It is from considerations of this nature, that the author has appended to this narrative the original observations, reports, and descriptions made by his companions or himself, while engaged in these exploratory journeys, together with the determinations made on such scientific objects as were referred to other competent hands. These investigations of the physical geography of the West, and the phenomena or resources of the country, constitute, indeed, by far the most important permanent acquisitions of the scrutiny devoted to them. They form the elements of classes of facts which will retain their value, to men of research, when the incidents of the explorations are forgotten, and its actors themselves have passed to their final account. It would have been desirable that what has here been done should have been done at an earlier period; but it may be sufficient to say that other objects engrossed the attention of the author for no small part of the intervening period, and that he could not earlier control the circumstances which the publication demanded. After his permanent return from the West--where so many years of his life passed--it was his first wish to accomplish a long-cherished desire of visiting England and the Continent, in which America, and its manners and institutions, might be contemplated at a distance, and compared by ocular proofs. And, when he determined on the task of preparing this volume, and began to look around for the companions of his travels, to avail himself of their notes, he found most of them had descended to the tomb. For the narrative parts, indeed, the manuscript journals, kept with great fulness, were still preserved; but the materials for the other division of the work were widely scattered. Some of them remained in the archives of the public offices to which they were originally communicated. Other papers had been given to the pages of scientific journals, and their reprint was inexpedient. The rich body of topographical data, and the elaborately drawn map of this portion of the United States, prepared by Captain Douglass, U. S. A., which would have been received with avidity at the time, had been in a great measure superseded by subsequent discoveries.[1] The only part of this officer's observations employed in this work, are his determinations of the geographical positions. The latter have been extended and perfected by the subsequent observations of Mr. Nicollet. At every point, there have been difficulties to overcome. He has been strenuous to award justice to his deceased companions, to whose memory he is attached by the ties of sympathy and former association. If more time has elapsed in preparing the work than was anticipated, it is owing to the nature of it; and he can only say that still more time and attention would be required to do justice to it.