“The rock,” says Ulloa, “from which the water precipitates itself is nearly perpendicular, and fifty toises in height, and on both sides bordered with lofty and spreading trees. The clearness of the water dazzles the sight, which is however charmed with its lustre as it falls from the precipice; after which it continues its course in a bed along a small descent, and is crossed by the road.” The roads by degrees assumed an Alpine character; in some places the declivity was so great, that the mules could scarcely keep their footing, while in others the acclivity was equally difficult. Occasionally the road grew so narrow that there was scarcely room for the mules to pass, while it lay at other times along the edge of tremendous precipices, where, had they made one false step, they must have inevitably toppled over and perished. The extraordinary dexterity of the mules in descending the fearful slopes of these mountains is one of the most surprising things related of the sagacity of animals. The mules themselves are sensible of the caution requisite in these descents; for coming at the top of an eminence they stop, and having placed their fore-feet close together, as in a posture of stopping themselves, they put their hind-feet together, but a little forwards, as if going to lie down. In this attitude, having taken a survey of the road, they slide down with the swiftness of a meteor. All the rider has to do is to keep himself fast on the saddle without checking the beast; for the least motion is sufficient to disorder the equilibrium of the mule; in which case they both unavoidably perish. The address of these creatures is here truly wonderful; for in this rapid motion, when they seem to have lost all government of themselves, they follow exactly the different windings of the road, as if they had before accurately reconnoitred, and previously settled in their minds the route they were to follow, and taken every precaution for their safety among so many irregularities. There would indeed otherwise be no possibility of travelling over such places, where the safety of the rider depends on the experience and address of his beast. But the longest habit of travelling these roads cannot entirely free them from a kind of dread or horror, which appears when they arrive at the top of a steep declivity; for they stop without being checked by the rider; and, if he inadvertently endeavours to spur them on, they continue immoveable, nor will they stir from the place till they have put themselves in the above-mentioned posture. Now it is that they seem to be actuated by reason; for they not only attentively view the road, but tremble and snort at the danger which, if the rider be not accustomed to these emotions, cannot fail of filling him with terrible ideas.