capillaey jloveviext of soil, moistuee. 



39 



from underground water sources by capillary action of the soil It 

 must be kept in mind, however, that in the case of the flumes evapo- 

 ration and capillarity are acting at the same time. 



Table 28.— Distribution of 

 ture in flume 96. 



disteibtttio' of atoistcee. 



The distribution of moisture in the flumes inclined upward at an 

 angle of 15° does not differ materially from the distribution in 

 the vertical flumes. In Table 28 is 

 given the distribution of moisture in 

 'flume 96 at various times. It will be 

 noticed that in this table, as in that 

 for the vertical flumes, there is rather 

 a uniform constant quantity of mois- 

 ture near the lower end and then a 

 gradually decreasing amount to- 

 ward the toj) of the flume. The rates 

 of decrease, however, are not com- 

 parable as far as the figure- in this 

 table and those for the other flumes 

 indicate. 



In the open flumes there are several factors which account for a 

 lack of uniformity in the distribution of moisture other than the 

 mere fact of elevation above the surface of the water. The rate of 

 evaporation is different for different points of the flume due to dif- 

 ferences in moisture content of the soil (18). The concentration at 

 the surface of the soluble salts of the soil, which will be different at 

 different points throughout the flume, would cause some difference in 

 the moisture content due to lessening evaporation. 



Distance. 



Percentage of crater. 











Top 5 



Bottom 







inches. 



5 inches. 





Inches. 



Per cent. 



Per cent. 



Per cent. 



28 



28.32 



29. 66 



28. 99 



40 



28.-56 



27 



28. -- 



52 



26.70 



26.26 



26.48 



64 



24. S3 



24. 87 



24.85 



76 



25.06 



24.20 



24. 63 



88 



21.71 



21.96 



21.83 : 



94 



. ■ ■ 



20.95 



20. 77 



100 



17.25 . 



17.73 



17.49 



Table 29. — N u m 6 e r of 

 flume and angle of in- 

 clination. 



EFFECT OF GRAVITY OX THE MOVE- 

 MENT OF SOIL MOISTURE BY CAPIL- 

 LARITY. 



No. of 

 flume. 



Angle of incli- 

 nation. 



34 I 30° downward. 



32 15° downward. 



31 I Horizontal. 



39 15° upward. 



42 45° upward. 



43 Vertical. 



As stated in this report, the plan was to 

 have capillarity act in the direction of grav- 

 ity, in a direction opposed to gravity, and in 

 a horizontal direction in which gravity was 

 eliminated as far as possible. To give an idea 

 of the influence of gravity in the movement 

 of soil moisture by capillarity there are given 

 below data on a complete set of flumes containing the heavy Riverside 

 soil. T\ Tiile the other soils show considerable variation, these varia- 

 tions are almost entirely in degree and it is not thought that the ad- 

 dition of these data to this report would be of any material benefit. 

 Table 29 gives a list of the flume- in the set under consideration 

 and their angle- relative to the horizontal. 



