When I fist read the description on how this worked I was totally amazed. The clocks never need winding by hand because the mechanism is powered by a difference in temperature. A variance of a degree between 15-30 C is enough to cause a liquid (ethyl chloride) in a sealed container to expand or contract and in turn wind a spring with a ratchet. The clocks are exquisitely made and are fairly rare. If you find on, even a non working one you can expect to pay over $2,000 US for it. I find the concept of a temperature driven clock fascinating. I can’t help but wonder if the dynamic properties of ethyl chloride could be used in other projects.