Cambridge University Library and the National Maritime Museum have digitised the Board of Longitude archive. The archive is available online at https://cudl.lib.cam.ac.uk/collections/longitude. This first film in a series of three, introduces the Board of Longitude and the 18th-century search for an accurate way of finding longitude at sea. The papers in the Board's archive record scientific endeavour, fateful voyages, bitter feuds and lifetimes of commitment to a common cause.