An American explorer, born at Savannah, Georgia; at first a teacher of mathematics in the navy, subsequently took to civil-engineering and surveying; in 1843 explored the South Pass of the Rockies, and proved the practicability of an overland route; explored the Great Salt Lake, the watershed between the Mississippi and Pacific, and the upper reaches of the Rio Grande; he rendered valuable services in the Mexican War, but was deprived of his captaincy for disobedience; after unsuccessfully standing for the Presidency in the anti-slavery interest, he again served in the army as major-general; a scheme for a southern railway to the Pacific brought him into trouble with the French government in 1873, when he was tried and condemned for fraud, unjustly it would seem; from 1878 to 1882 he was governor of Arizona; he was the recipient of distinctions from various geographical societies (1813-1890).