When all allowances have been made, much carelessness is evident in the explorations of the Long expedition. The bewilderment of Bell's party was inexcusable in men of science possessing instruments for determining latitude and longitude; their geographical errors to some extent nullified their observations of natural features. Cimarron River, the most important tributary of the Arkansas next to the Canadian, they missed entirely, and the relative size and location of the tributaries of the Arkansas remained uncertain for years after. Upon beginning the descent of the Arkansas they travelled two hundred miles without, so far as James's _Account_ shows, making a note on geography or topography; but possibly some allowance for this omission should be made because of the theft of manuscripts by the deserters. Of the itinerary of the expedition from the Platte to the Canadian, it has been said, "It would be scarcely possible to find in any narrative of Western history so careless an itinerary, and in a scientific report like that of Dr. James it is quite inexcusable."[10] To the account of the country traversed by the expedition, James added information relative to portions of Arkansas and Louisiana, much of which was already accessible to the public through the reports and writings of Hunter and Dunbar, Sibley, Darby, Stoddard, Schoolcraft, and others. However, this portion of James's narrative also draws data from Major Long's manuscript journals, not elsewhere available, and gives the only account of the attempted exploration of Red River under Captain Richard Sparks, based on the memoranda of members of the expedition.
After all criticisms have been urged to the utmost, the work of the expedition was, and is, of considerable value. The exploration of the Canadian River was an important contribution to American geography. It was thenceforth evident that the sources of the Red must be looked for farther south than had previously been supposed, although a generation was to elapse before their discovery. Otherwise, the exploration added greatly to the knowledge of a portion of the country but imperfectly known through hunters and traders. Especially is this true as regards details relative to natural history and ethnology; for the work was done in the spirit of modern scientific investigation, and in this respect anticipated later expeditions, for which American public sentiment in 1820 was hardly ripe. The collections included more than sixty skins of new or rare animals, several thousand insects, of which many hundreds were new, nearly five hundred undescribed plants, mineral specimens, many new species of shells, numerous fossils, a hundred and twenty-two animal sketches, and a hundred and fifty landscape views. While not primarily designed as a scientific report on these collections, James's _Account_ gives in the form of notes[11] much of the more important information derived from them. Perhaps no other portions of the work, however equal in value those devoted to the aborigines; as an authoritative source of knowledge of the sociology of the Kansa and Omaha tribes, the _Account_ has no rival.