98 THE SCIENTIFIC PAPERS OF 



lating medium. Both these conditions were fulfilled in the case of 

 the Malta and Alexandria cable. 



Excepting in the one instance mentioned, no fault appeared in 

 the cable after shipment, and having been laid very carefully, under 

 the direction of Mr. H. C. Forde, the Government Engineer, there 

 is every probability of its continuing for some years in good 

 working condition. 



The instruments for working the line were made by Messrs, 

 Siemens, Halske, and Co., under the author's general superintend- 

 ence. They are ink-recording instruments, fitted with peculiar 

 arrangements for discharging the residuary charge of the cable, 

 and having the peculiarity of being capable of being worked 

 by an exceedingly feeble battery power. One single Daniel! 's 

 cell suffices for the transmission of messages through each section 

 of the line, and when regularly working, not more than from eight 

 to ten cells need ever be employed. Although the line is divided 

 into three electrical circuits, messages are transmitted mechanically, 

 and instantaneously, at the intermediate station, by a system of 

 double relay, or translation, first introduced by Messrs. Siemens, 

 and Halske upon the continent. By this system of working, 

 messages can now be sent instantaneously, from London to Omsk 

 in Siberia, and there would be no electrical difficulty in establish- 

 ing the same direct inter-communication between London and 

 Calcutta. A detailed description of these instruments would fall 

 beyond the limits assigned to the present paper. The author 

 ,also passes over an important branch of the general subject,namely 

 the methods and apparatus employed for ascertaining the position 

 of faults in submarine lines, referring those interested to the docu- 

 ments published in the report of the Joint Committee on Sub- 

 marine Telegraphs.* 



The general superiority of the Malta and Alexandria cable over 

 other long submarine lines, previously constructed, cannot admit of 

 a doubt ; and it is to be hoped that it may continue in good work- 

 ing condition, both on account of its national importance, and also 

 for the sake of ensuring progress in this branch of engineering 

 science. At the same time, it will hardly be asserted by the most 

 ardent defender of the present form of submarine cable, that its 



* Vide " Report of the Joint Committee on the Construction of Submarine Tele- 

 graph Gabies," Appendix No. 12, &c. 



