In the first book-length history of the Board of Longitude, a distinguished team of historians of science brings to life one of Georgian Britain’s most important scientific institutions. Having developed in the eighteenth century following legislation that offered rewards for methods to determine longitude at sea, the Board came to support the work of navigators, instrument makers, clockmakers and surveyors, and assembled the Nautical Almanac. The authors use the archives and records of the Board, which they have recently digitised, to shed new light on the Board’s involvement in colonial projects and in Pacific and Arctic exploration, as well as on innovative practitioners whose work would otherwise be lost to history. This is an invaluable guide to science, state and society in Georgian Britain, a period of dramatic industrial, imperial and technological expansion.

This chapter covers the two decades from the first minuted meeting of the Commissioners of Longitude in 1737. During this time, small groups of Commissioners were called together sporadically for ad hoc meetings, principally to agree funding for specific projectors, notably clockmaker John Harrison and longitude veteran William Whiston. Over this initial period, relations with Harrison were cordial and supportive. Despite these promising developments, it was a period in which public opinion gradually reverted to mockery of those seeking the seemingly impossible longitude dream. The chapter seeks to emphasise in addition the value of looking at some of the schemes that more recent authors have dismissed as invalid. This has occurred not only when proposals seem unlikely to modern eyes but also when their authors were partly or wholly motivated by factors such as religion or financial need, and overlooks the reception of those proposals. The books published by Jane Squire are a particular focus, since they contain some of the best records of the Commissioners’ activities and thoughts during the earlier decades.

This brief epilogue considers the decades after the dissolution of the British Board of Longitude in 1828 and the ways in which its functions were subsumed by and distributed between other bodies, within the Admiralty and beyond.

This chapter scrutinises the British Longitude Act of 1714 and its immediate aftermath. It shows, first, the extent to which the wording of the Act drew on precedents from the previous century. Second, it argues that the Act was never intended to create a ‘Board of Longitude’ as a formal, standing committee with regular meetings. Rather, it nominated a number of individuals – by name or by virtue of their official role – seen fit to judge potential ideas. This is a powerful example of the way in which longitude legislation was revisable and open-ended. With this in mind, the chapter shows that the Act did indeed foster considerable activity and discussion around longitude matters over the next two decades. This activity was marked by considerable continuity in the persistence of schemes already being discussed before 1714: eclipses, lunar distances, artificial timekeepers, magnetic variation and dip, signalling, and dead reckoning.

Focusing on the period from the early 1760s to the resolution of the John Harrison affair in 1773, this chapter argues that it was only in this period that the ‘Board of Longitude’ came into being. This was largely in response to the debates surrounding the sea trials of Harrison’s fourth marine timekeeper (H4) and two other longitude schemes – Tobias Mayer’s tables and method for lunar distances and Christopher Irwin’s marine chair for observing Jupiter’s satellites. The transformation into a standing board manifested in regular rather than sporadic meetings and the appointment of a secretary to keep the Board’s papers in order as the Commissioners, for whom astronomer Nevil Maskelyne would become a central figure, sought to defend their decisions over the allocation of monetary rewards. The debates with Harrison, which focused on questions of adequate testing and the judging of trials, disclosure and replicability, and accusations of self-interest, would see the Board harden its stance through the use of legislation to ensure resolution. The Harrisons and their supporters, by contrast, sought to bolster support through lobbying and publication of their claims.

This chapter explores the long- and short-term roots of the British Longitude Act 1714, highlighting the degree of continuity with earlier precedents. It first explores the nature and impact of developments in navigational techniques and instruments, astronomy, timekeeping, the finding of longitude on land and the judging and funding of longitude proposals in sixteenth- and seventeenth-century Europe. It then delves into the chain of events and written and verbal discussions which gave rise to the new British rewards in 1713–1714. These saw the self-interested lobbying of two projectors gain momentum through a confluence of national and political interests, before becoming enshrined in law as rewards open to all comers.