266 Molesworth’s pocket-book
Discharge of Channels. (Bazin.)
r = Mean hydraulic depth in feet.
s — yaii Of water surface in any distance divided by that
distance.
v — Maximum surface velocity in feet per second.
V = Mean velocity in feet per second.
K = Coefficient—depending upon character of bed.
C = Coefficient of discharge.
Kj = \/ 1 4- -0000045 ^10-16 + “ ) for fine plaster
sides and bed.
K2 = 1 T- -000013 ^4-354 + -i-) for cut stone or
brickwork.
K3 = 1 "i" ‘00006 (1-219 + — ) rubble masonry.
K4 = 1 4- -00035 (-2438 + earth.
c==__
K + 25-3
V=kV’,! = C’’ when r exceeds 20.
r 1 2 4 6 8 10 15 20
Kl 141 144 146 147 147 147 147 147
k2 118 124 128 129 130 130 130 131
Ks 87 98 106 110 111 112 114 114
k4 48 62 76 84 88 91 96 98
•85 •85 •85 •85 •85 •85 •85 •85
C2 •82 •83 •83 •84 •84 •84 •84 •84
c3 ■11 •79 •81 •81 •81 •82 •82 •82
C4 •65 •71 ■15 •11 •lå ■lå •79 •80
Determination of Mean Velocity of Water in Canals. |
Major Cunningham has established by experiment that the
actual velocity of a floating thin, vertical rod reaching from
the surface nearly to the bed, is very nearly equal to the
mean velocity of the vertical plane in which it moves. The
float is a hollow cylindrical tube of sheet tin, about 1 Inch
diameter, loaded with rod iron at the bottom, so that the top
projects 2 or 3 inches above the surface of the water: the
whole Is hermetically sealed and painted.