: a 
>; 
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%, on the surface, with 30.79%, at 9 
fathoms, and 31.%, at 18 fathoms: and the next day, a few miles closer 
to shore, the surface salinity was only 26.74%p, though the deeper 
readings were rather higher than before, 2. ¢., 31.8%, at 11 fathoms 
and 32.52%, at 29 fathoms. On the 14th, on the contrary, some five 
miles further south, off Cape Porpoise, the surface salinity was 29.13%, 
with 31.92% at 10 fathoms, and 32.47% 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 ON GEORGES BANK. 
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%, on the southeastern 
side of the Bank (41° 10’ N, 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% 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 violent 
tidal currents. No 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 
imerease in salinity passing offshore, from 31.5%, near Boston Light 
ship 32.29%, off Cape Cod, and 33.13%, half way from the latter to 
Georges Bank, to a maximum of 33.25%p at Lat. 41° 34’ N, Long. 68° 
45’ W, over the northwest slope of the Bank. But on its northwest 
part, the surface salinity was only 33.16% , with 33.21%, on the bot- 
tom in35fathoms. The surface temperature on the Bank was 46°, 2° 
