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The Encyclopedia of Horology

Component record · Dial & hands

Moonphase Disc

Partially verified

Lacquered or gold disc

What it does

Displays the lunar cycle

How it works

Evolution

Traditional 59-tooth wheel

Known variations

    Identification for collectors

      Common failure modes

      • Corrosion

      Diagram

      moon disc carrying two moonsaperture and shuttersadvance wheel
      Schematic: moon phase drive. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

      Sources & references

      1. de Carle, D., Practical Watch Repairing
      2. de Carle, D., Watch and Clock Encyclopedia
      3. Daniels, G., Watchmaking

      Where sources disagree, the disagreement is stated rather than resolved silently.