974 BULLETIN OF THE BUREAU OF FISHERIES 



Fundy along the Grand Manan shore of the Grand Manan Channel, with still 

 another counter movement outward (westward) along the northern shore of the 

 channel. 



Bottle drifts identify the coastal belt between the west end of the channel and 

 Petit Manan, some 35 miles to the westward, as to some extent a dead zone (p. 907) 

 intervening between the coast line and the inshore edge of the gulf of Maine eddy; 

 but the latter approaches close to the outer islands off Mount Desert. 



In most summers the belt of surface water involved in the Gulf of Maine eddy 

 is much broader in the western side of the gulf than in the eastern, with the general 

 set more variable and its velocity smaller. As a rule a general tendency prevails 

 for the surface water to move out from the shore all along the coast from Penobscot 

 Bay to Cape Ann during July and August. Under these conditions a second dead 

 area develops off the mouth of Casco Bay, with the water generally setting in the 

 opposite direction (easterly or northeasterly) across it. A few miles farther out, 

 however, bottle drifts and dynamic contours unite to show a decidedly definite 

 continuation of the eddy southeastward and eastward across the basin, and so around 

 again to Nova Scotia, dominating this side of the gulf north of an imaginary line, 

 Cape Cod-Cape Sable. 



This state is illustrated by the bottle drifts for 1922 and 1923 and by the dy- 

 namic gradients for the summer of 1914. In other summers (typified by 1913 and 

 1919) the westerly and southerly component of the Gulf of Maine eddy parallels the 

 general trend of the coast line more closely as far as Cape Ann, even involving 

 Massachusetts Bay."^ 



Somewhere in the offing of Cape Cod a division takes place between the outflow 

 out of the gulf to the south and an easterly drift along the northern side of Georges 

 Bank, the latter, as a whole, being the center of a clockwise system of circulation. 

 As far as longitude 68°, or thereabouts, this easterly drift parallels the neighboring 

 side of the Gulf of Maine eddy; but to the east of this there is a definite separation, 

 with the water next the bank drifting around the eastern edge of the latter and so 

 out of the gulf at considerable velocity, a fact made evident by bottle drifts as 

 well as by dynamic evidence. Some clockwise movement is also to be expected 

 around the shoal part of the bank; otherwise the latter is comparatively dead. 



The bottle drifts, combined with current measurements, show the southerly 

 outflow from the western side of the gulf continuing around or across Nantucket 

 Shoals and so westward along the southern shores of New England and New York. 



An easterly set has been found dominant in the entrance to Nantucket Sound, 

 between Nantucket and Monomoy, in the only summers of record, contributing to 

 the circling movement around Nantucket but not to the Gulf of Maine eddy. If 

 this condition prevails as constantly as now seems probable, the local circulation of 

 the water offers a reasonable explanation for the rather abrupt general division be- 

 tween the waters west and east of Cape Cod, biologic as well as hydrographic. 



Bottle drifts suggest that this easterly outflow from Nantucket Sound is given 

 off from the southern side of an anticlockwise type of circulation that involves the 

 sound as a whole; but the tidal currents run so strongly there that more informa- 

 tion is needed before this can be stated positively. 



•• Vide the drifts of bottles from the Bay of Fundy to Cape Cod in 1919. 



