two brothers who, as geographers and travelers, conducted extensive investigations of the geography, geology, archaeology, and natural history of Ethiopia.

Their parents, a French father and an Irish mother, moved to France in 1818. In 1835 the French Academy sent Antoine on a scientific mission to Brazil. Arnaud spent some time in Algeria before the two brothers started for Ethiopia in 1837, landing at Mitsiwa (now Massawa, Eritrea) in 1838. After collecting much information on the geography and natural history of the country, the brothers returned to France in 1848. Antoine published a classified list and description of 234 Ethiopian manuscripts (1859), topographical findings (1860–73), and part of a geography of Ethiopia (1890). He became involved in controversies regarding his geographic findings, but subsequent explorers proved that his statements were correct, though he erred in contending that the Blue Nile was the main headstream of the Nile. In 1873 he published, along with findings from his stay in Ethiopia, the results of his earlier scientific mission to Brazil.

Arnaud visited Ethiopia again in 1853. A general account of the expedition that he undertook with his brother was included in his work Douze ans de séjour dans la Haute Éthiopie (1868; “Twelve Years in Upper Ethiopia”).