CAPILLARY MOVEMENT OE SOIL MOISTURE. 27 



Table 14 is interesting from the fact that at the end of the first 

 few days the use of water by the flumes containing the lighter soils 

 is greater than for the flumes containing the heavier soils. The use 

 of water by flume 50, containing the Whittier soil, is, after the first 

 few days, considerably slower than that by flume 200, containing the 

 light sandy Idaho soil. This fact is of importance and confirms the 

 observations in nature of the excessive loss by capillarity in convey- 

 ing channels constructed through sandy soils. This table, in con- 

 nection with figure 3, indicates the extensive and long-continued 

 capillary action in a horizontal direction in the lighter soils. 



DISTRIBUTION OF MOISTURE IN HORIZONTAL FLUMES. 



In considering the distribution of moisture in horizontal flumes 

 open on top to evaporation, it is difficult to obtain uniform comparable 

 results. This is due to the fact that the flumes were exposed to the 

 natural changes of meteorological condition and many of them were 

 in operation during the extremes of temperature. Another fact that 

 is of primary importance is the effect of temperature upon the vertical 

 distribution of moisture within the flume. With temperatures near 

 the freezing point and with the soil containing about its maximum 

 capillary capacity of moisture, a distribution of moisture is found in 

 the soil differing materially from the distribution in the same soil 

 with higher temperatures. It is not thought, therefore, of value in 

 presenting a few data to attempt any specific calculations, but only 

 general comments are made. 



In Table 15 the first column gives the date on which the sample 

 was taken ; the second column gives the distance along the top of the 

 flume, measured from the intersection of the top line of the' flume and 

 a vertical extension of the inside of the vertical part of the wick. 

 This point is 19^ inches above the water surface, measured along the 

 upper side of the wick. The third column gives percentages of 

 moisture at the various points for the top 5 inches of the flume, and 

 the fourth column for the bottom 5 inches of the flume. The fifth col- 

 umn gives the average percentages of moisture at the various points. 



Taking the average percentages of moisture in flume 31 at the same 

 point and on different dates, it is found that the percentage of mois- 

 ture gradually increases until the warmer weather in June. After 

 that time there may be a slight decrease in percentages of moisture 

 at the different points. Taking a sample at the 9-inch point, we find 

 this to be true and that the percentage of moisture on June 10 had 

 decreased about 2.2 per cent from what it was on May 23. Compar- 

 ing the percentage of moistures for the top 5 inches of soil at the 

 9-inch point, we find that throughout the entire time there was a 

 gradual increase in the percentage of moisture, while' the bottom 5 

 increased in moisture content until April and then decreased. 



