William Fothergill Cooke and Charles Wheatstone presented their work on the telegraph in 1839. Already in 1840 Samuel F.B. Morse developed the idea of ​​a submarine line across the Atlantic Ocean. In 1850 Great Britain and France were joined by cable. That same year, Bishop John T. Mullock, head of the Catholic Church in Newfoundland, proposed establishing a telegraph line from St. John's, Newfoundland to Cape Ray, and through the mouth of the St. Lawrence, from Cape Ray to Nova Scotia via Cabot Strait.

About the same time a similar plan occurred to Frederick Newton Gisborne, a telegraph engineer in Nova Scotia. In the spring of 1851, Gisborne obtained a grant from the Newfoundland legislature and, having created a company, began construction of the landline. In 1853 his company went bankrupt, he was arrested for debt and lost everything. The following year he introduced himself to businessman Cyrus West Field. Field invited Gisborne to his home to discuss the project. After the visit, Field considered the idea that the cable to Newfoundland could be extended across the Atlantic Ocean. Field adopted Gisborne's idea and created the New York, Newfoundland & London Telegraph Company, later the Atlantic Telegraph Company), to establish a telegraph line between America and Europe.

However, the viability of this business was difficult to predict. The longest submarine cable, at that time, was the Black Sea cable, 574 km, while it was needed to cross the Atlantic. In addition, the cable had to rest on the ocean floor more than 3 km deep. Since this would be the first attempt, there was a good chance that the placement of the cable would not be without problems.

Field lacked knowledge of submarine cables and the deep sea. He consulted Morse on telegraphy matters. And with Lieutenant Matthew Maury"), an authority on oceanography, seafloor issues. Maury was familiar with the work of John Mercer Brooke") on a topographical map of the North Atlantic. This is how he achieved the topography and lack of currents on the ocean floor. Cable routing seemed like it wouldn't be a problem. Funds were raised from both American and British sources through the sale of shares in the Atlantic Telegraph Company. Field would provide a quarter of the necessary capital.

Cyrus West Field and the Atlantic Telegraph Company made the first transatlantic telegraph cable. The project began in 1857 and was completed on August 5, 1858. The cable operated for only three weeks, but it was the first of the projects to achieve practical results. The first official telegram sent between the two continents was a congratulatory letter from Queen Victoria of the United Kingdom to President of the United States James Buchanan on August 16, 1858. The quality of the signal deteriorated rapidly, slowing the transmission speed until it was practically unusable. The cable deteriorated quickly due to excessive voltage being applied in an attempt to achieve faster operation. (It has been argued that manufacturing, storage and handling defects in the 1858 cable would have led to premature failure in any case.)[5]​.

Five more attempts to lay the cable were made over the next nine years—one in 1857, two in 1858, one in 1865, by the ship SS Great Eastern (built by John Scott Russell and Isambard Kingdom Brunel, captained by Sir James Anderson),[6]​ and another in 1866—before lasting connections were finally made with the 1866 cable also laid by the Great Eastern and The 1865 cable was recovered.

The first step was to complete the line between St. John and Nova Scotia, and in 1855 an attempt was made to lay a cable across Cabot Strait in the Gulf of St. Lawrence. It was established from a boat on the trailer of a steamship. When the cable became entangled due to a gale, the line was cut to prevent the ship from sinking. The following summer a new steamboat was fitted out and the link from Cape Ray, Newfoundland, to Aspy Bay, Nova Scotia, was successfully laid.

Contenido

El cable se componía de siete alambres de cobre, cada uno pesaba 26 kg/km (107 libras por milla náutica), cubierto con tres capas de gutapercha, con un peso de 64 kg/km (261 libras por milla náutica), y terminó con el asfaltado de cáñamo, sobre el cual una vaina de 18 hilos, cada uno de siete alambres de hierro, se colocó en forma de espiral. Pesaba cerca de 550 kg/km (1.1 toneladas por milla náutica), era relativamente flexible y capaz de soportar una fuerza de varias decenas de kN (varias toneladas). Fue realizado conjuntamente por dos empresas inglesas: Glass, Elliot & Co., de Greenwich, y RS Newall & Co., de Birkenhead. Al final de la fabricación se descubrió que las secciones respectivas se habían realizado con los filamentos retorcidos en direcciones opuestas. Aunque resultó una simple cuestión de unir las dos secciones, la opinión pública magnificó posteriormente este error.[7]​.

El Gobierno británico concedió a Field un subsidio de 1400 £ al año y prestó los barcos necesarios. Field solicitó la ayuda del Congreso de los Estados Unidos. La votación fue muy ajustada, con una serie de senadores anglófobos oponiéndose a cualquier concesión, y el proyecto de ley se aprobó por un solo voto de diferencia. En la Cámara de Representantes se encontró con una hostilidad similar, pero en última instancia, fue firmado por el presidente Franklin Pierce.

