CAPILLARY MOVEMENT OF SOIL MOISTURE. 



55 



Table 38. — Movement of 

 moisture at various times, 



in inches. 



about 9 per cent in favor of the open flume. The rate of movement 

 of the moisture in the closed flume is more uniform throughout the 

 30 clays than that in the open flume. The facts just stated would 

 appear to be contrary to what might have been forecast, for the 

 reason that evaporation from the open flume would deprive that 

 flume of some of the water furnished by the wick. In the closed 

 flume practically all of the water furnished by the wick would be 

 available for the capillary action of the 

 soil. These results would indicate first 

 that in the closed flume the soil in the 

 flume proper could not use all of the water 

 that the wick was capable of furnishing. 

 This would indicate a friction factor 

 caused either from partially confined air 

 or otherwise that would not appear to 

 occur in the open flume. It is found in 

 the open flume that either from evaporation 

 or from a more ready circulation of the 

 air the capillary action of the soil within 

 the flume was stimulated or that the fric- 

 tion was reduced. From observations made in connection with other 

 experiments it seems to the writer that the fact of more rapid 

 rate of movement in the open flume at the beginning of the experi- 

 ment is due to both of these factors. It is known that " trapped *' air 



has an effect upon capillary ac- 

 tion and that evaporation would 

 stimulate the circulation of the 



Number 

 of days. 



Flume. 



70 



71 - 



i 



3 

 5 

 10 

 15 

 20 

 30 



Inches. 

 23.10 



Inches. 

 ■ 21.30 



41.70 

 ■54. 60 

 64. 00 

 70. 15 

 80.05 



41. 30 

 51. SO 

 05. 50 

 73.70 



87.10 . 



Table 39. — Quantity of water used at 

 various times, in liters, and in per- 

 centages of total used in 30 days. 







Flume. 





Number 

 of days. 



















70 



71 



70 



71 





Liters. 



Liters. 



Per cent. 



Per ccrd. 



1 



3 

 5 



6 



6 



18 



21 



12 



12 



37 



42 



10 



17 



17 



51 



59 



15 



21 



21 



64 



72 



20 



26 



24 



79 



£3 



30 



33 



20 



100 



300 



ear. 



Table 39 shows that a rela- 

 tively greater quantity of water 

 was used by the closed flume dur- 

 ing the forepart of the experi- 

 ment than was used by the open 

 flume. This is a condition which 

 would be anticipated, as evapo- 

 ration deprives the open flume of 

 part of the water furnished by 

 the wick. The table shows very clearly that the covered flume does 

 not tax the wick to its capjacity in furnishing water from the tank to 

 the flume proper. 



Table 40 gives the quantity of water required to move moisture 

 in the flivme an average distance of 1 inch for different periods 

 of time. This table does not show effects other than would have 

 been anticipated. It is observed that there is a greater use of 

 water on the thirtieth day in flume 71 than during the fore part 



