HYDRAULICS 



373 



will first be tried for the main A. On referring to the hydraulic 

 tables for cast-iron pipes, it is found that, for a diameter of 



24 in. and a discharge of 19 cu. ft. per sec., the value of s, or - , 



is .0052; and. since 1= 10,000, this gives fc= 10,000 X. 0052 = 52 

 ft. as the required head between R and Oi. As this is greater 



than the actual difference in elevation (600556) between R 

 and Oi, the assumed diameter is too small. Trying a 30-in. 



pipe, the value of- is found to be .0017; therefore, h =10,000 



