Page:Physical Geography of the Sea and its Meteorology.djvu/48

22 68. Specimens from the depth of 19,800 feet.—Lieutenant Brooke, in the "Hancock," has obtained soundings in the North Pacific from the depth of 3300 fathoms, with specimens both of the ooze and the water at the bottom. These have been sent to Professor Ehrenberg of Berlin, for microscopic examination. He has not completed his study of these treasures, but he already reports the discovery in them of more than one hundred new species of animalculæ.



70. Its colour.—There is a river in the ocean: in the severest droughts it never fails, and in the mightiest floods it never overflows; its banks and its bottom are of cold water, while its current is of warm; it takes its rise in the Gulf of Mexico, and empties into Arctic seas; this mighty river is the Gulf Stream. There is in the world no other such majestic flow of waters. Its current is more rapid than the Mississippi or the Amazon, and its volume more than a thousand times greater. Its waters, as far out from the gulf as the Carolina coasts, are of indigo blue. They are so distinctly marked that their line of junction with the common sea-water may be traced by the eye. Often one-half of the vessel may be perceived floating in Gulf Stream water, while the other half is in common water of the sea—so sharp is the line, and such the want of affinity between those waters, and such, too, the reluctance, so to speak, on the part of those of the Gulf Stream to mingle with the littoral waters of the sea.

71. How caused.—At the salt-works of France, and along the shores of the Adriatic, where the "salines" are carried on by the process of solar evaporation, there is a series of vats or pools through which the water is passed as it comes from the sea, and is reduced to the briny state. The longer it is exposed to evaporation, the salter it grows, and the deeper is the hue of its blue, until crystallization is about to commence, when the now deep blue water puts on a reddish tint. Now the water of the Gulf Stream is salter (§ 102) than the littoral water of the sea through which it flows, and hence we can account for the deep indigo blue which all navigators observe in Gulf Stream water off the