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The Encyclopedia of Horology

Torsion-pendulum clock wound by ambient temperature/pressure change via a sealed bellows · Switzerland

Jaeger-LeCoultre Atmos Clock

Verified

Marketed as needing no manual winding: small changes in the temperature of a sealed gas capsule expand and contract a bellows that rewinds the mainspring, in principle allowing the clock to run indefinitely from ambient conditions.

Technical facts

Regulator
Torsion pendulum, very slow-decaying oscillation
Winding source
Sealed bellows responding to ambient temperature (and to a lesser extent pressure) change
Typical accuracy
Modest by mechanical-clock standards; marketed primarily on its perpetual-winding feature, not precision

Historical significance

  • Marketed as needing no manual winding: small changes in the temperature of a sealed gas capsule expand and contract a bellows that rewinds the mainspring, in principle allowing the clock to run indefinitely from ambient conditions.
  • The low-friction torsion pendulum permits the whole system to run on the very small amount of energy such temperature changes provide.
  • Long production run with many numbered case and dial variants; specific model dating should be done against Jaeger-LeCoultre's own published Atmos model history rather than generic 'Atmos' claims.

Photographs

Pendule Atmos
Pendule Atmos — Tangopaso, CC BY-SA 3.0. Wikimedia Commons file page
Atmos clock prototype, Jaeger-LeCoultre - Karl Gebhardt Horological Collection - Gewerbemuseum - Nuremberg, Germany - DSC01841
Atmos clock prototype, Jaeger-LeCoultre - Karl Gebhardt Horological Collection - Gewerbemuseum - Nuremberg, Germany - DSC01841 — Daderot, CC0. 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. Jaeger-LeCoultre, published Atmos clock history

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