History of the expedition under the command of Captains Lewis and Clarke : to the sources of the Missouri, thence across the Rocky Mountains and down the River Columbia to the Pacific Ocean : performed during the years 1804, 1805, 1806, by order of the government of the United States / prepared for the press by Paul Allen ; revised and abridged by the omission of unimportant details with an introduction and notes by Archibald M'Vickar.