Joining the observatories of Paris and Greenwich

Abstract In the closing years of the eighteenth century, France and Britain enjoyed a period of external peace that their scientific communities put to good use by finding an objective common to the leading academic institutions: the Académie royale des sciences in France, and the Royal Society in England. This was not an entirely new concept; the novelty was that the objective would be brought about by teams from each side working outside their own borders. It was part of both nations' long-running search for a means of establishing longitudes on land and at sea. The specific objective, however, was confined to establishing the accurate difference in longitude between the meridian of Greenwich Observatory and that of the Observatoire de Paris. Previous astronomical measurements, derived from the times of certain eclipses or transits as recorded at each observatory, were acknowledged to be inaccurate.