Every kiva of the first type has a lateral passageway for the admission of air, opening into the chamber on the floor level, generally under the large banquette. This passage, or tunnel, here designated a flue, communicates either directly with the outside or turns upward at a right angle and forms a small vertical ventilator which opens at the level of the plaza. Between the entrance into the flue from the kiva and the fire-hole there rises from the floor a device called the deflector (sometimes called an altar), the object of which was to prevent flames and smoke being drawn into the ventilator, or to evenly circulate the inflowing fresh air in the chamber. This deflector may be (1) a low stone wall, free on both ends; (2) a curved wall connected with the kiva wall on each side with orifices to allow the passage of air; (3) a stone slab in the kiva floor; (4) a bank, free at each end, supported by upright stakes between which are woven twigs, the whole being plastered with clay.[48] [Footnote 48: Cosmos Mindeleff quotes from Nordenskiöld a description of a Mesa Verde kiva, the deflector of which was made in the same way.] The supposed functions of the flue, the vertical passage, and the ventilator have been discussed by several archeologists. The uses to which the flue has been ascribed are as follows: (1) a chimney, (2) a ceremonial opening, (3) an entrance, (4) a ventilator. There is no sign of smoke on the interior of the vertical passage, which, being too small to admit a person, would seem to prove the first and third theories untenable. In the Navaho National Monument, where there are square rooms, or _kihus_, with banks similar to the deflectors of the circular kivas, a door takes the place of the flue and the vertical passage, and affords the only means for admitting fresh air to the room. Although it may have originated as a simple entrance to the room, it became so modified that it could no longer have served that purpose, ceremonially or otherwise. [Illustration: PLATE 22 STONE OBJECTS _a_ Pounding stone _b_ Projectile point _c_ Cover for vase _d_ Flat stone slab] The position of the entrance to the Cliff Palace kiva is yet to be definitely determined. Analogy, together with the structure of the roof, would indicate that it was by means of a hatchway, but no remains of a ladder were found, and no indication in the floor where a ladder formerly rested is visible. It may be that the large banquette indicates the position of the hatchway.[49] [Footnote 49: On this supposition the large banquette may have been the forerunner of the spectator's section in the modern rectangular Hopi kivas, of which it is a modification.]