BIGELOW: EXPLORATIONS IN THE GULF OF MAINE. 85 
the current charts which have appeared show a southwest flow along 
the outer edge of George’s Bank, next the Gulf Stream, it is a question 
whether this flow is a contant, or even a dominant one. 
Surface and bottom currents.— To obtain a satisfactory knowledge 
of the tidal currents at any locality, it is necessary to make observa- 
tions at intervals throughout a twelve-hour period, to insure read- 
ings for both flood and ebb, because the time of turning of the tide 
at the bottom often differs by a considerable period from the time 
of slack water on the surface. Nevertheless, our few isolated observa- 
tions are worth passing notice because they are the first attempts to 
measure the bottom currents of the Gulf of Maine with modern instru- 
ments. The diagrams (fig. 38) illustrate the considerable strength of 
the bottom currents even in the western side of the Gulf; and in the 
northeastern part, for example over German Bank, they are even 
stronger. 
The only region where enough observations were taken to allow a 
tentative statement of the relations of bottom to surface currents is 
the northern half of Massachusetts Bay (Stations 1, 2, 4, 5, 6). The 
surface current flows into this part of the Bay toward northwest and 
west at the height of the flood (Station 5) turning at least one half hour 
before the time of high water at Gloucester, and flowing easterly 
during the first half of the ebb (Stations 1 and 4). We made no records 
for the last three hours of the ebb. A few miles further off shore the 
direction at mid-ebb was southeast (Station 2); and in the centre of 
the Bay (Station 6) N.N. E. (all bearings being magnetic). In the 
southern half of the Bay the flood current ran toward the southwest, 
the ebb toward the northeast. These observations are not sufficiently 
extensive to show whether or not there is any dominant drift along- 
shore. But tidal records taken by the U. S. Coast Survey at the 
mouth of the Bay suggest that it may be occupied by an eddy-like 
circulation flowing slowly from north to south, there being a decided 
drift to the northwest near Cape Ann, with an easterly movement 
on Stellwagen bank and near Race Point (U. S. Coast Pilot, part 
1 and 2, 1911, p. 151). The bottom currents in Massachusetts Bay 
differ very noticeably from the surface ones (fig. 38) not only in being 
as a rule weaker, but in flowing in a different direction. At all the 
stations in the central and northern part of the Bay, the bottom flow 
was easterly, the records being made a few minutes before high water 
(Station 1), two-hour ebb (Station 4), mid-ebb (Station 6), and early 
flood (Station 5). This data, so far as it goes, suggests that if there 
be any tidal flow to the west on the bottom it must be restricted to 
