First Successful Transatlantic Telegraph Cable Celebrates 150th Anniversary

It enabled nearly instantaneous communication between Europe and North America

11 July 2016

On 13 July 1866, the SS Great Eastern—the largest ship afloat at the time—left Valentia Island, Ireland, paying out a continuous (and expensive) telegraph cable over her stern. The ship was 211 meters long and weighed 18,915 tons—nearly twice the size of the world’s second largest ship, the SS Great Britain. Two weeks later, the Great Eastern docked in Trinity Bay off Newfoundland, Canada, having carried the cable almost 4,000 kilometers across the Atlantic Ocean. Once activated, the cable allowed people in Europe and North America to communicate with each other nearly instantaneously.

Before that, communication between Europe and North America, including news bulletins, often took weeks. Westbound ships passing the coast of Newfoundland would throw their dispatches overboard in floating, watertight containers for fishermen to scoop out of the sea. News outlets paid the fishermen to bring the dispatches ashore to telegraph stations, and telegraph operators relayed the contents over wires to Ottawa, Boston, New York, and onward. The process was the origin of the journalism term scoop.

Political news, commodity and bond prices, and other time-sensitive information had taken weeks to travel between London and New York City. The transatlantic cable reduced the time to mere seconds.


The quest to establish a transatlantic telegraphic link took 12 years and five attempts. Cyrus Field, who had made enough money in the paper business to retire by age 35, decided to back the laying of the transatlantic cable in 1854. After several tries and a number of broken cables, the first cable to cross the Atlantic became active in early August 1858. It was laid by two ships: USS Niagara and HMS Agamemnon. The ships each carried half the cable to the middle of the ocean, where they met and spliced the ends together. Then they paid out the cable as they steamed in opposite directions back to shore.

The success was temporary, however. The cable’s core consisted of seven copper wires covered with three coats of gutta-percha (a natural thermoplastic latex produced by the sap of a tree found in Asia) and wound with tarred hemp. Protecting the core was a sheath of 18 iron wire strands arranged in a close spiral.

But that proved insufficient for protecting the conductor, and the cable degraded. By the time the celebratory banquet was held on 1 September, it was almost impossible to receive signals, and by 18 September, the cable was useless.

Political and economic instability leading up to and during the American Civil War delayed the next attempt to lay a cable across the Atlantic. But in 1865, Field was ready to try again. During an attempt that year, the cable broke partway across.

By the time the Great Eastern set sail to lay what proved to be the final cable, in 1866, engineers had learned much from the previous failures. 

Improvements were made to the cable’s insulation so it wouldn’t snap. And because the Great Eastern was larger than ships previously used, it could carry the entire cable, improving the chances for success. Nevertheless, laying a cable across the North Atlantic in waters as deep as 4 kilometers remained a formidable task.


The 1866 cable weighed 1,014 kilograms per km. It took eight months to fabricate at the rate of about 22 km of cable per day. It then took five months for barges in the Thames River in England to load the cable aboard the Great Eastern at a rate of about 32 km a day.

The cable’s designers took no chances that the cable would degrade like its predecessor. The cross-section of the copper conductor cores in both the 1865 and 1866 cables were three times larger than the 1858 cable. The new core consisted of seven twisted strands of pure copper, coated with Chatterton’s compound, an insulated waterproof adhesive. It was then covered with four layers of gutta-percha. That core was covered with hemp saturated with a preservative solution, and over the hemp were 18 spirally wound single strands of high-tensile steel wire, each covered with fine strands of manila yarn steeped in the preservative.

The ship landed and laid the last of the cable at Heart’s Content, Newfoundland, on 27 July 1866. The Great Eastern then steamed back out into the Atlantic, and the engineers onboard grappled for the broken 1865 cable, brought both pieces to the surface, and spliced them. There were now two working transatlantic cables—which doubled capacity and provided a backup.


When the 1866 transatlantic cable was activated, sending a message across the Atlantic was not cheap. It cost US $10 per word, with a 10-word minimum ($10 at the time was equivalent to a skilled worker’s weekly wage). At those prices, only large companies could afford to use the cable to send telegrams. In its first few months, about 95 percent of the cable’s capacity went unused.

In 1867, the Anglo-American Telegraph Co. reduced the rate to $46.80 for a 10-word message, and usage and revenue increased. Anglo-American’s transmission rate was approximately 8 words per minute, which increased to about 17 words as the staff became more skilled.

Newspapers were important customers: The New York Tribune spent $5,000 on a single dispatch by Horace Greeley in 1870 about the Franco-Prussian War. To save money on transatlantic news stories, the otherwise fiercely competitive newspapers formed United Press International, an agency whose news, photo, audio, and video services would provide content to thousands of news outlets around the world for most of the 20th century.

Thanks to the cable, near-instantaneous communication across the Atlantic had been achieved, with communication over land-based telegraph lines reaching as far west as San Francisco and as far east as Ceylon (now Sri Lanka).

The cable has been honored with two IEEE Milestones. Administered by the IEEE History Center and supported by the IEEE Foundation, the IEEE Milestone program recognizes outstanding technical developments around the world. In 1985 the History Center recognized the landing of the transatlantic cable with a Milestone plaque placed in Heart’s Content. In 2000, three Milestone plaques were placed at the sites of cable stations in three Irish locations, which were all connected by the cable: Valentia Island, Ballinskelligs, and Waterville.

Robert Colburn is a research coordinator at the IEEE History Center, which is funded by donations to the IEEE Foundation.

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