THE FLOW OF WATER IN" CONCRETE PIPE. 67 



and other obstructions. To convey water from -which deposits are not to be expected. 

 May be more freely assumed where high velocities will be attained. 



n=0.013 for well-made pipes, carefully jointed or monolithic without appreciable 

 shoulders, for waters containing a small amount of sewage. May be used also for 

 designing sewers where conditions are such that high velocities may be attained with 

 flushing streams. Applicable to storm sewers which carry but little deposit-creating 

 material at peak load, but which may have a heavy deposit of grease at the high -water 

 line of ordinary sewage flow. Recommended by Metcalf and Eddy for "concrete 

 sewers under good ordinary conditions of work." 1 



The values of n in the Manning formula are sufficiently close to 

 those in the Kutter formula that the same values may be used by 

 engineers partial to the Manning formula. The chief advantage of 

 the latter is its simplicity of computation, but as the Kutter formula 

 is practically never computed outside of a schoolroom — diagrams 

 being quite generally used — this objection is not material. 



For those who prefer the William-Hazen formula it would appear 

 that values for C w of 140, 130, and 120 will quite closely apply to 

 conditions as described for values of n of 0.0115, 0.012, and 0.013, 

 respectively. Figure 6, offered for the general solution of problems 

 by means of the Williams-Hazen formula, may be used for .the design 

 of open channels if the value of the hydraulic radius, R, of the pros- 

 pective water section in the open pipe, be computed into the terms 

 of the equivalent circular section of a full pipe. The value of D, 

 the diameter of the equivalent full pipe, may be computed since 

 D = 4R. 



Explanatory Notes on Table 11. 



Table 11 is similar to Table 3, but contains the data for experiments made on 

 pipes and conduits while they were but partially filled; that is, the surface of the 

 waterwas exposed to the air. In other words, the pipes and conduits were " flow lines" 

 rather than "pressure lines." With the following additions the explanation for 

 Table 3, page 20, applies to this table also. 

 Column 2. FF refers to F. C. Finkle, Los Angeles, Calif. 



AFB refers to A. F. Bruce, Glasgow, Scotland. 



E refers to Boyd Ehle, engineer on construction of Victoria Aqueduct. 



JBL refers to J. B. Lippincott, Los Angeles, Calif. 



C refers to the late F. C. Coffin. 



M refers to F. F. Moore, designing engineer, New York Board of Water 

 Supply. 



H refers to Theodore Horton, Albany, N. Y. 



P refers to Perrone, Italy. 



S, as before, refers to the writer. 



1 American Sewerage Practice, 1st ed., New York, 1914, vol. 1, p. 94. 



