TRANSMISSION OVER SUBMARINE CABLES 



107 



The process of calculating the resistance and inductance of a sub- 

 marine cable by the method just described may be summarized as 

 follows: 



(1) Determine from (47) the quantities qi . . . q„ in terms of A and 

 Bo, and then in terms of /i and /„ by (49) and (50). 



(2) Substitute these values of gi . . . g„ in (52) and obtain the 

 ratio /o//i. 



(3) Substitute for A, B^ and ^i . . . g„ in (56) their values in terms 

 of /„ and /i. 



(4) Eliminate /i from these two relations, thus obtaining £2 in 

 terms of I^- Then Zo = — E2/ 1^. 



(5) Substitute this value of Z2 and the value of Zi calculated 

 from (55) in equation (58). 



(6) The resistance and the inductance per unit length of the cable 

 may then be determined from the real and imaginary parts of the 

 latter equation. 



£5 



50 

 Fig. 6 



75 



100 



The resistance and inductance of a cable of cross-section shown 

 in Fig. 4 were computed by the method just described, the results 

 being given by curves E and F of Fig. 3. The cable in this case is 

 identical with that shown in Fig. 2 previously described, except that 

 the continuous iron sheath has been replaced by fifteen wires. The 



