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The Encyclopedia of Horology

Complication · Display

Compass Indication

Partially verified

A magnetic compass combined with a timepiece.

Definition

A magnetic compass combined with a timepiece.

Historical origin

A traditional combination in travellers' and military instruments, including sundial-and-compass sets.

How it works

A magnetised needle on a low-friction pivot indicates magnetic north; in a mechanical watch it must be isolated from the movement's steel and any magnetic fields.

Sundial compasses use the compass to orient the dial so its gnomon reads correctly.

Pocket watch context

Combined compass and sundial instruments precede portable mechanical watches and continued alongside them.

Wristwatch context

Occasionally fitted to military and outdoor watches, usually as a bezel scale rather than a needle.

Identification

  • A magnetic needle or an azimuth bezel scale

Servicing notes

This is specialist work. Levers, springs and cam profiles in complicated work are calibre-specific, and incorrect reassembly commonly damages parts that cannot be bought. Refer the movement to a watchmaker experienced with this mechanism.

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.