TIDE-RirS AND SEA DRIFT. 401 



747. Whence the Bed Sea derives its name. — These discoloura- 

 tions are no doubt caused by organisms of the sea, but whether 

 wholly animal or wholly vegetable, or whether sometimes the 

 one and sometimes the other, has not been satisfactorily ascer- 

 tained. I have had specimens of the colouring matter sent to me 

 from the pink-stained patches of the sea. They were animalcules 

 well deiiDed. The tints which have given to the Eed Sea its 

 name ma}^ perhaps be in some measure due to agencies similar to 

 those which, in the salt-makers' ponds, give a reddish cast (§ 71) 

 to the brine just before it reaches that point of concentration 

 wlien crystallization is to commence. Some microscopists main- 

 tain that this tinge is imparted by the shells and other remains 

 of infusoria which have perished in the gi*owing saltness of the 

 water. The Red Sea may be regarded, in a certain light, as the 

 scene of natural salt-works on a grand scale. The process is by 

 solar evaporation. ISs^o rains interfere, for that sea (§ 376) is in a 

 riverless district, and the evaporation goes on unceasingly, day 

 and night, the year round. The shores are lined with incrusta- 

 tions of salt, and the same causes which tinge with red (§71) the 

 brine in the vats of the salt-makers probably impart a like hue 

 to the arms and ponds along the shore of this sea. Quantities, 

 also, of slimy, red colouring matter are, at certain seasons of the 

 year, washed up along the shores of the Eed Sea, which Dr. 

 Ehrenberg, after an examination under the microscope, pro- 

 nounces to be a very delicate kind of sea-weed : from this matter 

 that sea derived its name. So also the Yellow Sea. Along the 

 coasts of China, yellowish-coloured spots are said not to be 

 uncommon. I know of no examination of this colouring matter, 

 however. In the Pacific Ocean I have often observed these dis- 

 colourations of the sea. Eed patches of water are most frequently 

 met with, but I have also observed white or milky appearances, 

 which at night I have known greatly to alarm navigators by their 

 being taken for shoals. 



748. The escape ofivarm waters from the Pacific. — These teeming 

 waters bear off through their several channels the surplus heat 

 of the tropics, and disperse it among the icebergs of the Antarctic. 

 See the immense equatorial flow to the east of Australia, and 

 which I have called the Polynesian Drift. It is bound for the 

 icy barriers of that unknown sea, there to temper climates, grow 

 cool, and return again, refreshing man and beast by the Avay, 

 either as the Humboldt current, or the ice-bearing current which 



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