Dating a Bulle Clock by Serial Number
Bulle Clocks are among the best-known early electric clocks with an electromagnetic pendulum. Many surviving examples can be approximately dated using the serial number stamped on the movement.
Enter the serial number of your Bulle Clock below to find its probable period of manufacture. The dating is based on surviving production and serial-number data together with comparisons to documented Bulle Clocks.
As no complete original production registers are known to survive, the periods shown here should be understood as approximate dating rather than exact dates of manufacture.
Date your Bulle Clock by serial number
Enter the serial number without punctuation or spaces.
Where can I find the serial number?
On Bulle movements, the serial number is stamped twice on the rear movement plate: on the left-hand side when viewed from the front and again on the left-hand side of the reverse. Both numbers should match.
The two photographs below show the serial-number positions on different Bulle movements.
Dating by serial number
The following table forms the basis of the serial-number search above. The dates should be understood as approximate periods of manufacture.
| Serial number | Approximate date |
|---|---|
| 1–2.499 | c. 1920 |
| 2.500–7.999 | c. 1920–1921 |
| 8.000–20.999 | c. 1922–1923 |
| 21.000–46.999 | c. 1924–1925 |
| 47.000–85.999 | c. 1926–1927 |
| 86.000–119.999 | c. 1928–1929 |
| 120.000–144.999 | c. 1930–1931 |
| 145.000–188.999 | c. 1932–1933 |
| 189.000–229.999 | c. 1934–1935 |
| 230.000–269.999 | c. 1936–1937 |
| 270.000–299.999 | c. 1938–1939 |
| 300.000–309.999 | c. 1939 to the post-war period – uncertain |
| 310.000–319.999 | c. 1948–1949 |
| 320.000–325.999 | c. 1950–1951 |
| 326.000–ca. 330.000 | c. 1952–1954 |
| above c. 330,000 | no reliable assignment |
Serial numbers from 300,000 to 309,999 cannot be reliably assigned to a narrow period of manufacture. For this reason, no more precise date is given.
Basis of the dating
The dating is based on published serial-number and production data attributed to research by John Hubby. The original online source containing his Bulle dating information is no longer available, but reproductions of the data survive in later specialist and collector sources.
Documented Bulle Clocks with known serial numbers and dates have also been used for comparison. These examples help to assess the plausibility of the surviving serial-number ranges.
About John Hubby
John Hubby has spent many years researching historic clocks and is particularly known for his work on torsion clocks. He joined the US-based National Association of Watch & Clock Collectors (NAWCC) in 1982 and served on its Board of Directors from 2001 to 2011. From 2009 to 2011 he served as Board Chair.
Within the NAWCC, he has been closely involved with torsion clocks, chaired a symposium on the subject in 2003 and served as guest curator for an Anniversary Clock exhibition at the National Watch & Clock Museum. His research has included investigating who made particular types of clocks and when they were made.
Hubby also compiled information on the production history of Bulle Clocks. His work therefore forms an important basis for serial-number and production data reproduced in later specialist and collector sources. It should not, however, be regarded as a substitute for a complete surviving original factory register.
The table should therefore be used as a guide to dating a Bulle Clock. Unusual or conflicting examples should also be assessed using other characteristics of the clock.
Identifying the movement type
In addition to the serial number, the movement design can help when identifying a Bulle Clock. Horologix provides a reference guide to early Bulle movement types.
Sources and further information
Several specialist sources and documented comparison clocks were used when compiling and checking the dating ranges shown on this page.
The dating has not been taken uncritically from a single source, but compiled and compared using several available references. External links on this page lead to websites and information resources operated by third parties. Their respective operators are responsible for their content. The content and availability of external websites may change at any time.
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