PHYSICAL OCEAN OGKAPH Y OF THE GULF OF MAINE 
781 
next day (10220), and at the same relative position off Marthas Vineyard on the 26th 
of that August (10261), yielded salinity sections similar in type (fig. 144), though 
with actual values considerably lower in the upper 150 meters. The bottom water 
at all these stations has been close to 35 per mille at depths greater than 300 meters. 
None of our stations have been located far enough out from the edge of the con- 
tinent to show the true tropical-oceanic distribution of salinity — namely, saltest at 
or very close to the surface and decreasing with increasing depth down to 600 to 1,000 
meters. Curves of this sort result, for example, from the observations taken by the 
United States Coast Survey steamer Bache on her profile from Bermuda to the 
Bahamas in January, 1914 (Bigelow, 1917a, figs. 8 and 9), and by the Dana near 
Bermuda in May, 1922 (Nielsen, 1925, fig. 5); but when the so-called “inner edge 
of the Gulf stream” approaches the edge of Georges Bank, as in July, 1914, doubtless 
one need run off only a few miles into the oceanic basin to find the salinity so distrib- 
uted there. 
GENERAL DISTRIBUTION OF SALINITY BELOW THE SURFACE 
The spacial relationships of the differences in salinity just outlined and the 
general state of the gulf in summer are made more graphic by the usual projections — 
horizontal and profile. 
The salting of the eastern side of the gulf, which takes place from June to 
August (p. 765), contrasted with the freshening of the western side of the basin as 
land water is dispersed seaward (p. 763), produces a decided alteration in the 
distribution of salinity from late spring through the summer at moderate depths as 
well as at the surface (p. 763). In 1915 these changes resulted in an increase in the 
salinity of the 40-meter level from about 32.5 per mille to about 32.8 to 33.5 per 
mille in the northeastern part of the basin during the interval between the last week 
of June (fig. 133) and the end of August, contrasting with a decrease in its 
western side from about 32.9 per mille to about 32.6 per mille, though very little 
seasonal alteration took place meantime in the coastal zone near Mount Desert, on 
the one hand (about 32.3 per mille), or near Cape Sable on the other (about 31.9 
per mille) . 
The most interesting feature of the 40-meter chart for July and August, 1914 
(fig. 145), which may be taken as typical of the season (there being no reason to 
suppose that this was either an abnormally fresh or an abnormally salt year), is 
the regular gradation from low values in the western side of the gulf to a tongue 
of high salinity (33 + per mille) in the eastern side of the basin, again giving place 
to a narrow zone of much fresher water along western Nova Scotia, with still lower 
values (31.8 per mille) near Cape Sable and eastward along the outer coast of Nova 
Scotia (Bigelow, 1917, fig. 33). 
A much wider extent of 33 per mille water in that August than is shown 
on the May and June charts for 1915 (figs. 125 and 133) no doubt reflects some 
seasonal drift inward from the Eastern Channel after the slackening of the Nova 
Scotian current, with the isohaline for 32.9 per mille revealing a tendency for the 
saltest band to circle westward along the coastal slope of Maine, bringing salinities 
as high as 32.9 to 33 per mille as far as the offing of Penobscot Bay. A tongue of 
