The Bureau des longitudes had its doubts about Delambre and Méchain’s measurements of the Paris meridian in Barcelona. It thus decided to do them again, and to extend the measurements to the Balearic islands. Jean-Baptiste Biot (1774-1862), helped by François Arago (1786-1853), was put in charge of the operation. Arago was soon to do the work alone, and managed to finish the measurements despite enormous problems stemming from war between France and Spain. He returned to France in 1809 after an incredible trek that contributed to his fame. He was elected to the Academy upon his return.

caption : Portrait of Arago. Lithography - credits : Observatoire de Paris