Lieutenant Simpson has described the ruins of the Chaco, eleven in number, occurring within a distance of twenty-five miles. The first of these met with in coming from the south is called at present (we presume in the absence of the knowledge of the true name) the Pueblo Pintado. The most remarkable feature of this great structure is the beauty and precision of the masonry. The fine, hard gray sandstone blocks are quite uniformly three inches in thickness and are laid without mortar, always breaking joints. The crevices between the ends of the blocks are filled with very thin pieces of stone, not over a quarter of an inch thick. The walls of the pueblo now standing, are at their greatest height, thirty feet, and furnish evidence from the marks of the floor-timbers that the building was three stories. The walls are between two and three feet thick at the base, though this is diminished with each succeeding story by a jog of a few inches, upon which the flooring timbers rest. These are from six to eleven inches in diameter, always of uniform size in the same room. On these beams small round sticks are laid transversely, and these in turn covered with thin cedar strips, lying transversely of the round sticks. In some rooms the chinks in the floor were filled with small stones and the whole covered with a layer of mortar. One room, however, had a floor of smooth cedar boards, seven inches wide and three-quarters of an inch thick. The edges and ends were squarely cut, and their smooth surfaces indicate that they were polished by being rubbed with flat stones. The size of these ruins may be better understood when we state that five buildings measured in circumference respectively 872, 700, 1700, 1300 and 1300 feet; while the number of rooms, still well-defined on the ground floor of each, is 72, 99, 112, 124 and 139. Some of these buildings undoubtedly had as high as a thousand rooms, while the smallest of them probably contained half that number. The smallest apartments are five feet square, while the largest are eight by fourteen feet. The ground plan of the buildings of this valley have three tiers of rooms, while one building, the Pueblo Bonito, has four tiers of apartments. The usual form of the buildings corresponds to three sides of a rectangle, with the fourth (one of the long sides of the figure) left unbuilt (except that in some cases it was inclosed by a semicircular stone wall), thus affording a partially enclosed court of large dimensions. The exterior walls are in all cases perpendicular, thus differing from the pueblos farther south. The terracing in the Chaco structures is upon the inside (court side) of the buildings.