Kritik der praktischen Vernunft
He occupied the chair of moral philosophy (1867–72), of biblical Greek (1875–88), and of Hebrew (1879–1900). In 1887 he was elected librarian in Trinity and, in 1900, completed catalogues of the library's manuscript holdings. He was one of a group of Irish scholars, including J. P. Mahaffy, who made significant contributions to the dissemination and study of the works of Immanuel Kant. His translation of Kant's "Critique of Practical Reason" remained the standard English version of the text well into the 20th century.