76 THE SCIENTIFIC PAPERS OF 



succession of tubes, connected together by universal joints. The 

 plan was more advantageous than using a strong cable, for each 

 tube took a firm position upon broken ground, allowing the cable 

 inside to make its own serpentine curve ; whereas a strong cable 

 would, owing to its elasticity, always be moving between its 

 supports, and be thus exposed to continual abrasion. 



Passing to the larger work of the Red Sea cable, he would first 

 explain the position in which he stood with regard to that under- 

 taking, or rather the position of the firm of Messrs. Siemens, 

 Halske & Co., of which he was a partner. They were employed 

 to superintend the electrical condition of the cable during sub- 

 mersion. Unfortunately they had not had an opportunity of 

 examining the cable regularly until it was on board ship ; and it 

 was one of the most prolific causes of failure that cables were not 

 thoroughly tested under water before they were deposited in the 

 ocean. In laying the Eed Sea cable faults occasionally occurred, 

 which, by the system of testing adopted, were instantly detected 

 and rectified ; but none of these would have happened if the cable 

 had been previously immersed. When the operation was com- 

 pleted, it proved, like most lines when just laid, very successful. 

 The telegraph was worked from Alexandria to Aden, a distance of 

 1200 miles, with double relay stations at Kosseir and Suakim, at 

 the rate of ten words per minute ; and the general condition of 

 the line was such as must be pronounced to have satisfied the 

 terms of the contracts. There were, no doubt, a few embryo 

 faults, which, by their system of testing every five minutes during 

 submersion, they were enabled to trace, and to map by means 

 of diagrams, representing the copper and gutta-percha resistances. 

 The times of observation were not left to the discretion of those 

 on land and on board the ship from which the cable was payed out, 

 but they were prescribed by a peculiar clock-work arrangement, 

 which reduced the work of the observer to a simple registration, 

 and obviated much uncertainty and delay in these operations. The 

 line was in a satisfactory electrical condition when laid, and he 

 believed it might have been worked successfully for a considerable 

 space of time, if a permanent system of daily tests and of timely 

 repairs had been at once established. The author had mentioned 

 some of the difficulties with which the cables had to contend, and 

 the injuries to which they were exposed : but, probably, he had not 



