The Atmos by Jaeger LeCoultre is a mechanical clock that winds itself from temperature and atmospheric pressure changes in the environment, it does not require manual winding. The movement contains an airtight capsule filled with a mixture of gases which expands and contracts with every shift in temperature. With each expansion & contraction of the chamber an internal main-spring is wound, which powers the clock. A variation of only one degree in temperature is enough to power the Atmos for two days. These clocks can run for years without human intervention.