RAINFALL AND EVAPORATION 



1894 (annual average 15-16 inches), by 

 only half an inch. Thus the only safe 

 criterion of the rainfall of any region is 

 the average amount for a period of at 

 least ten years. And it is satisfactory to 

 reflect, as Briggs remarks, that the Settle- 

 ment of the Great Plains has been made 

 on a normal rainfall which is far bet- 

 ter than an agriculture established dur- 

 ing a series of abnormally wet or dry 

 years. 



Evaporation. 



So far as the writer is aware. Dr. 

 Briggs of Washington was the first to 

 call attention to the enormous impor- 

 tance of evaporation in relation to dry- 

 farming. And this is a matter of equal 

 if not greater importance to the South 

 African farmer in a land of hot suns, 

 bare veldt, and dry, sweeping winds. To 

 watch a terrific thunder-storm, to see riv- 

 97 



