At the pass of Antarangra, 15,600 feet above the level of the sea, Dr Tschudi found two small lakes, scarcely thirty paces asunder. One of these is the source of the river San Mateo, which flows westward, passes Lima under the name of the Rimac, and discharges itself into the Pacific Ocean; the other sends its waters through a number of small mountain lakes to the river Pachachaca, a diminutive tributary of the mighty Amazon. The worthy doctor confesses that he could not resist the temptation to disturb the order of nature, by transporting a jug-full of the water intended for the Atlantic, into the lake communicating with the Pacific. Of a more serious cast were his reflections on the mighty power that had raised these tremendous mountains, on whose summits sea-shells and other marine substances testify to the fact of the ocean having once rolled over their materials. Between the Cordilleras and the Andes, 12,000 feet above the sea, lie the vast tracts of desolate tableland known as the Puna, a Peruvian word equivalent to the Spanish _despoblado_. These plains extend through the whole length of Peru from N.W. to S.E., a distance of 350 Spanish miles, continue through Bolivia, and run out eastward into the territory of the Argentine republic. Their sole inhabitants are a few shepherds, who live with their families in wretched huts, and tend large flocks of sheep, oxen, alpacas, and llamas, to which the yellow and meagre grasses of the Puna yield a scanty nourishment. The district is swept by the cold winds from the Cordilleras, the climate is most inhospitable, unintermitting snow and storm during four months of the year. A remarkable effect of the Puna wind is the rapid drying of dead bodies. A few days suffice to convert a dead mule into a perfect mummy, the very entrails free from corruption. Here and there the dry and piercingly cold wind, which causes extreme suffering to the traveller's eyes and skin, changes its temperature, or, it were better said, is crossed by a current of warm air, sometimes only two or three paces, at others several hundred feet, in breadth. These warm streams run in a parallel direction to each other, and Dr Tschudi deposes to having passed through five or six in the space of two leagues. He noticed them particularly in the months of August and September, and, according to his observations, their usual direction was that of the Cordillera, namely, from S.S.W. to N.N.E. He once travelled for several leagues in one of these currents, the width of which did not exceed seven-and-twenty paces. Its temperature was eleven degrees of Reaumur higher than the adjacent atmosphere. The existence of these warm streams is in some cases permanent, for the muleteers will frequently tell beforehand where they are to be met with. The causes of such singular phenomena, says Dr Tschudi, are well deserving the closest investigation of the meteorologist.