Guinness World Record for pendulum clock vindicates John Harrison 250 years on

By Culture24 Reporter | 20 April 2015

The Royal Observatory scoops the Guinness World Record for ‘most accurate mechanical clock with a pendulum swinging in free air’

a photo of the inner workings of a clock
© National Maritime Museum, London
From the world’s largest biceps to the biggest collection of Barbie Dolls, Guinness World Records come in many exotic forms –  but at the Royal Observatory Greenwich they have added to the extensive canon with one of the most oblique world records.

The Guinness World Record for the ‘most accurate mechanical clock with a pendulum swinging in free air’ has been awarded to the Burgess ‘B’ Clock, a timepiece made according to the writings of famous clockmaker and father of longitude John Harrison (1693-1776)

Harrison, whose marine chronometer solved the problem of establishing the longitude (east-west position) of a ship at sea, claimed to be able to make clocks that could keep time to within a second in 100 days.

The claim was outlined in a rambling and at times incoherent book which was met with derision and scorn by contemporaries.

a photo of the inner workings of a clock in glass case
© National Maritime Museum, London
One reviewer said of Harrison's book: “We are sorry to say that every page bears the marks of incoherence and absurdity, little short of the symptoms of insanity.”

Now a group known as the Harrison Research Group, led by clockmaker Martin Burgess, has put Harrison’s theories to the test by producing the Burgess Clock B.

Named after its maker, Martin Burgess, the clock took more than three decades of work before it was finished and subsequently adjusted and trialled at the home of Greenwich Mean Time, Royal Observatory Greenwich.

Running since March 2014 in a Perspex case made tamper-proof by the application of wax seals overseen by the Worshipful Company of Clockmakers and the National Physical Laboratory, the official 100-day trial started on January 6 and ended on April 16 2015.

The award was made at the Harrison Decoded conference on April 18 at the Royal Observatory Greenwich, which revealed that not only had the clock’s trial been successful in proving Harrison’s theory, but it had proved itself to be the world's most accurate mechanical clock with a pendulum swinging in free air.

"The results of this experiment are truly remarkable," said Rory McEvoy, the Curator of Horology at the observatory, who called the project "a new chapter in the history of precision timekeeping.”

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