CHAP, v.] GENERAL CONCLUSIONS. 307 



direction, the specific gravity fell rapidly from 1-02602 olf St. 

 lago on the 10th of August to 1 •02032 on the 12th, after which 

 it retained the low mean specific gravity of 1'02627 until the 

 21st of August, when the course was changed to a westerly one 

 along the equator. The specific gravity of the water on this 

 day was the lowest hitherto registered for a surface-water; it 

 was 1"02601, in lat. 3° 8' N., and on the boundary-line between 

 the equatorial and Guinea currents. The same low specific 

 gravity was observed in following the equatorial current as far 

 as St. Paul's Rocks, after which it quickly rose as the Brazilian 

 coast was approached; and the maximum of 1-02786 was ob- 

 tained on the 26tli of September, when off the entrance to 

 ];aliia,inlat. 13° 4' S. 



The observations in the South Atlantic were limited to a line 

 down the western side as far as the Abrolhos Bank, and thence 

 across to the Cape of Good Hope. In the region of the south- 

 east trade- wind, therefore, we have only a few observations close 

 to the coast ; and as we have seen in the North Atlantic, on the 

 voyage from Teneriffe to St. Thomas, the specific gravity is 

 higher in mid-ocean than either on the east or the west side, so 

 in the South Atlantic it is possible that the same may hold good. 

 From the Abrolhos Bank to Tristan d'Acunha the specific grav- 

 ity sinks steadily from 1-02785 to 1-02606, and from Tristan to 

 the Cape of Good Hope, along a course lying between the 35th 

 and the 37th parallels of south latitude, the mean specific grav- 

 ity was 1-02624. Between the same parallels of north latitude 

 the mean specific gravity was 1-02713. 



It must be remembered that the results obtained can only be 

 held good for the season of the year in -svliich they were ob- 

 served, and that the observations in different latitudes were 

 made in different seasons ; and, further, that all the observations 

 north of the line as far as 20° N. were obtained on the eastern 

 side, and those to the southward of it as far as 30° S. were ob- 

 tained on the western side of the ocean ; so that it would be 



