174 THE ADDRESSES, LECTURES, ETC., OF 



appearing in deep water it will be hopeless to bring the light cable 

 to the surface for the purpose of repair. It is possible that the 

 manufacture of cables will be made a matter of such absolute 

 certainty that the case of faults making their appearance in sub- 

 merged cables may be left entirely out of consideration, but in the 

 meantime telegraph companies have given the preference, and 

 wisely so, I think, to a cable which, though more costly than its 

 light competitor, affords a greater security to their property in case 

 of an accident or a fault. 



Whilst the art of submerging deep-sea cables, involving, as it 

 does, problems of very considerable scientific and practical interest, 

 has latterly received the attention of this Society, but little dis- 

 cussion has as yet taken place of the best means for effecting the 

 repair of cables after submersion. 



The important primary condition towards effecting the repair 

 of a submerged cable is that its general insulation should be 

 perfect, without which it would be impossible to determine the 

 position of a break or fault with any degree of accuracy. Another 

 important condition is the possession of a cable-ship furnished 

 with special facilities for manoeuvring. The old practice of using 

 ordinary steamships of the mercantile marine appears very primi- 

 tive and objectionable, as such vessels are ill-adapted for going 

 astern, are not steady when laden with cable and armed with 

 heavy deck machinery, and are incapable of turning or maintain- 

 ing their position against a side-wind unless going nearly full 

 speed, whereas the cable ship should be capable of effecting these 

 operations independently of any onward motion. The paying-out 

 and hauling-in machinery, the tackle for fixing and lighting buoys, 

 the arrangements for sounding, and the construction of grapnels 

 capable of finding, cutting, and holding the end of deep-sea cables, 

 are also matters influencing greatly these delicate operations, upon 

 which the permanent success of submarine telegraphy must mainly 

 depend. 



The transmission of telegraphic messages through long submarine 

 cables is a subject which was at one time involved in great practical 

 difficulty owing to the retardation by lateral induction experienced 

 by the electrical current in its transit. It is to our past President, 

 Sir William Thomson, that we are indebted for a solution of this 

 difficulty, through the application of his celebrated mirror instru- 



