Big Ben

:For other uses of Big Ben, see Big Ben (disambiguation)

Reliability

The clock is famous for its reliability. This is due to the skill of its designer, the lawyer and amateur horologist Edmund Beckett Denison, later Lord Grimthorpe. As the clock mechanism, created to Denison's specification by clockmaker Edward John Dent, was completed before the tower itself was finished, Denison had time to experiment. Instead of using the deadbeat escapement and remontoire as originally designed, Denison invented the double three-legged gravity escapement. This escapement provides the best separation between pendulum and clock mechanism. Together with an enclosed, wind-proof box sunk beneath the clockroom, the Great Clock's pendulum is well isolated from external factors like snow, ice and pigeons on the clock hands, and keeps remarkably accurate time.

Related Topics:
Horologist - Edmund Beckett Denison - Edward John Dent - Deadbeat escapement - Remontoire - Gravity escapement - Escapement

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The idiom of putting a penny on, with the meaning of slowing down, sprung from the method of fine-tuning the clock's pendulum by adding or subtracting penny coins. Even to this day, old pennies, phased out of British currency by the 1971 decimalisation, are used.

Related Topics:
1971 - Decimalisation

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Despite heavy bombing, it ran accurately throughout The Blitz. It slowed down on New Year's Eve 1962 due to heavy snow, causing it to chime in the new year 10 minutes late.

Related Topics:
The Blitz - New Year's Eve - 1962

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The clock had its first and only major breakdown in 1976. The chiming mechanism broke due to metal fatigue on 5 August 1976, and was reactivated again on 9 May 1977. During this time BBC Radio 4 had to make do with the pips.

Related Topics:
1976 - 5 August - 9 May - 1977 - BBC Radio 4 - Pips

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It stopped on 30 April 1997, the day before the general election, and again three weeks later.

Related Topics:
30 April - 1997 - General election

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On Friday, 27 May 2005 the clock stopped ticking for 90 minutes from 10.07pm, possibly due to hot weather (temperatures in London had reached an unseasonal 31.8°C/90°F). It resumed keeping time, but stalled again at 10.20 p.m. and remained still for about 90 minutes before starting up again. http://news.bbc.co.uk/1/hi/england/london/4589527.stm

Related Topics:
27 May - 2005

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