BIGELOW: OCEANOGRAPHY OF MASSACHUSETTS BAY. 387 
sity, for November 20, at the temperature in situ, disregarding pres- 
sure, was 25.24 at the surface, 25.27 at the bottom; 2. ¢., the vertical 
stability of the water was so slight that all that would be necessary to 
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Fic. 1.—Temperature sections off Cape Ann, November 20 (Station 10,047) ; 
December 4 (Station 10,048); December 23 (Station 10,049); January 16 
(Station 10,050); February 13 (Station 10,053); March 4 (Station 10,054) ; 
March 19 (Stations 1 and 2, W. W. Welsh); April 3 (Station 10,055); and 
off Gloucester Harbor, April 14 (Station 10,056) and May 17 (Station 32 
W. W. Welsh). 
cause a reversal of density, with consequent vertical circulation, 
would be a cooling at the surface of about 1°. Evidently then, 
dynamic overturning of the water might be expected to be active from 
this time onward as the surface became colder and colder with the 
