The Atmos Clock is a timepiece of near-perpetual movement needing no human intervention and almost no energy. Invented by Swiss engineer Jean-Léon Reutter in 1928 in Neuchâtel, the Atmos clock has been the Swiss government's official gift for important guests since 1950. Patented in 1928, the first version – known today as the Atmos 1 – was marketed by La Compagnie Générale de Radiologie (CGR) in 1930.^[32]

It derives energy from small temperature and atmospheric pressure changes in the environment, and can run for years without human intervention. Wound by a capsule filled with a mixture of temperature-sensitive gases, a 1 °C fluctuation is enough to store sufficient energy to supply the clock with two days' autonomy.^[33] Its balance, suspended from a steel-alloy wire thinner than a hair, performs two vibrations per minute; its gearing requires no lubricant. The Atmos' gearing is known for its accuracy: the moon-phase model, for example, accumulates a one-day discrepancy only once every 3,821 years.^[15]

The patents were subsequently purchased by Jaeger-LeCoultre in France 1936 and in Switzerland in 1937. The company then spent ten years perfecting the clock before beginning to manufacture it in its current technological form in 1946.^[15] In 1988, the Kohler and Rekow design agency created a two-piece limited edition showcase for the clock and, in 2003, the Manufacture released the Atmos Mystérieuse, driven by the Jaeger-LeCoultre Calibre 583 and comprising 1,460 parts.^[34]