Essential Information

Royal Observatory

16 Jan 2015

In July 2014 the NMM hosted on one-day conference, entitled Decoding Harrison, which presented the story of around forty years of collaborative research into John Harrison’s complex and surprising pendulum clock theory.

During the conference the exciting result of a previously unannounced and unofficial test of Martin Burgess’s ‘Clock B’ at the Royal Observatory was revealed.

'Clock B' at the Royal Observatory, Greenwich

‘Clock B’ is one of two clocks made from modern materials, chiefly duraluminium and invar, that follow the perceived format laid out in Harrison’s convoluted text: Concerning such mechanismthe lengthy title - too many characters to tweet – gives an accurate sense of the complexity of the book itself. For example, footnotes occasionally run across more than one page and if that was not enough, some even have their own footnotes. In short, it is not an easy read.

Observing 'Clock B' in its sealed case

The unofficial test was conducted with the clock sealed into a Perspex case, which was made tamper-proof by applying two wax impressions, kindly provided by the Worshipful Company of Clockmakers and the National Physical Laboratory on 1 April, 2014, over wires threaded through the nuts and bolts that hold it shut.

Master of the Worshipful Company of Clockmakers company, Jonathan Betts, adds his signature

On 6 January, 2015 – some 280 days after the case was sealed – Museum staff and the Master of the Worshipful Company of Clockmakers, Jonathan Betts, gathered to witness the going of the clock and initiate an official 100-day trial of its timekeeping. Using the a radio-controlled clock that receives the MSF time signal, the accuracy of the speaking clock was confirmed and then used to determine to going of ‘Clock B’. We determined that the clock was showing UTC -1/4 second.