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 
Z> = 4#. 
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. 
