This ruin, about 2 miles from the place where two large canyons open into Laguna creek, lies in a cavern worn in the side of a large butte on the left of the stream. It is appropriately called Scaffold House from a finely made wooden scaffold (fig. 1) which the ancients constructed in a vertical cleft in the cliff about 50 feet above the east end of the ruin. Although this scaffold is now inaccessible from the walls of the room below, all the beams and much of the earthen floor still remain. [Illustration: FIG. 1. Scaffold of Scaffold House.] The construction of the scaffold is as follows: The crevice in which it lies is rectangular, with the longest axis vertical. Several large logs placed horizontally, their ends fitted into holes pecked in the sides of the crevice, support smaller beams laid across them at right angles. These latter in turn are covered with small sticks on which are laid bark and clay, leaving a hatchway at a point about midway. The construction of this scaffold, probably as daring a piece of aerial building as can be found anywhere among cliff-dwellings, is so well preserved that it shows no sign of deterioration. We can only conjecture what its use may have been, but the plausible suggestion has been made that it was an outlook or place of defense. [Illustration: BUREAU OF AMERICAN ETHNOLOGY BULLETIN 50 PLATE 12 PICTOGRAPHS AT BETATAKIN] Scaffold House is about 300 feet long. The rooms, which are in fine condition, extend along the side of the cliff, those situated midway of the length of the ruin being fairly well preserved. There are not far from 56 rooms still to be traced, and at least two circular kivas, the walls of one of which are still in fair condition. The larger kiva measures about 15 feet in diameter; it is subterranean, with a deep bench or banquette on one side. There is no trace of the pilasters so conspicuous in the circular kivas of the Mesa Verde. The inner walls are smoothly plastered. Enough of the roof of this kiva remains to show the method of construction, and as this is the first example of such a roof the writer has ever examined a brief description of it may prove to be instructive. (See pl. 14.) The supports or rafters are three in number, consisting of a large middle log laid across the center of the kiva halfway between the banquette and the opposite side, and of two smaller logs, parallel with it, resting on the top of the kiva wall, one across the banquette, and the other at about an equal distance on the opposite side. A number of smaller transverse beams, parallel with one another, are supported by the three logs already mentioned, and upon these lie the layers of sticks, bark, and adobe which cover the roof. No hatchway or place for a vertical opening was to be seen, but as the covering of the banquette is missing it is quite possible that the entrance to the kiva may have had some connection with this feature.