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.

[1] In 1875, the Académie elected him a member of the astronomy section and in 1878 he was promoted to rear admiral and awarded the role of director of the Paris Observatory.

Mouchez set about a programme of reconstruction but failed to persuade the government to fund a new observatory outside the centre of Paris.

The principal outcome of the conference was a multi-national project to compile and index a photographic atlas of the heavens, the Carte du Ciel.