An Atmos 528 dating from the 1970s.

An Atmos 528 dating from the 1970s. These are remarkable clocks. Their history begins in the 1930s when there was considerable competition to produce a "perpetual motion" clock. A Swiss, Herr Reuter, produced the best solution that used both changes in atmospheric pressure and temperature to wind the clock. He sold the design to Jaeger le Coultre who called it the Atmos clock and have produced it ever since, in virtually unchanged form. In the early days there were problems with the part that used atmospheric pressure to wind the clock and this was discontinued. Since then, the clock uses only changes in temperature and is so sensitive that a one degree change is sufficient to fully wind it, which is for three days.The source of power is so small that it would require 65,000,000 Atmos clocks to power one 15 watt light bulb. In order to use such a minute power source the clock is constructed to the standards of a scientific instrument, and is close to friction free. In the 1930s Jaeger le Coultre were so proud of their achievement that they devoted one year's production to giving each head of state in the world an Atmos clock, about 300 in all. The clock is the official gift of the Swiss Government to any visiting head of state to this day. The case is made of bronze and the movement is made of brass. Both are gold plated in 24 carat gold. This clock is a 528 calibre which was Le Coultre's fourth and last great production run of these fine clocks, in my view the best Atmos made. This example is in excellent original condition.