6o 



SMALL WATER SUPPLIES. 



and we know that there are 33,000 ft.-lbs. of energy 

 in a horse-power. Now the resistance to flow in any 

 pipe is, as we have pointed out, as the square of the 

 velocity. So, presuming there is a pipe line carrying 

 a certain quantity of water, and we are going to lay a 

 branch to take, say, 1 of the quantity. If D = diame- 

 ter of the main, what will be the diameter of the 

 branch ? Its value 



/D' 

 / 6 



(15) 



D and d being in inches, but the main would continue, 

 or reduced in size only , that is a i2-in. main would 



FIG. 47. FIG. 48. 



become a lo-in. one. A loss in pipe lines which 

 would especially affect power questions is that due 

 to bends, for which we have the following equation, 

 giving the loss of head in feet. 



V = velocity ft. per second. 



A = angle shown in fig. 47, while L appears in the 



following table, when certain values of ^ are con- 



K 



sidered, viz. the ratio of semi-diameter of the actual 

 pipe to the radius of curvature, 



