AMPLIFICATION OF THE LAW OF POISBUTLLE 41

P is the pressure gradient and n is the constant. In the
first regime n = 1 and we have

P = KI
It> may be remarked here that hydraulicians have usually

p

<Jl

o.o,

&±

0.0 ' 0.05 0.1<D 0.15

Slope of Pressure in Water

FIG. 12.-—Efflux-shear curves passing through, tie critical regime.

.

Log Velociffes

-. 13.—A better mothod for bringing out tjh© charaeteristics of the viscous,
hydraulic, and critical regimes,

exnployed the expressions

P = KP

or

P = AI H- BI*
Putting Eq. (15) in the form
logP = n logf + logK
we observe th.at the relations may be presented more forcefully by
plotting tlue logarithms of the pressure gradients as abscissas