The Bird Woman’s greatest service was yet to come. They had finally discovered the source of the Missouri--a cool, clear, crystal brook, very different from the “Big Muddy” a thousand miles below. An Irishman in the party stood astride this narrow streamlet and called out, “Sure, an’ I never thought to see the day I could stand a-straddle of the big Missouri River!” Captain Clark and other men of the party started out in different directions to “forage for facts,” and try to find the small beginning of the other river which the Indians said would take them down to the great western sea. One day Lewis met a party of Shoshones and tried to persuade them to go with him and act as guides. He needed help moving the baggage over the mountains which are called “the Great Divide” because they separate the rivers which flow east into the Mississippi River from those which run west to the Pacific Ocean. Though he offered the Shoshones presents and other favors, they still refused to go. Then he appealed to the Indians’ curiosity by telling them that if they would come with him he would show them a black man with curly hair, for Captain Clark’s negro servant was one of the party; also that there was an Indian woman of their own tribe in the white men’s camp. This was more than the chief and several of his braves could resist, so they returned with Lewis. To the surprise and joy of all, the Shoshone chieftain discovered that the Bird Woman was his long-lost sister, who had been carried away by a hostile tribe, many years before. The Bird Woman helped her own tribe to a better understanding of the white men, and persuaded them to furnish horses, canoes, guides, and helpers over the Divide to the headwaters of the Snake River, which empties into the Columbia. When they were in their canoes, floating down this beautiful stream, they laughed to think how much easier it is to go down than to pull up against the current. But their speed greatly increased the danger. They rushed into rapids and nearly plunged over falls. One canoe ran upon a rock and they had a hard time rescuing from the boiling waters several men who, strange to say, could not swim. Once Lewis and one of the men, while climbing cliffs, slipped over the brink of a lofty precipice and narrowly escaped being dashed to pieces on the rocks far below.