Ships, Clocks & Stars: The Quest for Longitude

To mark the tercentenary of the Longitude Act of 1714, Ships, Clocks & Stars: The Quest for Longitude, a major new exhibition at the National Maritime Museum, tells the extraordinary story of the race to determine longitude at sea and how one of the greatest technical challenges of the 18th and 19th centuries was eventually solved.

The exhibition draws on the latest research to shed new light on the history of longitude - one of the great achievements of the Georgian age - and how it changed our understanding of the world.

In recent years, John Harrison has been cast as the hero of the story, not least in Dava Sobel’s seminal work Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. Ships, Clocks & Stars provides a new perspective on this famous tale. While John Harrison makes a good story and his marine sea-watch was vital to finally solving the problem of longitude, this was against a backdrop of almost unprecedented collaboration and investment. Famous names such as Galileo, Isaac Newton, James Cook and William Bligh all feature in this fascinating and complex history. Crucially, it was Astronomer Royal Nevil Maskelyne’s observations at the Royal Observatory in Greenwich, his work on the Nautical Almanac and the Board of Longitude that demonstrated the complementary nature of astronomical and timekeeper methods, ultimately leading to the successful determination of longitude at sea.

Highlights from the exhibition include all five of John Harrison’s famous timekeepers. H1, H2, H3 and H4 will move from the Royal Observatory Greenwich to be displayed in the National Maritime Museum for the first time in nearly 30 years. H5 is being loaned from the Worshipful Company of Clockmakers. Also featured is the original Longitude Act of 1714, which has never been on public display before; an intricate 1747 model of the Centurion, the ship which carried out the first proper sea trial of Harrison’s H1, and the elegant, padded silk ‘observing suit’ worn by Nevil Maskelyne at the Royal Observatory during the 1760s.

Passed by the British government in July 1714, the Longitude Act aimed to solve the problem of determining a ship’s longitude (east-west position) at sea. For a maritime nation such as Britain, investment in long distance trade, outposts and settlements overseas made the ability to determine a ship’s longitude accurately increasingly important. As different nations, including Spain, the Netherlands and France, sought to dominate the world's oceans, each offered financial rewards for solving the longitude problem. But it was in Britain that the approach paid off. With life-changing sums of money on offer, the challenge became the talk of London’s 18th-century coffee-houses and captured the imaginations and talents of astronomers, skilled artisans, politicians, seamen and satirists; many of whom came up with ingenious methods and instruments designed to scoop the Board of Longitude’s tantalising rewards and transform seafaring navigation forever.

The Royal Observatory in Greenwich was founded in 1675 specifically to carry out observations 'to find out the so much desired longitude of places for the perfecting of the art of navigation'. Under the 1714 Longitude Act, successive Astronomers Royal became leading voices on the Board of Longitude, judging proposals and encouraging promising developments. As solutions were developed, the Royal Observatory also became a testing site for marine timekeepers and the place at which the astronomical observations needed for navigational tables were made. The significance of this work eventually lead to Greenwich becoming the home of the world’s Prime Meridian in 1884.

The official publication of the exhibition, Finding Longitude: How clocks and stars helped solve the longitude problem, written by exhibition curators Richard Dunn and Rebekah Higgitt is published by Collins on 19 June 2014. Richard Dunn is Senior Curator and Head of Science and Technology at Royal Museums Greenwich and Rebekah Higgitt is Lecturer in History of Science at the University of Kent.