608 
BULLETIN OF THE BUKEAU OF FISHERIES 
this station. Consequently, I have not found it possible to chart the normal 
isotherms for values between (j° and 10° for the 40-meter level for August, except 
for the very obvious fact that the whole Gulf of Maine is then 4° to 5° warmer at this 
level than is the water along the outer coast of Nova Scotia, where the 40-meter 
temperature was about 1.9° to 3° in July, 1914, warming to about 3.4° off Shelburne 
by the first week of September in 1915 (stations 10313 and 10314). 
If the gulf north of Georges Bank be arbitrarily divided into two subdivisions 
by the meridian of Penobscot Bay (69° W. long.) , the average of all the 40-meter 
readings to the west of it is 7.4° for August, 8.8° in the eastern subdivision (omitting 
the Bay of Fundy). 
When the August temperatures for the several years are studied individually, 
instead of in combination, this separation into a cooler western and a warmer eastern 
subdivision of the gulf proper, but with much colder water east of Cape Sable, becomes 
still more apparent (figs. 52 to 54). Although the precise readings vary a degree 
or two at any given station from year to year, the 40-meter charts agree in locating 
the coldest area (6° to 8° in 1914; 9° in 1913 and 1915) in the western side of the 
gulf, extending eastward into the south-central part of the basin in wedgelike outline. 
Thus a line running from north to south across the gulf in the offing of Penobscot 
Bay would alternately cross warm water next the coast, fractionally cooler farther out, 
and warmer again in the southern side. 
In August, 1913 and 1915, the 40-meter level was warmest along the eastern 
side of the basin; closer in to western Nova Scotia in 1914. 
A detailed temperature survey of Massachusetts Bay, carried out during the 
last week of August, 1922 (stations 10631 to 10645), gave 40-meter values of 7° to 
8.5° — lowest close in to the land off Gloucester (where upwelling is so often made 
evident by low surface temperature) and along the inner edge of Stellwagen Bank 
(5° at station 10632), where tidal overturnings are to be expected because of the con- 
tour of the bottom. In other years August readings in the bay at the 40-meter level 
have ranged from about 6.5° (off Gloucester, August 9, 1913, and August 22, 1914, 
stations 10087 and 10253) to 8° at that same locality on August 31, 1915 (station 
10306). 
The 40-meter chart for 1914 (fig. 53) shows a band 1° to 3° cooler than the 
water on either side of it extending lengthwise of Georges Bank. Our July profile of 
the western end of the bank, in 1916, also cut across a similar but still cooler band 
(p. 629 ; about 4° to 5°) just outside the 100-meter contour (station 10352) . Although 
nothing in our previous experience foreshadowed summer temperatures there as low 
as those of that year, the presence near by of a similar cold stratum (10.8°) at about 
75 meters in July, 1913 (station 10061), and temperature gradients of the same sort 
recorded in the offing of Marthas Vineyard by Libbey (1891), show that a cool band 
of this sort may be expected along the offshore edge of Georges Bank in most summers. 
In some years this extends as far west as the longitude of Marthas Vineyard as late 
as August, but in other years it is obliterated there at an earlier date by encroach- 
ments of the warm oceanic water from outside the edge of the continent, as happened 
in 1914 when the 40-meter level had warmed to 12.5° to 13.7° right across the shelf 
abreast of Marthas Vineyard by the last week of August. 
