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If you need service then please see my Atmos service page.

If you need a specific part then please see my Atmos parts page.

Basic Information on the Atmos Clock.

I have an on-line Atmos Manual for all those nagging operating questions.

Taken from: Mike's Atmos Overhaul Class Notes – Supplemental

Most of the information contained in this article has been
obtained from the book,
“Living on Air – History of the Atmos Clock” by Jean Lebet.

Jean-Leon Reutter, in France, designed the Atmos Clock in 1927
and this is referred too as the Atmos 0.   These prototypes
were never sold and never called the Atmos 0 at that time.

His clocks were driven by a “mercury in glass” expansion
device which rotated a cylinder which wound the mainspring
by ratchet.  The mechanism operates on temperature change
only.   The clocks are slightly different to the later Atmos
models in minor details of escapement.

On June 01, 1929, Compagnie generale de radio (CGR) created
a department devoted to the manufacture and sales of the
Atmos clock.  Jean-Leon Reutter was appointed to manage that
department.  It is unclear how many were made and sold but
we refer to these at Atmos I’s.  Two French patents were
granted for the Atmos 0 (624.595) and for the Atmos I
(664.689) but that company never produced the Atmos 0.
They are very nicely made and typically they have a plate
saying "Reutter Brevet" or “Brevets J. L. Reutter S. G. D. G.”
(Brevet = Patent).

In September 1932 LeCoultre entered an agreement to develop
movements for CGR and first deliveries were made in mid 1933
and these movements were called the 30” A calibre.  Annual
production of these movements was between one and two
thousand for years 1933 and 1934.

On July 27, 1935, CGR agreed to transfer all production to
LeCoultre and all remaining stock and work in process.
LeCoultre continued to sell the Atmos I while it was
developing the Atmos II, which the primary improvement was
the change from ammonia and mercury “bellows” to a canister,
filled with ethyl chloride.

By January 15, 1936, LeCoultre announced its “new” Atmos
and they were still using the 30” A calibre movement.
These “new” Atmos’ were later called Atmos II’s.  By
November of 1936 the Atmos I production was stopped
completely.  Problems arose and “full” production of
the Atmos II did not start until mid 1939.

The next model was the Atmos III, which included the
519 calibers and 529 calibers.  Serial numbers for the
Atmos II and Atmos III are somewhat intertwined because
of LeCoultre purchasing the entire stock of CGR.

There is evidence of overlapping in all LeCoultre models,
so please don't get caught up in the “absolutes” of serial
numbers and caliber numbers.

The Atmos II and the Atmos III have serial numbers ranging
from around 4,000 to 59,999 and production went from 1936
until late 1955.

The Atmos IV included calibers 522 and 532 and have serial
numbers from 60,000 to 69,999.  The important thing to know
here is that this is LeCoultre's shortest full production
run ever.

The Atmos V consist of the caliber 526 and the Atmos VI,
VII, and VIII consists of the caliber 528 and the 528/1
represents the Atmos VIII.  Serial numbers start at 70,000
and went right up to 599,999.  The important point here is
that this is the last of the “genuine” Reutter design Atmos
made and production stopped late in 1983.

In late 1983, LeCoultre totally resigned the Atmos and came
up with the 540 caliber.  They also stopped the practice of
labeling the models numerically (Atmos 0 – Atmos VIII).
These serial numbers start with 600,000 and is still being
made today under various caliber numbers and model names.

The following is a break down of the movement caliber numbers
and the corresponding range of the Atmos serial numbers:

	Caliber #			Serial # Range

	550			Special 50th Anniversary
	540				600,000 and up
	526-5 & 528-6 & 528-8		107,000 - 599,999
	526-5 & 528-6 & 529 & 532  	70,000 - 106,999
	519 & 522 & 529 & 532	  	60,000 -  69,999
	Atmos II & 519 & 529 	    	4,000 -  59,999

	The serial numbers are located on top of the movement
next to the fast-slow adjustment.  On some early caliber 519's
and the Atmos II’s the serial number is located on the bottom
of the movement and you can see it through the front of the case.

    The following Acrobat file contains some of the Atmos clocks I have work on,
listed by serial number.  After the serial number is the date that was found
on the bellows.

    The bellows were made in batches, so there is some duplication but more than
enough information to date your specific Atmos to within a month or so.

    All I ask is that you reference where you obtained this information if you
use it anywhere on the Web including sales or auctions.$atmos.pdf

    This file contains is the serial #'s of over five hundred Atmos clocks that
I have repaired that still have had the original bellow intact.

    The serial numbers are located on top of the movement next to the fast-slow
adjustment.  On some early caliber 519's and the Atmos II's the serial number is
located on the bottom of the movement and you can see it through the front of the case.

    The caliber's from the 522 to the Atmos' made today are stamped, with the
particular caliber #, on the bottom of the case.  The Atmos II and caliber 519
were not stamped on the bottom and are nearly identical.  You can tell the
difference because the Atmos II has the speed adjustment as a turn screw rather
than a slide lever, which is found on the caliber 519 and all models since.

	    A service from,   E-mail address
	    Mike Murray         Founder of Clocksmiths

A specialist in Atmos and 400-day clock repair.
Also, I overhaul most plug in electric clocks.
In continuous service since 04/01/1982.

Mike's Clock Clinic
P. O. Box 562
1151 D Street
Fossil, OR  97830-0562

My Web site is located at
Main FTP site is located at:

Memberships: Clocksmiths; NAWCC
N.A.W.C.C. International 400-day Clock Chapter # 168
Formally Published in Chapter 168's "Torsion Times"
Former AWCI's 400-day (Anniversary) clock Bench Course Instructor!

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Copyright © 1996-2022 Michael P. Murray & Mike's Clock Clinic

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Created in January of 1996 and last updated January 11, 2022.