208 FIKST BOOK OF FORESTRY 



Formerly it was claimed that the forests would increase 

 the rainfall, making the clunate moister and more equable. 

 Great scientists and travelers have spoken on both sides of 

 the question ; and for over fift}^ years attempts have been 

 made to test the truth of these things in a scientific way 

 by carefully measuring temperature, rainfall, etc. Most 

 of these experiments, however, have failed, and there is 

 still much dispute as to just how much the forest can do. 

 At present it is generally believed that the forests do not 

 change the amount of rainfall very materially, and that 

 the arid oriental countries like Egypt, Asia Minor, and 

 Persia were, even during their most glorious days, dry as 

 they now are. On the other hand, the effects explained 

 above remain valid ; and, of course, the more the condi- 

 tions favor the destructive work of the water, the more 

 apparent is this protective influence of the forest. 



Thus, parts of the French Alps were cleared off aljout 

 the end of the eighteenth and the beginning of the nine- 

 teenth century. Floods followed this clearing off with such 

 regularity and force that many villages were destroyed 

 and others abandoned because the floods covered the 

 fields often yards deep with sterile gravel and bowlders. 

 Then France began the great task of reforesting these 

 mountains ; and, though not half completed, this task has 

 already cost many millions of dollars. 

 . In our own country we are not without like examples. 

 Lack of a forest cover in Mississippi led to a gullying 



