THE SOIL AND SOIL WATER 15 



Evaporation Rapid. Water is evaporating from the 

 soil out of doors nearly all the time when it is not raining; 

 and, as in the lamp wick the oil rises from the font as it 

 burns at the top of the wick, so the water rises from the 

 deeper soil as it evaporates at the surface. In countries 



FIG. 7. Showing the circulation of water. 



that, have frequent rains, the water rises from below 

 in dry weather nearly or quite as fast as it evapo- 

 rates, hence the soil is kept moist except at the very 

 surface. 



