The troops now entered a rugged defile, the Bishop’s Pass,[83] as it is called, capable of easy defence against an army. Very soon they experienced a most unwelcome change of climate. Cold winds from the mountains, mingled with rain, and, as they rose still higher, with driving sleet and hail, drenched their garments, and seemed to penetrate to their very bones. The Spaniards, indeed, partially covered by their armor and thick jackets of quilted cotton, were better able to resist the weather, though their long residence in the sultry regions of the valley made them still keenly sensible to the annoyance. But the poor Indians, natives of the _tierra caliente_, with little protection in the way of covering, sank under the rude assault of the elements, and several of them perished on the road. The aspect of the country was as wild and dreary as the climate. Their route wound along the spur of the huge Cofre de Perote, which borrows its name, both in Mexican and Castilian, from the coffer-like rock on its summit.[84] It is one of the great volcanoes of New Spain. It exhibits now, indeed, no vestige of a crater on its top, but abundant traces of volcanic action at its base, where acres of lava, blackened scoriæ, and cinders proclaim the convulsions of nature, while numerous shrubs and mouldering trunks of enormous trees, among the crevices, attest the antiquity of these events. Working their toilsome way across this scene of desolation, the path often led them along the borders of precipices, down whose sheer depths of two or three thousand feet the shrinking eye might behold another climate, and see all the glowing vegetation of the tropics choking up the bottom of the ravines. After three days of this fatiguing travel, the wayworn army emerged through another defile, the _Sierra del Agua_.[85] They soon came upon an open reach of country, with a genial climate, such as belongs to the temperate latitudes of southern Europe. They had reached the level of more than seven thousand feet above the ocean, where the great sheet of table-land spreads out for hundreds of miles along the crests of the Cordilleras. The country showed signs of careful cultivation, but the products were, for the most part, not familiar to the eyes of the Spaniards. Fields and hedges of the various tribes of the cactus, the towering organum, and plantations of aloes with rich yellow clusters of flowers on their tall stems, affording drink and clothing to the Aztec, were everywhere seen. The plants of the torrid and temperate zones had disappeared, one after another, with the ascent into these elevated regions. The glossy and dark-leaved banana, the chief, as it is the cheapest, aliment of the countries below, had long since faded from the landscape. The hardy maize, however, still shone with its golden harvest in all the pride of cultivation, the great staple of the higher equally with the lower terraces of the plateau.