26 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOEOLOGY, 



Mediterranean (p. 162), mentions that a continuance in tlie Sea 

 of Tuscany of ''gusty gales " from tlie south-west has been known 

 to raise its sm^face no less than twelve feet above its ordinary level. 

 This, he says, occasions a strong surface drift through the Strait of 

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

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

 miniatm^e river even in that 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 v/ater, loses 

 itself by broad spreading as soon as it finds sea room. As soon as 

 the force that begets it expends itself, the ciuTent is done. 



83. Supposing with Franldin, and. those of his school, that the 

 ThebedoftheGuif prossuro of the v;aters that ^yq forced into the Carib- 

 ing plane. boau Sca by the trade-winds is the sole cause of the 



GuK 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 

 Eemiell likens the stream to " an immense river descending from a 

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

 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 waters ofl" 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 ofl' 

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

 is easy to shov/ 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 represents 

 the smface of an inclined plane — inclined dowmvards from the north 

 towards the south — uj:) which plane the lower depths of the stream 

 onust ascend. If we 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 waters therefore, which in the 

 Straits are below the level of the Hatteras depth, so far from de- 

 scending, are actually forced up an inclined plane, whose submarine 

 ascent is not less than ten inches to the mile. 



* Navy officers of the United States Coast Survey liave sounded with the 

 deep-sea lead, and ascertained its depth here to be 370 fathoms (January, 185G). 



