650 
BULLETIN OF THE BUKEAU OF FISHERIES 
side of the Gulf of Maine after November, the thermal relation between surface and 
bottom temperatures may be reversed at different stages of the tide, as warmer 
water from offshore comes in with the flood and water chilled near shore moves out 
on the ebb. But whether the flood water will drift in at the surface, or whether it 
will sink to some deeper level as it approaches the coast, depends on the regional 
distribution of density. Accordingly, the flood tide may either raise the surface 
temperature slightly above that of the deeper water near land in winter or it may 
warm the mid stratum temporarily, a state which may persist until the last of the 
ebb. Both these alternatives are illustrated among the Massachusetts Bay stations 
for December 16 and 17, 1925 (stations 5, 6, 7, 9, 13, 14, and 17). The fact that the 
station off Cohasset (16) was not only coldest at the surface but gave the minimum 
temperature for the cruise (3.8°), although taken about the middle of the flood, 
probably results from the general drift discussed below (p. 972). 
The fourth week of December, 1925, saw very wintry weather, with several days 
of northwest gales, the minimum temperature of the air falling to — 1° F. ( — 18.3° C.) 
at Boston on the 21st and to about 5° F. (about —15° C.) on the 22d. This was 
reflected by an average cooling of about 1° for the waters of the bay between the 
16th and 17th and the 22d and 23d, which gives a rough measure of the radiation to 
be expected from the surface during two or three days of low air temperatures and 
high offshore winds at this time of year. 
Although the entire area was much more uniform in temperature on December 
22 and 23 than it had been a week earlier (all the readings for that date fell between 
4.95° and 2.5°), temperatures of 2.5° to 3° near Plymouth, in the one side, and a 
mile off Gloucester, in the other, 44 on the same day, contrasting with 4.5° to 5° in 
the central part of the bay (station 18; about 7° at station 10049 on December 23, 
1913), show the thermal gradation usual for the winter season. Thus, 4° to 7° may 
be taken as normal for the deep parts of the bay during the last week in December, 
and 2° to 4° for its coastal belt. 
The Bay of Fundy, in the opposite side of the gulf, experiences essentially the 
same cycle of temperature as Massachusetts Bay during December. Thus, Mavor’s 
(1923) tables show the whole column of its deep trough as virtually homogeneous, 
vertically, by November (fig. 79), and about reproducing Massachusetts Bay in 
temperature in December, notwithstanding the difference in latitude. Compare, for 
instance, 6.4° to 6.9° in the central parts of Massachusetts Bay on December 11, 1925, 
with 6.18° to 6.6° for the corresponding depth column in the Bay of Fundy on 
December 2, 1915, and 5.62° to 6.12° on December 5, 1917 (Mavor, 1923, p. 375). 45 
Some variation is to be expected in the vertical distribution of temperature in 
these bays in December from year to year. In 1913, as noted (p. 645), the water off 
Gloucester was homogeneous, surface to bottom, throughout that month; but in 
1920 more rapid chilling had lowered the temperature of the surface (5.56°) about 
1.5° below that of the 40-meter level (6.94°) at this locality by the end of the month 
« Observation taken by C. G. Corliss (p. 513.) 
« Mavor (1923) records 6.11° for the surface, 6.42° at 50 meters, and 6.6° at 175 meters on Dec. 2, 1916; 5.62° at the surface, 5.72° 
at 60 meters, 6.16° at 100 meters, and 6.18° at 175 meters on Dec. 5, 1917. 
