BOWDITCH, Nathaniel, an American mathematician, born in Salem, Mass., March 26, 1773, died in Boston, March 16, 1838. The son of a cooper, he was sent to school till 10 years of age, and was then taken into his father's shop. He was soon transferred to a ship chandlery, and remained in this business till he made his first voyage in 1795. His education and all his labors in mathematics were accomplished by improving his leisure while pursuing other avocations. An English sailor taught him the elements of navigation. He began the study of Latin alone, that he might read the Principia of Newton; and later in life he taught himself Spanish, Italian, and German. Between 1795 and 1803 he made five long voyages, successively as clerk, supercargo, and master, to the East Indies, Portugal, and the Mediterranean. On his return from his last voyage he arrived off Salem by night in a violent snow storm, and with no other guide than his reckoning, confirmed by a single glimpse of the light on Baker's island, found his way safely into the harbor. In 1802 he published his “New American Practical Navigator,” which passed through many editions, and was esteemed the best work of the sort ever published (English ed. by Kirby, London, 1802). On the close of his seafaring life, he was elected president of the Essex fire and marine insurance company, which situation he held till 1823. His attachment to his native place made him decline the chair of mathematics in Harvard university in 1808, in the university of Virginia in 1818, and at West Point in 1820. Among his productions were a chart of remarkable beauty and exactness of the harbors of Salem, Marblehead, Beverly, and Manchester; many contributions, chiefly on astronomical subjects, to the “Transactions” of the American academy of arts and sciences; the article on modern astronomy in vol. xx. of the “North American Review;” and many articles in the American edition of “Rees's Cyclopaedia.” He completed between 1814 and 1817 the great undertaking on which his fame chiefly rests, a translation of the Mécanique céleste of Laplace (4 vols., 1829-'38); the 5th volume, which Laplace had added to his work many years after the other, was subsequently issued under the editorial care of Prof. B. Peirce, accompanied by an elaborate commentary. It was estimated that there were at that time but two or perhaps three persons in America, and not more than 12 in Great Britain, who were able to read the original work critically. The French astronomer, thoroughly master of the mighty subject, very often omitted intermediate steps in his demonstrations, and grasped the conclusion without showing the process. It was the design of Dr. Bowditch to supply these deficiencies. Another object was to record subsequent discoveries, to continue the original work to the latest date, and to subjoin parallel passages from geometers who had treated of the same subjects. A third object was to show the sources from which Laplace had derived assistance. The elucidations and commentaries form more than half the work as produced by Dr. Bowditch. In 1823 he became actuary of the Massachusetts hospital life insurance company in Boston. During the latter years of his life he was a trustee of the Boston Athenæum, president of the American academy of arts and sciences, and a member of the corporation of Harvard college.—See “Memoir of Nathaniel Bowditch,” by his son, N. I. Bowditch (Boston, 1839).