640 



BULLETIN OF THE BUEEATJ OF FISHERIES 



The entire column of water down to 30 meters had cooled to about 10° at the 

 mouth of Penobscot Bay by October 9, 1915, with about 9° at 60 meters, correspond- 

 ing to a decrease of 3° at the siu-f ace, but a rise of about 1 ° at depths greater than 

 20 to 25 meters (fig. 71). 



The surface (9.4°) was about 0.7° colder than the bottom near Mount Desert 

 Island in 60 meters depth (10.1°) on October 9, 1915 (station 10328), the bottom 



3° 



6° 



Temperature, Centigrade 



T 8° 9° 10° ir 12° 13° 14° 15° 16° 17° 18° 19° 



Fig. 70.— Vertical distribution of temperature in the trough between the Isles of Shoals and Jeffreys Ledge, 

 to show the progress of autumnal cooling. A, August 15, 1914 (station 10262); B, October 4, 1915 

 (station 10325); C, December 30, 1920 (station 10493). The broken curve is for November 1 of the cold 

 year 1916 (station 10400) 



having warmed since August about as rapidly as the surface had cooled. Probably 

 the temperature would have been found homogeneous there from surface to bottom 

 at about 9.5° a week or so earlier in the season, as it was off Machias, Me., on that 

 same date (station 10327), with a reading of 9.4° at the surface and 9.83° close in 

 to the bottom. 



The whole column of water warms slowly in the deeper parts of the Bay of 

 Fundy. throughout the summer, and at a more nearly uniform rate vertically than is 



