269
OF ENGINEEB1NG FORMULÆ.
Flow of Water in Channels. Comparison of Formulæ.
R = Mean hydraulic depth in feet =. Area of cross-section
4- wetted perimeter. S = Sine of slope.
v = Velocity in feet per second.
Young’s coefficient, v = 84'3 4/ R S; Leslie for small streams,
•u=i68-8 J RS;
Eytelwein, u — 93-4 K S; Beardmore, i> = 94 - 2 nJ RS;
Leslie for large streams, D’AuMsson, Downing, v = 100 ;
Prony, i>=103 ^/k S -0’236; Welsbach,« = 99'92 ^/jR, S — ’0154 ;
Girard, t> = 102'8 V&S' — 1’64 ; St. Venant, i> = 106 4^(R S)'1;
Eilet, v = 0 • 64 ,\/ d h + • 04 d h, where d = the maximum
depth of the stream and h = fall of water per mile;
Neville, t>=93 V&S - -02; Provis, t>=60 VO + 120 4/7R S)Z;
Kutter, v =; G \/ ll S (see Kutter’s formula for value of C) ;
Bazin, u = C R S (see Bazin’s „ „ „ „ );
Humphreys and Abbott, s = C VR§, where C - - -86 g
Vs
and x varies from -85 to • 97 ;
_ 1. . 88’51 (VR — •03')
Dubuat, i>_ ........——--■===-. -O84(VK- -03);
v o-hyp- log-V s-i-6
/ }!S / B \2 B u
Young, v = ~ + , where
/ 1*5625 90 15 ■ \
A = -0000001 ( 413 + —-----——- - —---------— ), and
\ K 3 R + 8 4R + -03/
( 900 R2 1 / 6-88 * 0001146
Comparative Results of Formulæ in Rivers of various
Magnitude. (Stevenson.)
24-22
2123
31864
1 15 millions.
Actual discharge,
feet per second.
3 3
•770
36-9
2560
28 04
2083
464
2033
39938
1-49
22491 22357
1-218 *943
23389
•908
32 5
2987
16931
•675
41-23
27-69
• 25031
•972