BULLETIN 376;, U. S. DEPARTMENT OF AGRICULTURE. 



(&) The Kutter modification of the Chezy formula, 



1-811 , ,, ^^ . 0.00281 

 h 41.66 H 



I H(«.a6.-^)^| 



^fRs (5) 



in which C is elaborated so that it takes into consideration the in- 

 fluence of the hydraulic grade and of the mean hydraulic radius and 

 introduces a new variable, n, which is supposed to represent all the 

 retarding influences. 



(c) The Weisbach formula, 



h, = fi^ (6) 



From the same field data comparison is made between the follow 

 ing formulas : 



(d) The Tutton ^ formula for flow in wood-stave pipes, 



V = CiR°-«V'5i with Ci = 129 (7) 



Ci in this formula is not to be confused with C in the Chezy formula. 



(e) The Williams-Hazen general formula ^ for many kinds of pipes 



V = CwR°-«3s»-5*0.001-«-°^ (8) 



which may be arranged in the same form as formulas 9 and 12 for 

 comparison, becoming, with Cw=120, 



-n = — ^Tm — (J*a) 



For wood-stave pipe a value for Cw of 120 is recommended by Wil- 

 liams and Hazen. This recommendation is based on their study of 

 pipes Nos. 20, 41, 44, 47, and 48, Tables 2 and 3. The exponents 

 of the formula " were selected as representing as nearly as possible 

 average conditions, as deduced from the best available records of 

 experiments upon the flow of water in such pipes and channels as 

 most frequently occur in waterworks practice." 



(f ) The Moritz formulas :^ 



TT_. 8.6V^-« 0.38 V^« ,. 



^— Jl.26 ~~ J)1.28 '"-^ 



V = 1.72Do-^H''-555 (10) 

 Q = 1.35D"Ho.555 (11) 



These three formulas express the same values from different 

 points of view. Unlike formulas 4, 5, and 6, they were developed 



1 Tutton, C. H. Journal Assoc. Engin. Socs., 23 (1899), p. 151. 



2 Hydraulic Tables, WiUiams and Hazen, 2d ed. New York, 1909. 



3 Flow of water in pipes, E. A. Moritz, Eng. Rec., 68, No. 24, p. 667. 



