About noon the travelers had descended the mountains and gained the undulating plains that extend to the sea; the boundless prairie spread its broad carpet of verdure before them.
More than once during the journey the attention and interest of all, but especially of Paganel, were arrested by the curious illusion of the mirage, by which was presented in the sky, at the limits of the horizon, a semblance of the estancias, the poplars and willows near them, and other objects; the images being so much like the reality that it required a strong effort to realize their deceptive character.
The weather hitherto had been fine, but now the sky assumed a less pleasing aspect. Masses of vapor, generated by the high temperature of the preceding days, condensed into thick clouds and threatened to dissolve in showers of rain. Moreover, the proximity of the Atlantic, and the west wind, which here reigns supreme, rendered the climate of this region peculiarly moist. However, for that day at least the heavy clouds did not break; and at evening the horses, after traveling forty miles, halted on the edge of a deep "cañada," an immense natural ditch filled with water. A shelter was wanting, but the ponchos served for tents as well as clothing, and peaceful slumbers enwrapped all.
The next day, as they progressed farther, the presence of subterranean streams betrayed itself more noticeably, and moisture was seen in every depression of the ground. Soon they came to large ponds, some already deep and others just forming. So long as there were only lagoons, the horses could easily extricate themselves; but with these treacherous swamps it was more difficult. Tall grass obstructed them, and it was necessary to incur the danger before it could be understood. These quagmires had been already fatal to more than one human being.
Robert, who had ridden half a mile in advance, returned at a gallop, crying,—
"Monsieur Paganel! Monsieur Paganel! A forest of horns!"
"What!" replied the geographer, "have you found a forest of horns?"
"Yes, yes; or at least a field."
"A field! you are dreaming, my boy," said Paganel, shrugging his shoulders.
"I am not dreaming," retorted Robert; "you shall see for yourself. This is a strange country! People sow horns, and they spring up like corn! I should like very well to have some of the seed."