644 
BULLETIN OF THE BUREAU OP FISHERIES 
Meter 0 
W e again found the superficial stratum over this part of the shelf equally homoge- 
neous in temperature in November, 1916. While the bottom water then showed 
slight vertical cooling at depths greater than 30 to 40 meters, it was considerably 
warmer then than it had been there in August — a state obtaining as far southward 
as Chesapeake Bay (Bigelow, 1922, p. 123). 
Thus, the coast water off southern New England corresponds to the Gulf of 
Maine in the fact that the temperature tends to become uniformly homogeneous 
during September and October, though the change takes place at a temperature 3° 
to 4° higher than is the case to the northward of Cape Cod. “A seasonal change 
of this sort was, of course, to be expected in the absence of disturbances by extra- 
limital currents, as the first step in the vertical equalization of temperature so 
characteristic of northern coastal waters in late autumn and winter.” (Bigelow, 
1922, p. 123.) 
In 1916 the surface temperature near land a few miles west of Marthas Vineyard 
had fallen fractionally below that of the 30-meter level by November 10 to 11 (sta- 
tions 10405 to 10408); 
Temperature, Centigrade and although this pro- 
file lies a few miles 
west of the geographic 
limits covered by this 
report, it is repro- 
duced here (fig. 74) 
because the readings 
would have been 
nearly the same had 
it been run out from 
Marthas Vineyard on 
the same date. Its 
most instructive 
feature is its demon- 
stration of the fact, 
now sufficiently es- 
tablished, that 
autumnal cooling in 
the coastal waters off 
the northeastern 
United States proceeds from the land seaward. In 1916, as I have earlier remarked 
(Bigelow, 1922, p. 123), this process had progressed so far by that date as to nearly 
obliterate the preexisting stability of the water on the inner half of the shelf. 
Farther offshore, however, where the immediate surface alone had yet been chilled 
by the cool land winds, the underlying water at 20 to 50 meters still continued 1° 
to 2° warmer than the superficial stratum above or the bottom water below. As a 
result the curves for 12° and 13° might suggest a landward intrusion of water from 
offshore if taken by themselves. However, the salinities forbid this interpretation, 
proving this apparent tongue merely reminiscent of the maximum temperature to 
which this level had warmed during the preceding summer (Bigelow, 1922, p. 123). 
Fig. 73. — Vertical distribution of temperature off Marthas Vineyard to show autumnal cooling. 
A, August 25, 1914 (station 10259); B, October 22, 1915 (station 10333); C, November 1, 1916 
(station 10406) 
