38 



BULLETIN 835, U. S. DEPARTMENT- OF AGRICULTURE. 



Table 26. — Water used per inch of advance. 









Flume. 







Number 

 of days. 

























39 



53 



76 



E6 



206 





c. c. 



c. c. 



c. c. 



c . c. 



c. c. 



1 



406 



816 



272 



541 



297 



3 



530 



835 



245 



558 



278 



5 



543 1 



826 



266 



589 



290 



10 



531 



786 



302 



617 



325 



15 



656 



782 



327 



644 



301 



20 



573 



792 



366 



679 



348 



30 



40 

 50 



548 

 605 

 686 



840 

 891 



423 

 487 

 589 



676 

















Hume 76 at the end of the fiftieth day there was used twice as much 

 water per inch as for the first day. In flume 39 there is shown after 

 the third day somewhat of an increase in the use of water from day 

 to day, but it is much less marked than in any of the other flumes. 

 In flume 96 the use of water oix the thirtieth day is about 25 per cent 

 in excess of the use on the first day. The increase in the quantity of 



moisture required per 

 inch with the lapse of 

 time is p r o b a b 1 y due 

 largety to the effect of 

 evaporation. In flume 

 58 the distribution of 

 moisture was so uniform 

 as compared with the 

 other flumes that the 

 quantity of water in the 

 flume per inch through- 

 out its length is almost 

 the same, with the exception of the upper few inches. In the 

 other flumes there is a marked decrease in the percentage of moisture 

 from near the tank to the outer extremity of the flume. The relation 

 of the figures in this table to each other corresponds very closely with 

 the relation of the moisture equivalents for the soils represented. 



To show the amount of water removed from the tanks by the 

 flumes expressed in depth in inches on an area equal to the cross 

 section of the flumes. Table 27 is presented. 



At the end of the thir- 

 tieth day it was found 

 that the flumes had taken 

 from the tanks sufficient 

 water to cover the cross 

 section of the flumes to a 

 depth of from 16 to 40 

 inches. That is, where the 

 rate of loss is the same- 

 over the area of an acre 

 as over the area repre- 

 sented by the flumes, 

 then in 20 days the acre 

 of soil represented in flume 39 would have removed from the under- 

 ground water 16.78 acre-inches of water, while the soil represented 

 by flume 96 would have removed 39.65 acre-inches of water, or a 

 little more than twice as much. These tables are valuable in that 

 they give an indication of the quantity of water that may be removed 



Table 27. — Water removed front the tanks by 

 capillarity expressed in depth on an area equal 

 to tJie cross section of the flume. 









Hume. 







Number 

 of days. 

























39 



58 



76 



96 



206 





Inches. 



Inches. 



Inches. 



Inches. 



Inches. 



1 



4.58 



6.41 



3.05 



6.71 



4. 27 



3 



7.93 



9.15 



4.88 



12.20 



5.49 



5 



9.44 



11.59 



6.10 



16.47 



6.41 



10 



11.59 



14.03 



8.54 



23.79 



8.24 



15 



13.42 



15.56 



10.37 



29.28 



9.00 



20 



14.95 



17.08 



12. 51 



34.16 



9. 61 



30 



16.78 



19.83 



15. 99 



39.65 





40 

 50 



19.06 

 21.35 



22.42 

 25.01 



20.13 

 24.40 











