Sunday, September 23.  We passed, with a light breeze from the southeast, a small island on the north, called Goat island; above which is a small creek, called by the party Smoke creek, as we observed a great smoke to the southwest on approaching it.  At ten miles we came to the lower point of a large island, having passed two small willow islands with sandbars projecting from them.  This island, which we called Elk island, is about two and a half miles long, and three quarters of a mile wide, situated near the south, and covered with cottonwood, the red currant, and grapes.  The river is here almost straight for a considerable distance, wide and shallow, with many sandbars.  A small creek on the north, about sixteen yards wide, we called Reuben’s creek; as Reuben Fields, one of our men, was the first of the party who reached it.  At a short distance above this we encamped for the night, having made twenty miles.  The country, generally, consists of low, rich, timbered ground on the north, and high barren lands on the south:  on both sides great numbers of buffaloe are feeding.  In the evening three boys of the Sioux nation swam across the river, and informed us that two parties of Sioux were encamped on the next river, one consisting of eighty, and the second of sixty lodges, at some distance above.  After treating them kindly we sent them back with a present of two carrots of tobacco to their chiefs, whom we invited to a conference in the morning.

Monday, September 24.  The wind was from the east, and the day fair; we soon passed a handsome prairie on the north side, covered with ripe plums, and the mouth of a creek on the south, called Highwater creek, a little above our encampment.  At about five miles we reached an island two and a half miles in length, and situated near the south.  Here we were joined by one of our hunters, who procured four elk, but whilst he was in pursuit of the game the Indians had stolen his horse.  We left the island, and soon overtook five Indians on the shore:  we anchored and told them from the boat we were friends and wished to continue so, but were not afraid of any Indians; that some of their young men had stolen the horse which their great father had sent for their great chief, and that we could not treat with them until he was restored.  They said that they knew nothing of the horse, but if he had been taken he should be given up.  We went on, and at eleven and a half miles, passed an island on the north, which we called Good-humoured island; it is about one and a half miles long, and abounds in elk.  At thirteen and a half miles, we anchored one hundred yards off the mouth of a river on the south side, where we were joined by both the periogues and encamped; two thirds of the party remained on board, and the rest went as a guard on shore with the cooks and one periogue; we have seen along the sides of the hills on the north a great deal of stone; besides the elk, we also observed a hare; the five Indians whom we had seen followed us, and slept with the guard on shore.  Finding one of them was a chief we smoked with him, and made him a present of tobacco.  This river is about seventy yards wide, and has a considerable current.  As the tribe of the Sioux which inhabit it are called Teton, we gave it the name of Teton river.