336 A. D. Bache on the Tidal Currents of New York Bay. 
southern, C in mid-channel. 'T at the entrance is influenced by 
the shoals of the False Hook. G, F, and V, between the ocean 
as a group, we have for the luni-current interval 84 20™ or 58" 
after the time of high water at Sandy Hook for the commence- 
ment of ebb, the current of ebb beginning earliest at S, G, T, 
the flood first at F, S, T. The interval of ebb is about the same 
as that of the vicinity of Gedney’s channel, the flood three quar- 
ters of an hour earlier. This gives above a half hour for the 
difference of duration between the main ebb and flood, and the 
- gee ones of this part of the approach to New York 
a : : 
The mean epochs (table 4) are 84 14™ and 14 02, being 17™ 
and 46™ less than those found for the vicinity of Gedney’s chan- 
nel. The flood exceeds the ebb about 24™, whereas for the sta- 
tions near Gedney’s channel the ebb exceeds the flood by about 
34™, and in the south channel the ebb has greatly the advantage 
both in duration and velocity. This shows the influence of the 
secondary or draught currents through the False Hook channel. 
The average maximum velocity at these stations of both flood. 
and ebb is 1:41 miles, which last in the vicinity of Gedney’s 
channel was 1-71 miles, The mean maximum velocity of the 
ebb is but 0°91 miles, which was 1-03 miles for the stations near 
Gedney’s channel, and about the same at station S. The eb! 
makes out but slowly through the False Hook channel, the maxl- 
mum velocity of the flood at C is 1-62 miles, and of the ebb but 
0°78, and the means 1-02 and 0°50 miles per hour. Thetime aur 
ing which the ebb runs is 54 41™, and the flood 7" 08", a differ- 
ence of 1h 27™, and this in the axis of the stream. As the scout 
ing action of these currents may be regarded as varying with the 
roduct of the square of the mean velocity and the duration, we 
ve for station C the ratio of about 1 to 5 for the relative work 
of ebb and flood. At the edge of the False Hook Shoal the dura- 
tion of the ebb appears to be even less, there being but 5" 20™ of 
e@ he currents at C are plotted with the tide wave on dia- 
c= 3, (sketch 2). It appears that the curve representing the 
flood drift approaches the type form, while the ebb is anomalous 
—it is weak and inconstant. Weare now prepared ng The 
‘Tesults at station D, off the wreck of the brig Commerce, 4m° 
shown in diagram 4, (sketch 2), where they are compared with 
wave of July 18th. Th : 
. The greatest velocity of the flood is 123 miles against 
2ebb. The directions are nearly opposite. The cur 
ate 
