32 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS UIETEOEOLOGY. 



tains,* we should liave no '' considerable ciiiTents " whatever in the 

 sea. In consequence of the diurnal rotation of the planet on its 

 axis, each particle of oil, were resistance small, would approach the 

 poles on a spiral turning to the east with a relative velocity greater 

 and greater, imtil, 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 towards the west. Owing 

 to the principle here alluded to, all currents from the equator to 

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

 towards 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 miiform 

 system of currents just described would now be interrupted by 

 obstructions and local causes of various kinds, such as unequal dej)th 

 of water, contour of shore lines, &c. ; and we should have at cer- 

 tain places cm-rents greater in volume and velocity than at others. 

 But still there would be a system of currents and counter cmTents 

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

 waters of the north, and the v;arm waters of the gulf, made specifi- 

 cally lighter by tropical heat, and which we see actually preser^dng 

 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 tendencv (Plate IX.) of polar waters towards the 



towards tbe pole, cold • \ n , • i j -> xi i 



tovv-ards the equator, tropics and 01 tropical wators towards the poles. 

 Captain Wilkes, of the United States Exploring Expedition, 

 crossed one of these hj^perborean mider cm-rents two hundred 

 miles in breadth at the equator. 



98. No feature of the Gulf Stream excites remark among 

 Edges of the Gulf seamen more frequently than the sharpness of its 

 feature. '"° cdgcs, particularly along its inner borders. There, 

 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 



* '^ If there were no atmospliere, there would be no Gulf Stream or any other 

 considerable oceanic current (as distinguished from a mere surf;ice drift) what- 

 ever/' — Art. 37, Phyeical Geography, 8tli ed. Encyclop. Brit. 



