In 1947, Adam was appointed Vicar Apostolic of Libreville and bishop of the titular see of Rhinocorura; he became bishop of Libreville when it was elevated to a diocese in 1955, and he was made archbishop of the see in 1958. He retired in 1969 and moved to Franceville, where he died in 1981.
References
David E. Gardinier, Historical Dictionary of Gabon, 2nd ed. (The Scarecrow Press, 1994) p. 31