THE SOIL 



55 



water, and the water which is forced from the canal spreads 

 in a horizontal direction. Hence when land suffers from 

 infiltration water there is always wet soil, but not neces- 

 sarily a high water-table. The damage resulting from 

 infiltration is that caused by the saturation of the soil 

 with stagnant airless water and the salting of the soil 

 consequent on the evaporation of that water. 



Sandy ,r Dry Soil. 



Cl*y erWet Soil 



Higher Itve/ Canal 







Fie. 2. INFILTRATION- OF WATKK FROM CANALS. 



We know that the soil above the water table contains 

 moisture and it is important to know in what way that 

 water is raised there and how it is held. 



The explanation lies in the property possessed by water 

 in common with all liquids of exhibiting the phenomenon 

 of surface tension. 



We may study this property as follows : 



(1) If we dip a small particle into water and withdraw 

 it we find it covered with a thin film of water which 



