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The Encyclopedia of Horology

Complication · Calendar & astronomy

Retrograde Month

Partially verified

A month indicator that resets after December.

Definition

A month indicator that resets after December.

Historical origin

Part of complex calendar suites, often used to balance the dial design.

How it works

A twelve-stepped cam controls the month hand's position across a 180-degree or smaller arc.

Pocket watch context

Very rare.

Wristwatch context

Found in some perpetual calendars to avoid cluttering the dial with too many small sub-dials.

Identification

  • Month names in an arc

Servicing notes

Ensure the month indices align with the year change.

General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.

Diagram

date ring, thirty-one positionsdate aperturedriving wheel and jumper
Schematic: calendar work under the dial. 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., Watch and Clock Encyclopedia
  2. Britten, F. J., Old Clocks and Watches and Their Makers
  3. Horological Journal (British Horological Institute), technical articles

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