sentences:  In 1888, he was appointed professor of ophthalmology at the College of Physicians and Surgeons, Columbia University, and in 1902 he became emeritus professor.His son, Arnold Knapp (1869–1956) was also a noted ophthalmologist.In 1869, with Salomon Moos (1831–1895), he founded the "Archives of Ophthalmology and Otology" ("Archiv für Augen- und Ohrenheilkunde"), an international scientific monthly journal that was published in Wiesbaden (in German) and New York (in English).