PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 
825 
the water changed from a temperature of 1.1° to 13.3° C. (34° to 56° F.) within 
the length of the ship, and where the line of demarkation between the two waters 
was made plainly visible on the surface by ripplings, the transition zone from the 
one to the other is usually compressed within a few miles abreast the Gulf of Maine. 
The general characteristics of the coast water in boreal latitudes have been 
well described by Schott (1912) and are matters of common knowledge. I need 
merely state here that mean annual surface temperatures lower than 15° and mean 
salinities lower than about 33.5 per mille may be so classed, as distinguished from 
the much warmer and more saline (35.5 per mille) tropic water, which is commonly 
(though rather loosely) termed “Gulf Stream” as it skirts the North American 
plateau. 
In discussing the sources of the sector of the coast water included within the 
Gulf of Maine, it will be convenient to consider the upper and lower strata separately, 
for it is now proven they they draw chiefly from different sources. 
SUPERFICIAL STRATUM 
NOVA SCOTIAN CURRENT 
Until detailed study of the physical characters of the coast water off northeastern 
North America was undertaken by the United States Bureau of Fisheries, the Museum 
of Comparative Zoology, and the Biological Board of Canada, a northerly source was 
usually ascribed to the coastal water all along the seaboard of Nova Scotia, New 
England, and much farther to the south. This, in fact, has been described, time out 
of mind, as the “Arctic current.” As I have remarked in an earlier report (Bigelow, 
1915, p. 251), “almost all the ocean atlases show something of this sort; and it has 
been accepted in one form or another in almost all the textbooks on physical 
geography and oceanography (for example, Maury, 1855; Reel us, 1873; Attlmayr, 
1883; Thoulet, 1904; Krummel, 1911; Schott, 1912; the German Marine Observ- 
atory (Deutche Seewarte, 1882), the current charts of the United States Navy 
(Soley, 1911), and the British Admirality (1897) current chart.)” 
The low temperature of the surface water near shore, contrasted with the “Gulf 
Stream” offshore and with the oceans as a whole at the latitude in question, natu- 
rally suggests a northern origin until analyzed in relation to other factors (p. 686). 
Ostensible evidence to the same effect is afforded by the continuity of the cold zone 
all along the northeastern coasts of North America, with its mean temperature grad- 
ually decreasing from the south toward the Newfoundland-Baffins Bay region in 
the north. The southwesterly drift that has been reported repeatedly along the 
coasts of the northeastern United States and Nova Scotia argues in the same direc- 
tion; so, also, the extension of a generally boreal fauna southward and westward as 
far as Cape Cod, with planktonic communities of this category spreading still farther 
in this direction in winter. 
The observations on the temperature, salinity, and circulation of the gulf, detailed 
in other chapters, do, in fact, prove beyond reasonable doubt that water from 
the northeast (low in temperature) does flow past Cape Sable into the Gulf of Maine 
for a time in spring, sometimes into the summer. Before considering what part this 
actually plays in the Gulf of Maine complex a few words may well be devoted to its 
probable source. 
