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PNIVERSITY OF VIRGINIA PUBLICATIONS 

 Tuile I — Continued. 



12. The engineer, in the absence of a reliable formula, solves the problem 

 of the flow of water in clean pipes by compiling all the data available in 

 the form of experiments and computes either the coefficient c or m, knowing 

 the observed velocity of flow, from 



2gHj- 

 LV- 



— 1.5 



L 



(34) 



\ m 



The observations being plotted with respect to coordinate axes for 

 the variables V and in or c, the family of curves corresponding to different 

 values of the parameter D are then interpolated, thus constituting a 

 graphical table which at any time may be entered with two of the three 

 variables m, V , D, and the third read off. 



Such tables as these, as for example that of Mr. J. T. Fanning given 

 in his Water Supply Engineering in which m is given as a function of Y 

 and D; or that of Mr. Hamilton Smith, Jr., given in his Hydraulics, a 

 small table of which as prepared by Coffin is published in Public Water 

 Supplies by Tumeaure and Kussell, in which c is given as a function of 

 V and D ; may be said to constitute the most reliable, accurate and recent 

 information we possess on this subject. The writer has made use of these 

 tables as well as numerous experiments by Darcy, Weisbach, Fanning, Smith 



