CHAPTER XIII 



SEWER DIAGRAMS 



WHILE the earlier formulae were not so complex that their 

 solution was especially tedious, the later ones, and especially 

 Kutter's, are of that nature. It is therefore not only in keep- 

 ing with the general tendency of the times to reduce all com- 

 putations to graphic or other approximate and time-saving 

 methods, but it is almost a necessity if the formulae are to be 

 of practical use. 



Diagrams, to be of service, must fulfil the following condi- 

 tions: they must deal directly with the quantities of interest, 

 not with some function of those quantities; they must be on 

 a scale large enough so that the error of reading may be within 

 the allowable error of the result; they must be equally service- 

 able for all sizes, velocities, etc.; they must be so constructed 

 as to give well-defined intersections at all parts. An advan- 

 tage of the diagram, besides the time and labor saved, lies in 

 the possibility of comparing of the quantities involved, and this 

 should not be overlooked. 



The diagrams that have already been printed may 

 divided into two classes: first, those based on Latham's tables 

 or Eytelwein's formula; and second, those based on Kutter's 

 formula or on modifications of it, such as Flynn's tables. 



Of the first class may be cited the extensive diagrams of Mr. 

 W. T. Olive printed in the Proc. Inst. C. E., Vol. XCIII, p. 383, 

 very elaborate and complete and models of the sort. 



In the same publication, Vol. XCVI, p. 268, are diagrams 

 giving discharges as before, and also giving the relations between 

 the velocities and discharge at different depths in both circular 

 and egg-shaped sewers. 



The diagrams in the " Separate System of Sewage," first 



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