Legendary English clockmaker John Harrison claimed, in 1775, that his clocks could keep time to within a second in 100 days. Ridiculed for centuries, he has finally been vindicated as a clock built to his design was awarded a Guinness World Record for “the most accurate mechanical clock with a pendulum swinging in free air”.
The Harrison Decoded conference, held at the Royal Observatory Greenwich on April 18, saw the award of the world record, following a 100-day timekeeping trial of a clock built by Martin Burgess.
The idea of precision in horology presents a conundrum. Much as it is a fundamental quality in terms of how watches and clocks are made, precision in time-keeping is hardly ever mentioned since the advent of quartz and the internet – in absolute terms at least; the accuracy standards of COSC, the Poincon de Geneve and others (Rolex’s new Day-Date calibre 3255, for example) are much-vaunted by the Swiss watchmaking industry.
However, this announcement of a successful record attempt brings the subject right back into focus and shines a light on how watch and clock-making hover between pure engineering and pure craft.
The attempt was a hundred day trial to see if a claim made by John Harrison at the end of his career was credible or, as his contemporary detractors insisted, farcically overblown nonsense. The 1775 book in which Harrison claimed that his clocks could achieve an accuracy of one second in one hundred days was not well received, with one reviewer claiming that it revealed signs of insanity, writing, “indeed we are sorry to say that every page bears the marks of incoherence and absurdity”.
Harrison himself died the following year. Denied the chance to prove his claims, they were first ridiculed and later forgotten. Mechanical clocks did not reach the same level of accuracy for more than 150 years.
But anyone who has witnessed the remarkable precision of Harrison’s work (Jonathan Betts, the former curator at the Royal Observatory where the test took placed, told QP he only ever cleaned and never repaired a Harrison) and has any familiarity with his story would have known to take his claims seriously – though in defence of the reviewer Harrison’s decades-long pursuit of the Longitude prize demonstrated a certain singleness of mind and would have tested the patience of an ordinary man beyond reason.
The claim ignited the interest of artist and clockmaker Martin Burgess and he began a thirty year project to put Harrison’s theory into practice. Clock A, otherwise known as the Gurney Clock after the Norwich bank, was completed in the 1980’s and is on display in Norwich Castle Mall. Clock B lay unfinished in Burgess’ workshop until an American collector, Don Saff, acquired it in 2009. The clock was taken to Frodsham’s where a team under Philip Whyte restored it.
The clock was then installed at the Royal Observatory in Greenwich in March 2014. By this point, it was already known that the clock performed exceptionally well despite having several features that contradicted accepted practice over the last 250 years. One of these being the use of a shorter than normal “bob” (cord) for the pendulum, which turned out to stabilise the pendulum more quickly as atmospheric conditions changed – Harrison’s key advances were almost all about maintaining precision over ranges of environmental conditions.
The critical test was conducted under the eye of the National Physical Laboratory and the Worshipful company of Clockmakers and started on January 6th this year – the clock’s perspex case having been made tamper-proof by the application of wax seals. To the delight of the attendees at the conference where the results were announced, Jonathan Betts was able to announce that Clock B lost 5/8ths of a second over the 100 days – a phenomenal achievement and a tribute to Harrison.
For more information on John Harrison’s life and work, and to see his groundbreaking Longitude clocks, click here.