WILLIAM SIEMENS, /~.R.s. 6 1 



siderable importance to the last formula, which alone enables us tc 

 determine the situation of new faults in old defective cables, if 

 only its previous electrical condition is known. This knowledge 

 is unfortunately wanting in respect of nearly all the cables that 

 have hitherto been laid. In the case of the Rangoon and Singa- 

 pore cable, we propose to furnish each station with a complete 

 testing apparatus, and to cause daily tests to be instituted upon 

 the cable, when laid, of its electrical conditions on each section. 



Records of these observations should be forwarded daily to the 

 chief electrician in charge of the line, who will then have the 

 means at his disposal to watch the rise and gradual progress of 

 faults, and to apply the remedy at the proper moment, and with a 

 certain knowledge of the position and magnitude of every defect. 



Considering the circumstance that owing to great care, the 

 conductor of the Rangoon and Singapore cable is fully ten times 

 more perfectly insulated than the best conductor hitherto sub- 

 merged, we confidently expect that the result in practice will also 

 greatly exceed that of previous experience ; still the insulating 

 material employed remains the same, and is, therefore, liable to be 

 affected by the same causes of failure. 



The chief difficulty has hitherto consisted, in working india- 

 rubber in such a way as to obtain uniform and perfect coatings 

 upon the conductor without injury to the material itself. We 

 have endeavoured to remove this difficulty in constructing a 

 covering machine, which we have brought before Section G. of 

 this Association. 



We do not wish, however, to rest upon our individual efforts 

 for the further development of this important new branch of 

 applied science. Great efforts have been made latterly by others 

 eminently qualified to produce useful results. The insulating 

 power of gutta-percha has been vastly improved, and new insu- 

 lating materials are being produced. 



Our object in writing this communication is to show that 

 although submarine electric telegraphs have often failed, owing to 

 insufficient experience and insufficient care bestowed upon their 

 manufacture to guard against defects, the experience gained has 

 not been lost ; and that in bringing the present stock of know- 

 ledge to bear upon the subject, more complete success may be 

 insured. 



