Atlantic telegraph cable laying. Buoy launched from the SS Great Eastern during laying of the 1865 Atlantic telegraph cable. The buoy marks a break in the cable that needs repairing. This ship, a former ocean liner and the largest ship of its time, was large and powerful enough for the task of laying a telegraph cable on the ocean floor. It laid 4200 kilometres across the Atlantic, and a further 48,000 kilometres of submarine telegraph cables between 1866 and 1878. The 1865 trans-Atlantic cable replaced the failed 1858 cable. Artwork from 'Electricite' (1911) by Max de Nansouty, part of the 'Les merveilles de la science' series of 1867-1891 by Louis Figuier.