BRAZIL. 



493 



with great velocity through the Florida channel, into the Atlantic ocean. Proceeding norther- 

 ly along the coast of the United States, its velocity gradually diminishes, and its breadth en- 

 larges ; opposite Cape Henlopen, it is about 150 miles wide, with a current of from 3 to 5 

 miles an hour. To the east of Boston, in the meridian of Halifax, it is about 275 miles broad ; 

 turning to the east, its western margin touches the Great Bank of Newfoundland, whence it 

 flows towards the Azores, in the meridian of which it is about 550 miles broad. This great 

 stream is called the Gulf Stream, and is remarkable for the superior warmth of its waters to 

 those of the ocean. 



5. Vegetation. In some parts of the ocean the surface is covered with extensive patches 

 of floating sea-weed, which are so dense and large as to impede the passage of ships. Two 

 great fields of this kind are known in the Atlantic ocean ; one of which is between 25° and 

 36^ N. lat., and 30° and 32° W. long. ; and the other between latitudes 22° and 26° N., and 

 longitudes 70° and 72° W. Other species of fucus or sea-weed, the stems of which attain to 

 the enormous length of 700 or 800 feet, are attached to submarine rocks. These plants are 

 useful as manure, and the ashes of the species called rockweed, are known in commerce under 

 the name of kelp. One species of sea-weed is also eaten, boiled or dressed, as a salad. 



6. Islands. The principal islands on the western coasts of the Atlantic, as Iceland, Green- 

 land, Newfoundland, and the West India islands, and also the islands of Great Britain and 

 Ireland, on the eastern coast, are separately described. Besides these, the most important 

 are the Azores, the Canaries, the Madeiras, the Cape de Verde Island, St. Helena, Ascen- 

 sion, and Tristan da Cunha, which are described under the heads of Europe and Africa. 



MISCELLANEOUS NOTES. 



The South Atlantic contains few islands of any size, and no inlets of any consequence ; but 

 the JSTorth Atlantic abounds in large islands, and in deep and numerous inland seas, which pene- 

 trate far on each side into both the old and new worlds, and have fitted it for the most exten- 

 sive commerce on the globe. On its eastern shores it receives few large rivers except the Ni- 

 ger ; but on the west it receives the Plata, Orinoco, Amazon, Mississippi, and St. Lawrence, 

 — the largest rivers on the face of the earth. 



The usual color which sea-water exhibits is a bluish green, of various shades. Some main 

 tain, that this is its true and proper color ; others, that it is an optical illusion, occasioned by 

 the greater refrangibility of the blue rays of light, — opinions which may both be true to a cer- 

 tain extent. The ocean seems often to assume various other colors ; some of them no doubt 

 real, but as often illusory. Among the more general sources of deception, may be reckoned 

 the aspect of the sky ; thus, an apparently dark-colored sea is a common prognostic of an ap- 

 proaching storm ; not that the water then is really blacker than usual, but the dark color of the 

 clouds indistinctly seen in or reflected from the waves, is mistaken for the color of the sea itself. 



The variety of colors in the sea may probably arise from animal and vegetable matters diffus- 

 ed through the waters in a putrescent state, and communicating various tints. The yellow and 

 bright green shades seem to be owing to living marine vegetables, which grow at the bottom, 

 stretch their fibres through the water, or spread over the surface. 



The phosphorescence of the sea is a common but very remarkable phenomenon, concerning 

 the cause of which authors are not agreed. But most probably, as Newton conjectured, it pro- 

 ceeds from a variety of causes. It has been ascribed to luminous animals and to the phospho- 

 rescence of semiputrescent matter diffused through the ocean. It is well known, that various fishes 

 and other marine animals, emit light, which does not in every instance appear to be voluntary, 

 or to depend on the vital principle, as, in some of them, it continues, and perhaps increases, 

 after death ; but motion seems to be either a principal cause, or at least an exciting one ; for 

 this light more rarely occurs, and is much fainter, in still water, whilst it becomes more and 

 more brilliant as the motion increases. It is also more abundant immediately before and during 

 storms. 



