IS THE GULF STREAM A MYTH? 121 



America ; and this portion, though narrow, has a very 

 remarkable effect in increasing the coldness of the 

 American winters. But the main part, (heavier, by 

 reason of its coldness, than the surrounding water,) sinks 

 beneath the surface. And the well-known fact men- 

 tioned by Maury, that icebergs have been seen stemming 

 the Gulf Stream, suffices to show how comparatively 

 shallow that current is at this distance from its source, 

 and thus aids to remove a difficulty which we have 

 already had occasion to deal with. 



Doubtless the cooling influence of the arctic currents 

 is appreciable ; but it would be a mistake to suppose 

 that this influence can suffice to deprive the Gulf 

 current of its distinctive warmth. If all the effect of 

 the cold current were operative on the Gulf Stream 

 alone we might suppose that, despite the enormous 

 quantity of comparatively warm water which is con- 

 tinually being carried northwards, the current would be 

 reduced to the temperature of the surrounding water. 

 But this is not so. The arctic current not only cools 

 the Gulf current, but the surrounding water also 

 possibly to a greater extent, for it is commonly sup- 

 posed that a bed of ordinary sea-water separates the 

 two main currents from each other. Thus the charac- 

 teristic difference of temperature remains unaffected. 

 But in reality we may assume that the cooling effect 

 actually exercised by the arctic current upon the 

 neighbouring sea is altogether disproportionate to the 

 immense amount of heat continually being carried 

 northwards by the Gulf Stream. It is astonishing how 



