A JAEGER-LECOULTRE GILT BRASS ATMOS VENDOME, reference 5834.

Model: Atmos Vendome
Date: Circa 1981
Reference: 5834
Movement: Signed, Atmos
Dial: Signed, cream, black Roman numerals, black outer minute division with Arabic numerals division, black Breguet hands
Case: Signed, glazed sides, gilt brass top, and base with green insert over the columns and edges
Size: 210 mm length x 160 mm width x 240 mm height
Accompaniments: Jaeger-Lecoultre brown leather box, instructions, and warranty card

"We could say the Atmos clock breathes air to function". Operated on temperature changes alone, the Atmos clock was designed and developed in Switzerland in 1928 by the engineer Jean-Leon Reutter using mercury and ammonia bellows as the the power source andf his first model was the Atmos 1. On 27th July 1935 Jaeger-LeCoultre took over production of the Atmos 1, but the design was changed to use ethyl chloride as a power source and Jaeger-LeCoultre were not able to start productions until mid-1939, almost 4 years after the new Atmos 2 model had been announced.

The Atmos mechanism has been engineered to operate using a very small amount of energy, and so to maximise the output of the power source it must be as friction-free as possible. The power is generated by the expansion and contraction of liquid and gaseous ethyl chloride in a hermetically sealed metal container withjin the mechanism, this movement giving the mainspring enough power to drive the mechanism. The mechanism is so finely engineered that a temperature variation of only one degree between 15 °C and 30 °C, or a barometric pressure variation of 3 mmHg, is sufficient to provide the energy for two full days of operation for the early prototypes of Atmos clocks.

Dimensions: 210 mm length x 160 mm width x 240 mm height.