Transatlantic telegraph cable

A transatlantic telegraph cable is an undersea cable running under the Atlantic Ocean used for telegraph communications. The first was laid across the floor of the Atlantic from Telegraph Field, Foilhommerum Bay, Valentia Island in western Ireland to Heart's Content in eastern Newfoundland. The first communications occurred August 16, 1858, reducing the communication time between North America and Europe from ten days—the time it took to deliver a message by ship—to a matter of minutes. Transatlantic telegraph cables have been replaced by transatlantic telecommunications cables.
Cyrus West Field and the Atlantic Telegraph Company were behind the construction of the first transatlantic telegraph cable. The project began in 1854 and was completed in 1858. The cable functioned for only three weeks, but it was the first such project to yield practical results. The first official telegram to pass between two continents was a letter of congratulations from Queen Victoria of the United Kingdom to President of the United States James Buchanan on August 16. Signal quality declined rapidly, slowing transmission to an almost unusable speed. The cable was destroyed the following month when Wildman Whitehouse applied excessive voltage to it while trying to achieve faster operation. It has been argued that the faulty manufacture, storage and handling of the 1858 cable would have led to premature failure in any case. The cable's rapid failure undermined public and investor confidence and delayed efforts to restore a connection. A second attempt was undertaken in 1865 with much-improved material and, following some setbacks, a connection was completed and put into service on July 28, 1866. This cable proved more durable.
Before the first transatlantic cable, communications between Europe and the Americas took place only by ship. Sometimes, however, severe winter storms delayed ships for weeks. The transatlantic cable reduced communication time considerably, allowing a message and a response in the same day. Five attempts to lay a cable were made over a nine-year period – one in 1857, two in 1858, one in 1865, and one in 1866. Lasting connections were finally achieved with the 1866 cable and the 1865 cable, which was repaired by Isambard Kingdom Brunel's ship, captained by Sir James Anderson. In the 1870s duplex and quadruplex transmission and receiving systems were set up that could relay multiple messages over the cable.

Early history

In the 1840s and 1850s several individuals proposed or advocated construction of a telegraph cable across the Atlantic Ocean, including Edward Thornton and Alonzo Jackman.
As early as 1840 Samuel F. B. Morse proclaimed his faith in the idea of a submarine line across the Atlantic Ocean. By 1850 a cable was run between England and France. That same year Bishop John T. Mullock, head of the Roman Catholic Church in Newfoundland, proposed a telegraph line through the forest from St. John's to Cape Ray, and cables across the Gulf of St. Lawrence from Cape Ray to Nova Scotia across the Cabot Strait.
At about the same time a similar plan occurred to Frederic Newton Gisborne, a telegraph engineer in Nova Scotia. In the spring of 1851, Gisborne procured a grant from the legislature of Newfoundland and, having formed a company, began the construction of the landline. In 1853 his company collapsed, he was arrested for debt and he lost everything.

A plan takes shape

In 1854 Gisborne was introduced to Cyrus West Field. Field invited Gisborne to his house to discuss the project. From his visitor, Field considered the idea that the cable to Newfoundland might be extended across the Atlantic Ocean.
Field was ignorant of submarine cables and the deep sea. He consulted Morse as well as Lieutenant Matthew Maury, an authority on oceanography. The charts Maury constructed from soundings in the logs of multiple ships indicated that there was a feasible route across the Atlantic. The area seemed so ideal for cable laying that Maury named it Telegraph Plateau. Maury's charts also predicted that a route going directly to the US was too rugged to be tenable, as well as being longer. Field adopted Gisborne's scheme as a preliminary step to the bigger undertaking, and promoted the New York, Newfoundland and London Telegraph Company to establish a telegraph line between America and Europe.
The first step was to finish the line between St. John's and Nova Scotia, which was undertaken by Gisborne and Field's brother, Matthew. In 1855 an attempt was made to lay a cable across the Cabot Strait in the Gulf of Saint Lawrence. It was laid out from a barque in tow of a steamer. When half the cable was laid, a gale rose, and the line was cut to keep the barque from sinking. In 1856 a steamboat was fitted out for the purpose, and the link from Cape Ray, Newfoundland to Aspy Bay, Nova Scotia was successfully laid. The final cost of the project exceeded $1 million, but the transatlantic segment was going to cost much more.
In 1855, Field crossed the Atlantic, the first of 56 crossings in the course of the project, to consult with John Watkins Brett who was the greatest authority on submarine cables at that time. Brett's Submarine Telegraph Company laid the first ocean cable in 1850 across the English Channel and his English and Irish Magnetic Telegraph Company had laid a cable to Ireland in 1853 which was the deepest cable laid up to that date. Further reasons for the trip were that all the commercial manufacturers of submarine cable were in Britain, and Field had failed to raise significant funds for the project in New York.
Field pushed the project ahead with tremendous energy and speed. Even before forming a company to carry out the project, Field ordered 2,500 miles of cable from the Gutta Percha Company. The Atlantic Telegraph Company was formed in October 1856 with Brett as president and Field as vice-president. Charles Tilston Bright, who already worked for Brett, was made chief engineer. Wildman Whitehouse, a medical doctor, was appointed chief electrician. Field provided a quarter of the capital himself. After the remaining shares were sold, largely to existing investors in Brett's company, an unpaid board of directors was formed which included William Thomson, the future Lord Kelvin and a respected scientist. Thomson also acted as a scientific advisor. Morse, who was a shareholder in the Nova Scotia project and acted as the electrical advisor, was also on the board.

