Clock type · Domestic
Torsion (400-Day) Clocks
Partially verifiedClocks regulated by a rotating (torsion) pendulum rather than a swinging one, allowing for extremely long durations.
Movement & mechanism
- Torsion pendulum suspended by a thin wire or ribbon
- Escapement impulses the pendulum to rotate back and forth
- Frequently 400-day or 1000-day duration
Identification
- Rotating weights (often four balls) at the bottom
- Thin suspension wire visible behind the movement
- Glass dome covering the entire clock
Terminology
- Anniversary clock
- Suspension spring
- Torsion wire
Known variations
- Four-ball, disc and novel pendulum versions
Collecting notes
Condition and originality are paramount. For technical clocks like regulators or atmospheric clocks, the completeness of the original mechanism is more important than case condition. For decorative clocks (Boulle, Empire), the quality of the case craft is central.
Related photographs
No confidently matched photograph of this subject has been found yet. These photographs show a closely related record, and are not examples of the type described on this page.
Sources & references
- Britten, F. J., Old Clocks and Watches and Their Makers
- Loomes, B., The Early Clockmakers of Great Britain
- Roberts, D., British Skeleton Clocks
- Museum catalogue records
Where sources disagree, the disagreement is stated rather than resolved silently.