EXPERIMENTS WITH MIXED GRADES. 



185 



of the load is increased, and it may even be 

 enlarged several fold. The general effect of 

 adding coarse to fine is to reduce the stream's 

 capacity for the fine, but under some conditions 

 there is a slight increase. 



The general relations of capacity to slope, 

 discharge, and fineness (and presumably to 

 form ratio also) are the same for natural and 

 other complex grades of de'bris as for the sieve- 

 sorted grades of the laboratory, but some of 

 the constants are not quite the same. 



The sensitiveness of capacity to slope is on 

 the average the same for both classes of d6bris 

 grades, but the variation of sensitiveness in 

 relation to slope, as determined by the con- 

 stant a, is somewhat less for natural grades. 



As to the relation of capacity to discharge 

 comparison was limited to a single example, 

 and that suggested no modification of the 

 constants derived from work with laboratory 

 grades. 



The sensitiveness of capacity to fineness is 

 somewhat less for natural grades than for the 

 the laboratory grades. No values of the 

 constant <f> were obtained for complex grades, 

 and comparisons of sensitiveness were made 

 only by means of the synthetic index of relative 

 variation. The average value of that index, 

 for natural grades of de'bris transported under 

 laboratory conditions, is estimated at 0.20 to 

 0.25 for bulk fineness. 



