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The Encyclopedia of Horology

Precision electromechanical pendulum clock (master/slave system) · England

Shortt-Synchronome Free Pendulum Clock

Verified

Regarded as the most accurate mechanical/electromechanical pendulum clock system ever put into regular service, used as a time standard by observatories including Greenwich before quartz clocks superseded it.

Technical facts

Accuracy
Documented to within roughly a few hundredths of a second per day under observatory conditions
Configuration
Master pendulum in an evacuated tank, electrically synchronised with a slave clock every half-minute

Historical significance

  • Regarded as the most accurate mechanical/electromechanical pendulum clock system ever put into regular service, used as a time standard by observatories including Greenwich before quartz clocks superseded it.
  • Separates a free-swinging 'master' pendulum in near-vacuum from a synchronised 'slave' clock that performs all the work of driving hands and impulsing, so the master pendulum itself does almost no work and swings with exceptional regularity.

Photographs

Shortt Synchronome free pendulum clock
Shortt Synchronome free pendulum clock — Unknown authorUnknown author, Public domain. Wikimedia Commons file page

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Royal Museums Greenwich, published catalogue notes on the Shortt-Synchronome clock
  2. Science Museum Group collection records

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