Duometre Chronograph Moon

Inside the 42.5mm platinum or gold case of this Duometre Chronograph Moon resides Calibre 391 whose Duometre mechanism combines two separate gear trains which are linked to a single regulating organ. Jaeger-LeCoultre's engineers have developed this fully integrated movement around a manual-winding monopusher chronograph combined with moon phase and day/night complications, in addition to two power-reserve indicators and foudroyante seconds. As soon as the chronograph mechanism is activated, the foudroyante hand begins its whirling dance, beating six times during its one-second rotation and stopping instantaneously when the chronograph timer is stopped to provide a reading that is accurate to one sixth of a second. For perfect symmetry, the moon phase display is incorporated into the chronograph hours and minutes subdial at 3 o'clock, while the day/night indication travels past an aperture in the hours and minutes subdial. Foudroyante seconds appear in a subdial at 6 o'clock, framed by two openings that reveal part of the mechanism. The 50 hours of power reserve for each of the two barrels are displayed on arc-shaped bridges, one on each side of this subdial.