474 THE TROPICAL WORLD. 



Caribbean Sea and the Gulf of Mexico, from which it derives the name of the Gulf 

 Stream. It passes out through the Straits of Bemini, between Florida and Cuba, a 

 great river 32 miles wide, 2,200 feet deep, flowing at the rate of four miles an hour. 

 Its volume is a thousand times greater than that of the Amazon or the Mississippi, and 

 its banks of cold water are more clearly defined than are those of either of these rivers 

 at flood. So clear is the line of demarkation between the warm water of the river 

 and its cool liquid banks, that a ship sailing along may be half in one and half in the 

 other ; and a bucket of water dipped from one side will be twenty degrees cooler than 

 one from the other. Skirting the coast at a distance of about 100 miles, its width is 

 increased and its velocity diminished. Striking the projecting banks of Newfound- 

 land, its course is deflected almost due east, until it arrives at mid-ocean. Here it 

 spreads out like a fan, skirting the shores of Spain, France and Great Britain. It 

 then divides, one branch sweeping around the west coast of Iceland, the other 

 approaching the shores of Norway, and its temporary influence is perceptible in the 

 ameliorated climate of Spitzbergen. 



It is owing to this great ocean river that the temperature of the western shores of 

 Europe is so much higher than that of the eastern shore of America in the same lati- 

 tudes. Maury estimates that the amount of heat which the Gulf Stream diffuses over 

 the northern Atlantic in a winter's day is sufficient to raise the whole atmosphere 

 which covers France and Great Britain from the freezing point to summer heat. The 

 olives of Spain, the vines of France, the wheat-fields of England, and the green 

 expanse of the Emerald Isle, are the gifts of the tropical seas, dispensed through the 

 Gulf Stream. 



Near the Azores another branch of the Gulf Stream encounters the return flow 

 from the Arctic Ocean, bends around, and skirting the coast of Africa, returns to its 

 starting-place in the Gulf of Guinea, leaving in its great bend near the Azores an 

 expanse of almost motionless waters larger than the whole of France. This is known 

 as the Sargasso Sea, from the surface being covered with a seaweed called the Sar- 

 gassum natans. So thick is the covering of weeds that at a little distance it seems 

 solid enough to walk upon. Another curious species of seaweed, the Macrocrystis 

 pyrifera, is found in this grassy sea. The stem, not thicker than a man's finger, is 

 from 1,000 to 1,500 feet long, branching upward in filaments like pack-thread. Most 

 of these weeds probably grow on the spot ; but many are borne along by the Gulf 

 Stream, for everything that floats from other parts of the Atlantic tend to its eastern 

 side. The discovery of the bodies of strange animals and unknown trees and plants 

 flung ashore at the Azores suggested to Columbus the idea that there was land lying 

 beyond the western ocean ; so that to the Gulf Stream we are indebted for the dis- 

 covery of the New World. Bottles have been thrown overboard at various points in 

 the Gulf Stream, containing the date and position of the ship. Many of these have 

 been picked up. From these it appears that the stream takes eight months to flow 

 from the Gulf of Mexico to the shores of Europe, and the broader and slower current 

 takes a year to travel from the Bay of Biscay back to the Gulf of Mexico. 



The Gulf Stream, though the best known, and in many respects the most remark- 

 able of the great equatorial currents, is by no means the largest. The great current 

 of the Pacific and Indian Oceans may be regarded as one mighty stream flowing from 

 east to west. It crosses the Pacific in a sheet nearly 3,500 miles broad, spreading 



