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 details the creation and management of the Nautical Almanac, one of the Board of Longitude’s most important concerns. Appointed Astronomer Royal and thus a Commissioner of Longitude in 1765, Nevil Maskelyne oversaw its publication and that of associated texts, directing the work of a group of mathematical computers overseen by comparers. Hierarchical organisation and increasing costs preoccupied much of the Board of Longitude’s subsequent affairs. Calculated up to a decade in advance, the Nautical Almanac became a symbol of the Board’s repute among foreign academies and observatories, although its accuracy was later subject to satire and criticism. After Maskelyne’s death, work seems to have suffered and its management was overhauled by the Longitude Act of 1818 that brought it under Thomas Young’s management. Controversy wracked the Board’s direction of the Nautical Almanac for the next decade. Its assignment from 1831 to the astronomer William Stratford as superintendent was a major element of the aftermath of the Board’s abolition.

This chapter offers a survey of the ways in which the British Board of Longitude handled the range of schemes and projects that were presented by mathematicians and mariners, inventors and entrepreneurs during its final decades to 1828. Labels of impracticality, eccentricity and derangement have long been assigned to many of these proposals, notably in the classification scheme imposed by Astronomer Royal George Airy in his reorganisation of the Board’s archives from the 1840s. This chapter favours close reading of the ways in which schemes were assessed and managed at the time. In the bulky correspondence received, schemes for new devices, calculation methods or navigation techniques were mixed with projects for squaring the circle or endless mechanical power. The Board distinguished between those projects reckoned impossible or unsound, and those it judged irrelevant or beyond its scope. It is shown how much discretionary power the Board exercised, and how its accumulated papers preserve a wide range of protagonists’ technical and scientific interests.

This chapter reinterprets the demise of the Board of Longitude in 1828, which has been seen as resulting from reformist pressure or financial retrenchment. Such accounts underestimate continuation of the Board’s activities, notably managing chronometers, producing the Nautical Almanac and providing scientific advice. Changes were initially driven by Joseph Banks’s interests, notably the appointment of Royal Society fellows and Resident Commissioners including Thomas Young, who became secretary and a key organiser after Banks’s death. Schemes such as rewards for finding the Northwest Passage, improvement of optical glass, determining the figure of the Earth and the foundation of the Cape Observatory, were managed under Young’s aegis. The role of the Admiralty and its Secretaries John Wilson Croker and John Barrow were decisive. The Longitude Act of 1818 brought the Board under Admiralty control, and that of 1828 moved its work into the Admiralty. An Admiralty committee comprising Young and natural philosophers Michael Faraday and Edward Sabine was formed; the Nautical Almanac and chronometer testing remained within the Admiralty’s financial remit.

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.