CHAPTER VI. RELATION OF CAPACITY TO FINENESS OF DEBRIS. 



FORMULATION. 



To study the laws affecting the control of ca- 

 pacity for traction by fineness of debris, capaci- 

 ties should be compared which are subject to 

 like conditions in all other respects. For this 

 purpose data from Table 12 were arranged as 

 in Table 43, where the capacities in each hori- 

 zontal line are conditioned by the same slope, 

 discharge, and width of channel. Ah 1 the data 

 of that table pertain to a slope of 1.0 per cent; 

 but similar tables were constructed for slopes 

 of 0.5, 0.7, 1.4, and 2.0 per cent. 



The same data were also plotted on logarith- 

 mic paper; and, after a preliminary examina- 

 tion, five sets were selected for special investi- 

 gation. The plots of these appear in figure 50, 

 where ordinates are logarithms of capacity and 

 abscissas are logarithms of linear fineness. It 

 is to be noted that the zero of log C is not the 

 same for the different graphs. The graphs were 

 moved up or down, so as to avoid confusion 

 through intersection. 



The first law illustrated by the plots is that 

 capacity increases as fineness increases; the 

 second, that it increases more rapidly for small 

 fineness than for great fineness. Despite ir- 

 regularities of the data it is evident that the 



locus of log C=f (log F) is a curve, and that the 

 function has a general resemblance to those 



fjfj (G> (F) 



(B)fA) 



FIGUKE 50. Logarithmic plots of capacity for traction in relation to 

 fineness of de'bris; corresponding to data in Table 44. 



found in comparing capacity with slope and 

 discharge. 



TABLE 43. Values of capacity for traction, arranged to illustrate the relation of capacity to grades of debris. 



150 



