The subterranean passageway under the flue and beneath the floor of kiva V should not be overlooked in a study of the origin and function of the ventilator. This structure is without apparent connection with the ventilator, and yet it is so carefully constructed under it that it may have had some relation, a knowledge of which will eventually enlighten us regarding the meaning of both structures. The kivas of the Mesa Verde are much smaller than those of Walpi and other Hopi pueblos, one of them being barely 9 feet in diameter and the largest measuring not more than 19 feet, whereas the chief kiva at Walpi is 25 feet long by 15 feet wide. Evidently kivas of such diminutive size as those found at Cliff Palace could accommodate only a few at a time, and it is probable that they were not occupied by fraternities of priests but by a few chiefs; indeed, the religious fraternity, as we understand its composition in modern pueblos, had in all probability not yet been developed. Nevertheless the smallest kiva in Cliff Palace is as large as the room in Walpi in which the Sun priests, mainly of one clan, celebrate their rites. KIVA A Kiva A (pl. 17) is the most southerly kiva of Cliff Palace, the first of the series excavated in the talus, its roof having been on the level of the cave floor, or the fourth terrace. The walls of this kiva required little repair. Its height from the floor to the top of the walls is 8 feet 6 inches, and from the floor to the top of the pilasters 7 feet; the height of the banquette is 3 feet 6 inches. The interior diameter is 11 feet. There are six pilasters, with an average breadth of 20 inches; the distance between them averages 4 feet 6 inches. The opening into the ventilator is situated in the southwestern wall; its height is 2 feet 4 inches, the breadth, at the base, 14 inches, contracted to 11 inches at the top. The deflector, which is broken, is a thin slab of stone. The distance from the flue opening to the deflector is 2 feet 6 inches, and from the deflector to the round fire-hole 8 inches. The diameter of the fire-hole is 1 foot 8 inches, its depth 2 feet. Its western side is lined with small stones set on edge. There were possibly 4 niches in the side wall of the banquette, 3 of them on the east, measuring respectively 16 by 20 by 12 inches, 9 by 9 by 12 inches, and 3 by 3 by 5 inches, and the remaining one situated north by east from the middle of the kiva and measuring 6 by 4 by 8 inches.[50] [Footnote 50: The measurements of the kivas here given were determined by Mr. R. G. Fuller, who served as voluntary assistant during the summer.] There is a subterranean passageway (pl. 17, _b_), 6 feet 6 inches long, from this kiva into room 1, and also a tunnel (pl. 17, _a_), 6 feet in length, between kivas A and B. The former has stone steps and rises above the banquette; its width averages 18 inches. KIVA B