84 bulletin: museum of comparative zoology! 



of the flood near shore, is N. N. E. toward the Grand Manan Channel 

 and the Bay of Fundy, and along this coast the velocity increases 

 steadily from west to east, the rate in the channel being two knots. 

 Along the west coast of Nova Scotia the mean direction of the flood- 

 current is nearly north. The flood is weakest in the northern part 

 of Massachusetts Bay, and along shore from Cape Ann to Portland, 

 as shown in the Table (p. 143), though there are strong tidal currents 

 off the mouths of large rivers, and tide rips ofl" Portsmouth (Station 11). 

 In the central part of the Gulf (Stations 7, 27) the current is about .5 

 knot; but along the Nova Scotian Coast and off the mouth of the Bay 

 of Fundy it occasionally attains velocities of more than two knots, with 

 extensive and dangerous tide-rips on the various shoals, for example 

 the Grand Manan Bank. 



In a general way the ebb is the reverse of the flood, flowing out of 

 the Bay of Fundy in a generally S. W. to S. S. W. direction, and around 

 the coast of Nova Scotia to the S. and S. E. Along the coast of Maine 

 from the Grand Manan Channel to Mt. Desert the ebb flows about 

 S. W. But the current in the central part of the Gulf is about S. by E. 

 Off Casco Bay the ebb is southerly; along the coast from Portland 

 to Cape Ann it sets in general toward the E. S. E. but there are various 

 local currents here, yet to be explained. The strength of the ebb 

 current is proportional to that of the flood, strongest off the mouth of 

 the Bay of Fundy and along the coast of Nova Scotia; progressively 

 weaker to the westward. 



The data is insufficient to show whether the tidal currents result in 

 any definite eddy movement of the waters of the Gulf, nor have I 

 been able to find in them any evidence of an inflow, or alongshore 

 flow within the Gulf, such as might be credited to a branch of any 

 constant ocean current. This question was thoroughly studied by 

 Dawson (1910) for the Bay of Fundy and for the Nova Scotian Coast, 

 between the mouth of the St. John and Cape Sable, in 1904 and 

 1907. And his general conclusion is that ebb and flood are almost 

 opposite, veering at slack water onl}-, if at all; and that there is 

 little indication of any movement of water in a dominant direction. 

 The mean compass-bearings and strengths of the currents on Brown's 

 and George's Banks as given on the U. S. Coast Survey charts suggest 

 a drift from northeast to southwest. But the data on the tidal cur- 

 rents of George's Bank given by Mitchell (Rept. U. S. Coast and Geo- 

 detic Survey, 18S1, p. 175) show that there is a slight easterly drift, 

 and it is so represented on the current chart in the coast pilot. (U. S. 

 Coast Pilot, part 3, 1912, chart facing p. 9). And although most of 



