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 days . The clock , which was built using modern materials , was initially set ticking a year ago after being strapped to one of the Observatory 's supporting pillars . But it quickly became apparent the trial would be a success and wax seals were placed on its case so its accuracy could be verified , the Independent on Sunday reported . The time was measured using a radio-controlled clock , which received the national time signal , and the BT speaking clock . Jonathan Betts , a member of the Antiquarian Horological Society , said : 'As soon as we set the clock running it was clear that it was performing incredibly well , so then we got the case sealed because nobody was going to believe how well the clock was running . ' He added that the clock was not a replica of Harrison 's , but used his design and concept . 'It is important to realise his design goes against everything the establishment has claimed is the best throughout history , ' Mr Betts added . The modern-day clock has since been certified by the Guinness World Records , which the National Maritime Museum confirmed on Twitter . The Martin Burgess B clock has been part of a 100-day trial at the Royal Observatory ( above ) , 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 clock has since been certified by the Guinness World Records . When it was measured it was reading UTC time to within a quarter of a second . The National Maritime Museum confirmed the record on Twitter yesterday . It wrote : 'Our 100 day trail of `` Clock B '' won @ GWR for `` most accurate mechanical clock with a pendulum swinging in free air '' ! ' Rory McEvoy , the Observatory ’ s curator of horology , added : ‘ What we ’ ve seen here is something approaching a perfect clock , but we are not there yet. ’ Harrison died in 1776 . He has since been the subject of Dava Sobel 's bestselling book Longitude , as well as a film with the same name starring Michael Gambon ( right ) and Jeremy Irons ( left ) John Harrison was a carpenter born in 1693 in Lincolnshire . In the early 18th century a lot of Royal Navy ships were being lost at sea . Although latitude was relatively easy to determine using the sun , longitude was harder . The problem was considered so important Parliament offered financial rewards of up to £20,000 to anyone who solved it . Clockmakers argued that a heavy pendulum bob and short swing would be the best . But Harrison dismissed this theory and thought a clock with a lighter pendulum bob and wide swing would work better . He designed his first clock in 1713 aged 20 . His 'longitude ' clock , which was the basis of the Martin Burgess Clock B , would solve the problem of determining longitude at sea , he claimed . By knowing the amount of time the ship had been at sea and the local time by using the sun , sailors would be able to determine longitude accurately . Local time is one hour ahead for every 15 degrees of longitude east and one hour behind for every 15 degrees of longitude west . He was not taken seriously by any of his contemporaries and the possibilities of his clock were not explored until the 20th century . Harrison died in 1776 . He has since been the subject of Dava Sobel 's bestselling book Longitude , as well as a film with the same name starring Michael Gambon and Jeremy Irons .
Martin Burgess Clock B is based on John Harrison 's 18th century design . Clock was strapped to a pillar at the Royal Observatory in Greenwich . Time measured using a radio-controlled clock and the BT speaking clock . Certified by Guinness Book of Records , National Maritime Museum said .