14 THE OCEAN. 



Etzel tlie lead would not reacli the bottom at less than 150 fathoms 

 in the deepest hollow. 



To the south-west, the North Sea communicates by the Straits of 

 Dover with the Channel ; a narrow arm of the sea which may be con- 

 sidered as a mere accident of the earth's surface, as a kind of mari- 

 time trench, so inconsiderable is its depth compared with that of the 

 ocean. In order to form a true notion of the depth of the Channel, 

 compared with its width, one must imagine a miniature of this sea 

 drawn on a scale of one yard for two-thirds of a mile, on a perfectly 



Fig. 6.— Profile following the line of the greatest depth 



horizontal surface. This sheet of water would not have less than 

 547 yards of length, and its width would vary, according to the coast 

 lines, between 36 and 240 yards. And yet, notwithstanding this 

 considerable surface, the greatest depth would be less than 2 inches 

 at the entrance. In the deepest hollow of the Channel, between the 

 hillock representing Start Point and that of the Sept-Iles, it would 

 be less than 2i inches. A sparrow could hop this miniature sea.* We 

 see that it is as easy to exaggerate the importance of the depth of the 

 sea as it is the height of mountains. The section annexed to Plate I. 

 shows the proportionate depth of water between the shores of Dover 

 and Calais. 



On leaving the Channel, the parts of the oceanic bed which have 

 been explored by sounding are more and more distant towards the 

 west, and then become quite rare. Finally, many hundred miles 

 out at sea, where the true abysses commence, soundings have been 

 only taken at intervals of about 30 and even bo miles apart. The 

 points thus marked which have served for drawing the submarine 

 chart of the North Atlantic, are therefore by no means numerous, 

 but nevertheless we have in it a pretty exact representation of the 

 7'e/iefoi the ocean-bed. The average depth of water which separates 

 the coasts of North America and those of Europe is about 1915 

 fathoms, but the central valley presents a surface relatively uniform, 

 and much less varied than that of Europe or even the United States ; 

 the greatest slopes do not probably exceed those of the river-beds 

 which seem nearly horizontal ; and it may be said that the depth of 

 * Saxby, Nautical MagazinCy March, 1864. 



