Which watchmaker created the Atmos clock, whose mechanism runs from changes in air temperature?

Jean-Léon Reutter created the Atmos clock, whose mechanism runs from changes in air temperature.

Reutter invented the clock in the late 1920s. Its sealed capsule contains a gas that expands and contracts as the surrounding temperature changes. That movement winds the clock’s mainspring through a mechanical system, allowing the clock to operate without conventional daily winding.

Jaeger-LeCoultre became responsible for producing the Atmos commercially in Switzerland. The clock is therefore closely associated with the Jaeger-LeCoultre brand, but Jean-Léon Reutter is the inventor credited with the original mechanism. The commercial model appeared after improvements to make the design more reliable and practical.

The Atmos does not generate energy from heat in the same way as a modern electrical device. It uses tiny temperature-driven changes to wind its spring, and even a change of roughly one degree Celsius can provide useful power. Its slow balance wheel helps it run for long periods, but it remains a delicate mechanical instrument.