THE GULF STREAM. 27 



the laws of Hydrostatics, as at present expounded, appear by no 

 means to warrant the conclusion that it is, unless the aid of other 

 agents also be brought to bear. 



Admiral Smyth, in his valuable memoir on the Mediterranean 

 (p. 162), mentions, that a continuance in the Sea of Tuscany of 

 ''^ gusty gales''' from the southwest has been known to raise its sur- 

 face no less than twelve feet above its ordinary level. This, he 

 says, occasions a strong surface drift through the Strait of Boni- 

 faccio. But in this we have nothing like the Gulf Stream ; no 

 deep and narrow channel-way to conduct these waters off like a 

 miniature river even in the sea, but a mere surface flow, such as 

 usually follows the piling up of water in any pond or gulf above 

 the ordinary level. The Bonifaccio current does not flow like a 

 river in the sea across the Mediterranean, but it spreads itself out 

 as soon as it passes the Straits, and, like a circle on the water, 

 loses itself by broad spreading as soon as it gets to sea. 



10. Supposing the pressure of the waters that ?i.Ye forced into 

 the Caribbean Sea by the trade-winds to be the sole cause of the 

 Gulf Stream, that sea and the Mexican Gulf should have a much 

 higher level than the Atlantic. Accordingly, the advocates of this 

 theory require for its support " a great degree of elevation." Major 

 Rennell likens the stream to " an immense river descending from 

 a higher level into a plain." Now we know very nearly the aver- 

 age breadth and velocity of the Gulf Stream in the Florida Pass. 

 We also know, with a like degree of approximation, the velocity 

 and breadth of the same w^aters off Cape Hatteras. Their breadth 

 here is about seventy-five miles against thirty-two in the " Nar- 

 rows" of the Straits, and their mean velocity is three knots off 

 Hatteras against four in the "Narrows." This being the case, it 

 is easy to show that the depth of the Gulf Stream off Hatteras is 

 not so great as it is in the " Narrows" of Bemini by nearly 50 per 

 cent., and that, consequently, instead of descending, its bed rep- 

 resents the surface of an inclined plane from the north, up which 

 the lower depths of the stream must ascend. If w'e assume its 

 depth off Bemini to be two hundred fathoms, which are thought 

 to be within limits, the above rates of breadth and velocity will 

 give one hundred and fourteen fathoms for its depth off Hatteras. 

 The w^aters, therefore, which in the Straits are below the level of 

 the Hatteras depth, so far from descending, are actually forced up 



