One year after his arrival, the director of this natural history museum, Carl Franz Anton Ritter von Schreibers, recommended him to Coenraad Jacob Temminck, director of the natural history museum of Leiden, who was seeking an assistant.
Un ano despuois da súa chegada, o director do museo, Carl Franz Anton Ritter von Schreibers recomendouno a Coenraad Jacob Temminck, director do Museo Nacional de Historia Natural de Leiden (Nationaal Natuurhistorisch Museum), e este tomouno como axudante.