NATURAL PHILOSOPHY. 161 



proportion to its surface. A copper wire one-sixth of an inch in diameter, 

 coated with gutta-percha to the depth of nearly half an inch, would be 

 found capable, by aid of my apparatus, of transmitting 2o words per 

 minute 3000 miles. To work the ordinary telegraphs, the copper wire 

 must be three-eighths of an inch in diameter, and coated with gutta- 

 percha three-fourths of an inch, making a total diameter of about two 

 inches. 



ON THE CONSTRUCTION OF A SUBMARINE TRANSATLANTIC TELE- 

 GRAPH. 



The following communication, on the feasibility of constructing a sub- 

 marine line of telegraph across the Atlantic, has been addressed to the 

 Secretary of the Navy by Lieutenant Maury : 



g IK : The United States brig Dolphin, Lieutenant Commanding O. H. 

 Berry man, was employed last summer upon especial service connected 

 with the researches that are carried 011 at this office concerning the winds 

 and currents of the sea. Her observations were confined principally to 

 that part of the ocean which the merchantmen, as they pass to and fro 

 upon the business of trade between Europe and the United States, use as 

 their great thoroughfare. Lieutenant Berry man availed himself of this 

 opportunity to carry along also a line of deep sea soundings from the shores 

 of Newfoundland to those of Ireland. The result is highly interesting, in 

 so far as the bottom of the sea is concerned, upon the question of a 

 submarine telegraph across the Atlantic ; and I therefore beg leave to make 

 it the subject of a special report. 



This line of deep sea soundings seems to be decisive of the question as 

 to the practicability of a submarine telegraph between the two continents, 

 in so far as the bottom of the deep sea is concerned. From Newfoundland 

 to Ireland, the distance between the nearest points is about 1,600 miles ;* 

 and the bottom of the sea between the two places is a plateau, which 

 seems to have been placed there especially for the purpose of holding the 

 wires of a submarine telegraph, and of keeping them out of harm's way. 

 It is neither too deep nor too shallow ; yet it is so deep that the wires, but 

 once landed, will remain forever beyond the reach of vessels' anchors, 

 icebergs, and drifts of any kind, and so shallow that the wires may be 

 readily lodged upon the bottom. The depth of this plateau is quite 

 regular, gradually increasing from the shores of Newfoundland to the 

 depth of from 1,500 to 2,000 fathoms as you approach the other side. 

 The distance between Ireland and Cape St. Charles, cr Cape St. Lewis, in 

 Labrador, is somewhat less than the distance from any point of Ireland to 

 the nearest point of Newfoundland. But whether it would be better to 

 lead the wires from Newfoundland or Labrador is not now the question ; 

 nor do I pretend to consider the question as to the possibility of finding a 



*From Cape Freds, Nc-wfoundlarid, to Erris Hesd, Ireland, the distance is l,fill miles; 

 from Cape Charles, or Cape St. Lev. is, Labrador, to ditto, the distance is 1,601 miles. 



