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While some may think the construction of the Octa calibre has less powerful ties to the history of horology than the constant-
force device or resonance phenomenon, it in fact symbolizes an important historical horological ideal: giving timepieces the highest
possible degree of precision and autonomy.
It is commonly observed that church clocks are set so high in towers to enhance their visibility, however this positioning is
mostly because it often allows almost an entire month for the driving weights to drop the length of their cords. Over time, numerous
systems have been invented to increase the running time of a timekeeper’s device but only with limited success. Given the restricted
dimensions 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 this also resulted in lost stability. Therefore, it’s not unusual to find watches that run for several days displaying an ex-
tremely unpredictable level of accuracy.
This historical challenge was a powerful source of motivation for me. I then imagined that the best and most obvious so-
lution to lengthen the running time would be to increase the capacity of the spring development. Given its stability (1 metre long and
1 millimetre thick), the challenge 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 days running).
Once the challenge of autonomy was successfully met with this automatic winding calibre, I began 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, UTC, etc… and 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
Preface
Calibre Octa
An Horological Ideal_
