He was occupied with this work until in 1854, when he was appointed professor of physical geography and geology at Princeton University. This was his office until his death. He was also for several years lecturer on physical geography in the State Normal School in Trenton, New Jersey, and from 1861 to 1866 lecturer in the Princeton Theological Seminary. He also gave courses in the Union Theological Seminary, New York, and at Columbia College. He founded the museum at Princeton, many of the specimens of which are from his own collections.