Glossary · Regulation
Amplitude
The angular swing of a balance wheel from rest to one extreme and back.
Explanation
Amplitude is the angular swing of the balance, usually stated in degrees on a timing machine. It changes with wind, position, friction and escapement condition, so one number is not a health certificate. A fully wound modern lever watch may show a higher value than the same watch near the end of its reserve; a historic watch, small calibre or complicated watch may have a different expected range.
Read amplitude beside rate, beat error, lift angle setting and the test position. Low amplitude can follow dried lubricant, weak mainspring, worn pivots, poor escapement adjustment or incorrect test setup. High or unstable readings can also be misleading. Catalogue a measurement only with its conditions, and avoid turning a seller's timing photo into a complete service report.
Sources & references
- Daniels, G., Watchmaking — balance and escapement adjustment
- de Carle, D., Practical Watch Repairing — timing-machine interpretation
Where sources disagree, the disagreement is stated rather than resolved silently.
What to record
- Record wind state, position and lift-angle setting with the reading.
- Compare against the exact calibre and service history.
- Keep amplitude separate from accuracy and originality.
Do not keep running an unserviced watch just to improve a timing reading.
In the object catalogue
Catalogued objects whose own source record mentions “Amplitude”. The quoted line shows where; it is the seller’s or museum’s wording, not independent verification.
