Turret clock with double three-legged gravity escapement · England
The Great Clock of Westminster ('Big Ben', properly the bell)
Verified'Big Ben' properly refers to the Great Bell; the phrase is very widely used for the whole clock and tower, and this popular usage should be flagged rather than silently repeated as the technically correct name.
Technical facts
- Escapement
- Denison's double three-legged gravity escapement
- Pendulum
- Approximately 4 metres long, beating at roughly two-second intervals, with the well-known coin-adjustment method for fine regulation
- Movement maker
- E. J. Dent & Co., completed after Dent's death by his stepson Frederick Dent
Historical significance
- 'Big Ben' properly refers to the Great Bell; the phrase is very widely used for the whole clock and tower, and this popular usage should be flagged rather than silently repeated as the technically correct name.
- Denison's double three-legged gravity escapement isolates the pendulum from variations in the driving force caused by wind pressure on the massive external hands, a design innovation of lasting influence on precision turret clocks.
- The clock has undergone significant conservation work in the 21st century; researchers should check the relevant Parliamentary/UK Parliament conservation programme documentation for the current mechanical state rather than assuming an unaltered 1859 mechanism.
Photographs
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Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- UK Parliament, published history and conservation information on the Great Clock
- Antiquarian Horological Society, articles on Denison's gravity escapement
Where sources disagree, the disagreement is stated rather than resolved silently.