annual calendar displays the day and month in two windows and automatically advances the retrograde date for months with 29, 30 and 31 days. In non-leap years (three out of four years), the date can be manually advanced from 28 to 29 February by simply turning the crown. The date then automatically advances from 29 February to 1 March.

"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 in the Octa collection.
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.”
François-Paul Journe