Aug. 20, 1917 



Relation of Soil Water Movement 



401 



quickly as possible. As soon as the water in the trays had disappeared, 

 the cylinders were righted. All was absorbed by capillarity except 

 that with the coarsest sands, and, in the case of these, the small volume 

 of water remaining, 10 to 15 c. c, was added to the surface after the 

 cylinders had been righted. Protected from evaporation and direct 

 sunlight, they were allowed to stand for five days, during which time, 

 at intervals of i, 3, and 24 hours, 2, 3, 4, and 5 days, the depth of 

 penetration of the water was marked on the cylinders by means of a 

 fat pencil. In the first and second experiments the depth of penetra- 

 tion was distinctly indicated by the change in color of the soil, but with 

 the moister soils of the third experiment the exact depth of penetra- 

 tion was much more difficult to recognize, a fact to which Wollny has 

 called attention (17, p. 278-279); and with soils B and D it soon 

 became impossible. The data are reported in Table VIII. The initial 

 water content in the three experiments I, II, and III was approximately 

 0.5, i.o, 1.5 times the hygroscopic coefficient, respectively. Although 

 we actually recorded the measurements of the distance of penetration 

 in millimeters, the data are given in inches so as to permit a readier 

 comparison with field moisture data as ordinarily reported in this 

 country. 



Table VII. — Initial moisture condition of the soil in the different experiments 



100304°— 17- 



