SUMMARY NARRATIVE OF AN EXPLORATORY EXPEDITION TO THE SOURCES OF THE MI SSISSIPPI RIVER, IN 1820: RESUMED AND COMPLETED, BY THE DISCOVERY OF ITS ORIGI N IN ITASCA LAKE, IN 1832. WITH APPENDIXES, COMPRISING THE ORIGINAL REPORT ON THE COPPER MINES OF LAKE SUPERIOR, AND OBSERVATIONS ON THE GEOLOGY OF THE LAKE BASINS, AND THE SUMMIT OF THE MISSISSIPPI; TOGETHER WITH ALL THE OFFICIAL REPORTS AND SCIENTIFIC PAPERS OF BOTH EXPEDITIONS