At one point two lateral cañons opened side by side upon the San Juan. The partition was a stupendous pile of rock fifteen hundred feet in altitude, but so narrow that it seemed to the voyagers below like the single standing wall of some ruined edifice. Although the space on its summit was broad enough for a cathedral, it did not appear to them that it would afford footing to a man, while the enclosing fissures looked narrow enough to be crossed at a bound. On either side of this isolated bar of sandstone a plumb-line might have been dropped straight to the level of the river. The two chasms were tombs of shadow, where nothing ever stirred but winds. The solitude of this continuous panorama of precipices was remarkable. It was a region without man, or beast, or bird, or insect. The endless rocks, not only denuded, but eroded and scraped by the action of bygone waters, could furnish no support for animal life. A beast of prey, or even a mountain goat, would have starved here. Could a condor of the Andes have visited it, he would have spread his wings at once to leave it. Yet horrible as the scene was, it was so sublime that it fascinated. For hours, gazing at lofty masses, vast outlines, prodigious assemblages of rocky imagery, endless strokes of natural frescoing, the three adventurers either exchanged rare words of astonishment, or lay in reveries which transported them beyond earth. What Thurstane felt he could only express by recalling random lines of the "Paradise Lost." It seemed to him as if they might at any moment emerge upon the lake of burning marl, and float into the shadow of the walls of Pandemonium. He would not have felt himself carried much beyond his present circumstances, had he suddenly beheld Satan, High on a throne of royal state, which far Outshone the wealth of Ormus and of Ind. He was roused from his dreams by the quick, dry, grasshopper-like voice of Phineas Glover, asking, "What's that?" A deep whisper came up the chasm. They could hardly distinguish it when they stretched their hearing to the utmost. It seemed to steal with difficulty against the rushing flood, and then to be swept down again. It sighed threateningly for a moment, and instantaneously became silence. One might liken it to a ghost trying to advance through some castle hall, only to be borne backward by the fitful night-breeze, or by some mysterious ban. Was the desert inhabited, and by disembodied demons?