(1800-1875) according to VIAF; (1818-1894) according to VIAF, BNF, WorldCat, 400 lettres de musiciens au Musée royal de Mariemont, Malou Haine. It is 1818-94 of course, since some of the documents he translated were first published, indeed composed, later than 1875 (and his time machine sketches have been lost).