The movement
Calibre M-31 leaves the Vallée de Joux as 137 parts. The going train steps down from the mainspring barrel through the centre, third and fourth wheels to an escape wheel turning six times a minute, where a Swiss lever escapement releases it in beats of 28,800 an hour.
The balance is free-sprung and poised in six positions, its hairspring terminated by hand in a Breguet overcoil so the coil breathes concentrically rather than pulling the staff off centre. Bridges are bevelled on an oiled boxwood lap and black-polished against tin — the one operation nobody has yet made a machine do faster than a person.
- Frequency
- 28,800 A/h
- Reserve
- 68 hours
- Jewels
- 27