First transatlantic cable

The cable consisted of seven copper wires, each weighing 26 kg/km, covered with three coats of gutta-percha, weighing 64 kg/km, and wound with tarred hemp, over which a sheath of 18 strands, each of seven iron wires, was laid in a close helix. It weighed nearly 550 kg/km, was relatively flexible and was able to withstand a pull of several tens of kilonewtons.
The cable from the Gutta Percha Company was armoured separately by wire rope manufacturers, as was the usual practice at the time. In the rush to proceed, only four months were allowed for completion of the cable. As no wire rope maker had the capacity to make so much cable on that timescale, the task was shared by two English firms – Glass, Elliot & Co., of Greenwich, and R.S. Newall and Company, of Birkenhead. Late in manufacturing it was discovered that the respective sections had been made with strands twisted in opposite directions. This meant that the two sections of cable could not be directly spliced wire-to-wire as the iron wire on both cables would unwind when it was put under tension during laying. The problem was easily solved by splicing through an improvised wooden bracket to hold the wires in place, but the mistake subsequently became magnified in the public mind.
The British government gave Field a subsidy of £1,400 a year and loaned ships for cable laying and support. Field also solicited aid from the U.S. government. A bill authorizing a subsidy was submitted in Congress. The subsidy bill passed the Senate by a single vote, due to opposition from protectionist senators. In the House of Representatives, the bill encountered similar resistance, but passed, and was signed by President Franklin Pierce.
The first attempt, in 1857, was a failure. The cable-laying vessels were the converted warships HMS Agamemnon and USS Niagara borrowed from their respective governments. Both ships were needed as neither was sufficient to hold 2,500 miles of cable alone. The cable was started at the white strand near Ballycarbery Castle in County Kerry, on the southwest coast of Ireland, on August 5, 1857. The cable broke on the first day, but was grappled and repaired; it broke again over the Telegraph Plateau, nearly 3,200 m deep, and the operation was abandoned for the year. 300 miles of cable had been lost, but the 1,800 miles remaining was still sufficient to complete the task. Also in this period, Morse clashed with Field, was removed from the board, and took no further part in the enterprise.
The problems with cables breaking were largely due to difficulty controlling the tension of the cable with the braking mechanism as the cable was payed out. A new mechanism was designed and successfully trialed in the Bay of Biscay with Agamemnon in May 1858. On June 10, Agamemnon and Niagara set sail to try again. Ten days out they found themselves in a severe storm and the enterprise was nearly brought to a premature end. The ships were top heavy with cable that could not all fit in the hold and struggled not to capsize. Ten sailors were hurt and Thomson's electrical cabin was flooded. The vessels arrived at the middle of the Atlantic on June 25 and spliced cable from the two ships together. Agamemnon paid out eastwards towards Valentia Island, Niagara payed out westward towards Newfoundland. Again the cable repeatedly broke. The first time after less than 5.5 km, again after some 100 km and for a third time when about 370 km of cable had run out of each vessel.
The expedition returned to Queenstown, County Cork, Ireland. Some directors were in favour of abandoning the project and selling off the cable, but Field persuaded them to keep going. The ships set out again on July 17 and the middle splice was finished on July 29, 1858. The cable ran easily this time. Niagara arrived in Trinity Bay, Newfoundland on August 4 and the next morning the shore end was landed. Agamemnon made an equally successful run. On August 5, she arrived at Valentia Island, and the shore end was landed at Knightstown and then laid to the nearby cable house.

