No kiva has been found in De Chelly with a roof in place. Nearly all of them are inclosed in rectangular chambers, and it seems more than probable that the roofing of the kiva was simply the roofing of the inclosing chamber. As a rule the inclosing rectangular walls were erected at the same time as the kiva proper, and the outside of the inner circular wall was not finished at all. In a few instances the space between the outer rectangular and inner circular wall was filled in solid, or perhaps was so constructed, but usually the walls are separate and distinct. CHIMNEY-LIKE STRUCTURES There are peculiar structures found in some of the ruins, whose use and object are not clear. Reference has already been made to them in the descriptions of several ruins, and for want of a better name they have been designated chimney-like structures. At the time that they were examined they were supposed to be new, and the first hypothesis formed was that they were abortive chimneys, but further examination showed that this idea was not tenable. Subsequently Nordenskioeld's book on the Cliff Dwellers of the Mesa Verde was published, and it appears therefrom that this feature is very common in the region treated; so common as to constitute the type. [Illustration: Fig. 78--Plan of chimney-like structure in ruin No. 15.] Figure 78 is a plan of one of these structures which occurs in ruin No. 15 in Canyon de Chelly. This ruin has already been described in detail (page 118). The chimney-like structure is attached to a rectangular room with rounded corners, which is supposed to have been a kiva, and which was two stories high. Excavation revealed the floor level about 71/2 feet below where the roof was placed. In the center of the south wall there is an opening 1.5 feet high and eighty-five one-hundredths of a foot (10.2 inches) wide. The south wall is built over a large bowlder, and a tunnel or opening passes under this to a rounded vertical shaft, about a foot in diameter, which opens to the air. This perhaps is better shown in the section (figure 79). At first sight this would appear to be a chimney, but there are several objections to the idea. The interior of the shaft is not blackened by smoke, and while the tunnel is somewhat smoke-stained, the deposit is not so pronounced as on the walls of the room. The front of the tunnel in the room has a lintel composed of a single stick about an inch in diameter, as shown in the section. The roof of the tunnel was the underside of the large bowlder mentioned, and the stick lintel was of no use except to show that no fire could have been built under it. The roof of the southern end of the tunnel, where it opens into the shaft, is considerably lower than at the other end. The floor of the tunnel and the sides were smoothly plastered, but the plastering does not appear to have been subjected to the action of fire.