CLIMATE. The chief determining influences on the climate are the trade winds and the great differences in elevation. The country is more temperate than might be expected from its posi tion in the tropics. The trade winds coining west from the Atlantic deluge the eastern mountains, drop cold rain and snow upon the Puna, give a smaller supply of water to the central range, and moisten the plain of the Sierra to some extent. So little water is left for the maritime range that it is included with the coastal desert in the dry belt. These facts explain the aridity of the west slope of Peru. Once in seven or eight years a marvelous change conies over the face of this desert. Sufficient rain comes over the mountains to bring life out of the parched surface; grass and flowering plants appear, attracting thou sands of cattle and goats from the irrigated val leys to the new pasturage, which withers again in a few weeks. Only about inches of rain
fall in Lima in a year. The mean annual tem perature of the coast provinces is 68° F. In the hottest months. January and February, the mean temperature is between 82' and 86'. The dry heat is not oppressive: and after 11 A.M., when the torrid sun has rarefied the atmosphere over the desert, sea air comes rushing to this area of low pressure. all life is refreshed by the breeze, and often a little rain is scattered over the maritime range. In the evening. when the surface of the desert grows cool, the wind sets to sea again. inringing cool breezes from the mountains. Con ditions are nowhere unhealthful excepting in the low, hot plains of the north and east. The whole mountain region lying between 3000 and 9000 feet above the sea has a temperate and healthful cli mate. Thus in nearly all parts of Peru the cli mate is exceptional.