THE GULF STREAM. 33 



constant and uniform tlirongliout. On sncli a globe, the equili- 

 brium remaining undisturbed, tliere would be neither wind nor 

 current. Let us now suppose that all the water within the 

 tropics, to the depth of one hundred fathoms, suddenly becomes 

 oil. The aqueous equilibrium of the planet would thereby be 

 disturbed, and a general system of currents and counter-currents 

 would be immediately commenced — the oil, in an unbroken 

 sheet on the surface, running towards the poles, and the water, 

 in an under-cuiTcnt, towards the equator. The oil is supposed, 

 as it reaches the polar basin, to be reconverted into water, and 

 the water to become oil as it crosses Cancer and Capricorn, 

 rising to the surface in the intertropical regions, and retuiming 

 as before. Thus, without wind, we should have a perpetual and 

 unifonn system of tropical and polar currents ; though witliout 

 wind, Sir John Herschel maintains,* we should have no " con- 

 siderable currents " 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 gi-eater and greater, 

 until, 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 jDoles 

 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 uniform 

 system of currents 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. Kow, 

 do not the cold waters of the north, and the warm waters of the 

 gulf, made specifically lighter by tropical heat, and wliich we 



* " If there were no atmosphere, there •would be no Gulf Stream or any- 

 other considerahle oceanic current (as distinguished from a mere sui'face drift) 

 whatever."— Art. 37, Physical Geography, 8th ed. Eucyclop. Brit. 



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