Dr. Nichols was born in Vassalboro, Maine, educated in Providence, R.I., and received his M.D. from the Medical Department of the University of Pennsylvania in 1843. He became an assistant to Dr. Brigham at the Utica, N.Y., Asylum in 1847, and in 1849 he was appointed Superintendent of the Bloomingdale Asylum in New York City. He remained there for three years. On the recommendation of Dorothea Dix, he was called to Washington, D.C., to oversee the construction of the new Government Hospital for the Insane. He remained as Superintendent of the Government Hospital for the Insane for 25 years. During his tenure, he doubled the asylum land and hospital size and kept the institution abreast of the most enlightened curative treatments of the time.
In 1877, Dr. Nichols returned to Bloomingdale Asylum as superintendent. When consideration was being given for the hospital to move to a new site in White Plains, he was requested by the hospital governors in 1889 to visit institutions in Europe so the best plans could be made for the construction and organization of the new institution. He died shortly after his return from Europe.
Dr. Nichols was an honorary member of the Medico-Psychological Association of Great Britain and served as President of the Association of Medical Superintendents of American Institutions for the Insane (1873–1879).