Searching for a fault in the cable after its recovery from the ocean bed.
"The American Civil War between 1861 and 1865 brought only a temporary halt to Cyrus Field in his attempts to lay the Atlantic cable. New money was raised by the Atlantic Telegraph Company, a three-times heavier cable was spun and the Great Eastern was commission ed to lay its 3700 km across the Atlantic; she was then the only vessel afloat able to carry the cable in her holds. On 23 July, 1965, the Great Eastern left again from Valentia, Ireland, having joined her cable to a short length of shore line. She carried on board Professor William Thomson, later Lord Kelvin (1824-1907) the greatest name in Victorian science; his duties as a consultant were to report on the electrical behavior of the cable during the laying operations. On August 2, 1900 km having been paid out successfully, an electric fault was discovered in the cable and it was decided to pick up the cable, to cut out the bad portion, and splice in a new one. But on hauling it aboard it chafed over the drum at the bows, and suddenly it snapped. For the next nine days valiant attempts were made again and again to find the cable and three times the grapple iron lifted it for some distance above the ocean floor, only for the line to part under the terrific strain. When all available wire ropes and hawsers had been exhausted, defeat was reluctantly admitted , and the Great Eastern returned to Crookhaven in Ireland" (From Semaphore to Satellite, Published by the International Telecommunication Union, Geneva 1965)