20 



BULLETIN 835, U. S. DEPARTMENT OF AGRICULTURE. 



Table 7.— Depth to which renter removed from tanks would cover area of 100 



square inches. 



Number 

 of days. 



Flume. 



19 



43 



63 



80 



100 



209 



1 

 2 

 3 

 4 



10 

 15 

 29 

 30 

 40 

 50 

 60 



Inches. 

 5.49 

 6.10 

 6.71 

 6.86 

 7.78 

 8.24 

 8.62 

 9.06 

 9.31 



Inches. 



4.27 

 6.10 

 6.45 

 6.71 

 7.42 

 8.08 

 8.54 

 9.36 

 9.70 

 10.00 



Inches. 

 4.88 

 6.10 

 6.71 

 7.32 

 9.00 

 10.62 

 11.35 

 12. 21 

 12.57 

 13.06 



Inches. 

 2.44 

 3.05 

 4.27 

 4.47 

 - 5. 49 

 5.86 

 6.24 

 7.17 

 7.48 



Inches. 

 4.88 

 6.71 

 8.54 

 9.72 

 12.81 

 14.34 

 14.95 

 16.17 

 17.39 

 18.37 



Inches. 

 2.59 

 2.74 

 2.82 

 2.89 







3.36 



3.86 





13.42 













Table 7 shows that if a body of water were covered with -10 inches 

 of dry soil of the type in flume 100, there would be removed from it 

 by capillarity in the first 10 days a depth of 12.81 inches of water. 



If some means were provided to remove from the end of the wetted 

 soil column in flume 100 after the end of the first day all the water the 

 soil column of this length could transmit, there would be lost from this 

 body of water at least 1.83 acre-inches each day, and in one year the 

 loss would amount to 55.66 acre-feet per acre. This, then, is the trans- 

 mitting power of the soil column at the end of the first clay. That 

 this amount is not lost each day following the first is due to the fact 

 that the soil can not take this amount by capillarity through the dis- 

 tance from the free water. If a calculation were made for this soil 

 to transmit water from the twentieth to the thirtieth day and at the 

 distance from the water to the outer extremity of the moisture at this 

 time, the transmitting power could be 3.17 acre-feet per acre per 

 year or only 6.67 per cent of the transmitting power at the end of the 

 first day. If the same calculation is made for flume 19, it is found 

 that the transmitting power of this soil for the period from the 

 twentieth to the thirtieth day is only about one-third that of flume 

 100. and about the same relative percentage at the end of the first day. 



In flume 19 it is found that the moisture has traveled upward into 

 the flume a total distance of 28.05 inches in three days and that there 

 has been removed from the tank at the end of three days a total of 

 1,100 cubic centimeters or sufficient to fill the flume to a depth of 

 6.71 inches. Using these figures, it is found that at the end of the 

 third day there was by volume 23.9 per cent of water in the 28.05 

 inches of wetted soil. By the same means of calculation Table 8 is 

 computed. 



Table 8 indicates that for a period of 30 days the light sandy 

 soils contained a smaller percentage of moisture in the wetted area 

 day by day. The heavier soils, as represented by flumes 43, 63, and 



