A brass Jaeger-LeCoultre Atmos clock
Second half 20th century
Rectangular mount with glass panels signed Jaeger-LeCoultre Atmos, on stepped plinth, the white dial with Roman numerals, the movement top numbered 731215. Accompanied by a guarantee certificate and original packaging.
H. 22.9 x W. 19.8 x D. 15.3 cm
– Steltman Watches, The Hague (2009)
– Private collection, the Netherlands
Atmos is the brand name of a mechanical torsion pendulum clock manufactured by Jaeger-LeCoultre in Switzerland which does not need to be wound manually. It gets the energy it needs to run from temperature and atmospheric pressure changes in the environment, and can run for years without human intervention. The clock is driven by a mainspring, which is wound by the expansion and contraction of liquid and gaseous ethyl chloride in an internal hermetically sealed bellow. The first Atmos clock was designed by Jean-Léon Reutter, an engineer in Neuchâtel, Switzerland, in 1928. This non-commercial prototype, which predated the Atmos name but is now known unofficially as Atmos 0, was driven by a mercury-in-glass expansion device. The mechanism operated on temperature changes alone.