?A 



BULLETIX 835, U. S. DEPAETAIEXT OE AGRICULTURE. 



served in nearly all of the flumes tliat less water is required per inch 

 about the third day than at any other time. In all cases, however, 

 more water was required per inch at the end than was required at the 

 beginning of the experiment. It is observed that for soils of the 

 heavier type represented in flume 54, for some time after the com- 

 mencement of the experiment less water is required per inch than 

 for the following day, but after about the thirtieth day there is a 

 very rapid increase of the water requirements. It is probable that 

 there is some concentration of moisture at the top of the vertical lift 

 before the' moisture changes direction to the inclined part of the flume 

 and that this moisture is partially drawn upon to advance the mois- 

 ture in the inclined part of the flume. After a few days this surplus 

 supply, if such it may be called, is exhausted and then the moisture 

 to advance the wetted area in the flume can be derived only from the 

 supply in the tank. It must be kept in mind also that with the lapse 

 of time a greater wetted area is exposed to evaporation, and this in 

 itself would account for some additional water requirement per inch. 

 In some* cases the water requirement per inch at the end of the for- 

 tieth day was about double the requirement the first day. but in the 

 heavier soils this is not so j>ronounced. 



Table 20. 



-Water used to advance moisture 1 inch at different times, in cuMc 

 centimeters. 



Number 

 of days. 



-lume. 



^ 



34 



54 



74 



94 



294 



1 

 3 

 5 

 10 

 15 

 20 

 30 

 40 

 50 

 57 



c. c. 

 319 

 346 

 425 

 450 

 545 



c. c. 

 3S5 

 447 

 498 

 533 

 569 

 607 

 684 



c. c . 

 743 

 707 

 700 

 677 

 680 

 697 

 735 

 806 

 846 

 884 



c. c. 

 290 

 338 

 336 



364 



411 

 419 

 507 

 567 



c. c. 

 666 

 562 

 671 

 597 

 634 

 647 

 724 



c. c. 

 311 

 360 









































FLUMES INCLINED UPWARD FROM THE HORIZONTAL AT AN ANGLE OF 15°. 



To throw some light upon the effect of a relatively small inclina- 

 tion of the flumes upward from the horizontal, the data will be given 

 and discussed for the flumes inclined upward at an angle of 15° and 

 open on top to evaporation. The flumes are the same in every respect 

 as the others, except the angle of inclination. In these flumes there 

 is a vertical lift of 4 inches before a change is made in the direction 

 of the flumes. 



They show a much less movement of the moisture and a much less 

 use of water than the horizontal flumes, but a more extended move- 

 ment of the moisture and greater use of water than the vertical 

 flumes. 



