PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 
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about 0.4 per mille on March 24, 1920, to about 0.9 per mille on April 19 (fig. 106), and 
to 0.6 per mille on April 6 off Boston Harbor, where the whole column of water had 
been virtually uniform, surface to bottom, on March 5. However, the curves for the 
several pairs of stations remained more nearly parallel from March to April in the 
eastern side of the gulf, although the salinity had increased considerably in the mean- 
time (figs. 108, 114). 
Fig. 111. — Vertical distribution of salinity at the mouth of Massachusetts Bay, off Gloucester, during the 
winter and spring of 1912-1913. A, November 20 (station 10047); B, December 23 (station 10049); C, 
February 13 (station 10053); D, March 4 (station 10054); E, March 19 (W. W. Welsh station 1) F 
April 3 (station 10055) 
SALINITY IN HORIZONTAL PROJECTION BELOW THE SURFACE IN 
APRIL 
The deeper down in the gulf the salinity is charted in horizontal projection for 
April, the more nearly does it parallel the winter state. Thus the band of low salin- 
ity (31 per mille) so conspicuous along the northwestern margin of the gulf on the 
surface chart for mid-April (fig. 101) is but faintly suggested at 40 meters (fig. 115), 
where the recorded values were only slightly lower (32 to 32.3 per mille) than in the 
center of the basin (32.4 to 32.5 per mille) and closely reproduced the March state 
(fig. 93) . How little effect the vernal inrush of river water exerts on the deep strata 
of the Massachusetts Bay region before the end of April appears from the deep 
readings taken there in the third week of the month in 1925 (fig. 102). 
8951—28 17 
