The Tercentenary of The Royal Observatory at Greenwich

Extract

According to Flamsteed's own account, the Royal Observatory was founded as a direct consequence of the representation in 1674 by a Frenchman, who described himself as Le Sieur de St. Pierre, to the English Court that he had discovered a method of determining longitude at sea ‘from easy celestial observations’, and claimed the appropriate award. The solution to the ‘longitude problem’ was then, as it had been for many years and was to be for a further 90 years, of paramount importance; several countries had offered large prizes for a practical solution, and l'Observatoire de Paris had been founded in 1667, a year after l'Academie Royale. (Observations were systematically made for the purpose of improving the determination of longitude by observation of the satellites of Jupiter; but this method, successful on land, was doomed to failure because of the impracticability of using long-focus telescopes at sea.)