Buzzards Bay; negative signals are due to water 
flowing eastward into Vineyard Sound. 
There is a pronounced disparity between 
the amounts of water flowing in the two di- 
rections. In this cycle, over two and a half 
times as much water passed through Woods Hole 
when the current was running eastward, as had 
passed through the other way during the pre- 
ceding westward flow. The inequality is 
frequently much worse than this, sometimes 
amounting to four times greater eastward flow 
than westward. Woods Hole passage acts as a 
half-wave rectifier! 
We were worried that this might be an 
artifact produced by a change in the flow 
geometry with the current direction. The G.E.K. 
output represents an integrated velocity average 
across the cross section, rather than an inte- 
grated flow. A shift in the current from a deep 
part of the channel will increase the G.E.K. 
signal. However, there seemed to be no reason 
to expect such an effect across the harbor where 
our measurements were made. Moreover, the same 
asymmetry shows up quite distinctly on the U. S. 
Coast & Geodetic Survey hourly tidal current 
charts for all stations in the passage between 
Buzzards Bay and Vineyard Sound, except the one 
in the most constricted part of the Hole. 
From the U. S. Coast & Geodetic Survey 
chart of Woods Hole, we estimate the average 
depth of the channel across our section to be 
26 feet at mean low water. From this we reckon 
that 1 millivolt on our chart is equivalent to 
a water flow of about 160 cubic meters a second, 
or 5.7 x 103 cubic feet per second. Accordingly, 
the maximum westward flow in Figure II is 
about 860 m’/sec.; the maximum eastward flow is 
about 1600 m?/sec. The total westward flow is 
about 11 x 106 m3; the total eastward flow is 
about 27 x 10° m3, 
Part of this discrepancy arises from the 
greater duration of the eastward flow; this 
phenomenon has been nicely explained by 
Redfield’. The remainder of the difference is 
probably due to the rectifying action of a 
shallow sill on tidal oscillations. The tidal 
range in Buzzards Bay is about twice as great 
as in Vineyard Sound at Woods Hole, so that 
more water is pumped over the sill to the east- 
ward. 
VERTICAL SOUNDINGS 
We took the apparatus to sea aboard R. V: 
Atlantis and attempted vertical soundings in 
the Gulf Stream southeast of Nantucket. 
The first lowering was made north of the 
Stream at Atlantis Station 6156, in the 
180 
vicinity of Richardson Buoy 'E''. We started 
with a 6000 foot length of tubing wound on a 
reel, but could not get an acceptable signal 
through this. A reel of tubing on deck with a 
negative internal hydrostatic head presents a 
standing invitation to bubble formation. We 
also found it quite cumbersome to have to discon- 
nect the line each time we needed to turn the 
reel. 
We next tried working with a free 250 meter 
length of tubing with much better results, as 
shown in Figure III. For this lowering the 
shorter reference line was weighted and dropped 
to a depth of 30 meters. The long sounding line 
was taped to the hydrographic wire, with the 
weighted end of the line dangling about 10 
meters below the lead weight on the wire, so as 
to avoid electrical pickup from the wire. On 
this occasion the line was taped to the wire 
every 20 meters, but we later found that 50 
meter intervals were not too long. As the line 
was brought in again, these tapes were cut. 
Instead of reeling the line in, we just let it 
float freely away from the ship in a big loop. 
The absence of any voltage gradient below 
100 meters in Figure III implies that the water 
there had no east-west motion relative to the 
ship: the ship and the water were moving to- 
gether, if at all. Since the loran log covering 
this period shows the ship to have moved east- 
ward only about one-fifth of a mile in 4 hours, 
there would appear to have been very little east- 
west current. 
The very pronounced signal near the surface 
in Figure III is, of course, due to the ship. 
A second lowering was made at Atlantis 
Station 6157 (38°15'N, 68°15'W) well inside the 
Gulf Stream. The results of this lowering are 
shown in Figure IV. The reference line in this 
case went to 15 meters, while the long line 
extended an equal amount below the hydro wire. 
At this station we were greatly troubled by 
a signal fluctuation amounting to several milli- 
volts with a period of five to ten minutes. It 
was very difficult to see what changes, if any, 
were produced as we raised and lowered the line 
to measure at different depths. Not until we 
had returned to Woods Hole did we discover that 
the gyrocompass record of the ship's heading 
showed similar fluctuations. These were re- 
portedly due to a practice of putting the rudder 
hard over when the ship was hove to on station: 
the ship headed up into the wind as she drifted 
forward and then fell away from the wind 
drifting backwards. These heading changes could 
probably have been avoided without too much 
difficulty, if they were indeed the source of 
the trouble. However, fluctuations in the wind 
force and in the resulting wind drift of the 
