DISTRIBUTION OF RAINFALL. 143 



In discussing the causes that have operated on the 



development of the Chihan flora, the same eminent 



writer has been misled by incomplete and erroneous 



information as to the climate of the region in question, 



and more especially as to the distribution of rainfall, 



which is no doubt the most important factor. It is 



true that the peculiar character of the Chilian climate 



makes it very difficult to express by averages the 



facts that mainly influence organic life. Between the 



northern desert region, where rain in a measurable 



quantity is an exceptional phenomenon, and the 



southern forest region, extending from the Straits of 



Magellan to the province of Valdivia, Central Chili 



has in ordinary years a long, dry, rainless summer, 



followed by rather scanty rainfall at intervals from 



the late autumn to spring. About once in four or 



five }'ears an exceptional season recurs, when rain 



falls in summer as well as winter, and in which the 



total fall may be double the usual amount, and at 



longer intervals, usually after a severe earthquake, 



storms causing formidable inundations occur, when 



in a few days the rainfall may exceed the ordinary 



amount for an entire year. When several such storms 



are repeated in the same year, we may have a total 



rainfall of three or four times the ordinary average.* 



* The last season of excessive rainfall was that of 1877- I have seen 

 no complete returns, but it appears that the rain of that year com- 

 menced in Central Chili in Februar)', a very rare phenomenon ; that 

 more than six inches of rain fell in April, of which, at Santiago, four 

 inches fell in twenty-four hours. More heavy rain fell in May, and 

 finally in July a succession of storms flooded large districts, destroying 

 property and life, the fall for the month being more than fourteen inches 

 at Valparaiso. Much interesting information respecting the climate of 

 Chili will be found in a, work by Don B. Vicuna Mackenna, "Ensayo 



