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POPULAR SCIENCE MONTHLY. 



It follows that the prevention of surface evaporation, to the 

 utmost extent possible, is of the first importance. 



Now, the simplest, cheapest, and most universally practicable 

 mode of diminishing evaporation from a bare land surface is to 



3 6 9 12 



First VFooi Second^ Foot 

 Depth of Soil Column - 





keep it constantly in loose, fine tilth, to a depth which varies with 

 soil and climate. In humid climates four inches has been found 



