Soon a new appearance attracted our attention. First, clouds of dust, which gradually took a well-defined shape, and formed themselves into immense pillars, rapidly spinning round upon themselves, and travelling slowly about the plain. At one place, where several smaller valleys opened upon us, these sand-pillars, some small, some large, were promenading about by dozens, looking much like the genie when the fisherman had just let him out of the bottle, and saw him with astonishment beginning to shape himself into a giant of monstrous size. Indeed I doubt not that the story-teller was thinking of such sand-pillars when he wrote that wonderful description. You may see them in the East by thousands. As they moved along, they sucked up small stones, dust, and leaves; and our driver declared that they had been known to take the roofs off houses, and carry flocks of sheep into the air; “but these that you see now,” said he, “are no great matter.” We estimated the size of the largest at about four hundred feet in height, and thirty in diameter; and this very pillar, walking by chance against a house, most decidedly got the worst of it, and had its lower limbs knocked all to pieces. When the sun grows hot, the bare earth heats the air that lies upon it so much that an upward current rises from the whole face of the valley; and to supply its place the little valleys and ravines that open into it pour in each its stream of cooler air; and wherever two of these streams, flowing in different directions, strike one another, a little whirlwind ensues, and makes itself manifest as a sand-pillar. The coachman’s “molino de viento,” as he called it, may very well have happened, but it must have been a whirlwind on a large scale, caused by the meeting of great atmospheric currents, not by the little apparatus we saw at work. There seems to be hardly a village in the plain; and the only buildings we see for miles are the herdsmen’s houses of stone, flat-roofed, dark inside, and uninviting in their appearance, and the great cattle-pens, the corrals, which seem absurdly too large for the herds that we have yet seen; but in two or three months there will be rain, the ground will be covered with rank grass, the corrals will be crowded with cattle every evening; the mirage will depart when real water comes, dust and sand-pillars will be no longer to be seen, and all the nine horses and mules of the diligence-team, floundering, splashing, and kicking, will hardly keep the heavy coach from settling down inextricably in the mire. And so on until October, and then the season of water, “la estación de las aguas,” will cease, and things will be again as they are now.