32 



BULLETIN 835, U. S. DEPARTMENT OF AGRICULTURE. 



Table 17. — Comparative movement ^ of moisture, 

 in percentages of movement in flume 34- 



teorological 

 might have 



any other flumes, although flume 94 maintained nearly the same rate 

 after the first day. In view of the fact that these flumes were oper- 

 ated at different seasons of the year, it is not possible to say to what 



extent the variable me- 

 conditions 

 influenced 

 the results. 



In Table 18 there is 

 shown for each flume 

 the percentage of the 

 total distance moved in 

 30 days that had been 

 moved in 1, 3, 5, 10, 15, 

 and 20 days. 



Table 18 shows in an- 

 other way what has been 

 previously stated. The heavier soil and less porous soils show a rel- 

 atively greater percentage of movement of moisture the first day or 

 two and a relatively slower rate of movement the last few days. The 

 lighter and more porous soils show the more uniform and more ex- 

 tended movement of the moisture. It is found that in all the flumes, 

 in 5 days, or one-sixth of the 30 days, more than one-third of the 

 total 30-day distance was traveled; in 10 days, or one-third of the 

 time, more than one-half the distance has been traveled, and in 20 

 days, or two-thirds of the time, more than four-fifths the distance 

 has been covered. 



In the discussion previously given of these flumes only the 30-day 

 limit of time was used. However 

 54, the heavy Whittier soil, 









Flume. 







Number 

 of clays. 

























4 



34 



54 



~4 



94 





Per cent. 



Per cent. 



Per cent. 



Per cent. 



Per cent. 



1 



Ill 



100 



41 



85 



82 



3 



111 



100 



42 



87 



85 



5 



108 



100 



39 



87 



87 



10 



102 



100 



34 



79 



83 



15 



99 



100 



31 



78 



78 



20 

 30 





100 

 100 



29 



27 



78 

 75 



78 

 80 







in figure 4 the curve for flume 



Table 18. — Movement of moisture ly 

 days, in percentages of total move- 

 ment in 30 days. 



shows that after 30 days the 

 rate of movement of the mois- 

 ture continues to grow less and 

 less every day, although there is 

 considerable uniformity in the 

 rate of decrease of movement. 

 The figures would indicate that 

 the movement of moisture 

 would reach a considerably 

 greater distance than that 

 shown upon the figure. It is 

 seen that in flume 74 (Upland soil) after 47 days the rate of movement 

 of the moisture is not much less than it was at 30 days, and the evi- 

 dence is that the moisture would continue to move in this flume rather 

 indefinitely ; especially would this be true were evaporation prevented. 







Flume. 





Number 

 of days. 



















34 



54 



74 



94 





Fer cent. 



Per cent. 



Per cent. 



Per cent. 



1 



14 



22 



16 



15 



3 



28 



37 



29 



26 



5 



32 



46 



37 



35 



10 



50 



62 



53 



52 



15 



65 



74 



68 



65 



20 



79 



85 



82 



80 



30 



100 



100 



100 



100 



