Caliber # 1 (original Reutter Atmos), Atmos II, 519, 522, 526, 528-6, 528-8 and Caliber 540, respectively.
A "Caliber Number" - such as Caliber 528, 540, etc, are numbers that we use to determine the movement *type* of an Atmos and not necessarily the style of the case.
The of an Atmos Clock is usually located on the top of the Movement, by the Speed Adjustment Lever.
On some very older models, the serial number may actually be on the front of the Movement -near the hands and on Antique Reutter Clocks the serial number is often on the Back "Drum" portion.
These brackets are beautifully constructed original items, not copies.
And to perfect it to such a degree that the Atmos practically achieved perpetual motion. The technical principle is a beguiling one: inside a hermetically sealed capsule is a mixture of gas and liquid (ethyl chloride) which expands as the temperature rises and contracts as it falls, making the capsule move like a concertina.Aside from the different Cases and Dials, the Pendulum on an Atmos Clock can also be different from one model to the next.For Example: The Pendulum of an "Atmos Caliber II" has straights, black lines (see photo), the Pendulum of a Caliber 519 has round "dimples", the Caliber 526 has wide vertical indentations and the Caliber 528 has thin vertical indentations.Lucite casing in good condition with no 'fros1970 Jaeger-Le Coultre Atmos perpetual motion clock. Atmos clock sold in the USA by Gruen Cosmos, NY in the 60's.
Wooden case with 4 windows to see the dial and movement.
There have been many models and "styles" of Atmos Clocks produced by Jaeger-Le Coultre since the late 1930's; however at this time there is no known Atmos Clock reference book that lists all Atmos models and their respective serial numbers.