CAUSES OF DROUGHT. 19 



cultivated country. The open sandy country with 

 scattered trees and shrubs or occasional thickets, which 

 is found at Santarem and Monte- Alegre on the lower 

 Amazon, are examples, as well as the open cultivated 

 plains of Southern Celebes ; but in both cases the forest 

 country in adjacent districts has a moister and more 

 uniform climate, so that it seems probable that the 

 nature of the soil or the artificial clearing away of the 

 forests, are important agents in producing the departure 

 from the typical equatorial climate observed in such 

 districts. The almost rainless district of Ceara on the 

 North -East coast of Brazil and only a few degrees south 

 of the equator, is a striking example of the need of 

 vegetation to react on the rainfall. We have here no 

 apparent cause but the sandy soil and bare hills, which 

 when heated by the equatorial sun produce ascending 

 currents of warm air and thus prevent the condensation 

 of the atmospheric vapour, to account for such an 

 anomaly ; and there is probably no district where 

 judicious planting would produce such striking and 

 beneficial efi'ects. In Central India the scanty and 

 intermittent rainfall, with its fearful accompaniment of 

 famine, is no doubt in great part due to the absence of a 

 sufiicient proportion of forest-covering to the earth's 

 surface ; and it is to a systematic planting of all the 

 hill tops, elevated ridges, and higher slopes that we can 

 alone look for a radical cure of the evil. This would 

 almost certainly induce an increased rainfall ; but even 

 more important and more certain, is the action of forests 

 in checking evaporation from the soil and causing 

 perennial springs to flow, which may be collected in 



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