They started early the next morning, and, pursuing the route recommended by the squaw, encamped in the evening at the entrance of the gap mentioned by her. Through this gap they passed next day, and, at the distance of six miles, reached the top of the dividing ridge which separates the waters of the Missouri from those of the Yellowstone. Nine miles from the summit, they reached the Yellowstone itself, about a mile and a half below where it issues from the Rocky Mountains. The distance from the head of the Missouri to this place is forty-eight miles, the greater part of which is through a level plain. They halted for three hours to rest their horses, and then pursued the Buffalo Road along the banks of the river.

Although but just emerging from a high, snowy mountain, the Yellowstone is here a bold, rapid, and deep stream, one hundred and twenty yards in width. They continued their course along the river till the 23d, when the party embarked on board of two canoes, each of which was twenty-eight feet long, sixteen or eighteen inches deep, and from sixteen to twenty-four inches wide. Sergt. Prior, with two men, was directed to take the horses to the Mandans for safe keeping until the re-union of the expedition.

July 24.—At eight o'clock, Capt. Clarke and the remainder of his party embarked, and proceeded very steadily down the river. They passed the mouths of several large rivers emptying into the Yellowstone; one of which was called the Big-horn, from the numbers of that remarkable species of sheep seen in its neighborhood. Next day, Capt. Clarke landed to examine a curious rock, situated in an extensive bottom on the right, about two hundred and fifty paces from the shore. It is nearly two hundred paces in circumference, two hundred feet high, and accessible only from the north-east; the other sides consisting of perpendicular cliffs, of a light-colored, gritty stone. The soil on the summit is five or six feet deep, of a good quality, and covered with short grass. From this height, the eye ranges over a wide extent of variegated country. On the south-west are the Rocky Mountains, covered with snow; on the north, a lower range, called the Little Wolf Mountains. The low grounds of the river extend nearly six miles to the southward, when they rise into plains, reaching to the mountains. The north side of the river is bounded by jutting, romantic cliffs, beyond which the plains are open and extensive, and the whole country enlivened by herds of buffaloes, elks, and wolves. After enjoying the prospect from this rock, to which Capt. Clarke gave the name of Pompey's Pillar, he descended, and continued his route. At the distance of six or seven miles, he stopped to secure two bighorns, which had been shot from the boat, and, while on shore, saw in the face of the cliff, about twenty feet above the water, a fragment of the rib of a fish, three feet long, and nearly three inches round, embedded in the rock itself.

BEAVERS, BUFFALOES, MOSQUITOES.

The beavers were in great numbers along the banks of the river, and through the night were flapping their tails in the water round the boats.

Aug. 1.—The buffaloes appeared in vast numbers. A herd happened to be on their way across the river. Such was the multitude of these animals, that although the river, including an island over which they passed, was a mile in width, the herd stretched, as thick as they could swim, completely from one side to the other. Our party, descending the river, was obliged to stop for an hour to let the procession pass. We consoled ourselves for the delay by killing four of the herd, and then proceeded, till, at the distance of forty-five miles, two other herds of buffaloes, as numerous as the first, crossed the river in like manner.

Aug. 4.—The camp became absolutely uninhabitable, in consequence of the multitude of mosquitoes. The men could not work in preparing skins for clothing, nor hunt in the low grounds: in short, there was no mode of escape, except by going on the sand bars in the river, where, if the wind should blow, the insects do not venture. But when there is no wind, and particularly at night, when the men have no covering except their worn-out blankets, the pain they inflict is scarcely to be endured.

On one occasion, Capt. Clarke went on shore, and ascended a hill after one of the bighorns; but the mosquitoes were in such multitudes, that he could not keep them from the barrel of his rifle long enough to take aim.

This annoyance continued, till, on the 11th of September, they write, "We are no longer troubled with mosquitoes, which do not seem to frequent this part of the river; and, after having been persecuted with them during the whole route from the falls, it is a most happy exemption. Their noise was very agreeably exchanged for that of the wolves, which were howling in various directions all round us."

Aug. 12, 1806.—The party continued to descend the river. One of their canoes had, by accident, a small hole made in it; and they halted for the purpose of covering it with a piece of elk-skin. While there, about noon, they were overjoyed at seeing the boats of Capt. Lewis's party heave in sight. The whole expedition being now happily re-united, at about three o'clock all embarked on board the boats; but as the wind was high, accompanied with rain, we did not proceed far before we halted for the night.