"Here we are, fellows, east of the Three Forks of the Missouri," said Uncle Dick, when they had gotten out their maps for that evening's study. "At first, neither Lewis nor Clark followed the Gallatin at all. As we know, Clark went but a short distance up the Madison. But when the explorers were going east, as we saw before, Clark came down to the Shoshoni Cove, at the junction where we made our last camp, over west. When he struck in here, on the Gallatin, Clark had with him the Indian girl, Sacagawea. Besides the Indian woman and her child, he had eleven men and fifty horses. Ordway, as we have seen, had taken nine men and started downstream with the boats. No one knew this country except the Indian girl. "Yes, and she must have been across here before, too," said Billy. "There are three passes at the head of the East Gallatin--the Bozeman and the Bridger and the Flathead. The Indian girl told them to take the one farthest south, which is Bozeman Pass. "The books say that on July 13th Clark camped just where the town of Logan is, in the Gallatin Valley. They say he followed southeast from there and crossed Bozeman Creek near this town. The Indian girl knew there was a buffalo road there, and they stuck to that. Good authorities think that they camped, July 14th, near where old Fort Ellis afterward was located. That's across the East Gallatin. There is an easy pass there, and there is no doubt at all that the Indian girl led Clark through that easiest pass, which the Indians would be sure to find when going between their hunting ranges. "Of course, old man Bozeman did not come in here until the mining strikes, 1863 or 1864. He was a freighter and knew this country, although he didn't know it well enough to keep from getting killed by the Indians. "Up the Gallatin, too," went on Billy, "is where they say John Colter ran after he got away from the Blackfeet. He didn't have any clothes on to speak of even then--he sure traveled light. But, anyhow, he lived to discover Yellowstone Park, or part of it, and to tell a lot of stories which everybody said were lies." "Can we see much of the trail, if we go over with the pack train?" asked Rob. "Not so very much," said Billy. "Even the old road is wiped out, now that the railroad has come. In some places you can find where the trail once ran, or is supposed to have run, but you have to go by the general landmarks now. "When you come to the central ridge beyond old Ellis, you get the last summit between here and Yellowstone waters. The tunnel runs under that now. The railroad books say that is fifty-five hundred and sixty-five feet--the highest of the three northern transcontinental passes. "So you can figure now, I reckon," he concluded, "that you are mighty near at the head of the Gallatin, a day's march from here. And if you want to, you can take the railroad in town, all the way down the Yellowstone and clean on home to Chicago or St. Louis, without getting off the cars."