First contact

Test messages were sent from Newfoundland beginning August 10, 1858; the first successfully read at Valentia was on August 12, and the first successfully read at Newfoundland on August 13; further test and configuration messages followed until August 16, when the first official message was sent via the cable: "Directors of Atlantic Telegraph Company, Great Britain, to Directors in America:—Europe and America are united by telegraph. Glory to God in the highest; on earth peace, good will towards men." Next was the text of a telegram of congratulation from Queen Victoria to President James Buchanan at his summer residence in the Bedford Springs Hotel in Pennsylvania which expressed a hope that it would prove "an additional link between the nations whose friendship is founded on their common interest and reciprocal esteem." The President responded that, "it is a triumph more glorious, because far more useful to mankind, than was ever won by conqueror on the field of battle. May the Atlantic telegraph, under the blessing of Heaven, prove to be a bond of perpetual peace and friendship between the kindred nations, and an instrument destined by Divine Providence to diffuse religion, civilization, liberty, and law throughout the world." The messages were hard to decipher – Queen Victoria's message of 98 words took sixteen hours to send.
These messages engendered an outburst of enthusiasm. The next morning a grand salute of 100 guns resounded in New York City, the streets were decorated with flags, the bells of the churches were rung, and at night the city was illuminated. On September 1 there was a parade, followed by an evening torchlight procession and fireworks display, which caused a fire in the Town Hall. Bright was knighted for his part, the first such honour to the telegraph industry.

Failure of the first cable

The operation of the 1858 cable was plagued by conflict between two of the senior members of the project, Thomson and Whitehouse. The points of disagreement were highly relevant to the ultimate causes of the cable failure. Whitehouse was a medical doctor by training but had taken an enthusiastic interest in the new electrical technology and had given up his medical practice to follow a new career. He had no formal training in physics; all his knowledge had been gained through practical experience. The two clashed even before the project had started when Whitehouse disputed Thomson's law of squares when he presented it to a British Association meeting in 1855. Thomson's law predicted that transmission speed on the cable would be very slow due to an effect called retardation. To put this to the test, Bright gave Whitehouse overnight access to the Magnetic Telegraph Company's long underground lines. He joined several lines together to a distance similar to the transatlantic route and declared that there would be no problem. Morse was also present at this test and supported Whitehouse. Thomson believed that Whitehouse's measurements were flawed and that underground and underwater cables were not fully comparable. Thomson believed that a larger cable was needed, which would improve the retardation problem predicted by the law of squares. In mid-1857, on his own initiative, he examined samples of copper core of alleged identical specification and found variations in resistance up to a factor of two. But the cable manufacturing was already underway and Whitehouse supported use of a thinner cable so Field went with the cheaper option.
Another point of contention was the itinerary for cable laying. Thomson favoured starting mid-Atlantic and the two ships heading in opposite directions. This would halve the time taken to complete. Whitehouse wanted both ships to travel together from Ireland so that progress could be reported back to the base in Valentia through the cable. Whitehouse overruled Thomson's suggestion on the 1857 voyage, but Bright convinced the directors to approve a mid-ocean start on the subsequent 1858 voyage. Whitehouse, as chief electrician, was supposed to be on board the cable laying vessel, but he declined to go at the last moment. He repeatedly found excuses to do this; for the 1857 attempt, the trials in the Bay of Biscay, and the two attempts in 1858. In 1857, Thomson was sent in his place, and in 1858 Field diplomatically assigned the two to different ships to avoid conflict, but in the event Thomson went alone.

Thomson's mirror galvanometer

After his experience on the 1857 voyage, Thomson realised that a better method of detecting the telegraph signal was required. He spent the time waiting for a new voyage inventing his mirror galvanometer. This was an extremely sensitive instrument, much better than any existing equipment. He requested £2,000 from the board to build several of them, but was only given £500 for a prototype, and permission to trial it on the next voyage. The mirror galvanometer was extremely good at detecting the positive, or negative edge of a telegraph pulse respectively representing a Morse 'dash' and a Morse 'dot'. Thomson believed he could use this instrument with the low voltages from regular telegraph equipment even over the vast length of the Atlantic cable. He successfully tested the instrument on 2,700 miles of cable in underwater storage at Plymouth.
The mirror galvanometer proved to be yet another point of contention. Whitehouse wanted to work the cable with a very different scheme. He wanted to drive the line with a massive high-voltage induction coil, producing several thousand volts, so that enough current was available to drive standard electromechanical printing telegraphs used on inland telegraphs. Thomson's instrument had to be read by hand. It was not capable of printing, but much later he invented the syphon recorder for the second transatlantic attempt in 1866. The decision to start mid-Atlantic combined with Whitehouse dropping out of another voyage left Thomson, on board Agememnon sailing towards Ireland, with a free hand to use his equipment without Whitehouse's interference. Although Thomson had the status of a mere advisor to engineer C. W. de Sauty, it was not long before all electrical decisions were deferred to him. Whitehouse in Valentia remained out of contact until the ship reached Ireland and landed the cable.
Around this time, the board started to have doubts over Whitehouse's generally negative attitude. Not only did he repeatedly clash with Thomson, but he was also critical of Field, and his repeated refusal to carry out his primary duty as chief electrician on board ship made a very bad impression. With the removal of Morse, Whitehouse had lost his only ally on the board, but at this time no action was taken.

