Jaeger LeCoultre Atmos perpetual motion clock, caliber 528-8, serial number 519513 , made in 1973 Good running condition, keeps accurate time (+/-5min.per week), movement is in good condition, bellows inspected, works good. The case back corner has a small crack (see pictures and video for more details https://youtu.be/99XD6ASsUoc ) Secure shipping using double boxed packing. Jaeger-Le Coultre's famous 'Atmos' clock was first developed in 1928. The clock is automatically wound without any intervention by the owner. Changes in air temperature makes winding the clock's mainspring. A change in temperature of one degree can provide enough power to run the clock for few days, and the mainspring has enough power in reserve to run the clock for a year. Energy is conserved by the very slow-moving twisting pendulum which 'beats' only twice per minute. "JLC ATMOS clock is one of the world’s most innovative clocks, the Jaeger-LeCoultre Atmos is a visionary technical masterpiece. Powered by atmospheric pressure and temperature changes, it’s essentially a perpetual motion device, allowing it to run for years without human intervention. The Atmos is such a ground-breaking creation that it’s chosen as a traditional gift to heads of state and dignitaries". The movement is very silent. Warning!!! These clocks can have troubles to wind in premises with high quality climate control systems (where air temperature is very stable). The clock must not be moved without locking the pendulum - moving the lever at the base bottom from the left to the right. To change the time, the minute hand must be moved by turning it clockwise.