Atmos clock
Encyclopedia
Atmos is the brand name of a mechanical clock
Clock
A clock is an instrument used to indicate, keep, and co-ordinate time. The word clock is derived ultimately from the Celtic words clagan and clocca meaning "bell". A silent instrument missing such a mechanism has traditionally been known as a timepiece...

 manufactured by Jaeger-LeCoultre
Jaeger-LeCoultre
Jaeger-LeCoultre is a high-end luxury watch and clock manufacturer based in Le Sentier, Vaud, Switzerland. In addition, Jaeger-LeCoultre also has a long tradition of supplying movements and parts to other prestigious watch companies in Switzerland. Since 1996, Jaeger-LeCoultre has been a fully...

 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.

Its power source is an internal hermetically sealed capsule containing a mixture of gaseous and liquid ethyl chloride, which expands into an expansion chamber as the temperature rises, compressing a spiral spring; with a fall in temperature the gas condenses and the spring slackens.
This motion constantly winds the mainspring
Mainspring
A mainspring is a spiral torsion spring of metal ribbon that is the power source in mechanical watches and some clocks. Winding the timepiece, by turning a knob or key, stores energy in the mainspring by twisting the spiral tighter. The force of the mainspring then turns the clock's wheels as it...

. A temperature variation of only one degree in the range between 15 and 30 degrees Celsius, or a pressure variation of 3 mmHg, is sufficient for two days' operation.

In order to run the clock on this small amount of energy, everything inside the Atmos has to work in as friction-free a manner as possible. For timekeeping it uses a torsion pendulum
Torsion pendulum clock
A torsion pendulum clock, or torsion clock, is a mechanical clock which keeps time with a mechanism called a torsion pendulum. This is a weighted disk or wheel, often a decorative wheel with 3 or 4 chrome balls on ornate spokes, suspended by a thin wire or ribbon called a torsion spring...

, which consumes less energy than an ordinary pendulum
Pendulum
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position...

. The torsion pendulum executes only two torsional oscillation
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...

s per minute, which is 1/60th the rate of the pendulum in a conventional clock.

History

The first clock powered by changes in atmospheric pressure and temperature was invented by Cornelis Drebbel in the early seventeenth 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
Ben Jonson
Benjamin Jonson was an English Renaissance dramatist, poet and actor. A contemporary of William Shakespeare, he is best known for his satirical plays, particularly Volpone, The Alchemist, and Bartholomew Fair, which are considered his best, and his lyric poems...

.

Experimental clocks powered by atmospheric pressure and temperature changes were next made during the Enlightenment
Age of Enlightenment
The Age of Enlightenment was an elite cultural movement of intellectuals in 18th century Europe that sought to mobilize the power of reason in order to reform society and advance knowledge. It promoted intellectual interchange and opposed intolerance and abuses in church and state...

. Early examples are a clock developed by Pierre de Rivaz
Pierre de Rivaz
Pierre de Rivaz 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.-Notes:...

 in 1740, and Cox's timepiece
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 . Cox claimed that his design was a true perpetual motion machine, but as the device is powered from changes in atmospheric pressure via a mercury barometer, this is not the case...

, a clock developed in the 1760s by James Cox and John Joseph Merlin. The oldest predecessor still running today is the 1864 Beverly Clock
Beverly Clock
The Beverly Clock is a clock situated in the 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 Beverly....

.

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
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

-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
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 bellows
Bellows
A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...

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.

External links

  • LeCoultre Atmos Clock History Detailed drawing of movement, gallery of pictures. Clock repairer specializes in Atmos, much info on models, part supply, history.
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