THE QUANTITY DISCHARGED FROM PIPES. 195 



Q = ?cPv = 0.7854^; (1) 



and on substituting the value of v obtained from (1) of Art. 

 103, this becomes 



which gives the value of Q in cubic feet per second, since 

 all the dimensions are in feet. 



If we require the number of gallons discharged per min- 

 ute for a diameter of d inches, (1) becomes 



(3) 



where C is a constant whose value for / = .03 is 30, but 

 which is often taken somewhat less (say 27), to allow for 

 contingencies.* 



Assuming that 1 cubic foot = 6.2322 gallons, we have, 

 from (1), for the number of gallons discharged in 24 hours, 



Q = - l-tfv x 86400 x 6.2322 

 o i o 



(4) 

 From (1), we have 



which, in (1) of Art. 103, gives 



that is, the height of resistance of friction in pipes 

 varies inversely as the fifth power of the diameters, 

 and directly as the length of the pipes. 



* See Cotterill'e App, Mecbe., p. 4K. 



