CLIMATE OF CHILI. 433 



north to south. On the other hand, it varies everywhere with the altitude, so that 

 every district in Chili has its special climate. 



Under equal latitudes the mean temperature on the west side of the New 

 World is distinctly lower than on the east side, on an average about 6° Fahr. 

 Hence a climate corresponding in Chili to that of Buenos Ayres in respect of its 

 mean annual heat must be sought 9° of latitude farther north, that is to say, in 

 the Atacama Desert. 



In Chili the two extreme seasons, summer and winter, are clearly marked, 

 and, speaking generally, all the inhabited part may be said to lie in the temperate 

 zone south of the southern tropic. The central district between Santiago and 

 Valparaiso is traversed by the 33rd degree of south latitude, and consequently lies 

 in the heart of the temperate zone, where considerable contrasts occur between the 

 different periods of the year. Thus at Valparaiso the mean summer temperature 

 exceeds that of winter by about 11° Fahr. In South Chili, as, for instance, at 

 Valdivia, the contrast is still more marked, and corresponds to the differences 

 observed in West Europe. 



With the alternations of heat and cold coincides a shifting of the aerial 

 currents, for the persistent trade winds, being intercepted by the cordilleras, are 

 not felt on the low-lying Chilian coastlands. By the physical conformation of the 

 land, which is disposed in the direction from north to south, the atmospheric 

 currents are compelled to take the same meridional direction, either from the pole 

 towards the equator or from the equator towards the pole. In spring and 

 summer the southern or polar winds are predominant ; in winter the northern or 

 equatorial prevail. 



But when these general winds blow with less vigour, the aerial movements are 

 limited to the play of the land and sea breezes, the former prevailing at night, the 

 latter refreshing the atmosphere on the inland plains during the day. At times 

 the terrales, as the land breezes are called, assume the character of tmmontanas. 

 llising on the Argentine pampas east of the Cordillera, they also take the name of 

 puelches, which is the appellation given to the Patagonian tribes of the interior by 

 the western Araucanians. These puelches usually coincide with the normal trade 

 winds, the result being often somewhat analogous to that of the P^^renean autan, 

 or of the vnudaire and foehn of the Valais and the Grisons in the Swiss Alps. 

 They are alternately hot and cold, and towards the end of summer, when they 

 sweep down from the Andes over the southern plains of Chili after traversing the 

 arid Argentine pampas, they bring a stifling atmosphere, which raises the normal 

 temperature of the laud 16° or 18° Fahr. At the end of winter and beginning 

 of spring the reverse phenomenon takes place ; at tbis period they arrive after 

 traversing vast stretches of snowy wastes, and consequently lower the temperature 

 by as many degrees as they had raised it six months previously. 



Both North Chili proper and, still more, the lately-annexed Peruvian and 



Bolivian provinces fall within the rainless zone. For a distance of " about 600 



miles (farther than from Liverpool to Oporto) there is no inhabited place, with the 



possible exception of Pisagua, where drinkable water is to be had. Nowhere in 



29 



