48 THE ADDRESSES, LECTURES, ETC., OF 



without any leakage at the end, and we can by our formula 

 determine the importance of this jar as compared with the jar 

 of unit capacity. Having thus determined the position of a fault 

 in a cable under different circumstances, the vessel proceeds to the 

 spot, takes it up, repairs it, and puts the cable back in its normal 

 condition. 



CONCLUSION. Having now conducted you somewhat hurriedly 

 over the field of electrical tests, I hope I have succeeded in 

 satisfying your minds that the application of a well arranged 

 system of tests is not only most desirable, but absolutely essential 

 for the success of submarine cables. I would go further, and 

 assert that a fault should never occur during the laying of a cable, 

 for, however microscopic a fault may be, it ought to be detected 

 before it goes overboard, and a good sheathing should secure the 

 core against mechanical injury. When I addressed you before on 

 the subject of deep-sea telegraphs, the Great Eastern was on 

 the point of leaving these shores. I then expressed my confi- 

 dence in the insulation of the cable, but some doubt as regards 

 the efficiency of the outer covering. The failure which has since 

 unfortunately occurred has not diminished my confidence in the 

 insulated conductor, and in the eventual success of the under- 

 taking, if only the outer covering and the arrangements for 

 putting the cable to the bottom are more carefully attended to. 

 It is to be hoped that those interested in that great undertaking 

 may have profited by the experience they have gained, and that 

 we may next summer hear of a complete success of that great 

 undertaking, which, as far as electrical science is concerned, ought 

 certainly to be a success.* 



The Chairman : I am sure you will all join me in returning our 

 best thanks to Mr. Siemens for the able manner in which he has 

 brought the subject before us. 



* This paper was read in the early spring of 1866. Since then this complete 

 success has been achieved. Editor of the R. U. S. I. Journal. 



