866 BULLETIN OF THE BUREAU OP FISHERIES 



movement around the shoal part of the bank, drifting northward around its western 

 flank and southward past the eastern flank. Drifts into the Gulf of Maine basin, at 

 considerable velocities, result from the two stations in the center of the Eastern 

 Channel. 



At the time these observations were made the Northern Channel seems to have 

 been dominated (as basins generally are in our latitudes) by an anticlockwise drift, 

 southwesterly (toward the Gulf of Maine) in its northern side and southeasterly 

 (away from the gulf) in its southern side. This latter drift, with the inward current 

 in the Eastern Channel, suggests that Browns Bank was then the center of a clock- 

 wise eddy. 



Current measurements also were taken in the center of the gulf, near Cashes 

 Ledge (lat. 42° 53', long. 68° 54'), on September 1 to 4, 1875, through a period of 58 

 hours, from which Harris (1907, pi. 7) has deduced a southerly set of about 4 miles 

 per day. This agrees with the clockwise circulation to be expected around Cashes 

 Ledge, this station being situated on its southeastern slope. Examination of the 

 original data (supplied by the U. S. Coast and Geodetic Survey), however, makes 

 it more likely that the dominant set varied with the wind there during the 

 period of observation. The first 48 hours of the set (which apparently covered two 

 tidal periods, because extending from "no current" to "no current") show a result- 

 ant toward the S. 26° W. of about 4 miles per 24 hours, as Harris represents it; but 

 this period includes 8 hours (in groups of 3, 1, and 4) when no readings were taken, 

 but during at least four of which the current almost certainly had an easterly com- 

 ponent, judging from the stage of the tide as indicated by the veering of the current. 

 The successive hourly directions also proved much more nearly rotary for the sec- 

 ond tidal period than for the first, and with wide variation in its velocity while run- 

 ning in corresponding directions. It is wisest, therefore, to attempt no deduction of 

 the dominant direction of the set from these data. 



SUMMARY 



The current measurements so far taken in the gulf when combmed indicate 

 the following circulatory movements: In the eastern side of the gulf the tendency is 

 northward along Nova Scotia into the Bay of Fundy in its southern side, northward 

 toward New Brunswick, and out of the bay along the south side of Grand Manan, 

 with a counterflow into the bay via the Grand Manan Channel. 



There is a gap in the observations for the coast section between Grand Manan 

 and Cape Elizabeth. Off the latter the general set is southerly, though often de- 

 flected or temporarily reversed by the wind. 



Two drifts are indicated in the region of Massachusetts Bay — one anticlockwise 

 around its coast line and the other southerly across its mouth and down along 

 Cape Cod. The drift is out to the eastward from Nantucket Sound, generally 

 southerly and easterly past Nantucket Shoals. The records taken at Nantucket 

 Lightship show a veering to the west and northwest around the shoals in summer, 

 though not in winter. Two clockwise movements are suggested farther east — one 

 around Georges Bank as a whole and a smaller one around its shoalest part. 



