ADJUSTMENT OF OBSERVATIONS. 



75 



It is sometimes desirable to treat duty as a 

 volume of debris, including voids that is, as 

 the space occupied by debris as a deposit, 

 either before or after transportation. In such 

 cases the American engineer commonly uses 

 the cubic yard as a unit of volume and 24 hours 

 as a unit of time. To obtain the approximate 

 duty in cubic yards of debris per 24 hours, 

 divide the duty in gm./sec. by 14. The exact 

 value of the appropriate divisor depends on the 



specific gravity of the debris particles and on 

 the percentage of voids in the debris aggregate. 



EFFICIENCY. 



The measure of efficiency, as defined on page 



Q 



36, is E ^770- The computed efficiencies are 

 V* 



tabulated in Table 12, along with the adjusted 

 capacities and duties. 



TABLE 12. Adjusted values of capacity, based on data of Table 4, with corresponding values of duty and efficiency. 



it., grade of debris; to, width of experiment trough in feet; Q, discharge in cubic feet per second; S, slope of channel bed, in per cent; C, capa 

 for stream traction, in grams per second; C/,duty of water for traction,-^: , efficiency of current,-^.] 



