Atmos is the brand name of a mechanical

torsion pendulum clock :''Kundo reverts here. For other use, see Kundo (disambiguation)'' A torsion pendulum clock, more commonly known as an anniversary clock or 400-day clock, is a mechanical clock which keeps time with a mechanism called a torsion pendulum. This is ...

manufactured by

Jaeger-LeCoultre Manufacture Jaeger-LeCoultre SA, or simply Jaeger-LeCoultre (), is a Swiss luxury watch and clock manufacturer founded by Antoine LeCoultre in 1833 and is based in Le Sentier, Switzerland. Since 2000, the company has been a fully owned subsidiary ...

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 Chloroethane, commonly known as ethyl chloride, is a chemical compound with chemical formula CH3CH2Cl, once widely used in producing tetraethyllead, a gasoline additive. It is a colorless, flammable gas or refrigerated liquid with a faintly sweet ...

in an internal

hermetically sealed A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers, but as technology advanced it applied to a larger categor ...

metal bellows. The ethyl chloride vaporises into an expansion chamber as the temperature rises, compressing a spiral spring; with a fall in temperature the gas condenses and the spiral spring expands, winding the mainspring. This motion constantly winds the

mainspring A mainspring is a spiral torsion spring of metal ribbon—commonly spring steel—used as a power source in mechanical watches, some clocks, and other clockwork mechanisms. ''Winding'' the timepiece, by turning a knob or key, stores energy in ...

. A temperature variation of only one degree in the range between and , or a pressure variation of 3 mmHg, was calculated to provide energy for two days' operation for an early prototype, while for a more recent Atmos 540 model the corresponding value has been computed as 4.3 days per °C. To run the clock on this small amount of energy, everything in the Atmos must be as friction-free as possible. For timekeeping it uses a

torsion pendulum A torsion spring is a spring that works by twisting its end along its axis; that is, a flexible elastic object that stores mechanical energy when it is twisted. When it is twisted, it exerts a torque in the opposite direction, proportiona ...

, which consumes less energy than an ordinary

pendulum A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward th ...

. 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 A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and one second for the return swing, a frequency of 0.5 Hz. Pendulum A pendulum is a weight suspended from a pivot so that ...

typically found in a

longcase clock A grandfather clock (also a longcase clock, tall-case clock, grandfather's clock, or floor clock) is a tall, freestanding, weight-driven pendulum clock with the pendulum held inside the tower or waist of the case. Clocks of this style are common ...

, where each swing (or half-period) takes one second.

History

The first clock powered by changes in atmospheric pressure and temperature was invented by Cornelis Drebbel in the early 17th century. Drebbel built as many as 18 of these, the two most notable being for King James VI & I of Britain, and Rudolf II of Bohemia. The King James clock was known as the Eltham Perpetuum, and was famous throughout Europe. It is mentioned in two works of

Ben Jonson Benjamin "Ben" Jonson (c. 11 June 1572 – c. 16 August 1637) was an English playwright and poet. Jonson's artistry exerted a lasting influence upon English poetry and stage comedy. He popularised the comedy of humours; he is best known for t ...

. Clocks powered by atmospheric pressure and temperature changes were subsequently developed by

Pierre de Rivaz Pierre de Rivaz (17111772) was a French clockmaker of the 18th century, from Saint-Gingolph. He built a clock in 1740 that was powered by variations in air temperature and pressure, a type of Atmos clock. See also *Marine chronometer A marin ...

in 1740, and by James Cox and John Joseph Merlin (

Cox's timepiece Cox's timepiece is a clock developed in the 1760s by James Cox. It was developed in collaboration with John Joseph Merlin (with whom Cox also worked on developing automata). Cox claimed that his design was a true perpetual motion machine, but as ...

) in the 1760s. The

Beverly Clock The Beverly Clock is a clock in the 3rd-floor lift foyer of the Department of Physics at the University of Otago, Dunedin, New Zealand. The clock is still running despite never having been manually wound since its construction in 1864 by Arthur ...

in Dunedin, New Zealand, is still running despite never having been manually wound since its construction in 1864. The first Atmos clock was designed by Jean-Léon Reutter, an engineer in Neuchâtel, Switzerland, in 1928. This noncommercial 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.... On 1 June 1929, Compagnie Générale de Radio (CGR) in France began manufacturing the first commercial model, Atmos 1, which used a mercury and

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

bellows A bellows or pair of bellows is a device constructed to furnish a strong blast of air. The simplest type consists of a flexible bag comprising a pair of rigid boards with handles joined by flexible leather sides enclosing an approximately airtig ...

power source. On 27 July 1935, Jaeger-LeCoultre took over production of Atmos 1 while it developed a second design which used the present ethyl chloride power source. This model later named the Atmos 2, was announced on 15 January 1936, but problems delayed full production until mid-1939. Subsequent models were based on this design. To date, over 500,000 Atmos clocks have been produced.

References

External links

Official website
{{Authority control Clock brands