Torsion-pendulum clock wound by ambient temperature/pressure change via a sealed bellows · Switzerland
Jaeger-LeCoultre Atmos Clock
VerifiedMarketed 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.
Background
The Atmos clock is a mechanical torsion pendulum timepiece manufactured in Switzerland by Jaeger-LeCoultre. The clock utilizes a unique power source derived from environmental temperature changes, eliminating the need for manual winding. Energy is captured by a hermetically sealed bellows containing ethyl chloride, which expands or contracts to wind the mainspring as temperatures shift.
Jean-Léon Reutter designed the first Atmos clock in 1928, and Jaeger-LeCoultre assumed production of the commercial Atmos 1 model on 27 July 1935. Following these developments, a new model was announced in 1936, establishing the design basis for all subsequent versions of the clock. Over 500,000 of these clocks have been manufactured throughout the history of the production line.
Written from the encyclopedia entries listed under Sources; each statement was checked against the cited text.
Construction and mechanism
- The clock utilizes a low-energy torsion pendulum that completes one full oscillation every sixty seconds.
- The operation of the device depends on extremely low-friction engineering to function on the minimal energy provided by temperature fluctuations.
Where sources differ
- Date. This record gives: “Jaeger-LeCoultre began manufacture in 1936 (Atmos I onward)”. The cited history has Jaeger-LeCoultre taking over production of the Atmos 1 on 27 July 1935, with a new model announced in 1936.
Photographs
Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- Atmos clock, Wikipedia (English), retrieved 2026-10-28 (text CC BY-SA 4.0)
- Jaeger-LeCoultre, published Atmos clock history
Where sources disagree, the disagreement is stated rather than resolved silently.