Correspondence, notes, drafts and manuscripts, articles, newspaper clippings, receipts, printed materials, maps, and photographs pertaining primarily to Riggs' unpublished book, "Drake of the Seven Seas." Correspondents include Ricardo J. Alfaro, Herbert Eugene Bolton, George T. Bye, Helen Maud Cam, Jacob Canter, John A. Hamilton, Leonard B. Loeb, John F. Stevens, Earl O. Titus, and Arthur E. Young.