BIGELOW: OCEANOGRAPHY OF MASSACHUSETTS BAY, 



397 



once more reestablished itself. The minimum surface salinity was 

 reached about iSIay 5, near the Isles of Shoals, from which time on a 

 rise is to be expected to the summer condition. 



There was no separation between the waters just outside the Isles 

 of Shoals, and the channel between them and the mainland so far as 

 surface salinity is concerned. But the salinity sections (fig. 5, 6) 

 show that the progressive freshening was much more strictly a surface 

 phenomenon outside the islands than it was nearer the mainland, 

 as might be expected from the fact that the inshore stations lie 

 near the mouth of the Piscataqua River. After about May 5, w^hen 

 the water was freshest, there followed not only a rise in surface salinity, 

 but a progressive though slight increase in mean salinity of the whole 



Fig. 6. — Salinity sections between the Isles of Shoals and the mainland, 

 April 13 (Station 11 W. W. Welsh); April 16 (Station 13 W. W. Welsh); 

 April 22 (Station 16 W. W. Welsh) ; April 23 (Station 17 W. W. Welsh) ; 

 May 3 (Station 23 W. W. Welsh) and May 13 (Station 29 W. W. Welsh). 



column (Station 25 Welsh, mean 31. 1%©; Station 26 Welsh, mean 

 about 31.29cc; Station 27 Welsh, mean about 31A%c, Station 28 

 Welsh, mean about 31.4%o ; Station 29 Welsh, mean 31.5%c ; Station 

 31 Welsh, mean 32. 7% c, the depths varjdng from 20-26 fathoms). 

 And though the rise on the surface was once interrupted by heavy 

 rain (Station 30 Welsh, :May 16) the mean of 29 fathoms, 31.6%c, 

 was practically unchanged from the last station. The weather was 

 stormy during the period May 5-15, with a northwest gale on the 

 10th and 11th and 12th (i. e., Stations 27 and 28 Welsh), which may 

 partly explain the rising salinity'. But the fact that it continued to 

 grow Salter after this, except as just noted, shows that the spring in- 

 flux of river water had passed its maximum, and was gradually being 

 absorbed by the general circulation of the Gulf. 



