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The Encyclopedia of Horology

Complication · Calendar & astronomy

Solar Time Display

Partially verified

A display showing time according to the sun's position (apparent time).

Definition

A display showing time according to the sun's position (apparent time).

Historical origin

The standard for timekeeping before the adoption of mean time.

How it works

Often paired with a mean time display to show the equation of time difference.

May use a specialized dial or a second set of hands.

Pocket watch context

Common in eighteenth-century astronomical watches.

Wristwatch context

Rare in modern watches, usually as part of an equation of time complication.

Identification

  • Dial marked 'Solar Time' or 'Apparent Time'
  • Equation of time indicator

Servicing notes

Requires synchronization with the mean time train.

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

Diagram

subsidiary secondschapter ringminute and hour hands
Schematic: dial layout and hands. 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.