July 16. We continued our route between a large island opposite to our last night's encampment, and an extensive prairie on the south. About six miles, we came to another large island, called Fairsun island, on the same side; above which is a spot, where about twenty acres of the hill have fallen into the river. Near this, is a cliff of sandstone for two miles, which is much frequented by birds. At this place the river is about one mile wide, but not deep; as the timber, or sawyers, may be seen, scattered across the whole of its bottom. At twenty miles distance, we saw on the south, an island called by the French, l'Isle Chance, or Bald island, opposite to a large prairie, which we called Baldpated prairie, from a ridge of naked hills which bound it, running parallel with the river as far as we could see, and from three to six miles distance. To the south the hills touch the river. We encamped a quarter of a mile beyond this, in a point of woods on the north side. The river continues to fall.
Tuesday, July 17. We remained here this day, in order to make observations and correct the chronometer, which ran down on Sunday. The latitude we found to be 40° 27' 5"4/10. The observation of the time proved our chronometer too slow, by 6' 51"6/10. The highlands bear from our camp, north 25° west, up the river. Captain Lewis rode up the country, and saw the Nishnahbatona, about ten or twelve miles from its mouth, at a place not more than three hundred yards from the Missouri, and a little above our camp. It then passes near the foot of the Baldhills, and is at least six feet below the level of the Missouri. On its banks are the oak, walnut, and mulberry. The common current of the Missouri, taken with the log, is 50 fathoms in 40", at some places, and even 20".
Wednesday, July 18. The morning was fair, and a gentle wind from southeast by south, carried us along between the prairie on the north, and Bald island to the south: opposite the middle of which, the Nishnahbatona approaches the nearest to the Missouri. The current here ran fifty fathoms in 41". At thirteen and a half miles, we reached an island on the north, near to which the banks overflow; while on the south, the hills project over the river and form high cliffs. At one point a part of the cliff, nearly three quarters of a mile in length, and about two hundred feet in height, has fallen into the river. It is composed chiefly of sandstone intermixed with an iron ore of bad quality; near the bottom is a soft slatestone with pebbles. We passed several bad sandbars in the course of the day, and made eighteen miles, and encamped on the south, opposite to the lower point of the Oven islands. The country around is generally divided into prairies, with little timber, except on low points, islands, and near creeks, and that consisting of cottonwood, mulberry, elm, and sycamore. The river falls fast. An Indian dog came to the bank; he appeared to have been lost and was nearly starved: we gave him some food, but he would not follow us.
Thursday, July 19. The Oven islands are small, and two in number; one near the south shore, the other in the middle of the river. Opposite to them is the prairie, called Terrien's Oven, from a trader of that name. At four and a half miles, we reached some high cliffs of a yellow earth, on the south, near which are two beautiful runs of water, rising in the adjacent prairies, and one of them with a deerlick, about two hundred yards from its mouth. In this neighbourhood we observed some iron ore in the bank. At two and a half miles above the runs, a large portion of the hill, for nearly three quarters of a mile, has fallen into the river. We encamped on the western extremity of an island, in the middle of the river, having made ten and three quarter miles. The river falls a little. The sandbars which we passed to-day, are more numerous, and the rolling sands more frequent and dangerous, than any we have seen; these obstacles increasing as we approach the river Platte. The Missouri here is wider also than below, where the timber on the banks resists the current; while here the prairies which approach, are more easily washed and undermined. The hunters have brought for the last few days, no quadruped, but deer: great quantities of young geese are seen to-day: one of them brought calamus, which he had gathered opposite our encampment, and a large quantity of sweet-flag.
Friday, July 20. There was a heavy dew last night, and this morning was foggy and cool. We passed at about three miles distance, a small willow island to the north, and a creek on the south, about twenty-five yards wide, called by the French, L'eau qui Pleure, or the Weeping Water, and emptying itself just above a cliff of brown clay. Thence we made two and a half miles to another island; three miles further to a third: six miles beyond which is a fourth island; at the head of which we encamped on the southern shore; in all eighteen miles. The party, who walked on the shore to-day, found the plains to the south, rich, but much parched with frequent fires, and with no timber, except the scattering trees about the sources of the runs, which are numerous and fine. On the north, is a similar prairie country. The river continues to fall. A large yellow wolf was this day killed. For a month past the party have been troubled with biles, and occasionally with the dysentery. These biles were large tumours which broke out under the arms, on the legs, and, generally, in the parts most exposed to action, which sometimes became too painful to permit the men to work. After remaining some days, they disappeared without any assistance, except a poultice of the bark of the elm, or of Indian meal. This disorder, which we ascribe to the muddiness of the river water, has not affected the general health of the party, which is quite as good, if not better, than that of the same number of men in any other situation.
Saturday, July 21. We had a breeze from the southeast, by the aid of which we passed, at about ten miles, a willow island on the south, near high lands covered with timber, at the bank, and formed of limestone with cemented shells: on the opposite side is a bad sandbar, and the land near it is cut through at high water, by small channels forming a number of islands. The wind lulled at seven o'clock, and we reached, in the rain, the mouth of the great river Platte, at the distance of fourteen miles. The highlands which had accompanied us on the south, for the last eight or ten miles, stopped at about three quarters of a mile from the entrance of the Platte. Captains Lewis and Clarke ascended the river in a periogue, for about one mile, and found the current very rapid; rolling over sands, and divided into a number of channels; none of which are deeper than five or six feet. One of our Frenchmen, who spent two winters on it, says that it spreads much more at some distance from the mouth; that its depth is generally not more than five or six feet; that there are many small islands scattered through it, and that from its rapidity and the quantity of its sand, it cannot be navigated by boats or periogues, though the Indians pass it in small flat canoes made of hides. That the Saline or Salt river, which in some seasons is too brackish to be drank, falls into it from the south about thirty miles up, and a little above it Elkhorn river from the north, running nearly parallel with the Missouri. The river is, in fact, much more rapid than the Missouri, the bed of which it fills with moving sands, and drives the current on the northern shore, on which it is constantly encroaching. At its junction the Platte is about six hundred yards wide, and the same number of miles from the Mississippi. With much difficulty we worked round the sandbars near the mouth, and came to above the point, having made fifteen miles. A number of wolves were seen and heard around us in the evening.
July 22. The next morning we set sail, and having found at the distance of ten miles from the Platte, a high and shaded situation on the north, we encamped there, intending to make the requisite observations, and to send for the neighbouring tribes, for the purpose of making known the recent change in the government, and the wish of the United States to cultivate their friendship.