Self-winding clock that uses changes in temperture

I'm sure you've heard of self-winding mechanical watches. While clever, they aren't quite as magical as the sound for they use the swinging of the wearer's arm to continuously rewind an internal spring. Here is a clock that self-winds - the Perpetual ATMOS Clock. Clearly, you don't swing the clock around on the end of your arm. So, how does it wind itself?

The secret lies in small changes in air temperature. When the temperature rises, gases inside of a small chamber expand, which compresses a spiral spring. When the temperature drops again (as it is bound to do), the gas condenses and the spring relaxes. The resulting reciprocating motion, though small, is enough to winds clock's mainspring.

Here is a where you can learn more about the Perpetual ATMOS Clock.

[ Found via the MAKE magazine blog ]

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