with her we felt welcome to make ourselves as comfortable as we could. Vetancur, the seventeenth-century chronicler, describes the mesa as “a league in circuit and thirty _estados_ in height.”[6] Modern writers estimate its height at 357 feet, and its irregular but practically level top as seventy acres in extent.[7] The great rock is almost cut in two by a savage cleft “like a pair of eye-glasses, a small saddle representing the bridge.”[8] Sand in the course of time has drifted over this dangerous bridge, and with disintegrated stone fallen in from either side, there has been formed a narrow but treacherous passage, which we were told the boys dare one another to cross, but where no man will risk his neck. It will be convenient therefore to designate the two parts hereafter by the terms “north” and “south” mesa. Although there are no signs of human dwellings on the south mesa and no known tradition that it was ever inhabited, Lummis writes of “a perfect cliff-house” perched there on a dizzy eyrie. [Illustration: THE SAND-RAMP, OR “NEW TRAIL” _Bolton_] When seen from below, the outer walls of the dwellings seem to be part of the mesa itself, merely hewn from the solid rock. Closely approached, they are found to be as much fortress as house. Three parallel lines of stone and adobe, a thousand feet long and forty feet high, running east and west, are separated from one another by _calles_ or streets of moderate width—the _calle_ between the middle row and the south row being left wider than the others, to provide a plaza for open-air ceremonials. Each of these structures consists of three storeys built in terraces, after a fashion common enough in the pueblo country. The lowest storey is between twelve and fifteen feet high, and had originally no openings save trap doors on its top. It was used exclusively for the storage of supplies, enough of which could be kept there to withstand a long siege. The Ácomas therefore enter their houses by ladders from the ground to the second storey, but the third storey and the roofs are reached by steep and narrow steps on the division walls.[9] In all terraced pueblos, economy of construction was one feature of this type of house. A far more important consideration was necessity for mutual defense, felt by every small community exposed to raids. No one could foresee when would appear a roving band of hostile Navajos, Apaches or Comanches, but their forced tribute upon the crops at some time was as certain as the dawning of the day.