This item is Lewis' narrative journal of the river trip from Pittsburgh to the winter camp of the Lewis and Clark Expedition, together with meteorological observations. There are also entries by William Clark. Of the 126 leaves in this journal, 31 contain questions by Nicholas Biddle, with William Clark's replies, dated 1810. Includes parts II and III of Nicholas Biddle, "Notes on Indians...", and list of measurements of bones and other natural history specimens, in Lewis' hand. Also contains some sketches and two small maps.

William Clark kept this diary on an expedition to make a treaty with the Osage Indians in the Missouri Territory. A sketch drawn under the September 16 entry is apparently a draft of Clark's Fort Osage map, while the first page of notes presents color scheme used on another draft. See Kate L. Gregg, Westward with Dragoons (1937: 48) for the map in printed version.

Meriwether Lewis and William Clark were explorers. This collection contains the manuscript journals kept by Lewis and Clark on their travels to the source of the Missouri River and across the continent to the Pacific Ocean. There are interlineations throughout by Nicholas Biddle, who published his narrative "History of the Expedition of Captains Lewis and Clark" (1814).