PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 



761 



mille, a minimum of 0.1 per mille. This salting was greatest (0.7 to 0.8 per mille for 

 the whole column) across the mouth of the bay (stations 30 to 34) and inward over 

 its deep central part (stations 18A and 3), consistent with the fact that the source for 

 any change of this order must lie in the still higher salinities of the deep water of the 

 basin in the ofBng. In spite of small local variations, however, which are always to 

 be expected from station to station near shore, depending partly on the stage of the 

 tide when the observations are taken, the average difference in salinity between the 

 surface of the bay and the 40-meter level was almost precisely the same on the June 

 cruise (0.7 per mille) as it had been three weeks earlier in the season. 



The June stations (fig. 132) on the continental shelf off Shelburne, Nova Scotia 

 (10291 to 10295), though outside the geographic limits of the gulf, strictly construed, 



Fig. 133.— Salinity at a depth of 40 meters, last bait of June, 1915 



are interesting in this connection as affording a cross section of the westward extrem- 

 ity of the Nova Scotian current at the time. Here the vertical range of salinity 

 was wider than anywhere in the Gulf of Maine in that month, with values compar- 

 atively uniform, depth for depth, over the shelf but considerably higher outside the 

 100-meter contour (station 10295). 



Horizontal projections give a more graphic spacial picture of the seasonal alter- 

 ations just stated. At the 40-meter level the relationship between May (fig. 125) 

 and June (fig. 133) is much the same as at the surface (p. 756) — the eastern side of 

 the gulf Salter than in May, the western and northern sides of the basin less so, as 

 reflected by a translation of the isohaline for 32.5 per mille well out into the basin 

 from the position close to the coast of Maine, which it had previously occupied. 



