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. THEY PART WITH SOME OF THEIR COMPANIONS.