To add to their distress, the air was filled for several days with thick clouds of earthy particles and cinders, which blinded the men, and made respiration exceedingly difficult.11 This phenomenon, it seems probable, was caused by an eruption of the distant Cotopaxi, which, about twelve leagues southeast of Quito, rears up its colossal and perfectly symmetrical cone far above the limits of eternal snow,--the most beautiful and the most terrible of the American volcanoes.12 At the time of Alvarado's expedition, it was in a state of eruption, the earliest instance of the kind on record, though doubtless not the earliest.13 Since that period, it has been in frequent commotion, sending up its sheets of flame to the height of half a mile, spouting forth cataracts of lava that have overwhelmed towns and villages in their career, and shaking the earth with subterraneous thunders, that, at the distance of more than a hundred leagues, sounded like the reports of artillery!14 Alvarado's followers, unacquainted with the cause of the phenomenon, as they wandered over tracts buried in snow,--the sight of which was strange to them,--in an atmosphere laden with ashes, became bewildered by this confusion of the elements, which Nature seemed to have contrived purposely for their destruction. Some of these men were the soldiers of Cortes, steeled by many a painful march, and many a sharp encounter with the Aztecs. But this war of the elements, they now confessed, was mightier than all. At length, Alvarado, after sufferings, which even the most hardy, probably, could have endured but a few days longer, emerged from the Snowy Pass, and came on the elevated table-land, which spreads out, at the height of more than nine thousand feet above the ocean, in the neighborhood of Riobamba. But one fourth of his gallant army had been left to feed the condor in the wilderness, besides the greater part, at least two thousand, of his Indian auxiliaries. A great number of his horses, too, had perished; and the men and horses that escaped were all of them more or less injured by the cold and the extremity of suffering.--Such was the terrible passage of the Puertos Nevados, which I have only briefly noticed as an episode to the Peruvian conquest, but the account of which, in all its details, though it occupied but a few weeks in duration, would give one a better idea of the difficulties encountered by the Spanish cavaliers, than volumes of ordinary narrative.15 As Alvarado, after halting some time to restore his exhausted troops, began his march across the broad plateau, he was astonished by seeing the prints of horses' hoofs on the soil. Spaniards, then, had been there before him, and, after all his toil and suffering, others had forestalled him in the enterprise against Quito! It is necessary to say a few words in explanation of this.