48 BULLETIN 835, IT. S. DEPARTMENT OF AGRICULTURE. 



line is curved. By trying different constants, the logarithmic line 

 changes in curvature, so that such constants may be found which 

 make the logarithmic line straight. 



Logarithmic cross-section paper may be purchased which has both 

 coordinates divided in logarithmic scale and also semilogarithmic 

 cross-section paper having one ordinate so divided. When evalua- 

 tions of equations having constant terms are to be made, these papers 

 are very convenient, since the curves may be plotted without looking 

 up the logarithms; but since the method described by Steinmetz 



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Fig. 8. — Method of developing formula for movement of moisture in flume 43. 



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requires logarithms to be tabulated in order to calculate the con- 

 stants, common cross-section paper will usually suffice. 



In figure 8 the data representing moisture movement in flume 

 13 are plotted. The values of log y and log x are also plotted and 

 found to be a straight line, so that log <y=log a-\-n log x and the 

 curve is a parabola. Table 36 gives the data, the logarithms of 

 x and y and the calculated log y as obtained from the formula which 

 was derived. . 