Cable is damaged and Whitehouse dismissed

When the Agememnon reached Valentia on August 5, Thomson handed over to Whitehouse and the project was announced as a success to the press. Thomson had been receiving signals without problem throughout the voyage using the mirror galvanometer, but Whitehouse immediately connected his own equipment. The effects of the poor handling and design of the cable, coupled with Whitehouse's repeated attempts to drive the cable with high voltages, up to 2,000 volts, resulted in the insulation of the cable being compromised. Whitehouse attempted to hide the poor performance and was vague in his communications. The expected inaugural message from Queen Victoria had been widely publicised and when this was not forthcoming the press started to speculate that the there were problems. Whitehouse announced that five or six weeks would be required for "adjustments". The Queen's message had been received in Newfoundland, but Whitehouse had been unable to read the confirmation copy sent back the other way. Finally, on August 17, he announced receipt. What he did not announce was that the message had been received on the mirror galvanometer when he finally gave up trying with his own equipment. Whitehouse had the message re-entered into his printing telegraph locally so that he could send on the printed tape and pretend that it had been received that way.
In September 1858, after several days of progressive deterioration of the insulation, the cable failed altogether. The reaction to this news was tremendous. Some writers even hinted that the line was a mere hoax, and others pronounced it a stock exchange speculation. Whitehouse was recalled for the board's investigation and Thomson took over in Valentia tasked with reconstructing events, which at that stage, Whitehouse had successfully obfuscated. Whitehouse was held responsible for the failure, and dismissed. The damage to the cable may not have been entirely due to Whitehouse and it may have failed eventually anyway, although Whitehouse certainly brought that about much sooner. There may have been a preexisting fault, or weakness, in the cable, especially in the first hundred miles from Ireland. This section was the old 1857 cable, spliced into the new lay, and was known to be poorly manufactured. Samples showed that in places the conductor was badly off centre, and could easily break through the insulation altogether through the mechanical strains on it during laying. Tests were conducted on samples of cable submerged in seawater. When perfectly insulated there was no problem applying thousands of volts. However, a sample with a pinprick hole "lit up like a lantern" when tested and a large hole was burned in the insulation.
Although the cable was never put into service for public use, and never worked well, there was time for a few messages to be passed that went beyond testing. The collision between the Cunard Line ships Europa and Arabia was reported on 17 August. The British Government used the cable to countermand an order for two regiments in Canada to embark for England, saving £50,000. A total of 732 messages were passed before failure.

Preparing a new attempt

Field was undaunted by the failure. He was eager to renew the work, but the public had lost confidence in the scheme and his efforts to revive the company were futile. It was not until 1864 that, with the assistance of Thomas Brassey and John Pender, he succeeded in raising the necessary capital. The Glass, Elliot, and Gutta-Percha Companies were united to form the Telegraph Construction and Maintenance Company, which undertook to manufacture and lay the new cable. C.F. Varley replaced Whitehouse as chief electrician.
In the meantime, long cables had been submerged in the Mediterranean and the Red Sea. With this experience, an improved cable was designed. The core consisted of seven twisted strands of very pure copper weighing 300 pounds per nautical mile, coated with Chatterton's compound, then covered with four layers of gutta-percha, alternating with four thin layers of the compound cementing the whole, and bringing the weight of the insulator to 400 lb/nmi. This core was covered with hemp saturated in a preservative solution, and on the hemp were helically wound eighteen single strands of high tensile steel wire produced by Webster & Horsfall Ltd of Hay Mills Birmingham, each covered with fine strands of manila yarn steeped in the preservative. The weight of the new cable was 35.75 long hundredweight per nautical mile, or nearly twice the weight of the old. The Haymills site successfully manufactured of wire, made by 250 workers over eleven months.

