Capillary Movements of Soil Moisture. 105 



On this basis spherical soil grains of one size and the 

 closest packing, having diameters of 



m. m. m. m. m m. m. m. m. m. 

 1. .5 .1 .05 .01 



would form capillary tubes whose largest cross sections 

 are nearly equivalent in area to circles having diameters of 



m. m. m. m. m. tn. m. m. m. m. 

 .289 .1445 .0289 .01445 .00289 



Did such soil grains have the attractive power of glass 

 for water and were their triangular pores capable of rais- 

 ing water to the height of circular tubes of equivalent 

 cross sections they should be able to lift water at 32 F. 

 to very nearly the height of 



.4ft .8ft. 4ft. 8 ft. and 40 ft. respectively. 



194. Observed Height of Capillary Rise of Soil Moisture. 



To measure the rise of water by capillarity in ordinary 

 soils four cylinders, 10 feet long and .04611 sq. ft. in sec- 

 tion, were filled, two with a sandy loam and two with 

 a clay loam, the first containing 18.88 per cent, and the 

 second 32.63 per cent, of water uniformly distributed 

 throughout the columns. On one of each set of tubes a 

 soil mulch was developed 3 inches deep, when they were 

 all placed in front of a ventilator where a current of air 

 was maintained across their tops during 314 days. At 

 the end of this time the tubes were cut into 6-inch sec- 

 tions and the water content of the soil determined, with 

 the results given in the table which follows: 



It is clear from this table that there has been an up- 

 ward movement of water and loss through the surface 

 even from the bottom layers of soil in the case of the 

 medium clay, and probably also from the sandy loam. 

 This follows from the fact that the clay soil contained, 

 when put into the cylinders, 32.63 per cent., whereas the 

 lower six inches is 1.38 per cent, drier in the mulched cyl- 

 inder and 3.17 per cent, drier in the cylinder not mulched. 



