BIGELOW: OCEANOGRAPHY OF MASSACHUSETTS BAY. 399 



the 14th, the surface had warmed up to 40.2°, though the bottom read- 

 ing was still 39°. But although the water here agreed with the Boon 

 Island region so closely in temperature, it differed widely in salinity, 

 for on the 9th it was only 29.51%o on the surface, with 30.79%o at 9 

 fathoms, and 31. %o at 18 fathoms : and the next day, a few miles closer 

 to shore, the surface saHnity was only 26.74%o, though the deeper 

 readings were rather higher than before, i. e., 31.8%o at 11 fathoms 

 and 32.52%o at 29 fathoms. On the 14th, on the contrary, some five 

 miles further south, off Cape Porpoise, the surface salinity was 29.13%o, 

 with 31.92%o at 10 fathoms, and 32.47%o at 21 fathoms, these differ- 

 ences between stations so close together being probably the result of 

 the tidal currents which were encountered in this region in the sum- 

 mer of 1912 (Bull. M. C. Z., 1914, 58, p. 87). 



Temperature and salinity ox Georges B.ank. 



The data obtained from Georges Bank during the past season, 

 is more important than its scantiness would suggest, because our 

 knowledge of oceanographic conditions in that interesting region 

 is extremely fragmentary. Mr. Clapp's water samples showed that 

 in February the surface salinity was 33.04%o on the southeastern 

 side of the Bank (41° 10' X, 66° 30' W) which proves that it was not 

 washed by the Gulf Stream, at least at that time. In the middle of 

 April (Mr. Douthart's records, p. 419), the surface temperature, on 

 the northern side of the Bank, was 44°; temperature at 25 fathoms 

 (bottom), 43°; with 41.5° at 70 fathoms on its northern slope. The 

 surface salinities varied from 33.21%(-, to 33.38%c at stations within a 

 few miles of one another, the differences probably being due to more 

 or less active vertical mixing which must result from the very ^^olent 

 tidal currents. Xo water samples were taken below the surface. 

 The second set of records, April 26 to 27, is more instructive, because 

 a series of water samples was taken from Boston Light ship to the 

 northwestern edge of the Bank, as well as a bottom sample, and 

 surface and bottom temperatures, on the latter. These showed an 

 increase in salinity passing offshore, from 31.5%o near Boston Light 

 ship 32.29%o off Cape Cod, and 33.13%o half way from the latter to 

 Georges Bank, to a maximum of 33.25%o at Lat. 41° 34' X, Long. 68° 

 45' W, over the northwest slope of the Bank. But on its northwest 

 part, the surface salinity was only 33.16%o, with 33.21%^ on the bot- 

 tom in 35 fathoms. The surface temperature on the Bank was 46°, 2° 



