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The construction of the Octa calibre has less powerful ties with the history of horology as the constant-force device or resonance
models do. Nevertheless, it symbolizes a horological ideal: giving timekeepers the highest possible degree of precision and autonomy.
It can be observed, that if church clocks are set so high in towers, apart from 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 running
time of timekeeper’s devices, only meeting limited success. Given the restricted volume of a wristwatch, the size of the mainspring was
immediately limited. Watchmakers then discovered the trick of adding an extra wheel to the customary gear train, in order to extend
the length of its development. Unfortunately, using this system only led them to observe that the level of energy actually reaching the
balance remained poor. To compensate, they fitted a smaller balance consuming less energy, but which also lost in stability. Therefore,
it’s not unusual to find watches that run for several days displaying an extremely unpredictable level of accuracy.
This challenge was a powerful source of motivation. I then imagined that the best and most obvious solution to lengthen the
running time would be to increase the capacity of the spring development. Given its stability (1 metre and 1 millimetre thick), the chal-
lenge was to integrate it on the same level as the gear train and escapement. Thanks to the low torque of this spring, I could achieve
extremely fast automatic winding (one and a half hour on a Chappuis cyclotest for over 5 day’s 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 chrono-
graph with large date display, retrograde annual calendar, UTC 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 one of a kind automatic calibre could be presented
to the public.
François-Paul Journe
Préface
Calibre Octa
An Horological Ideal_
