OCEANOGRAPHY 421 



salinity is under 35 per mille on the surface; farther out in the 

 Benguela Current the salinity is for the most part between 35 and 



36 per mille. As the water is carried northward by the current, 

 evaporation becomes greater and greater; the air becomes com- 

 paratively warm and dry. Thereby the salinity is raised. The 

 Benguela Current is then continued westward in the South Equa- 

 torial Current; a part of this afterwards turns to the north-west, 

 and crosses the Equator into the North Atlantic, where it joins 

 the North Equatorial Current. This part must thus pass through 

 the belt of calms in the tropics. In this region falls of rain occur, 

 heavy enough to decrease the surface salinity again. But the 

 other part of the South Equatorial Current turns southward along 

 the coast of Brazil, and is then given the name of the Brazil 

 Current. The volume of water that passes this way receives at 

 first only small additions of precipitation; the air is so dry and 

 warm in this region that the salinity on the surface rises to over 



37 per mille. This will be clearly seen on the chart; the sal test 

 water in the whole South Atlantic is found in the northern part of 

 the Brazil Current. Farther to the south in this current the 

 salinity decreases again, as the water is there mixed with fresher 

 water from the South. The River La Plata sends out enormous 

 quantities of fresh water into the ocean. Most of this goes north- 

 '^ard, on account of the earth's rotation; the effect of this is, of 

 course, to deflect the currents of the southern hemisphere to the 

 left, and those of the northern hemisphere to the right. Besides 

 the water from the River La Plata, there is a current flowing 

 northward along the coast of Patagonia — namely, the Falkland 

 Current. Like the Benguela Current, it brings water with lower 

 salinities than those of the waters farther north; therefore, in 



.proportion as the salt water of the Brazil Current is mixed with 

 the water from the River La Plata and the Falkland Current, its 

 salinity decreases. These various conditions give the explanation 

 of the distribution of salinity and temperature that is seen in the 

 chart. 



