0888 Huygens ’ s clocks

Shortly after The Royal Society’s founding in 1660, Christiaan Huygens, in partnership with the Society, set out to solve the outstanding technological challenge of the day: the longitude problem, i.e. ­ nding a robust, accurate method of determining longitude for maritime navigation (Yoder 1990). Huygens had invented the pendulum clock in 1657 (Burke 1978) and, subsequently, had demonstrated mathematically that a pendulum would follow an isochronous path, independent of amplitude, if cycloidal-shaped plates were used to con­ ne the pendulum suspension (Yoder 1990). Huygens believed that cycloidal pendulum clocks, suitably modi­ ed to withstand the rigours of sea travel, could provide timing of su ̄ cient accuracy to determine longitude reliably. Maritime pendulum clocks were constructed by Huygens in collaboration with one of the original fellows of The Royal Society, Alexander Bruce, 2nd Earl of Kincardine. Over the course of three years (1662{1665) Bruce and the Society supervised sea trials of the clocks. Meanwhile, Huygens, remaining in The Hague, continually corresponded with the Society through Sir Robert Moray, both to inquire about the outcome of the sea trials and to describe the ongoing e¬orts Huygens was making to perfect the design of maritime clocks. On 1 March 1665, Moray read to the Society a letter from Huygens, dated 27 February 1665, reporting of (Birch 1756)