The Bulle clock is an early electric clock invented by Marius Lavet and marketed from 1920 to approximately 1952. It uses a single dry-cell battery to power an electromagnetic escapement. The serial number is typically found stamped on the movement plate.
Serial Number Chart
| Serial Numbers | Year |
|---|---|
| 1 – 5,000 | 1920–21 |
| 5,001 – 20,000 | 1922–23 |
| 20,001 – 50,000 | 1924–25 |
| 50,001 – 100,000 | 1926–27 |
| 100,001 – 175,000 | 1928–29 |
| 175,001 – 250,000 | 1930–31 |
| 250,001 – 330,000 | 1932–34 |
| 330,001 – 400,000 | 1935–37 |
| 400,001 – 460,000 | 1938–40 |
| 460,001 – 510,000 | 1941–45 |
| 510,001 – 560,000 | 1946–49 |
| 560,001 – 600,000 | 1950–52 |