The Mandans used to build good houses almost circular in form. The floor was sunk a foot or more below the surface of the ground. The framework was made of large and strong timbers. The outside walls sloped inward and upward from the ground to a height of about five feet. They were composed of boards. The roof sloped from the top of the wall up to a central point; it was made of poles, covered with willow matting and then with grass. The whole house, wall and roof, was then covered over with a layer of earth a foot and a half thick. When such a house contained a fire sending out smoke, it must have looked like a smooth, regularly sloping little volcano. In California, where there are so many different sorts of climate and surroundings, the Indian tribes differed much in their house building. Where the climate was raw and foggy, down near the coast, they dug a pit and erected a shelter of redwood poles about it. In the snow belt, the house was conical in form and built of great slabs of bark. In warm low valleys, large round or oblong houses were made of willow poles covered with hay. At Clear Lake there were box-shaped houses; the walls were built of vertical posts, with poles lashed horizontally across them; these were not always placed close together, but so as to leave many little square holes in the walls; the flat roof was made of poles covered with thatch. In the great treeless plains of the Sacramento and San Joaquin they made dome-shaped, earth-covered houses, the doorway in which was sometimes on top, sometimes near the ground on the side. In the Kern and Tulare valleys, where the weather is hot and almost rainless, the huts are made of marsh rushes. [Illustration.] Skin Tents. (From Photograph.)