The continuously-loaded submarine telegraph cable

In this paper the submarine telegraph cable is discussed. The earlier non-loaded type is referred to briefly and the more recent loaded type is treated in somewhat greater detail. It is shown that, in the non-loaded cable, distortion and attenuation of signals may be reduced and speed of signalling thereby raised by increasing the section of the conductor, but a limit to this procedure is at length reached by consideration of economy and facilities for manipulation. The discovery of the alloys which exhibit high values of permeability on the application of low magnetizing forces is referred to, as is also the fact that this discovery made possible the loading of telegraph cables, with consequent great increase in speed of signalling. A description is given of the method of application of the loading material to the annealing and testing. Finally, the theory of transmission of impulses through loaded cables is briefly discussed and some details are given in regard to methods of testing during manufacture and after laying. Special reference is made to the Fanning Island-Suva (Fiji) section of the Pacific Cable (1926).