'Atmos II' self-winding clock
From Object Wiki
| 'Atmos II' self-winding clock | |
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| Manufacturer | Jaeger le Coultre |
| Production years | (unknown) |
| Production location | Le Sentier (in Le Chenit), Vaud, Switzerland |
A clock automatically wound by changes of atmospheric temperature and pressure. A fall of temperature of 30F provides enough power to drive the clock for over 24 hours.
[edit] How it works
The driving motor of the clock, a sectioned example of which is shown on the left, consists of a drum on the inside of which is mounted a flexible metallic bellows. The space between the bellows and the outer drum casing is hermetically sealed and contains ethyl chloride, the vapour pressure of which varies very rapidly with temperature. Increase of temperature raises this pressure and causes the bellows to expand against a spring. A similar effect would be produced by a fall of barometric pressure. By means of a connecting system, the expansion and contraction of the bellows is caused to wind up the clock mainspring., which has a year’s reserve of power. Arrangements are made to prevent over winding and the mainspring normally operates under nearly uniform tension. The design of the clock itself has many features of interest. The horizontal balance wheel is controlled by an elinvar spring, whose elasticity does not vary appreciably with temperature. The balance, which is driven by a detached lever escapement makes only 1440 oscillations in 24 hours, compared with 43,200 for a seconds pendulum. Owing to the slow action of the moving parts and the precision of their finish, the use of oil in the clock has been entirely eliminated.
[edit] Memories
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Do you remember stories about clocks? Add your memories. |
My grandmother, b ca 1850, had a treasured Atmos clock that sat on her mantel. I and my mechanically inclined brothers always wanted to take it down and open it. She knew it was wound by temperature changes. We wanted to put it in an oven to watch it wind. We had taken inoperative alarm clocks apart and saw how a balance wheel worked. We couldn't carry that idea over to the slow movement of the Atmos.
Bill Drissel bill@drissel.su
[edit] In the Science Museum's Records
Inv. No: 1939-259