"What becomes of any house built of cottonwood logs in ten or twenty years?" smiled his uncle. "But the _Journal_ and other books tell us that here or about here is where the old stockade once stood. It was opposite to where Fort Clark later was built in 1831. You see, Fort Clark was on the west side, on a high bluff, and in its time quite a post, for it was one hundred and thirty-two by one hundred and forty-seven feet in size, and well built. Fort Clark was about fifty-five miles above the Northern Pacific Railroad bridge at Bismarck, North Dakota. We've had a good day's run of it. "All Clark tells us about Fort Mandan is that it was on the north bank, that the ground was sandy, and that they cleared the timber to make room. He says they had cottonwood and elm and some small ash, but complains that the logs were large and heavy and they had to carry them in on hand spikes, by man power. They used no horses in rolling up the logs. "But Patrick Gass tells more about the way they did. They had two rows of cabins, in two wings, at right angles, and each cabin had four rooms in it. I think the men slept upstairs, for when the walls were up seven feet they laid a puncheon floor, covered with grass and clay, which Gass says made 'a warm loft.' This projected about a foot, and a puncheon roof was put over that. "The outer wall was about eighteen feet high. They had several fireplaces. They made a couple of storerooms in the angle of the two wings, and then put up their stockade in front, to complete their square. This stockade was made of upright logs, and had a gate, like most of the frontier posts, so that, what with their swivel gun and all their rifles, they could have made quite a fight against any sort of an attack, although they had no trouble of any kind. "They were not very far from the Mandan villages. Quite a settlement this was, in these parts--not mentioning nine deserted villages inside of sixty miles below--two Mandan villages, built with the Mandan dirt-covered lodges, like those of the Rees; and besides that, villages of Sioux and Gros Ventres, and of a band they called the Watasoons, and seventy lodges of Crees and Assiniboines who came in later and the fierce Minnetarees--plenty of savages to warrant the expedition in taking no chances." "I've read that the Indians at first were not so friendly," said Rob. "There were British traders among them, weren't there?" "Oh yes, the Northwest Fur Company was in there, and an Irishman by the name of McCracken was on the ground at the time. Alexander Henry got there in 1806, you know. Now, Lewis sent out a note by McCracken to the agent at Fort Assiniboine. Those traders were none too friendly, and tried to stir up trouble. Two more of the Nor'westers, Larocque and McKenzie, came in, with an interpreter and four men, and the interpreter, LaFrance, took it on him to speak sneeringly of the Americans. It did not take Captain Lewis long to call him to account."