BIGELOW: EXPLORATIONS IN THE GULF OF MAINE. 63 
curve of 31.8 divides Massachusetts Bay lengthwise, reaches eastward 
as far as longitude 69° 61’ W, thus including Station 7, then curves 
back abruptly to within fifteen miles of Cape Neddick, whence it runs 
northeasterly roughly parallel to the coast, as far as the mouth of 
Penobscot Bay, and the curves for values below 31.8 show a similar 
swing. In this region the lowest off-shore salinities observed were 
31.08, at Station 14 abreast of Cape Porpoise, 31.2 off the mouth of 
Casco Bay, and 31.2 at Station 16, near Seguin. But even lower 
salinities were found at the mouths of the large rivers, 7. e. 30.6 at 
Station 21a in Penobscot Bay. The second intrusion of compara- 
tively fresh water was encountered off the mouth of Penobscot Bay, 
where the curve of 32.4 swings off shore southward for some twenty- 
five miles; but though relatively fresh, this mass of water was abso- 
lutely less so than the waters off Cape Ann, its salinity lying between 
32 and 32.4, instead of below 32. 
The conditions in Massachusetts Bay are complex. Both in July 
and in August the surface salinities of its central portion were between 
31.8 and 32; but along the north shore from Nahant to Cape Ann, 
much higher salinities were occasionally noted, 7. e., 32.14 six miles 
southeast of Baker’s Island on July 15th, while a few miles away 
(Station 6) the salinity was 31.9 two days previous. At Station 1, 
off Eastern Point, the salinity was 32.07, while at Station 2 it was only 
31.7. At Station 44, the only one in the southern half of the Bay, 
it was likewise higher (32.03) than at the stations made on the same 
day in the central and northern part of the Bay, the salinity at Sta- 
tion 45 being 31.9, at Station 46 only 31.6. The curves show, further- 
more, that while the comparatively saline water of the southern half 
of the Bay may have been directly continuous, on the surface, with 
the salt off-shore waters, the high salinities noted along the north 
sbore were isolated patches enclosed by fresher water, 7. e., by the 
curve of 31.8. This phenomenon is important in connection with the 
fact that it was at just these same localities that abnormally low 
temperatures were recorded (p. 438). Its significance will be dis- 
cussed later (p. 90). The salinity of the surface waters of the 
greater part of the Gulf, in July and August, was 32.4 or more. Off Cape 
Cod the curve for this value lies about twenty miles off shore; but 
abreast of Cape Ann it swings eastward toward Cashe’s Ledge, cor- 
responding to the intrusion of fresh water in that region. It then curves 
toward the coast once more, enclosing Platt’s Bank, whence it runs 
northeastward almost to Monhegan Island, enclosing Stations 21 and 
26. Off the mouth of Penobscot Bay, as already noted, it is forced 
