A clock based on a design from 300 years ago has stunned experts by keeping accurate to a second for 100 days. The modern-day Martin Burgess Clock B is based on John Harrison's 18th century clock, which he thought up to solve the problem of determining longitude at sea. It has been part of a 100-day trial at the Royal Observatory, in Greenwich, to see if the claim - that the clock would neither lose nor gain more than a second in 100 days - was true. The Martin Burgess Clock B (left), which is based on a design by carpenter John Harrison (right) from 300 years ago, has stunned experts by keeping accurate to a second for 100 daysMartin Burgess Clock B is based on John Harrison's 18th century designClock was strapped to a pillar at the Royal Observatory in GreenwichTime measured using a radio-controlled clock and the BT speaking clockCertified by Guinness Book of Records, National Maritime Museum said
It wrote: 'Our 100 day trail of "_" won @GWR for "most accurate mechanical clock with a pendulum swinging in free air"!'.