 Upon his return to the U.S. in 1865, he became surgeon in the New York Eye and Ear Infirmary, and physician and pathologist in 1871 to the Roosevelt Hospital (now Mount Sinai West).He was the founder of the first pathological laboratory in US, and his writings upon pathological subjects were accepted as standard authorities.His first important literary work, "A Handbook of Post-Mortem Examination and Morbid Anatomy" (1872) was later rewritten and enlarged into "A Handbook of Pathological Anatomy and Histology" (1885) and became a textbook for medical colleges.