The Gates of the Rocky Mountains form a gorge of between five and six miles long, and beyond it the scenery is of very great beauty. Anxious now to reach the sources of the Missouri and the headwaters of the Columbia, Lewis and Clarke paused but to note the chief features of the neighborhood, and shortly reached a spot where the great river they had followed so far divides into three forks. To these they gave the names of Jefferson, Madison and Gallatin, after three great politicians of the young republic, and, after some hesitation between them, selected the first, flowing in a south-westerly direction, as the most likely to be the true Missouri. The event proved that they were right. The Jefferson led them through the very central recesses of the Rocky Mountains, and on the 12th August, 1805, a small gap between the lofty mountainous ridges was reached, from which issued the springhead of the mighty Missouri. The exact position of the source of the river, the course of which they had followed for no less than 3,000 miles, was carefully noted by the explorers, and found to be N. lat. 45°, W. long. 112°; and, after congratulating each other on the great success achieved, the journey was resumed with fresh ardor and enthusiasm. It was now of the utmost importance to obtain guides, as the expedition was totally at a loss as to the direction to be taken to reach the Columbia. Traces had again and again been seen of the encampments of Snake Indians, and a fairly good native road traversed the mountains; but the red men had evidently heard rumors of the approach of the pale skins, those scourges from the South and East who had already driven so many tribes westward. In the absence of guides, it was decided to follow the Indian road to the summit of the mountains; and the same day which witnessed the discovery of the source of the Missouri, was also the date of the first visit of white men to the summit of the ridge forming the watershed between the Pacific and the central table-lands of North America. Pausing but a few minutes to gaze upon the wonderful panorama stretching away to the South Sea, for which so many previous explorers had sought in vain, the Americans began the descent of the Rocky Mountains, and at a distance of about three-quarters of a mile from their summit, they came to a small “creek of clear water running to the westward.” Subsequent observations proved this to be the Columbia; but, unable without assistance to be sure of its identity with the second river to be explored, the leaders of the party still followed the Indian road, and on the 13th July were rewarded for their patience by coming upon a small party of Indians, who fled at their approach.