Jaquet Droz Grande Seconde Moon watch

Since the Moon Phase requires a greater level of precision, Jaquet Droz developed Mechanism 135, an in-house movement featuring a high precision 135-tooth wheel inside a Jaquet Droz 2660QL3 caliber. While a traditional 59-tooth movement accumulates an error of one day every two years and eight months, the Jaquet Droz Moon Phase need only be adjusted by one day every 122 years thanks to a corrector discreetly incorporated into the middle of the case. The precision of the Grande Seconde Moon movement is thus infinitely closer to the actual lunar month which lasts exactly 29 days, 12 hours, 44 minutes and 2.8 seconds.

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