THE LAYING OF SUBMARINE CABLES. Ill 



As an instance of a shallow-water cable we may take the 

 cable laid along the coast of the Gulf of Guinea, between Accra 

 ou the Gold Coast and Sierra Leone. This cable is 1,019 knots 

 in length, and laid in water not more than 720 fathoms in the 

 deepest part, the average depth being about 100 fathoms. 

 The lightest type used in this cable is type B^, the different 

 types being spliced together in the following lengths, starting 

 from Sierra Leone : — 



5 knots of type A 



5 „ ,, E 



46-8 ,, „ B 



939 „ „ Bi 



18-4 knots of type B 

 3 „ „ E 

 2 „ „ AA 



The letters indicating the types or sizes of cable are as used 

 by the Telegraph Construction and Maintenance Company. 

 The various types made by this Company are shown in section 

 in Fig. 39. 



The weights per mile of these types in air and water are : — 



Type AA 20 tons in air and 15 tons in water. 



A 12 „ „ 9 „ 



E 7 „ „ 5i „ 



B 75 cwt. ,, 54 cwt. „ 



Bi 60 „ „ 40 „ 



D 40 ,, ,, 23 „ 



Let us consider a simple case of two cables, one of 260 miles 

 and one of 940 miles, to be laid in one expedition between the 

 three ports A, B and C (Fig. 52). The cable, say, between the 

 ports A and B follows the coast line, where the depth does not 

 exceed 500 fathoms, and is suitable for an intermediate type of 

 cable, while that between the ports A and C is a cross-sea 

 cable, where the depth reaches 2,000 fathoms. As shown in 

 the plan the cables will be made up as follows : — 



Short Cable, 260 miles. — Six miles of shore-end at Port B, 

 nine miles of shore-end at Port A, 245 miles of intermediate. 

 Each type to have light and heavy sections. 



Long Cable, 940 miles. — Nine miles of shore-end and 160 

 miles of intermediate from Port A, 11 miles of shore-end and 

 220 miles of intermediate from Port C, 540 miles of deep-sea 

 cable. Each type to have light and heavy sections. 



