646 



BULLETIN OF THE BUBEAU OF FISHERIES 



Meter 



bay (Nos. 16 and 17) were then fractionally cooler at the surface than deeper — evi- 

 dence that the water had been rapidly losing heat from the surface for some days 

 previous, which can be associated with a cold northwest gale on November 23. No 

 great horizontal variation in temperature was to be expected over so small an 

 area; in fact, all the readings for this cruise fell within the limits of 4.80° and 6.93°. 

 The slight dififerences recorded from station to station on this cruise prove unex- 

 pectedly instructive, because the coldest water (4.8° to 5.8°) then formed a more or 



less definite pool close 

 Temperature, Centigrade inshore, a few miles 



1° 2° 3° 4° 5° 6° 7° 8° 9° 10° 11" ^orth of Plymouth, 



li X 'L \k I with appreciably 

 higher temperatures 

 (6.8° to 6.9°) to the 

 northward as well as 

 oflf the mouth of Ply- 

 mouth Harbor and in 

 Cape Cod Bay to the 

 south. Although the 

 data do not suffice to 

 bound this cold area 

 offshore, the general 

 distribution of tem- 

 perature to be ex- 

 pected at that season, 

 and actually recorded 

 there later in the 

 month (fig. 76), makes 

 it virtually certain 

 that it was also en- 

 tirely surrounded by 

 higher temperatures 

 to the east. 



On this same day 

 (December 3), C. G. 

 Corliss, superintend- 

 ent of the Gloucester 

 hatchery, found the 



fiQ. 76.— Vertical distribution of temperature in the offing of Gloucester on successivo dates of SUrfaCC Water 4.4 m 



the autumn and winter. A, October 1, 1916 (station 10324); B, November 20, 1912 (station Qloucestcr HarboP 

 10047); C, December 4, 1912 (station 1C048); D, December 23, 1912 (station 10049); E, i t- eo * 1 Vt 



December 29, 1921 (station 10489); F, January 16, 1913 (station 10050); G, February 9, and 5.6 at a locality 



1921; H, February 13, 1913 (station 10063) 1 tO 2 mHeS off itS 



mouth, a gradation that illustrates the progression of winter cooling from the land 

 out to sea, but does not suggest any considerable thermal difference between the 

 two sides of the bay at the time. Unfortunately, no corresponding readings were 

 taken in the central part; but the water was about 2° warmer 7 miles off Glouces- 



