Washington Irving embarked on a trilogy of books on the American West that would prove decisive in molding his compatriots' conception of the Great Plains, the Rocky Mountains, and the Pacific Northwest.<BR>Irving's own encounter with the West came in 1832 when he accompanied the Commissioner of Indian Affairs on a month-long journey to what is now eastern Oklahoma. His account of that trip, A Tour on the Prairies (1835), described wild landscape, rugged inhabitants, and dramatic chases and hunts with an eye for romantic sublimity and a keen appreciation of the frontiersman's "secret of personal freedom."<BR>In The Adventures of Captain Bonneville (1837), Irving focused on a single memorable figure - an army officer and fur trader who may also have been an American spy tracking British ambitions in the far country - to reveal the flavor of frontier life in the Rockies and beyond. This lively saga, based on Bonneville's own memoir of his wandering career, is Irving's most fully realized portrait of mountain men and western Indians.