Having now made what observations our means afforded, we proceeded to descend. We had accomplished an object of laudable ambition, and beyond the strict order of our instructions. We had climbed the loftiest peak of the Rocky mountains, and looked down upon the snow a thousand feet below; and, standing where never human foot had stood before, felt the exultation of first explorers. It was about two o'clock when we left the summit, and when we reached the bottom, the sun had already sunk behind the wall, and the day was drawing to a close. It would have been pleasant to have lingered here and on the summit longer; but we hurried away as rapidly as the ground would permit, for it was an object to regain our party as soon as possible, not knowing what accident the next hour might bring forth.

We reached our deposite of provisions at nightfall. Here was not the inn which awaits the tired traveler on his return from Mont Blanc, or the orange groves of South America, with their refreshing juices and soft fragrant air; but we found our little cache of dried meat and coffee undisturbed. Though the moon was bright, the road was full of precipices, and the fatigue of the day had been great. We therefore abandoned the idea of rejoining our friends, and lay down on the rock, and, in spite of the cold, slept soundly.

16th.--We left our encampment with the daylight. We saw on our way large flocks of the mountain-goat looking down on us from the cliffs. At the crack of the rifle, they would bound off among the rocks, and in a few minutes make their appearance on some lofty peak, some hundred or a thousand feet above. It is needless to attempt any further description of the country; the portion over which we traveled this morning was rough as imagination could picture it, and to us seemed equally beautiful. A concourse of lakes and rushing waters--mountains of rocks naked and destitute of vegetable earth--dells and ravines of the most exquisite beauty, all kept green and fresh by the great moisture in the air, and sown with brilliant flowers, and everywhere thrown around all the glory of most magnificent scenes,--these constitute the features of the place, and impress themselves vividly on the mind of the traveler. It was not until 11 o'clock that we reached the place where our animals had been left, when we first attempted the mountains on foot. Near one of the still burning fires we found a piece of meat, which our friends had thrown away, and which furnished us a mouthful--a very scanty breakfast. We continued directly on, and reached our camp on the mountain lake at dusk. We found all well. Nothing had occurred to interrupt the quiet since our departure, and the fine grass and good cool water had done much to re-establish our animals. All heard with great delight the order to turn our faces homeward; and towards sundown of the 17th, we encamped again at the Two Buttes.

In the course of this afternoon's march, the barometer was broken past remedy. I regretted it, as I was desirous to compare it again with Dr. Engleman's barometers at St. Louis, to which mine were referred; but it had done its part well, and my objects were mainly fulfilled.

19th.--We left our camp on Little Sandy river about seven in the morning, and traversed the same sandy, undulating country. The air was filled with the turpentine scent of the various artemisias, which are now in bloom, and, numerous as they are, give much gayety to the landscape of the plains. At ten o'clock, we stood exactly on the divide in the pass, where the wagon-road crosses; and, descending immediately upon the Sweet Water, halted to take a meridian observation of the sun. The latitude was 42° 24' 32".

In the course of the afternoon we saw buffalo again, and at our evening halt on the Sweet Water the roasted ribs again made their appearance around the fires; and, with them, good humor, and laughter and song, were restored to the camp. Our coffee had been expended, but we now made a kind of tea from the roots of the wild-cherry tree.

23d.--Yesterday evening we reached our encampment at Rock Independence, where I took some astronomical observations. Here, not unmindful of the custom of early travelers and explorers in our country, I engraved on this rock of the Far West a symbol of the Christian faith. Among the thickly inscribed names, I made on the hard granite the impression of a large cross, which I covered with a black preparation of India-rubber, well calculated to resist the influence of wind and rain. It stands amidst the names of many who have long since found their way to the grave, and for whom the huge rock is a giant gravestone.

One George Weymouth was sent out to Maine by the Earl of Southampton, Lord Arundel, and others; and in the narrative of their discoveries, he says: "The next day we ascended in our pinnace that part of the river which lies more to the westward, carrying with us a cross--a thing never omitted by any Christian traveler--which we erected at the ultimate end of our route." This was in the year 1605; and in 1842 I obeyed the feeling of early travelers, and left the impression of the cross deeply engraved on the vast rock one thousand miles beyond the Mississippi, to which discoverers have given the national name of Rock Independence.

