A new and accurate method of finding a ship's position at sea, by projection on Mercator's chart ... [electronic resource] The principles of the method being fully explained and illustrated by problems, examples, and plates, with rules for practice, and examples from actual observation. By Capt. Thomas H. Sumner.
Electronic text and image data. Ann Arbor, Mich. : University of Michigan, Digital Library Initiatives, 2000. Includes both TIFF files and keyword searchable text. [Making of America] This volume is made possible by a grant from the Andrew W. Mellon Foundation as part of Making of America IV: the American voice, 1850-1877.