230 SOILS: PROFEBTIES AND MANAGEMENT 



supporting power of the films. As a silt soil contains a 

 larger number of such angles, its capillary pull is greater 

 than that of a sand, and consequently the ultimate move- 

 ment would be of greater scope. The finer the texture, 

 then, the slower is the rate of capillary movement but the 

 greater is the distance.^ 



The relation of texture to rate and height of capillary 

 movement in dry soil is shown by the following un- 

 published data, obtained in the laboratory of the Depart- 

 ment of Soil Technology, Cornell University : — 



Effect of Texture on Rate and Height of Capillary 

 Rise from a Water Table through Dry Soil 



Soil 



1 HOUB 



1 Day 



2 Days 



3 Days 



4 Days 



5 Days 



Sand . . . 

 Clay . . . 

 Silt .... 



Inches 



3.5 



.5 



2.5 



Inches 



5.0 



5.7 

 14.5 



Inches 



5.9 



8.9 



20.6 



Inches 



6.8 

 10.9 



24.2 



Inches 



6.8 

 12.2 

 26.2 



Inches 



6.9 

 13.3 

 27.4 



It is seen that the movement in sand is rapid, one-half 

 of the total rise being attained in one hour. The maxi- 

 mum height is reached in about three days. The silt in 

 this case seems to be of just about the right textural con- 

 ditioa for a fairly rapid rise, yet it exerts enough capil- 

 lary pull to attain a good distance above the water table. 

 The friction in the clay is greater, however, and this 

 results in a slower rate. Whether the clay would ever be 

 able to exhibit a rise comparable with its tremendous puU- 



^WoUny, E. Untersueliungen uber die Kapillare Leitung 

 des Wassers im Boden. Forsch. a. d. Gebiete d. Agri.-Pliysik, 

 Band 7, Seite 269-308. 1884. Also, Forseh. a. d. Gebiete d. 

 Agri.-Physik, Band 8, Seite 206-220. 1885. 



