OF WESTERN SOUTH AMERICA, 139 



temperature ou the coast throughout a great part of the year is 

 nearly the same — from 68° to 70° Eahr. As we approach the 

 southern tropic, differences of season become marked ; and in 

 Southern Peru and Xorthern Chili we encounter di"fferences of 

 from 10 to 12 degrees of Fahrenheit between the means of 

 summer and whiter. Throughout the whole region the mean 

 temperature increases inhmd, even at considerable heights on the 

 slopes of the Andes, as the influence of the southerly currents 

 becomes less effective *. 



Somewhat south of Copiapo the desert region of Western South 

 America becomes gradually modified ; the climate passes slowly 

 from the state of excessive aridity to a medium condition some- 

 what resembling that of the drier parts of Southern Europe, 

 where occasional, and sometimes heavy, rain in winter is succeeded 

 by a long dry summer. Such is the character of the climate of 

 Central Chili between the parallels of 3V and 36"^ S. latitude ; and 

 it is marked by the ap|)earance of a peculiar flora, including a 

 large number of endemic genera as well as species, for the most 

 part nearly allied to forms inhabiting the middle and higher zones 

 of the Andes. Even at Coquimbo, in latitude 30^ S., where the 

 average annual rainfall is said to be only about Ik inch, a good 

 many of the characteristic types of the flora of Central Chili are 

 able to maintain themselves. It should be remarked that through- 

 out the so-called rainless zone of Peru and Chili fogs fre([uently 

 rest in winter on the hills near the coast, and that an appreciable 

 amount of precipitation in the form of dew must be deposited. 

 To this we must attribute the appearance of a comparatively 

 abundant vegetation at that season, which has been observed at 

 several places on the coast, as, for instance, on the hills about 

 Lima. A recent journey of Professor Fricdrich Philippi has 

 made known the curious fact that on some of the liigher ranges 

 near the coast of Northern Chili, where cloud or fog is seen to 

 rest during a great part of the year, abundant vegetation exists, 

 including several plants of the moist region of Southern Chili, 

 This ceases abruptly at the lower limit to which tixe cloud habitu- 

 ally extends. 



In Southern Chili a very rapid change of climate occurs, owing 

 to the influence of relatively warm westerly winds, which appa- 



In his excellent * Handbueli der Klimatologie,' p. 127, Dr. Ilauu lias dis- 

 cussed the general causes which, in tropical and subtropical regions, depress the 

 coast- temperature on the western side of continents and raise it on the eastern 

 coasts. 



