THE NATURAL BRIDGES. 221 



bridges of rocks, like the natural bridge in Virginia, 

 The highest of these bridges was forty-six feet in length, 

 and nearly forty in breadth; its thickness in the centre was 

 about seven feet. Humboldt experimented on its height, 

 and found it three hundred and twelve feet above the level 

 of the torrent. For the safety of travellers the Indians of 

 the valley had formed a small balustrade of reeds, ex- 

 tending along the precipitous road leading to the bridge. 



Sixty feet below this bridge was another, to which the 

 travellers were led by a narrow pathway, descending 

 along the brink of the crevice. In the middle of the 

 second bridge was a hollow of more than twenty -four feet 

 square, through which they perceived the bottom of the 

 abyss. The torrent seemed to flow through a dark ca- 

 vern, from which arose a melancholy noise, caused by 

 the numberless flights of nocturnal birds that haunted 

 the crevice. Humboldt at first mistook them for bats 

 of gigantic size. Thousands of them were seen flying 

 over the surface of the water. The Indians assured 

 him that these birds were of the size of a fowl, with 

 a curved beak and an owl's eye. They were called 

 cacas. It was impossible to catch them, on account of 

 the depth of the valley ; and they could be examined 

 only by throwing down rockets, to illumine the sides of 

 the crevice. 



Leaving the bridges of Icononzo, the travellers pursued 

 their journey until they came to the mountain of Quin- 

 diu. At the entrance of this mountain, near Ibague, 

 they saw the truncated cone of Zolima covered with per- 

 petual snow. The little river of Combeima wound along 

 a narrow valley, and forced its way across a thicket of 

 palm-trees. 



