Ernest Amédée Barthélemy Mouchez

Ernest Amédée Barthélemy Mouchez (; 24 August 1821 – 25 June 1892) was a French naval officer who became director of the Paris Observatory and launched the ill-fated Carte du Ciel project in 1887.

Life Born in Madrid, Spain, Mouchez embarked on a career in the French Navy as an ensign in 1843. This was a period of relative international maritime peace and much of the navy's activities were dedicated to exploration and discovery. Mouchez was initially occupied on hydrographic studies along the coasts of Korea, China and South America, penetrating 320 km up the Paraguay River and exploring the Abrolhos Islands. He improved the practice of surveying at sea, adapting terrestrial instruments for naval use, and was especially concerned with the problems of determining longitude. He developed the use of the theodolite and meridian telescope to improve the error in establishing longitude from around 30″ to 3–4″.

Attaining the rank of post captain in 1868, he embarked on a series of expeditions to chart the coast of Algeria.

Returning to his Algerian survey, he brought it to a conclusion in 1873, when he was elected to the Bureau des Longitudes and, in the following year, was sponsored by the Académie des sciences to observe the transit of Venus from St. Paul Island in the Indian Ocean. On 9 December he made a sequence of superb photographic plates of the event.

Mouchez died in Wissous, Seine-et-Oise.

Honours A statue in Le Havre was unveiled by Benjamin Baillaud in 1921. A Street in Paris was given his name.