SPECIFIC GRAVITIES AND OCEANIC CIRCULATION. 



339 



with depth at these two points down to 200 fathoms, the distance between the two 

 stations being about 1140 miles : — 



Serial Temperatures. 



Depth in 



Lat. 7° 35' N. 



Lat. 11° 20' S. 



Difference of 



fathoms. 



Long. 149° 49' W. 



Long. 150° 30' W. 



Temperature. 



Surface. 



81-0 



80-0 



+ 1*0 



20 



79-3 



79-8 



- 0-5 



30 



79-3 



79-6 



- 0-3 



45 



78-2 



79-4 



- 1-2 



50 



74-0 



790 



- 5-0 



60 



63-4 



78-0 



-14-6 



70 



56-2 



76-7 



-20-5 



80 



52-6 



75-3 



-22-7 



90 



51-0 



73-7 



-22-7 



100 



50-3 



72-0 



-21-7 



120 



49-8 



68-3 



-18-5 



140 



49-4 



64-0 



-14-6 



160 



49-0 



58-9 



- 9-9 



180 



48-6 



54-2 



- 5-6 



200 



48-2 



50-8 



- 2-6 



In the one case, there is upwelling by which the cold water of lower depths is raised 

 towards the surface, so that at 90 fathoms its temperature is 22° 7 lower than it is at the 

 same depth in the position south of the equator only 1140 miles distant. The observa- 

 tions point to this region of extensive upwelling as one of the chief sources of supply 

 of the water of the surface currents of the Pacific which accompany the trade winds of 

 this ocean. Since the temperature for a great distance all round this cold area is higher, 

 it follows that the origin of this low temperature can only be derived from greater depths. 



But the salinity of these two regions is as equally marked as the temperature. The 

 station south of the equator here given is the nearest to the station above at which serial 

 salinities were observed. 



Serial Salinities. 



Deptli in 



Lat. 7° 35' N. 



Lat. 13° 28' S. 



fathoms. 



Long. 149° 49' W. 



Long. 149° 30' W. 



Surface. 



1-0257 



1-0263 



25 



256 



267 



50 



258 



268 



100 



257 



269 



200 



256 



257 



300 



255 



256 



400 



255 



255 



