GENERAL EXPLANATION 5 
K ei Flood 
n Eh Gea UBER Oe Uk Hy We NT OT ah EC 
6 k---#---- tee ee eS Iday --+-+---- >| 
5 Greater flood--> 
4 Lesser flood --~ 
3 
2 
! o 
\>+Slack water 
fo} == 5 
; ea water Slack water 
2 
3 I 
+-Lesser ebb 
4 
5 
6 
k--Greater ebb 
Ebb 
FIGURE 7.—Current in San Francisco Bay Entranco at time of rope eS: (At time of equatorial tides a normal semidiurnal current 
prevails. 
A Flood 
Knots kk ka ariel sua tntioe reac ca iia ama Setar ane RT ES TEIN fects eect addin Fae Se sat aah aT a >| 
5 Maximum flood --- ~~ 
Maximum flood--7» 
4 
3 
2 4 aie 
‘--Minimum flood 
! 
fe} . 
‘Slack water 
! 
2 
S 
4 
5 
L--Maximum ebb 
yEbb 
FIGURE 8.—Current in San Bernardino Strait, P. I., at time of tropic tides. 
of flow in the opposite direction will be decreased by a corresponding amount. This 
will tend to advance the time of one slack and retard the time of the following slack. 
If the velocity of the nontidal current exceeds that of the tidal current, the resultant 
current will flow continuously in one direction without coming to a stop. In this case 
the velocity will vary from a maximum to a minimum and back to a maximum in 
each tidal cycle. 
11. In a graphical representation of a combined tidal and nontidal current, the 
shape of the plotted curve is not affected but its position relative to the line of zero 
velocity is changed by an amount represented by the velocity of the nontidal current. 
In Figure 9 the curve represents a reversing tidal current when referred to AB 
