Deserts i r 5 



There is no doubt whatever that where forests have 

 been recklessly destroyed there the climate has been 

 most seriously injured. The Ceylon coffee-planters 

 cut down forests to make more room for their planta- 

 tions, and many of them were ruined in consequence. 

 The trees were gone, but so, to a large extent, was the 

 rain also ; and the additional space gained was value- 

 less, for the coffee could not grow for lack of moisture. 



So, also, the destruction of the olive-trees in Pales- 

 tine has diminished the rainfall there, and with the 

 rainfall the productiveness of the land, for centuries 

 past. Now that trees have been planted again, the 

 rain is said to be returning. 



So much, then, is certain : cut down forests and you 

 will have less rain ; and, though the natives of 

 Namaqua Land, South Africa, attributed the great 

 diminution in their rainfall to the presence of the 

 missionaries, others had no hesitation in ascribing it to 

 their own wasteful way of cutting wood. 



But though loss of forest brings loss of rain, it is 

 dif&cult to say precisely how the change is brought 

 about, and whether rain is actually caused by transpira- 

 tion or not. 



Wherever there is vegetation, be it grass or be it 

 forest, there, as has been shown, large quantities of 

 water are constantly passing off into the air in the form 

 of vapour. And the amount is large, not merely con- 

 sidering the means by which it is pumped up, but it is 

 large actually ; very large, when we compare it with the 

 amount of rain which falls. 



For instance, from the record kept at Greenwich it 

 appears that during July, our wettest month, the 

 average fall of rain is something under three hundred 



