THE SEA AXD THE ATMOSPHERE. 19 



witli ^vires 'properly insulated, are held to be within effectiYe 

 telegraphic reach. 



60. One of the chief physical difficulties Yvhich seem now to 

 Faulty cables. stand in the way of these Imes lies with the " cables." 



It so happens that all deep-sea lines have at the present Y/riting 

 ceased to work. The two Malta lines in the Mediterranean are out 

 of order ; so also are the Red Sea lines : no messages have passed 

 ])etween Kurrachee and Aden for some time, and the line to Algiers 

 has been suspended, if not abandoned, for the present. 



61 . All these lines had cables incased in a wrapping of iron wire ; — 

 Their iron wrappings, and it is a qucstioH whether the difficulty with them 

 all be not owing to that circumstance. The wire wrapping of 

 the Atlantic cable has been found in a state almost of complete dis- 

 integration, like the iron fastenings of coppered ships. This 

 evidence of galvanic action excites suspicions as to the proper 

 insulation of that cable. Iron, sea-water, and copper, will make a 

 battery of no inconsiderable power ; and the decayed state of the 

 iron Ydre in this instance encom^ages the belief as to defective 

 insulation. 



62. Such are the facts. But the facts do not prove that gutta 

 imperfect insula- pcTcha is au imperfcct insulator. With regard to 

 ^''"■- the Atlantic cable, they suggest that the insulation 

 of that cable, though perfect at first, might have been injured by the 

 handlmgs to which the cable was afterwards subjected, and above 

 all by the heavy strains which v^ere brought upon it by the " brakes " 

 during the operation of laymg it along the plateau. 



63. These facts, however, do not suggest the same for the Bed 

 riie Red Sea and ^^^ ^^^ ' Mediterranean cables, for these cables had 

 iMediterraaeanca- all been dowu for somo time, and had been working 

 ' ''■ more or less satisfactorily ; nevertheless, we are re- 



mmded by these failures now, and that too from a fresh quarter, 

 that iron wrappmgs about a telegraphic wire are of no use in the 

 deep sea.* 



64. Two metals, as a copper conductor and an iron wrapper, 

 A galvanic battery Y' ould secm uot to be dcsirable for the same cord, for 

 m the sea. ^^ ^^^^ q£ jg^kage a galvanic batter}^ is at once formed 

 m ihe sea, and brought hito play upon the cable. Not only so, the 



"Therefore it may now be considered a settled principle in submarine 

 telegraphy, that the true character of a cable for the deep sea is not that of an 

 iron rope as large as a man's arm, but of a single copper wire, or a fascicle of 

 wires, coated with gutta percha, pliant and supple, and not larger than a lady's 

 finger.' —Letter to Secretary of the Navy, November 8, 1850. 



c2 