In obedience to my instructions to survey the river Platte, if possible, I had determined to make an attempt at this place. The India-rubber boat was filled with air, placed in the water, and loaded with what was necessary for our operations; and I embarked with Mr. Preuss and a party of men. When we had dragged our boat a mile or two over the sands, I abandoned the impossible undertaking, and waited for the arrival of the party, when we packed up our boat and equipage, and at nine o'clock were again moving along on our land journey. We continued along the valley on the right bank of the Sweet Water, where the formation, as already described, consists of a grayish micaceous sandstone, and fine-grained conglomerate, and marl. We passed over a ridge which borders or constitutes the river hills of the Platte, consisting of huge blocks, sixty or eighty feet cube, of decomposing granite. The cement which united them was probably of easier decomposition, and has disappeared and left them isolate, and separated by small spaces. Numerous horns of the mountain-goat were lying among the rocks; and in the ravines were cedars, whose trunks were of extraordinary size. From this ridge we descended to a small open plain, at the mouth of the Sweet Water, which rushed with a rapid current into the Platte, here flowing along in a broad and apparently deep stream, which seemed, from its turbid appearance, to be considerably swollen. I obtained here some astronomical observations, and the afternoon was spent in getting our boat ready for navigation the next day.

24th.--We started before sunrise, intending to breakfast at Goat island. I had directed the land party, in charge of Bernier, to proceed to this place, where they were to remain, should they find no note to apprize them of our having passed. In the event of receiving this information, they were to continue their route, passing by certain places which had been designated. Mr. Preuss accompanied me, and with us were five of my best men, viz.: C. Lambert, Basil Lajeunesse, Honore Ayot, Benoist, and Descoteaux. Here appeared no scarcity of water, and we took on board, with various instruments and baggage, provisions for ten or twelve days. We paddled down the river rapidly, for our little craft was light as a duck on the water; and the sun had been some time risen, when we heard before us a hollow roar, which we supposed to be that of a fall, of which we had heard a vague rumor, but whose exact locality no one had been able to describe to us. We were approaching a ridge, through which the river passes by a place called "canon," (pronounced kanyon,)--a Spanish word, signifying a piece of artillery, the barrel of a gun, or any kind of tube; and which, in this country, has been adopted to describe the passage of a river between perpendicular rocks of great height, which frequently approach each other so closely overhead as to form a kind of tunnel over the stream, which foams along below, half choked up by fallen fragments. Between the mouth of the Sweet Water and Goat island, there is probably a fall of three hundred feet, and that was principally made in the canons before us; as, without them, the water was comparatively smooth. As we neared the ridge, the river made a sudden turn, and swept squarely down against one of the walls of the canon, with great velocity, and so steep a descent that it had, to the eye, the appearance of an inclined plane. When we launched into this, the men jumped overboard, to check the velocity of the boat; but were soon in water up to their necks, and our boat ran on. But we succeeded in bringing her to a small point of rocks on the right, at the mouth of the canon. Here was a kind of elevated sand-beach, not many yards square, backed by the rocks; and around the point the river swept at a right angle. Trunks of trees deposited on jutting points, twenty or thirty feet above, and other marks, showed that the water here frequently rose to a considerable height. The ridge was of the same decomposing granite already mentioned, and the water had worked the surface, in many places, into a wavy surface of ridges and holes. We ascended the rocks to reconnoitre the ground, and from the summit the passage appeared to be a continued cataract, foaming over many obstructions, and broken by a number of small falls. We saw nowhere a fall answering to that which had been described to us as having twenty or twenty-five feet; but still concluded this to be the place in question, as, in the season of floods, the rush of the river against the wall would produce a great rise; and the waters, reflected squarely off, would descend through the passage in a sheet of foam, having every appearance of a large fall. Eighteen years previous to this time, as I have subsequently learned from himself, Mr. Fitzpatrick, somewhere above on this river, had embarked with a valuable cargo of beaver. Unacquainted with the stream, which he believed would conduct him safely to the Missouri, he came unexpectedly into this canon, where he was wrecked, with the total loss of his furs. It would have been a work of great time and labor to pack our baggage across the ridge, and I determined to run the canon. We all again embarked, and at first attempted to check the way of the boat; but the water swept through with so much violence that we narrowly escaped being swamped, and were obliged to let her go in the full force of the current, and trust to the skill of the boatmen. The dangerous places in this canon were where huge rocks had fallen from above, and hemmed in the already narrow pass of the river to an open space of three or four and five feet. These obstructions raised the water considerably above, which was sometimes precipitated over in a fall; and at other places, where this dam was too high, rushed through the contracted opening with tremendous violence. Had our boat been made of wood, in passing the narrows she would have been staved; but her elasticity preserved her unhurt from every shock, and she seemed fairly to leap over the falls.