LIST OF ILLUSTRATIONS 



facing 

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facing 



Frontispiece 



Rock disintegration by heat and cold 



Wearing action of water on rock 



Plants as soil formers 



Glacial soil and alluvial soil . 



Stratification of rock and soil 



Auger for taking soil samples 



Relative sizes of soil particles 



Graphic statement of mechanical analyses of soils . 



Scheme for determining soil class (after Whitney) . 



Ideal arrangement of soil particles .... 



Section showing structure of loam soil in good tilth 



Plowed land, showing good and poor tilth 



Apparatus for simple mechanical analysis of soil . 



Apparatus for the determination of the apparent specific 



gravity of soil 



A walking plow and its attachments 

 Cross sections of furrows turned at different angles 

 Apparatus for the estimation of organic matter in soil 

 Apparatus for estimating rate of percolation and water-holding 



capacity 



Soil particles and surrounding films of hygroscopic and capil 



lary water 



Erosion of soil by water and by wind . . . facing 

 Section of soil with and without a mulch 

 Systems of laying out tile drains . 



Drain tile outlets facing 



Sections of land showing locations of tile drains and water 



. tables 



Diagrammatic explanation of water control in a humid region 

 Apparatus for moisture measurement . . . facing 

 Apparatus for demonstration of effectiveness of mulches in 



conserving soil water 



Apparatus for observation of transpiration of water from 



* plants 



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