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 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.