214 J. D. Dana on an Isothermal Oceanic Chart, 



Newfoundland Banks, and then makes its Gulf Stream flexure. 

 The line of 44° F., for the same reason — the spreading of the 

 Gulf Stream waters — diverges far from the equator in its 

 easterly course, and even rises in a long loop between Great 

 Britain and Iceland. 



The cold currents flowing down the eastern coast of Ame- 

 rica bend the isocrymes far south close along the coast, and 

 make a remarkable southern flexure in the isocrymes of 68° F., 

 outside of the Gulf Stream flexure. So on the western coast 

 of Britain, the isocryme of 44° F. has a deep southern flex- 

 ure, for a like cause. 



The waters of the tropical current gradually cool down in 

 their progress, through the influence of the colder waters 

 which they encounter ; and along the isocryme of 62° they 

 have in the colder seasons a common temperature with that 

 of the ocean, so that the course of the Gulf Stream is but 

 faintly marked in it. And also in the western half of the 

 region covered by the isocryme of 56°, the colder and warmer 

 waters have reached this as a mean temperature. Owing 

 to the influence of the polar current on the northern coast of 

 South America, the equator of heat lies at a distance from 

 the land. 



Up the western coast of Africa flows the cold current from 

 the south and west, bending upward all the isocrymal lines ; 

 and passing north of the equator, it produces a large south- 

 ern bend, off the coast of Africa, in the northern isocryme of 

 74 , outside of the warm current flexure from the coast of 

 Guinea, and also a large northern flexure in the heat-equa- 

 tor.* 



The Atlantic tropical current also flows in part down the 

 eastern coast of South America, giving a deep flexure to each 

 of the isocrymes, besides making these lines to diverge from 

 the equator, through all their length. Again, the polar cur- 

 rent passes northward nearer the coast-line, bending far 

 back the western extremity of each of the isocrymes. 



* Along the ocean, near Africa, south and south-east of the Cape Verdes, 

 Captain Wilkes found a current setting to the northward for much of the timo. 

 until pasting tiio equator. 



