The fame of French scientist and geographer Joseph N. Nicollet rests upon his monumental map and report of the Upper Mississippi Valley. The map, published by the United States government in 1843, remained the foundation of Upper Mississippi cartography until the era of modern surveys. Nicollet's journals illuminate the 1836 trip to the source of the Mississippi and a journey up the St. Croix River in 1837. His day-by-day accounts include careful notes on geographical features, flora and fauna, and the aurora borealis. But above all, his keen observations on the customs and culture of the Ojibwe Indians provide the first systematic recording and a remarkably sympathetic depiction of the people of the area. Martha Bray's introduction and annotation to this translation by Andre Fertey provide a brief biography of one of the fathers of American science.