This chapter examines the Board of Longitude’s relationships with watchmakers in the five decades after their dealings with John Harrison. In this period in which the chronometer – a term brought into more common use in the period – began to develop into a stable technology, the Board still fielded proposals for schemes about mechanical timekeeping and actively engaged with a small number of makers. Acting within the remit of a new Longitude Act in 1774 that significantly changed the terms for testing and reward, the Board increasingly relied on land trials at the Royal Observatory, Greenwich, alongside a small number of long-distance voyages, which provided an additional arena for testing the nascent technology. During this period, the Board became embroiled in two debates that further shaped its horological dealings and saw its authority contested in Parliament. The first, over the work of Thomas Mudge, saw the Board’s authority undermined. The second, centring on a long and bitter dispute between watchmakers Thomas Earnshaw and John Arnold (and son), finally saw the Board’s authority recognised.