In the late 1920s, Jean-Leon Reutter, a young Paris engineer produced a clock with a timekeeping mechanism designed specifically to consume the smallest possible amount of power to keep the clock running satisfactorily.
As well as changes to the mechanism, Reutter's clock included a mercury and gas filled bellows that would react to the most sensitive changes in temperature and atmospheric conditions, and in so doing, created a gentle rocking motion that gave power to the clock when needed.
Serial numbers from 6,500 to 24,999 were used in the 1940s.
Serial numbers from 25,000 to 126,999 were used for 1950s' Le Coultre Atmos clocks, and the 1960s' Atmos numbers start at 127,000 and run through 299,999.
The torsion pendulum has a period of precisely one minute; thirty seconds to rotate in one direction and thirty seconds to return to the starting position.
This is thirty times slower than the 0.994 m (39.1 in) seconds pendulum typically found in a longcase clock, where each swing (or half-period) takes one second.
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 1970s' serial numbers start at 300,000 and are sequential through 519,999.The 1980s' serial numbers start at 520,000 and stop about 649,999.An Atmos clock takes a month to produce in the factory, then another five weeks of trial and adjustment before it is ready for shipment A rare and important Jaeger Lecoultre 150th Anniversary gilt brass Atmos clock, circa 1983, Atmos patented movement, 14 jewels with white dial with pierced centerfield, case numbered, movement signed and numbered, height 33 cm (including dome glass)A Jaeger-Le Coultre 'Atmos' perpetual clock, with plated brass case with glass panels to all sides and top, spirit level to the base, raised on adjustable feet, the chapter ring with Arabic numerals.19 x 14 x 24 cm A fine Jaeger-Le COULTRE 'Atmos' four glass brass clock, circa 1990s, Swiss made, marked 400096, a mechanical torsion pendulum clock with chapter ring and visible escapement deriving energy from atmospheric and temperature changes thereby removing requireme Jaeger Le Coultre Atmos clock by Luigi Colani in a brass & 24 karat gold plated case, with a hinged lift top front, 528 caliber, produced 1974-75, with original leather cased presentation case.