EXPERIMENT STATION BULLETINS. 



509 



The foregoing exposition as to the cause and mechanism of the phe- 

 nomena of thermal water translocation, will probably be made more clear 

 by figure 3. This diagramatic representation, however, by no means pic- 

 tures the real cause and mechanism,' absolutely and accurately, but it 

 will serve, it is believed, to make what has already been said more clear. 



Let the ordinate represent the eftective pull of the cold column of soil, 

 and the willingness of the warm column of soil to part with water, at 



T=>£:ncnNT or MO/i5TUTi^ 



FIG. 3. CURVE ILLUSTRATING THE CAUSE AND MECHANISM OF THE THERMAL 

 AIOVEMENT OF WATER IN SOILS OF UNIFORM MOISTURE CONTENT. 



different moisture content; and the abscissa, the different percentages 

 of water contained by the soil. By plotting the effective i>ull and willing- 

 ness against the moisture content it will be seen that the effective pull 

 decreases and the willingness increases, with rise in moisture content. 

 At the point where the two lines cross probably occurs the maximum 

 thermal translocation of water. After this point of intersection, the 

 willingness of the warm soil to give up water is large, but since the ef- 

 fective pull is being reduced to minimum, the water is not moved. If 

 now a parabola is drawn along the lines Wl* with its maximum value at 



