386 PHYSICAL GEOOKAPHY OF THE SEA, AND ITS METEOROLOGY. 



times the other, has not been satisfactorily ascertained. I have 

 had specimens of the colourinor matter sent to me from Ihe pink- 

 stained patches of the sea. They were animalculae well defined. 

 The tints which have given to the Red Sea its name may per- 

 haps 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 when crystalli- 

 zation is to commence. Some microscopists maintain that this 

 tinge is imparted by the shells and other remains of infusoria 

 which have perished in the growing 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. No rains interfere, for that sea (§376) is in a 

 riverless district, and the evaporation goes on unceasing^ly, 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 Red 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. Red patches of water are most fre- 

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

 appearances, which at night I have known greatly to alarm navi- 

 gators by their being taken for shoals. 



748. These teeming waters bear off through their several 

 The escape of warm channels the surplus heat of the tropics, and dis- 

 paciflc. perse 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 way, 

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

 enters the Atlantic around Cape Horn, and changes into 

 warm again as it enters the Gulf of Guinea. It was owing to 

 this great southern flow from the coral regions that Captain Ross 



