Geographers deem that branch of a river as its true source which originates at the remotest distance from its mouth, and, agreeably to this definition, the combined narratives, to which attention is now called, show this celebrated stream to arise in Itasca Lake, the source of the Itasca River. Owing to the time which has intervened since these expeditions were undertaken, a mere revision of the prior narrations, in the _journal form_, was deemed inexpedient. A concise summary has, therefore, been made, preserving whatever information it was thought important to be known or remembered, and omitting all matters not partaking of permanent interest. To this summary, something has been added from the original manuscript journals in his possession. The domestic organization and social habits of the parties may thus be more perfectly understood. The sympathies which bind men together in isolated or trying scenes are sources of interest long after the link is severed, and the progress of science or discovery has passed beyond the particular points at which they then stood. Events pass with so much rapidity at present, in the diffusion of our population over regions where, but lately, the Indian was the only tenant, that we are in danger of having but a confused record of them, if not of losing it altogether. It is some abatement of this fear to know that there is always a portion of the community who take a pleasure in remembering individuals; who have either ventured their lives, or exerted their energies, to promote knowledge or advance discovery. It is in this manner that, however intent an age may be in the plans which engross it, the sober progress and attainments of the period are counted up. An important fact discovered in the physical geography or natural history of the country, if it be placed on record, remains a fact added to the permanent stores of information. A new plant, a crystal, an insect, or the humblest invertebrate object of the zoological chain, is as incontestable an addition to scientific knowledge, as the finding of remains to establish a new species of mastodon. They only differ in interest and importance. It is not the province of every age to produce a Linnæus, a Buffon, or a Cuvier; but, such are the almost endless forms of vegetable and animal life and organization--from the infusoria upward--that not a year elapses which may not enlarge the boundaries of science. The record of discovery is perpetually accumulating, and filling the list of discoverers with humbler, yet worthy names. Whoever reads with care the scientific desiderata here offered will find matter of description or comment which has employed the pens of a Torrey, a Mitchell, a Cooper, a Lea, a Barnes, a Houghton, and a Nicollet.