CAPILLARITY IN MOIST AND DRY SOILS 



181 



tains a small amount of water, it is to be expected that 

 the total capillary rise, and the rate of movement of 

 water, would be most rapid. That is, a slight dampness 

 of the soil is conducive to the most rapid capillary 

 movement. Briggs found the limit of capillary move- 

 ment in dry Sea Island soil light, fine, sandy loam 

 to be about 36 centimeters, or 15 inches, in 14 days; 

 while, in the same soil in a moist condition, water was 

 raised through a column 165 centimeters, or 66 inches, 

 in height 4.5 as great a height as in the dry soil. Stew- 

 art found the following limits for three sands of slightly 

 different texture when dry and wet. 



These results are in accord with field experience. 

 The figures for the moist soil most nearly represent 

 the heights to which soils raise water, and further, under 

 field conditions, the soil, with the exception of the immedi- 

 iate surface, seldom becomes air dry in the humid 

 regions. Consequently, capillary movement concerns 

 chiefly moist soils. 



There are two factors operative to prevent capillary 

 distribution from moist to dry soil. One of them is 

 resistence to wetting. The other is the very slow move- 

 ment of water in thin capillary films, that is, when 



