All cables of any great length are worked by reverse currents.
Two submarine cables start from Otranto, one for Valona, the other for Corfu.
There is also a manufacture of electric cables.
Among the men of business it was undoubtedly Sir John Pender (1815-1896) who contributed most to the development of this colossal industry, and to his unfailing faith in their ultimate realization must be ascribed the completion of the first successful Atlantic cables.
Actual or projected routes for telegraph cables across the deep sea have also been sounded with extreme accuracy in many cases; but beyond these lines of sounding the vast spaces of the ocean remain unplumbed save for the rare researches of scientific expeditions, such as those of the " Challenger," the " Valdivia," the " Albatross " and the " Scotia."