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The Encyclopedia of Horology

Pocket watches · Winding

Fusee Pocket Watches

Verified

Watches in which the mainspring drives a tapered, grooved pulley (the fusee) through a chain or gut line, equalising torque as the spring unwinds.

Mechanism

As the mainspring weakens, the chain acts on progressively larger fusee radii, keeping torque at the great wheel roughly constant — a mechanical answer to poor early mainspring quality.

Typical characteristics

  • Visible chain between barrel and fusee cone under the top plate
  • Stop-work to prevent overwinding
  • Almost always key-wound through the case back or dial

Identification characteristics

  • Chain and cone visible with the movement out of the case
  • Key-wind, key-set arrangement
  • English plate layout with full plate and pierced balance cock

Collector significance

A defining feature of English work and an important dating characteristic: fusee construction suggests, though does not prove, earlier manufacture.

Known variations

  • Chain fusee
  • Gut-line fusee
  • Reverse fusee

Photographs

Spindeluhr fusee verge watch fabris 02
Spindeluhr fusee verge watch fabris 02 — Sergio Fabris, CC BY-SA 4.0. Wikimedia Commons file page

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Britten, F. J., Old Clocks and Watches and Their Makers

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