This is a Jaeger-LeCoultre Atmos clock. It is a unique table clock that runs without a battery or manual winding. The mechanism is powered by the contraction and expansion of a gas mixture within a sealed capsule, which responds to ambient temperature changes. The clock's design allows the complex internal machinery to be viewed from all angles through its glass case. The Atmos clock is known for its silent operation and near-perpetual motion. The technology was first perfected in 1928, with Jaeger-LeCoultre manufacturing the clocks since 1935.
eBay