About ten o'clock we encountered a series of rapids extending some eight hundred or a thousand yards, in the course of which the river has a probable aggregate fall of sixteen feet. These rapids bear the malappropriate title of the Big Falls. Following these, were a series called Prairie Rapids. At half-past four we passed the entrance of the River St. Francis, a considerable stream on the left bank. At this spot, Hennepin terminated his voyage in 1681, and Carver in 1766. There is an island at the point of confluence. At six o'clock we passed the entrance on the west shore of the stream called _Corneille_, by the French, which is the true interpretation of the Sioux name _Karishon_, and the Chippewa term _Andaig_, which mean the crow, and not the raven. We encamped five miles below, on the east bank, having been thirteen hours in our canoes, with a generally strong current. My mineralogical gleanings, during the day, had given some specimens of the interesting varieties of the quartz family, for which the geological drift is noted, and a single piece of agatized wood. The geological floor on which the river runs, has been indicated. At five o'clock the following morning (30th) we resumed the descent, and at the distance of two leagues reached the entrance of the Missisagiegon, or Rum River. It is Carver, I believe, who first gives us this name, for a stream which the Indians describe as a river flowing from a lake of lakes--a term, by the way, which the French, with their usual adherence to Indian etymology, have called _Mille Lacs_. The term _missi_, in this word, does not signify great, but a collected mass, or all kinds, and sometimes everywhere--the allusion being to water. _Sa-gi-e-gon_ is a lake, and when the prefixed term _missi_, is put to it, nothing could more graphically describe the large body of water, interspersed with islands, which give a confused aspect, from which the river issues. The Dacotas call this lake _Mini Wakan_, meaning Spirit-water, which is probably the origin of the name of Rum River.