CHAPTER V. 



RIO NEGRO. 



1839. 



The winds proved light and variable during our passage to Rio 

 Negro, and we occasionally experienced a southwesterly current, of 

 little strength. On the 18th January, when seventy-eight miles 

 distant from the mouth of the Rio la Plata, we passed through the 

 discoloured water of that river. Its temperature was 4° less than that 

 of the surrounding sea. After getting to the southward of the river, 

 the direction of the current changed, and it was found to be setting to 

 the northward. 



Towards evening, on the 19th, we met many discoloured patches 

 in the water, and found they proceeded from a species of Salpee, which 

 we had not before seen. When the night closed in, the sea became 

 very luminous, the vessels in passing through the water leaving long 

 bright trains behind them. Vivid lightning in the west showed a dark 

 bank of clouds, betokening a storm. About 10 o'clock p. m., a haze 

 suddenly enveloped us ; the temperature of both air and water fell 

 from 67° to 57°, ten degrees, giving a cold clammy feeling to the air. 

 The water became quite smooth, and the breeze died away ; all on 

 deck seemed awakened to a sense of danger. We immediately 

 shortened sail and sounded, but found no bottom with one hundred 

 and fifty fathoms of line. The vessels of the squadron came up in close 

 order, sailing as it were in a sea of silver, from the light of which 

 their forms became visible. The effect was beautiful, and increased 

 the mysterious and alarming sensation. Shortly after, we had a 

 change of wind to the southwest, followed by a dense fog, which 

 lasted for a day ; but the temperature of both air and water remained 

 six to eight degrees colder, until the 23d, when it again rose to the 

 height it had been before. 



(93) 



