88 SUBMARINE CABLE LAYING AND EEPAIRING. 



■with a core of 650 lb. of copper and 400 lb. of gutta-percha per 

 naut to give a minimum speed of 40 words per minute. The 

 speed actually attained on ordinary traffic reaches the high 

 figure of 47 to 48 words (of five letters) per minute. Particulars 

 of the construction, laying and testing of this cable were given 

 in an able article on the subject in The Electrician of October 12, 

 1894, by Mr. Arthur Dearlove. The cable, which is 1,847 nauts 

 in length, was manufactured, shipped and laid complete in five 

 months from the date the contract was signed. 



The conductor, formed of a large central solid wire with a 

 strand of 12 small wires surrounding it, has a resistance of 

 1-682 ohms per naut, and the dielectric a capacity of 0*420 

 microfarad per naut. The " K R " constant is therefore an 

 exceptionally low one — viz., 0*706 per naut — by which a high 

 speed of signalling is obtained. 



The sheath of the deep-sea portion was of 18 No. 14 steel 

 wires, each taped and compounded, and having a breaking 

 strain of 8-2 tons. 



The other cable laid in the same year was designed, manu- 

 factured and laid by Messrs. Siemens Bros. & Co. for the 

 Commercial Cable Company. The speed of signalling was 

 guaranteed to be 33 per cent, more than in the two former 

 cables laid for this company by the same contractors in 1884, 

 and the actual speed attained has exceeded the guarantee. 

 The length laid is 2,161 nautical miles, of a total weight of 

 5,460 tons, comprising : — 



495 tons of copper (510 lb. per naut). 



315 „ gutta-percha (325 lb. per naut). 



575 „ jute. 

 3,000 „ steel. 

 1,075 „ compound. 



The cable was manufactured at the rate of 50 to 55 nauts 

 per day of 24 hours. The " Faraday " made two trips, the 

 first to lay and buoy the shore-ends (in all over 600 miles) 

 and the second with the balance of the shallow-water cable 

 and the whole of the deep-sea portion. The entire cable was 

 laid in 20 days' actual time engaged. 



Principles of Construction. — Coming now to the manufac- 

 ture of submarine cables, there are two departments kept quite 



