American scholar, born on the 30th of March 1821 in Fairfield, Herkimer county, NY, where his father was professor of chemistry in Fairfield Medical College. At the age of nine an accident lamed him for life. He graduated from Yale in 1842, having entered the Junior class in 1840; studied in the Theological Department of Yale, and in 18441845 was a tutor in Middlebury College. He was tutor at Yale in 18451848, assistant professor of Greek in 18481851, and professor of Greek, succeeding President Woolsey, from 1851 until his death in New Haven on the 14th of November 1872. As an undergraduate he showed himself an able mathematician, but the influence of Edward Elbridge Salisbury, under whom Hadley and W. D. Whitney studied Sanskrit together, turned his attention toward the study of language. He knew Greek, Latin, Sanskrit, Hebrew, Arabic, Armenian, several Celtic languages and the languages of modern Europe; but he published little, and his scholarship found scant outlet in the college classroom. His most original written work was an essay on Greek accent, published in a German version in Curtiuss Studien zur griechischen und lateinischen Grammatik. Hadleys Greek Grammar (1860; revised by Frederic de Forest Allen, 1884) was based on Curtiuss Schulgrammatik (1852, 1855, 1857, 1859), and long held its place in American schools. Hadley was a member of the American Committee for the revision of the New Testament, was president of the American Oriental Society (18711872), and contributed to Websters dictionary an essay on the History of the English Language. In 1873 were published his Introduction to Roman Law (edited by T. D. Woolsey) and his Essays, Philological and Critical (edited by W. D. Whitney).
See the memorial by Noah Porter in The New Englander, vol. xxxii. (Jan. 1873), pp. 3555; and the sketch by his son, A. T. Hadley, in Biographical Memoirs of the National Academy of Sciences, vol. v. (1905), pp. 247254.