80 THE PHYSICAL GEOGRAPHY OF THE SEA. 



tintil, finally, it would reach the pole, and whirl about it at the 

 rate of nearly a thousand miles the hour. Becoming water and 

 losing its velocity, it would approach the tropics by a similar, but 

 reversed spiral, turning toward the west. Owing to the princi- 

 ple hero alluded to, all currents from the equator to the poles 

 should have an eastward tendency, and all from the poles toward 

 the equator a westward. Let us now suppose the solid nucleus 

 of this hypothetical globe to assume the exact form and shape of 

 the bottom of our seas, and in all respects, as to figure and size, 

 to represent the shoals and islands of the sea, as well as the coast 

 lines and continents of the earth. The uniform system of cur- 

 rents just described would now be interrupted by obstructions 

 and local causes of various kinds, such as unequal depth of water, 

 contour of shore lines, &c. ; and we should have at certain places 

 currents greater in volume and velocity than at others. But still 

 there would be a system of currents and counter currents to and 

 from either pole and the equator. Now, do not the cold waters 

 of the north, and the warm waters of the Gulf, made specifically 

 lighter by tropical heat, and which we see actually preserving- 

 such a system of counter currents, hold, at least in some degree, 

 the relation of the supposed water and oil ? 



97. In obedience to the laws here hinted at, there is a constant 

 Warm currents flow tcndencv (Plate IX.) of polar waters toward tbe 



toward the pole, cold . / ^ ^ 



toward the equator, tropics and of tropical watcrs toward the poles. 

 Captain Wilkes, of the United States Exploring Expedition, 

 crossed one of these hyperborean under currents two hundred 

 miles in breadth at the equator. 



98. ISTo feature of the Gulf Stream excites remark among 

 Edges of the Gulf scamcu morc frequently than the sharpness of its 



stream a striking . ^ ^ ^ ^ "^ . . , ■, ^ rrn 



feature. cdgcs, particularly along its inner borders. I here, 



it is a streak on the water. As high up as the Carolinas this 

 streak may be seen, like a greenish edging to a blue border — the 

 bright indigo of the tropical contrasting finely (§ 70) with the dirty 

 green of the littoral waters. It is this apparent reluctance of 

 the warm waters of the stream to mix with the cool of the ocean 

 that excites wonder and calls forth remark. But have we not, so 

 to speak, a similar reluctance manifested by all fluids, only upon 

 a smaller scale, or under circumstances less calculated to attract 

 attention or excite remark ? 



