This biography is based chiefly upon the Maury Papers, comprising letters, diaries, scientific notebooks, and other manuscripts, which were presented to the United States Government in 1912 by Maury’s only living child, Mrs. Mary Maury Werth, and other descendants, and then deposited in the Division of Manuscripts, Library of Congress. Other valuable sources are the letter books, numbering many volumes, in the Office of the Superintendent of the United States Naval Observatory in Washington, and the official papers relating to Maury in the Navy Department Library. Miscellaneous Maury letters are to be found in the New York Public Library, the Public Library of the City of Boston, the United States Naval Academy Museum, the Peabody Institute Library of Baltimore, the Virginia State Library, the Virginia Historical Society Library, and the Yale University Library. Mrs. C. Alphonso Smith, Raleigh, North Carolina, has one Maury letter and some fifty others, written by contemporaries in reference to the Maury Testimonial which was presented to him in England after the Civil War. Of great importance, also, are Maury’s own voluminous writings, and the numerous references to him in the periodicals and newspapers of his time. For assistance in gathering material for this biography I wish to acknowledge my indebtedness to various members of the Maury family. In the first place, I wish to mention the “Life of Maury” by his daughter, Diana Fontaine Maury Corbin, which was of considerable help to me. Of his living descendants, Mrs. James Parmelee, a granddaughter, of Washington, D. C., and Mrs. Matthew Fontaine Maury, Jr., a daughter-in-law, of Cincinnati, Ohio gave me much assistance. Mrs. Werth of Richmond, Virginia, and her two daughters, Mrs. N. Montgomery Osborne of Norfolk, Virginia, and Mrs. Littleton Fitzgerald of Richmond, very patiently answered my numerous questions and furnished me interesting and very desirable information. The list of all the other persons who have helped me, in one way or another, in the writing of this book would be too long to set down in a preface; but among the many I wish to single out by name the following: Mr. J. C. Fitzpatrick, Assistant Chief, Division of Manuscripts, Library of Congress; Captain Edwin T. Pollock, U. S. Navy, Superintendent, and Mr. William D. Horigan, Librarian, of the United States Naval Observatory; Captain Dudley W. Knox, U. S. Navy (Retired), Superintendent, and Miss Nannie Dornin Barney, Archivist, of the Naval Records and Library of the Navy Department; Mr. Andrew Keogh, Librarian, Yale University Library; Mr. H. M. Lydenberg, Reference Librarian, New York Public Library; Mr. Charles F. D. Belden, Director of the Public Library of the City of Boston; Miss Helen C. Bates, Reference Librarian, Detroit Public Library; Dr. William G. Stanard, Corresponding Secretary and Librarian, Virginia Historical Society; Mr. Edward V. Valentine, Acting President of the Virginia Historical Society; Dr. H. R.