938 
BULLETIN OF THE BUREAU OF FISHERIES 
they show can be accepted only as a rough approximation, not in detail. Some 
smoothing of the curves has proved necessary in the construction of the chart, also. 
Even with this reservation these contours show that the basin of the gulf 
(potentially, at least) was then the site of one major cyclonal (i. e., anticlockwise) 
eddy, with its center taking the form of a troughlike depression extending from the 
Eastern Channel northward and inward toward the offing of the Bay of Fundy. 
It is interesting that this general eddy seems also to have involved the latter, with 
the surface water drifting inward along the Nova Scotian side, outward next the 
New Brunswick shore and past Grand Manan. 
The highest velocities then indicated were a drift northward into the gulf along 
the western slope of Browns Bank and a counter movement outward along the 
Georges Bank side of the Eastern Channel. With the correction used here for the 
difference in depth this indraft works out at about 13.5 centimeters per second, 
equivalent to 0.27 knot, or about 6)^ miles in 24 hours. The calculated velocity 
for the outdraft around Georges Bank is lower — 0.22 knot, or 5 34 miles in 24 hours. 
These velocities, however, are on the assumptions, first, that the water in the center 
of the Eastern Channel was stationary and, second, that the difference in depth 
between the trough of the channel and the crests of its two slopes was correctly 
allowed for in the calculation (p. 934). 
By contrast, the whole western side of the gulf was “dead,” dynamically, as 
late as the middle of March, in 1920, its upper stratum only tending to drift south- 
ward (anticlockwise) very slowly, except at the mouth of Massachusetts Bay, where 
greater velocity in this direction is suggested by contour lines more closely crowded 
(fig. 188). It is interesting to find that the effect of the discharge from the Kenne- 
bec and Penobscot was most evident in speeding up the southwesterly surface drift 
some 40 miles out from the land — not close in to the latter, as the surface chart of 
density for the same date (fig. 187) would have suggested if taken by itself. 
Lower densities at two of the stations in the basin (20054 and 20052) than in 
the general vicinity are best interpreted as isolated pools, which, if correct, implies 
sudsidiary clockwise eddies; so, too, a corresponding high appearing on the east- 
ern edge of Georges Bank on the dynamic chart (fig. 188). While these seem not 
to have seriously interrupted the general anticlockwise movement, they are inter- 
esting illustrations of the persistence of such pools, which have drifted off from the 
general zone of low density next the coast. 
The comparatively dead state of the water over the whole eastern half of 
Georges Bank at this season also deserves a word. The chart suggests a slow drift 
southward and so out of the gulf across the western half of the bank at this time, 
but the contour of the bottom makes it more likely that the surface water was 
actually moving eastward around its northern edge, because the underlying strata 
(which in this case supplied the motive power) are necessarily directed by the sub- 
marine slope, against which any southward drift must strike. Thus, we may con- 
clude that the dynamic movement of water around the basin was even more definitely 
eddylike and anticlockwise in March than the chart (fig. 188) suggests. 
Lacking March data for the region of Nantucket Shoals, the chart fails to show 
whether a definite dynamic outflow is to be expected around the latter to the west- 
ward from the gulf at that season. 
