The Gulf Stream system's constancy was once shown by a drift 
bottle carried from Yucatan Channel to Ireland in just under one year. 
Its most direct path must have been past Florida, along the east 
coast of the United States, and across the North Atlantic; the 
minimum speed at which this bottle traveled is computed to be about 
0.6 knot and in all probability was considerably higher. Figure 23 
shows the seasonal percent frequency of the prevailing surface current 
derived from speed groups ranging from 0.2 to greater than 4.0 knots 
for specific regions shown in Figure 22. 
Surface drift currents recorded weekly for a period of two years 
between the Bahamas and Hatteras (unpublished data) indicated the mean 
axis of the Gulf Stream to pass through 34°36'N, 75°05'W. From March 
through August the axis was located south of the mean position at 
about 34°34'N, in September through November at about 34°35'N, and 
from December through February at 34°L0'N. The current was most 
constant north of 34°30'N, with 72 percent of all observations ranging 
between 2.0 and 3.9 knots and sets between 031° and 070°r: the mean 
direction was o49°T, South of 34°30 'N the speeds were somewhat weaker, 
and the current tended to be more variable. Of all observaticns, 63 
percent ranged between 2.0 and 3.4 knots, the sets lying between Osue 
and 060°T ; the mean direction was 043°r. 
The constancy of the current is verified by other surface ship 
drift data tabulated in the 1° quadrangle 34°-35°N, 75°-76°W, where a 
slight seasonal change is evident; in summer, mean speed is higher by 
O.2 knot and persistency is greater by apoue 4 percent than during 
winter. During all months the current sets northeast 77 to 95 percent 
of the time; mean speed is about 2 knots and maximum speed over 5 knots. 
58 
