Correspondence of Hussey, his wife, Ethel Fountain Hussey, members of their family, and friends pertaining to personal matters, astronomical work, travel abroad, and affairs at the universities where Hussey held appointments, particularly the University of Michigan; diaries of Argentina and South Africa travels and activities in the University of Michigan Observatory; two student notebooks containing notes on John Williams Langley's course in physics; notes on mathematics; and account books, reports, and scrapbooks. Correspondents include James B. Angell, Levi L. Barbour, Luther Burbank, Marion L. Burton, William W. Campbell, William L. Clements, Ralph H. Curtiss, David Starr Jordan, and Robert P. Lamont.