NO. 13 SALINITY OF PACIFIC SURFACE WATFR- -CI. ARK 21 



NARRATIVE 



Our first observation, made not long after leaving San Francisco 

 Bay, showed water of a comparatively low density ( 1.0212 s ), pos- 

 sibly indicating the influence of the bay water. From Marin county 

 to the mouth of the Columbia River we passed through water vary- 

 ing in density from 1. 0251 to I.0259, with an average of 1.0255 ; this 

 variation was probably due to our crossing- closely approximated 

 isohalines running more or less parallel to the shore line, though 

 possibly part of it was due to the effect upon the surface water of 

 the various rivers which enter the ocean along this coast. Off the 

 mouth of the Columbia River the density was, as would naturally 

 be expected, very low (1.0218) ; it rose to 1.0252 further north and 

 fell to F.0243 in the Straits of Fuca. 



At Tacoma, in the Straits of Georgia, and at Union Bay, Van- 

 couver Island, the density was low, ranging between 1.0211 (at Ta- 

 coma) and 1.0221 (at Union Bay), on account of the drainage from 

 the land ; but in Queen Charlotte Sound we found it to be again 

 about the same ( 1.0244) as it was in the Strait-, of Fuca. 



From the Queen Charlotte Sound as far as long. 145 ° W. the density 

 was very uniform (1.0250) ; at that point a slight rise was noted 

 (1.0253) which was maintained to long. 158 W., beyond which lo- 

 cality, in the vicinity of the Shumagin Islands, it dropped to 1.0240, 

 rising again south of the eastern end of the Aleutian chain to 1.0247. 



Near Bogoslofr the density was slightly greater ( 1.0250), and on 

 the course from Unimak to Siguam a further slight increase was 

 noticed, which was augmented between Atka and Semisopochnoi. 

 In the south central part of the Bering Sea the density was very 

 slightly less, lint on returning to the vicinity of Semisopochnoi we 

 found the same figure which we had previously observed between 

 Atka and Semisopochnoi. Our observation south of Amchitka is 

 rather low, and may possibly be incorrect. Between Kyska and 

 Copper Island the readings were the same as those in the south 

 central Bering Sea (1.0253), and slightly less than those between 

 Atka and Semisopochnoi. From Copper Island to and about Bering 

 Island a slightly lessened density ( 1.0252) was noted, and a further 

 decrease w r as observed between Bering Island and Kamchatka 

 (1.0250). 



Near Starichkof Island a comparatively low density was found 

 (1.0246), which rose off Cape Asacha ( [.0248) and again about the 



