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The Encyclopedia of Horology

Precision pendulum regulator clock · England

George Graham's Astronomical Regulator Clocks

Partially verified

Graham is credited with perfecting the deadbeat escapement (building on earlier work associated with Richard Towneley and Thomas Tompion, whose workshop Graham inherited) and with introducing a mercury-compensated pendulum to counteract thermal expansion.

Technical facts

Escapement
Deadbeat (graham) escapement
Pendulum
Mercury-compensated pendulum in Graham's later regulators, correcting for thermal expansion of the pendulum rod

Historical significance

  • Graham is credited with perfecting the deadbeat escapement (building on earlier work associated with Richard Towneley and Thomas Tompion, whose workshop Graham inherited) and with introducing a mercury-compensated pendulum to counteract thermal expansion.
  • His regulator clocks were used by Astronomers Royal Edmond Halley and James Bradley at the Royal Observatory, Greenwich, for exacting positional astronomy over long periods, making Graham's clocks working scientific instruments rather than purely decorative pieces.
  • As a representative body of work rather than a single named object, specific surviving Graham regulators should each be individually catalogued and dated against the holding institution's own records.

Background

George Graham was an influential English clockmaker who introduced design improvements to the pendulum clock during the early 18th century. Graham introduced the deadbeat escapement in his precision regulators around 1715, although it had been invented around 1675 by the astronomer Richard Towneley and first used by Graham's mentor Thomas Tompion. Beyond his horological work, Graham was widely acquainted with practical astronomy and contributed to the field by constructing various scientific apparatus. His efforts supported the work of Astronomers Royal, providing tools for exacting positional measurements.

Written from the encyclopedia entries listed under Sources; each statement was checked against the cited text.

Later history

  • A 28-day duration longcase regulator with a deadbeat escapement, dating to approximately 1745, is currently held at the Moyse's Hall Museum.

Related photographs

Graham Escapement
Graham Escapement — Frederick J. Britten, Public domain. Wikimedia Commons file page
⏲️ Deadbeat Escapement Mechanical Countdown Timer MKII・ STL File for 3D ...
⏲️ Deadbeat Escapement Mechanical Countdown Timer MKII・ STL File for 3D ... — cults3d.com, Rights unverified — web image search result, review pending. Web page (cults3d.com)
CLOCK 252: The deadbeat escapement
CLOCK 252: The deadbeat escapement — awci.com, Rights unverified — web image search result, review pending. Web page (awci.com)

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

  1. George Graham (clockmaker), Wikipedia (English), retrieved 2026-10-28 (text CC BY-SA 4.0)
  2. Britten, F. J., Old Clocks and Watches and Their Makers
  3. Royal Museums Greenwich, published catalogue notes on precision regulator clocks

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