On the acquisition of Louisiana, in the year 1803, the attention of the government of the United States, was early directed towards exploring and improving the new territory. Accordingly in the summer of the same year, an expedition was planned by the president for the purpose of discovering the courses and sources of the Missouri, and the most convenient water communication thence to the Pacific ocean. His private secretary captain Meriwether Lewis, and captain William Clarke, both officers of the army of the United States, were associated in the command of this enterprise. After receiving the requisite instructions, captain Lewis left the seat of government, and being joined by captain Clarke at Louisville, in Kentucky, proceeded to St. Louis, where they arrived in the month of December.

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.

We had a violent storm of wind and rain last evening; and were engaged during the day in repairing the periogue, and other necessary occupations; when, at four o'clock in the afternoon, sergeant Pryor and his party arrived on the opposite side, attended by five chiefs, and about seventy men and boys. We sent a boat for them, and they joined us, as did also Mr. Durion, the son of our interpreter, who happened to be trading with the Sioux at this time. He returned with sergeant Pryor to the Indians, with a present of tobacco, corn, and a few kettles; and told them that we would speak to their chiefs in the morning. Sergeant Pryor reported, that on reaching their village, which is at twelve miles distance from our camp, he was met by a party with a buffalo robe, on which they desired to carry their visitors: an honour which they declined, informing the Indians that they were not the commanders of the boats: as a great mark of respect, they were then presented with a fat dog, already cooked, of which they partook heartily, and found it well flavoured. The camps of the Sioux are of a conical form, covered with buffalo robes, painted with various figures and colours, with an aperture in the top for the smoke to pass through. The lodges contain from ten to fifteen persons, and the interior arrangement is compact and handsome, each lodge having a place for cooking detached from it.

The fog was so thick that we could not see the Indian camp on the opposite side, but it cleared off about eight o'clock. We prepared a speech, and some presents, and then sent for the chiefs and warriors, whom we received, at twelve o'clock, under a large oak tree, near to which the flag of the United States was flying. Captain Lewis delivered a speech, with the usual advice and counsel for their future conduct. We then acknowledged their chiefs, by giving to the grand chief a flag, a medal, a certificate, with a string of wampum; to which we added a chief's coat; that is, a richly laced uniform of the United States artillery corps, and a cocked hat and red feather. One second chief and three inferior ones were made or recognized by medals, and a suitable present of tobacco, and articles of clothing. We then smoked the pipe of peace, and the chiefs retired to a bower, formed of bushes, by their young men, where they divided among each other the presents, and smoked and eat, and held a council on the answer which they were to make us tomorrow. The young people exercised their bows and arrows in shooting at marks for heads, which we distributed to the best marksmen; and in the evening the whole party danced until a late hour, and in the course of their amusement we threw among them some knives, tobacco, bells, tape, and binding, with which they were much pleased. Their musical instruments were the drum, and a sort of little bag made of buffalo hide, dressed white, with small shot or pebbles in it, and a bunch of hair tied to it. This produces a sort of rattling music, with which the party was annoyed by four musicians during the council this morning.

We smoked, and he again harangued his people, after which the repast was served up to us. It consisted of the dog which they had just been cooking, this being a great dish among the Sioux, and used on all festivals; to this were added, pemitigon, a dish made of buffalo meat, dried or jerked, and then pounded and mixed raw with grease and a kind of ground potato, dressed like the preparation of Indian corn called hominy, to which it is little inferior. Of all these luxuries which were placed before us in platters with horn spoons, we took the pemitigon and the potato, which we found good, but we could as yet partake but sparingly of the dog. We eat and smoked for an hour, when it became dark: every thing was then cleared away for the dance, a large fire being made in the centre of the house, giving at once light and warmth to the ballroom. The orchestra was composed of about ten men, who played on a sort of tambourin, formed of skin stretched across a hoop; and made a jingling noise with a long stick to which the hoofs of deer and goats were hung; the third instrument was a small skin bag with pebbles in it: these, with five or six young men for the vocal part, made up the band. The women then came forward highly decorated; some with poles in their hands, on which were hung the scalps of their enemies; others with guns, spears or different trophies, taken in war by their husbands, brothers, or connexions. Having arranged themselves in two columns, one on each side of the fire, as soon as the music began they danced towards each other till they met in the centre, when the rattles were shaken, and' they all shouted and returned back to their places. They have no step, but shuffle along the ground; nor does the music appear to be any thing more than a confusion of noises, distinguished only by hard or gentle blows upon the buffalo skin: the song is perfectly extemporaneous. In the pauses of the dance, any man of the company comes forward and recites, in a sort of low guttural tone, some little story or incident, which is either martial or ludicrous; or, as was the case this evening, voluptuous and indecent; this is taken up by the orchestra and the dancers, who repeat it in a higher strain and dance to it. Sometimes they alternate; the orchestra first performing, and when it ceases, the women raise their voices and make a music more agreeable, that is, less intolerable than that of the musicians. The dances of the men, which are always separate from those of the women, are conducted very nearly in the same way, except that the men jump up and down instead of shuffling; and in the war dances the recitations are all of a military cast.

Among others who visited us was the son of the grand chief of the Mandans, who had his two little fingers cut off at the second joints. On inquiring into this accident, we found that it was customary to express grief for the death of relations by some corporeal suffering, and that the usual mode was to lose two joints of the little fingers, or sometimes the other fingers. The wind blew very cold in the evening from the southwest. Two of the party are affected with rheumatic complaints.

