GENERAL FORMULA FOR ALL THE RESISTANCES. 209 



Hence, the whole head lost in the length AB is 



or, putting P = qL, the total discharge through the ser- 

 vice pipes between A and B, (1) becomes 



The discharge at the end B of the pipe is Q P.' If 

 the pipe is so long that Q P = 0, all the water passes 

 into the service pipes, and (2) becomes 



(See Ency. Brit., Vol. XII., p. 486.) 



112. General Formula when all the Resistances 

 to the Flow of Water are Considered. Let ft l be 



the coefficient of resistance for enlargements and contrac- 

 tions (Arts. 108 and 109), and /3 2 the coefficient of resist- 

 ance for elbows and bends (Arts. 110 and 111). Then 

 adding together (3) of Art. 105, (4) of Arts. 108 and 109, 

 (1) of Arts. 110 and 111, we have for the entire head h, 



,)? + (1+3 + (3, +0,)^, (1) 



