Royal Museums Greenwich explored This year the Royal Observatory in Greenwich celebrates its 350th anniversary. It was founded in 1675 by King Charles I “for finding out the longitude of places for perfecting nagivation and astronomy”. It’s also the home of Greenwich Mean Time (GMT) and the prime meridian. The observatory is an historic site as well as a museum and a science attraction. For decades, both astronomers and clockmakers attempted to find ways for seafarers to measure longitude. In theory, to find out how far east or west a sailor was from home, they needed to compare their local time with the time back home at exactly the same moment. Designing a clock that would remain accurate during long voyages at sea at first seemed impossible. By the 1760s however, the English carpenter and clockmaker John Harrison had proved that such a timekeeper was feasible. The groundbreaking H4 marine chronometer was tested at sea and his next chronometer, H5 underwent testing at the Royal Observatory. Harrison's first four designs are on display at the Observatory’s ‘Time and Longitude’ gallery. The Clocktime team are enjoying an entertaining historical series called James May’s Great Explorers, currently on air on 5SELECT from Channel 5. The former Top Gear presenter chronicles the lives of three renowned, sometimes controversial seafaring explorers, namely Christopher Columbus, Sir Walter Raleigh and Captain James Cook. The broadcaster and journalist James May visited Pendulum of Mayfair in Maddox Street and demonstrated the problem of clock accuracy when a pendulum is rocked. We hear from Dr Louise Devoy, Senior Curator, whose responsibilities include the historical astronomical instruments collection, including astrolabes, sundials, quadrants, night dials and orreries. To reduce friction, John Harrison replaced the pendulum with swinging balances, anti-friction bearings and invented the grasshopper escapement. James May says, “I think he deserves a phwoar!” We are told it took him almost 30 years and four attempts to achieve the accuracy of the H4. For the first time in history, the navy had access to a possible solution for the longitude problem. They needed their top navigator to test H4 by replicating its design. Larcum Kendall was asked to replicate H4. His copy called K1, was tested by the famous explorer Captain James Cook and the astronomer William Wales on the South Seas journey aboard HMS Resolution. Cook returned from his three-year South Seas voyage in 1775 and at just 46 years of age, he was the first person on earth to cross the arctic circle. You can access the documentary here.
