88 BULLETIN : MUSEUM OF COMPARATR^E ZOOLOGY. 



densities in the attempt to reconstruct the movements of its waters 

 the most important subject on which the cruise may throw light. 

 Perhaps the most striking oceanographic feature of the Gulf of ^Nlaine 

 in summer, certainly the one which has aroused the most speculation, 

 is the existence of a cold band of surface water which bathes the coast 

 from Portsmouth as far as the Penobscot, and extends thence across 

 the mouth of the Bay of Fundy and along the western coast of Xova 

 Scotia, gradually growing broader and broader to the eastward. If we 

 were to judge from surface temperatures alone we would naturally 

 assume that this cold water was e\-idence of a cold current following 

 the coast ; and it has often been referred to as an Arctic current solely 

 on this ground. But, as we have seen, the surface currents, at least 

 in summer, afford no support to such a view, while serial temperatures 

 and salinities show that the phenomenon can be explamed on very 

 different grounds. 



The coldest surface water was found over German Bank and in the 

 Grand IManan Channel; but serial temperatures show that this low 

 temperature, at these stations, was solely a surface phenomenon, the 

 bottom waters being much warmer there than at corresponding depths 

 in the basin or on the west coast of the Gulf. Furthermore the mean 

 temperatures for the upper forty fathoms, i. c, for the whole depth 

 at Stations 29, 33, and 35, are no lower than they are in the western 

 part of the Gulf; (Station 29, 49.8°; Station 33, 49.5°; Stations 

 27 and 2S, 49°; Station 11, 45.7°; Station 7, 49.1°; Station 2, 46.4°: 

 Station 43, 51.1°.) We find, too, that in the northeast part of the Gulf, 

 there is much less change in salinity from surface to bottom than in the 

 western half. And when we take into consideration the extraordinary 

 violence of the tide, both on German Bank and in Grand Manan 

 Channel, and the numerous tide-rips, with which everyone who has 

 sailed these waters is familiar, it can hardly be doubted that the low 

 surface and high bottom temperatures are merely the e\'idence of 

 thorough mixing of surface and bottom waters, caused by the active 

 vertical circulation which necessarily results from the strong currents. 

 Verrill (1873, p. 438) explained the phenomenon correctly when he wrote 

 "the constant mixture of the cold bottom water with the warmer 

 surface waters by means of the strong tides and local wind currents, 

 causes the remarkably low temperatures observed in the shallow waters 

 of these shores." The temperature conditions on JefFrey's Bank re- 

 sult from a similar phenomenon, though as tidal currents are less strong 

 here than they are further to the eastward, the equalization of tem- 

 perature from surface to bottom is less complete; and the diminishing 



