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The Encyclopedia of Horology

Complication · Calendar & astronomy

Leap Year Cycle Display

Partially verified

A small window or sub-dial showing the 1, 2, 3, 4 (L) cycle of years.

Definition

A small window or sub-dial showing the 1, 2, 3, 4 (L) cycle of years.

Historical origin

An essential part of a perpetual calendar's interface.

How it works

A small hand or disc geared to the 48-month wheel shows the position in the leap year cycle.

Pocket watch context

Common on grand complication pocket watches.

Wristwatch context

Standard on almost all perpetual calendar wristwatches.

Identification

  • A sub-dial numbered 1 to 4
  • Often located within the month or leap year indicator

Servicing notes

Essential for setting the calendar correctly after the watch has stopped.

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.