''Great Eastern'' and the second cable

The new cable was laid by the ship Great Eastern captained by Sir James Anderson. Her immense hull was fitted with three iron tanks for the reception of of cable, and her decks furnished with the paying-out gear. At noon on July 15, 1865, Great Eastern left the Nore for Foilhommerum Bay, Valentia Island, where the shore end was laid by Caroline. This attempt failed on August 2 when, after 1,062 miles had been paid out, the cable snapped near the stern of the ship, and the end was lost.
Great Eastern steamed back to England, where Field issued another prospectus, and formed the Anglo-American Telegraph Company, to lay a new cable and complete the broken one. On July 13, 1866, Great Eastern started paying out once more. Despite problems with the weather on the evening of Friday, July 27, the expedition reached the port of Heart's Content in a thick fog. The next morning at 9 a.m. a message from England cited these words from the leader in The Times: "It is a great work, a glory to our age and nation, and the men who have achieved it deserve to be honoured among the benefactors of their race." "Treaty of peace signed between Prussia and Austria." The shore end was landed during the day by Medway. Congratulations poured in, and friendly telegrams were again exchanged between Queen Victoria and the United States.
used for lifting the cable
In August 1866, several ships, including Great Eastern, put to sea again in order to grapple the lost cable of 1865. Their goal was to find the end of the lost cable, splice it to new cable, and complete the run to Newfoundland. They were determined to find it, and their search was based solely upon positions recorded "principally by Captain Moriarty, R.N." who placed the end of the lost cable at longitude 38° 50' W.
There were some who thought it hopeless to try, declaring that to locate a cable down would be like looking for a small needle in a large haystack. However, Robert Halpin navigated HMS Terrible and grappling ship Albany to the correct location. Albany moved slowly here and there, "fishing" for the lost cable with a five-pronged grappling hook at the end of a stout rope. Suddenly, on August 10, Albany "caught" the cable and brought it to the surface. It seemed to be an unrealistically easy success, and that is how it turned out. During the night, the cable slipped from the buoy to which it had been secured and the process had to start all over again. This happened several more times, with the cable slipping after being secured in a frustrating battle against rough seas. One time, a sailor even was flung across the deck when the grapnel rope snapped and recoiled around him. Great Eastern and another grappling ship, Medway, arrived to join the search on the 12th. It was not until over a fortnight later, in early September 1866, that the cable was finally retrieved so that it could be worked on; it took 26 hours to get it safely on board Great Eastern. The cable was carried to the electrician's room, where it was determined that the cable was connected. All on the ship cheered or wept as rockets were sent up into the sky to light the sea. The recovered cable was then spliced to a fresh cable in her hold, and paid out to Heart's Content, Newfoundland, where she arrived on Saturday, September 7. There were now two working telegraph lines.

Repairing the cable

Broken cables required an elaborate repair procedure. The approximate distance to the break is determined by measuring the resistance of the broken cable. The repair ship navigated to the location. The cable was hooked with a grapple and brought on board to test for electrical continuity. Buoys were deployed to mark the ends of good cable and a splice was made between the two ends.

Communication speeds

Initially messages were sent by an operator sending Morse code. The reception was very bad on the 1858 cable, and it took two minutes to transmit just one character, a rate of about 0.1 words per minute. This was despite the use of the highly sensitive mirror galvanometer. The inaugural message from Queen Victoria took 67 minutes to transmit to Newfoundland, but it took a staggering 16 hours for the confirmation copy to be transmitted back to Whitehouse in Valentia.
For the 1866 cable, the methods of cable manufacture, as well as sending messages, had been vastly improved. The 1866 cable could transmit eight words a minute – 80 times faster than the 1858 cable. Oliver Heaviside and Mihajlo Idvorski Pupin in later decades understood that the bandwidth of a cable is hindered by an imbalance between capacitive and inductive reactance, which causes a severe dispersion and hence a signal distortion; see telegrapher's equations. This has to be solved by iron tape or by load coils. It was not until the 20th century that message transmission speeds over transatlantic cables would reach even 120 words per minute. London became the world center in telecommunications. Eventually, no fewer than eleven cables radiated from Porthcurno Cable Station near Land's End and formed with their Commonwealth links a "live" girdle around the world; the All Red Line.

Later cables

Additional cables were laid between Foilhommerum and Heart's Content in 1873, 1874, 1880, and 1894. By the end of the 19th century, British-, French-, German-, and American-owned cables linked Europe and North America in a sophisticated web of telegraphic communications.
The original cables were not fitted with repeaters, which potentially could completely solve the retardation problem and consequently speed up operation. Repeaters amplify the signal periodically along the line. On telegraph lines this is done with relays, but there was no practical way to power them in a submarine cable. The first transatlantic cable with repeaters was TAT-1 in 1956. This was a telephone cable and used a different technology for its repeaters.


A 2018 study in the American Economic Review found that the transatlantic telegraph substantially increased trade over the Atlantic and reduced prices. The study estimates that "the efficiency gains of the telegraph to be equivalent to 8 percent of export value".