"Beginning at the mouth of the Missouri, you will take observations of latitude and longitude, at all remarkable points on the river, and especially at the mouths of rivers, at rapids, at islands, and other places and objects distinguished by such natural marks and characters, of a durable kind, as that they may with certainty be recognised hereafter. The courses of the river between these points of observation may be supplied by the compass, the log-line, and by time, corrected by the observations themselves. The variations of the needle, too, in different places, should be noticed. "The interesting points of the portage between the heads of the Missouri, and of the water offering the best communication with the Pacific ocean, should also be fixed by observation; and the course of that water to the ocean, in the same manner as that of the Missouri. "Your observations are to be taken with great pains and accuracy; to be entered distinctly and intelligibly for others as well as yourself; to comprehend all the elements necessary, with the aid of the usual tables, to fix the latitude and longitude of the places at which they were taken; and are to be rendered to the war-office, for the purpose of having the calculations made concurrently by proper persons within the United States. Several copies of these, as well as of your other notes, should be made at leisure times, and put into the care of the most trust-worthy of your attendants to guard, by multiplying them against the accidental losses to which they will be exposed. A further guard would be, that one of these copies be on the cuticular membranes of the paper-birch, as less liable to injury from damp than common paper. "The commerce which may be carried on with the people inhabiting the line you will pursue, renders a knowledge of those people important. You will therefore endeavour to make yourself acquainted, as far as a diligent pursuit of your journey shall admit, with the names of the nations and their numbers; "The extent and limits of their possessions; "Their relations with other tribes or nations; "Their language, traditions, monuments; "Their ordinary occupations in agriculture, fishing, hunting, war, arts, and the implements for these; "Their food, clothing, and domestic accommodations; "The diseases prevalent among them, and the remedies they use; "Moral and physical circumstances which distinguish them from the tribes we know; "Peculiarities in their laws, customs, and dispositions; "And articles of commerce they may need or furnish, and to what extent.