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The Encyclopedia of Horology

Clock type · Precision

Hacking Clocks (Precision)

Partially verified

Precision clocks or watches with a mechanism to stop the seconds hand for synchronization.

Movement & mechanism

  • Stop-seconds (hacking) lever that arrests the balance
  • Used for synchronizing multiple timepieces in military or scientific contexts
  • High-grade chronometer-standard movements

Identification

  • Presence of a pull-out crown or lever that stops the seconds hand
  • Highly legible dial with seconds track
  • Chronometer-grade movement

Terminology

  • Stop-seconds
  • Synchronization
  • Hacking

Known variations

  • Pocket watch and small clock 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.

Diagram

escape wheelpallets and leveroscillator
Schematic: escapement arrangement. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Sources & references

  1. Britten, F. J., Old Clocks and Watches and Their Makers
  2. Loomes, B., The Early Clockmakers of Great Britain
  3. Roberts, D., British Skeleton Clocks
  4. Museum catalogue records

Where sources disagree, the disagreement is stated rather than resolved silently.