RELATION OF CAPACITY TO SLOPE. 



105 



actor is a distinct minimum. From the neigh- 

 borhood of width 0.66 foot there is increase of 

 i t in the direction of greater width, and also in 

 the direction of less width. 



(8) The position of the minimum is appar- 

 ently the same for low slopes as for high. 



(9) The minimum is most strongly marked 

 in case of the gentler slopes. 



The second group of curves all pertain to 

 grade (C) and a slope of 1.0 per cent but differ 

 in respect to discharge. Each of them shows 

 a minimum, except the curve for discharge 



Grade 



Grade (CJ 



'O W-lft. 



W-lft 



0. 



363 ft.^ec. 



I Z 



Slope 



FIGURE 31. Variations of i'i in relation to slope. 



0.093 ft. 3 /sec., which has but two fixed points. 

 They show also that 



(10) The position of the minimum is related 

 to discharge. For large discharges it is asso- 

 ciated with relatively large widths, for smaller 

 discharges with smaller widths. 



(11) The minimum is more pronounced, or 

 the associated rates of change in the index are 

 higher in case of small discharge than of large- 



Various analogies, which appear in another 

 part of this paper, render it probable that all 

 the preceding inferences are of a general char- 

 acter; but those in regard to width are not sus- 

 tained by all the data. 



The curves of the third group are based on 

 observations with grade (B) and are drawn, 

 like those of the first group, to contrast the 

 relations of the index to width for different 



