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The Encyclopedia of Horology

Complication · Display

Altimeter

Partially verified

A complication that indicates altitude above sea level based on atmospheric pressure.

Definition

A complication that indicates altitude above sea level based on atmospheric pressure.

Historical origin

Adapted from aviation instruments for use in explorer's watches.

How it works

Uses an aneroid capsule (a sealed metal chamber) that expands or contracts with air pressure changes.

This motion is amplified through a lever system to move a dial pointer.

Pocket watch context

None.

Wristwatch context

Found in specialized tool watches like the Oris Big Crown ProPilot Altimeter.

Identification

  • A secondary scale for altitude, often in feet or meters
  • Requires a vented case to allow air pressure to reach the capsule

Servicing notes

The pressure chamber is sensitive to moisture; seals must be checked frequently.

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

Diagram

top plate or bridgespillar platebalance and cockwheel train between the plates
Schematic: plate and bridge layout. 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.