Atmos clock
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The Atmos is a type of clock manufactured by Jaeger LeCoultre in Switzerland.
Inside a hermetically sealed capsule is a mixture of gas and liquid (ethyl chloride) which expands as the temperature rises in the expansion chamber, which then compresses a spiral spring, with a fall in temperature the gas condenses and the spring slackens. This motion constantly winds the mainspring, a variation in temperature of only one degree in the range between 15 and 30 degrees Celsius being sufficient for two days' operation.
To convert this small amount of energy into motion, everything inside the Atmos has to work as friction-free as possible. The balance, for example, executes only two torsional oscillations per minute, which is 150 times slower that the pendulum in a conventional clock.
In 1928 a Neuchatel engineer called Jean-Leon Reutter built a clock driven by a mercury in glass expansion device which rotated a cylinder which wound the mainspring by ratchet. The mechanism operated on temperature change only. But it took the Jaeger-LeCoultre workshop a few more years to convert this idea into a technical form that could be patented.
An early predecessor is Cox's timepiece, a clock developed in the 1760s by James Coxand and John Joseph Merlin, while the oldest predecessor still running today is the 1864 Beverly Clock.
