"That was in 1804, only a little more than a lifetime ago and nearly a century and a half after LaSalle explored the river and took possession of the country. Little, if anything, was known about the country at the time of its purchase by the United States more than was known in LaSalle's time. A few hardy traders went up and down the river, buying furs of friendly Indians, and that was all. "Naturally, after Jefferson had bought it, he wanted to know something about his purchase. So he appointed two men to explore the new country. I want you to remember their names, because they did a great work. One was Meriwether Lewis and the other William Clark, and you will find their trip described in your school history as 'the Lewis and Clark expedition.' I can't see why their exploration was not attended by as much danger and hardship as LaSalle's, which had been undertaken so many years before. The dense forests and great rivers of the West were all unknown and there were many hostile Indians. "What did you boys do, when you made up your minds to explore the rivers in Illinois last summer?" "We built a boat," Hank told him. "Exactly. And that was what Lewis and Clark did, or, rather, it was done for them at Government expense. A keel boat, fifty-five feet long and drawing not more than three feet of water, was made for them at Pittsburgh, where, if you remember, two rivers unite to form the Ohio. This boat had places for twenty-two oarsmen and carried a large, square sail. Steamboats were not known in those days, although a few years afterward Robert Fulton ran one on Hudson River. The Government also provided two smaller boats and loaded them with coffee, sugar, crackers, dried meats, carpenter's tools, presents for the Indians, and things like that. A few horses also were taken along in the large boat. "The leaders selected a crew of twenty-five men, and one fine day the whole outfit started down the Ohio River. When they reached the Mississippi they turned north and soon made their way up the great river to St. Louis. St. Louis was a French trading station then. Now it is a large city. A few years ago the hundredth anniversary of the Louisiana purchase was celebrated by holding a world's fair in St. Louis. "There more men joined the expedition and considerable information that President Jefferson wanted was picked up about the Indian tribes who lived up and down the river. "Finally, May 14, 1804, the explorers started on the real trip. It wasn't easy work any longer, for they had to row against the mighty current of the Mississippi. After they had gone a few miles they came to another great river, which was pouring a dirty looking, yellow flood into the Mississippi. Who can tell me what that river was?" "The Missouri," said Benny, who had been studying about it in school. "The Mississippi River, with its principal tributary, the Missouri, is the longest river in the world."