equator, preserve an equal temperature, which prevents them from being condensed into true clouds. This is certainly the cause of the extraordinary phenomenon of the total absence of thunder and tempests; and on this account it is, that a slight covering of straw, which may absorb the dews and humidity of the night, is considered as a sufficient shelter for the dwellings.
At the back of the cordillera of the coast, and in the intermediate space between it and the more elevated one which is named the royal cordillera, or the cordillera of the Andes, are situated the provinces denominated La Sierra, extending from the jurisdiction of Chachapoyas to the great mineral territory of Potosi. The summits of their lofty mountains, never freed from the immense weight of permanent snow that oppresses them, are the origin and source of the waters which, being precipitated in torrents, have gradually formed the deep and rugged excavations of the earth, denominated, in common with the streams and rivulets that intersedl them, quebradas, and in which are cultivated all the vegetable productions necessary to the sustenance of man. The declivities of these mountains afford a pasture for sheep; but the superior part of them consists of rocky surfaces, either totally bare, or covered by a weak moss.
From this description it may be deduced, that if, according to the most precise calculations, a square league can commodiously maintain eight hundred persons, as is asserted by Marshal Vauban, in his project for a royal tithe, there are in Peru tracts of twenty, and even thirty leagues in extent, which would not repay the industrious efforts of the husbandman with a single herb that would serve as pasture for the smallest
