The Atmos Millénaire Atlantis was designed by Robert Kohler for Jaeger-LeCoultre to celebrate the passing of the new millennium in 2000. It features a perpetual calendar with phases of the moon (1 day of inaccuracy every 3821 years) and the years accurate to 3000.Jean-Léon Reutter invented the first prototype of an Atmos clock in 1928 and since 1935 has been commercialized and improved by Jaeger-LeCoultre. Atmos clocks have always been sought after by fans of the celebrated firm.

To achieve the concept of eternal motion, the clock derives its energy from the expansion and contraction of a capsule that includes a mixture of gas and liquid that responds to changes in barometric pressure. When the capsule is connected to the mechanism of the watch, temperature fluctuations constantly drive the movement without the need for manual mounting. For example, a one-degree change in the range between 15 and 30 degrees Celsius would cause the mechanism of the watch to be turned on for approximately two days of operation.