In the course of the day one of the Mandan chiefs returned from captain Lewis's party, his eyesight having become so bad that he could not proceed. At this season of the year the reflection from the ice and snow is so intense as to occasion almost total blindness. This complaint is very common, and the general remedy is to sweat the part affected by holding the face over a hot stone, and receiving the fumes from snow thrown on it.

The party now consisted of thirty-two persons. Besides ourselves were sergeants John Ordway, Nathaniel Pryor, and Patrick Gass: the privates were William Bratton, John Colter, John Collins, Peter Cruzatte, Robert Frazier, Reuben Fields, Joseph Fields, George Gibson, Silas Goodrich, Hugh Hall, Thomas P. Howard, Baptiste Lepage, Francis Labiche, Hugh M'Neal, John Potts, John Shields, George Shannon, John B. Thompson, William Werner, Alexander Willard, Richard Windsor, Joseph Whitehouse, Peter Wiser, and captain Clarke's black servant York. The two interpreters, were George Drewyer and Tousaint Chaboneau. The wife of Chaboneau also accompanied us with her young child, and we hope may be useful as an interpreter among the Snake Indians. She was herself one of that tribe, but having been taken in war by the Minnetarees, by whom she was sold as a slave to Chaboneau, who brought her up and afterwards married her.

These mountains have their sides and summits partially varied with little copses of pine, cedar, and balsam fir. A mile and a half beyond this creek the rocks approach the river on both sides, forming a most sublime and extraordinary spectacle. For five and three quarter miles these rocks rise perpendicularly from the water's edge to the height of nearly twelve hundred feet. They are composed of a black granite near its base, but from its lighter colour above and from the fragments we suppose the upper part to be flint of a yellowish brown and cream colour. Nothing can be imagined more tremendous than the frowning darkness of these rocks, which project over the river and menace us with destruction. The river, of one hundred and fifty yards in width, seems to have forced its channel down this solid mass, but so reluctantly has it given way that during the whole distance the water is very deep even at the edges, and for the first three miles there is not a spot except one of a few yards, in which a man could stand between the water and the towering perpendicular of the mountain: the convulsion of the passage must have been terrible, since at its outlet there are vast columns of rock torn from the mountain which are strewed on both sides of the river, the trophies as it were of the victory. Several fine springs burst out from the chasms of the rock, and contribute to increase the river, which has now a strong current, but very fortunately we are able to overcome it with our oars, since it would be impossible to use either the cord or the pole.

The Missouri and all it's branches from the Cheyenne upwards abound more in beaver and otter, than any other streams on earth, particularly that proportion of them lying within the Rocky Mountains. The furs of all this immense tract of country including such as may be collected on the upper portion of the River St. Peters, Red river and the Assinniboin with the immense country watered by the Columbia, may be conveyed to the mouth of the Columbia by the 1st of August in each year and from thence be shipped to, and arrive in Canton earlier than the furs at present shipped from Montreal annually arrive in London. The British N. West Company of Canada were they permitted by the United States might also convey their furs collected in the Athabaske, on the Saskashawan, and South and West of Lake Winnipeg by that rout within the period before mentioned. Thus the productions of nine tenths of the most valuable fur country of America could be conveyed by the rout proposed to the East Indies.

My friends, I have been asked to show you my heart. I am glad to have a chance to do so. I want the white people to understand my people. Some of you think an Indian is like a wild animal. This is a great mistake. I will tell you all about our people, and then you can judge whether an Indian is a man or not. I believe much trouble and blood would be saved if we opened our hearts more. I will tell you in my way how the Indian sees things. The white man has more words to tell you how they look to him, but it does not require many words to speak the truth. What I have to say will come from my heart, and I will speak with a straight tongue. Ah-cum-kin-i-ma-me-hut (the Great Spirit) is looking at me, and will hear me.

My name is In-mut-too-yah-lat-lat (Thunder traveling over the Mountains). I am chief of the Wal-lam-wat-kin band of Chute-pa-lu, or Nez Perces (nose-pierced Indians). I was born in eastern Oregon, thirty-eight winters ago. My father was chief before me. When a young man, he was called Joseph by Mr. Spaulding, a missionary. He died a few years ago. There was no stain on his hands of the blood of a white man. He left a good name on the earth. He advised me well for my people.

Our fathers gave us many laws, which they had learned from their fathers. These laws were good. They told us to treat all men as they treated us; that we should never be the first to break a bargain; that it was a disgrace to tell a lie; that we should speak only the truth; that it was a shame for one man to take from another his wife, or his property without paying for it. We were taught to believe that the Great Spirit sees and hears everything, and that he never forgets; that hereafter he will give every man a spirit-home according to his deserts: if he has been a good man, he will have a good home; if he has been a bad man, he will have a bad home. This I believe, and all my people believe the same.

The first white men of your people who came to our country were named Lewis and Clarke. They also brought many things that our people had never seen. They talked straight, and our people gave them a great feast, as a proof that their hearts were friendly. These men were very kind. They made presents to our chiefs and our people made presents to them. We had a great many horses, of which we gave them what they needed, and they gave us guns and tobacco in return. All the Nez Perces made friends with Lewis and Clarke, and agreed to let them pass through their country, and never to make war on white men. This promise the Nez Perces have never broken.