This model was produced between 2005 and 2008
The first Chronograph wristwatch with flyback and large date offering a power reserve of 120 hours.
With the Octa Chronographe, François-Paul Journe revolutionise the classical conception of the chronograph. Integrated within the Octa automatic winding calibre measuring 30,80 mm in diameter and 5.70 mm in thickness, the chronograph is housed in a space of only 1 mm thick. This space is also occupied by the twin concentric large date display discs. To achieve such a performance, François-Paul Journe imagined flattening the usual column wheel to transform it into a cam wheel. This means it is the profile rim instead of the column which actions the chronograph levers. A single sliding lever returns the chronograph seconds and minutes to zero by disengaging the brakes at the precise moment when it hits the specially profiled reset parts.
These two innovations make it possible to reduce the mechanism to three levels. In this more compact version, the result is a sturdy movement ensuring long term reliability.
It is fitted with a fly-back and return-to-zero functions, as well as a 60-minute counter. The date is shown on the dial by large-sized separate numerals, according to a patented display mode. The guilloché silver hour, minute and small second sub dials are screwed with a steel circle to the 18-carat gold watch face.
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 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.”