01071cam a2200241 4500 758121570 TxAuBib 19920325120000.0 020401s1851||||||||||||||||||||||||und|u 13014215 TxGR TxAuBib Sumner, Thomas H. A new and accurate method of finding a ship's position at sea, by projection on Mercator's chart [Book] : 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. 3rd ed., rev. Boston : T. Groom & Co., 1851. 90 p. : fold. front., 5 pl. (incl. 4 fold. charts) ; 25 cm. Last folded chart torn from book. 19920325. Boston (Mass.), 1851. 1851, Groom, T. & Co. Groom, T. & Co, 1851. RV8