The first attempt

The first attempt, in 1857, was a failure. The ships chosen for the installation of the cable were converted warships: HMS Agamemnon&action=edit&redlink=1 "HMS Agamemnon (1852) (not yet drafted)") and USS Niagara&action=edit&redlink=1 "USS Niagara (1855) (not yet drafted)"). The cable began near Ballycarbery Castle, County Kerry, on the south-west coast of Ireland, on 5 August 1857.[8] The cable broke on the first day at almost 3.2 km depth, and the operation was abandoned that year.

Second attempt

The following summer, the Agamemnon and the Niagara, after several trials in the Bay of Biscay, tried again. The ships were to meet in the middle of the Atlantic, where the two halves of the cable were to be spliced ​​together, and while the Agamemnon would unwind eastward to the island of Valentia, the Niagara would unwind west toward Newfoundland. On June 26, the center splice was made and the cable sank. Once again the cable broke, first after less than 5.5 km (three nautical miles), again after about 100 km (54 nautical miles), and for the third time when about 370 km (200 nautical miles) of cable had been left outside each vessel.

Third attempt

The expedition returned to Queenstown to depart again on 17 July with little enthusiasm among the crews. The center splice was completed on July 29, 1858. The cable ran easy this time. The Niagara reached Trinity Bay, Newfoundland, on August 4, and the next morning the end of the shore came ashore. The Agamemnon had an equally successful career. On 5 August, she reached Valentia Island, with the shore end coming ashore at Knightstown and then connecting with the nearby local cable.[9]​.

First message

On August 16, 1858, the first message sent over the cable was a congratulatory telegram that Queen Victoria sent to American President James Buchanan and expressed her hope that there would result "an additional bond between nations whose friendship is based on their common interest and mutual esteem." The president responded that “it is the most glorious triumph, because it is much more useful to humanity, than was ever won by the conqueror on the battlefield. That the Atlantic telegraph, under the blessing of heaven, will become a link of perpetual peace and friendship between sister nations, and an instrument destined by Divine Providence to spread religion, civilization, liberty and law throughout the world.

Those messages generated an explosion of enthusiasm. The next morning a celebration of 100 guns resounded through New York City, the streets were decorated with flags, church bells rang, and at night the city was illuminated.[12] The Atlantic cable was a subject of countless sermons and a prodigious amount of storytelling.

First cable failure

Operation of the new cable was problematic because the company's two senior electrical engineers had very different ideas about how the cable should be operated.[13] Additionally, Lord Kelvin and Dr. Whitehouse were at opposite ends of the cable and could only communicate over the cable itself.

Lord Kelvin, who was at the western end, believed that it was only necessary to generate a low voltage to detect the peak rise of the current coming out of the wire, and once this had been done, nothing would be gained by further monitoring (Morse code uses a positive current for a dot and a negative current for a dash). Lord Kelvin invented the mirror galvanometer, precisely to quickly observe the change of current.

At the eastern end of the cable stood Dr. Whitehouse. He was the company's chief electrician and a medical doctor, but his knowledge of electricity was self-taught. Whitehouse believed that, in order to obtain a change in current at the receiving end as quickly as possible, the cable must be connected to a high voltage source (several thousand volts via induction coils). The situation was made worse because whenever intelligible Morse code was received on the mirror galvanometer at the eastern end, Whitehouse insisted that the galvanometer be disconnected and replaced with his own patent recording telegraph, which was much less sensitive.

The effects of poor handling and design of the cable, along with Whitehouse's repeated attempts to operate the cable at high voltages, led to deterioration of the cable's insulation. It took more and more time to send messages. Towards the end, sending a half-page text message took a day.

In September, the isolation continued to deteriorate. On October 20, the cable stopped working. In total 732 telegrams had been transmitted.

The reaction to this news was tremendous. Some writers even suggested that the telegraph cable was a hoax, and others thought it was stock market speculation. In the subsequent investigation, Dr Whitehouse was held responsible for the failure, but the company did not escape criticism for employing an electrical engineer without recognized qualifications. Although the handling and conservation of the cable also had its influence: the part of the cable that was not used in the first attempt was left outdoors while the remaining section was built. This deteriorated the gutta-percha insulation.

Reconsideration of the plan

Because of repeated failures, shareholders stopped investing. Furthermore, the following year the Red Sea cable also ended in failure. Submarine cable companies were forced into a fundamental review. In 1859, the British government established a special committee which issued a report that believed that the Atlantic cable was possible.

Cyrus Field was not discouraged by the failure. He was eager to return to work, but the public had lost confidence in the system and his efforts to revive the company were futile. Field received the report: "we decided to try the cable operators again across the Atlantic." Until 1864, with the help of Thomas Brassey and John Pender, he was unable to raise the necessary capital. A start-up company Telcon, later part of BICC, was engaged to manufacture and lay the new cable.

In addition, Field fired Whitehouse as chief electrician and replaced him with Thomson. Thomson took the above observations into account and increased the cross-sectional area of ​​the copper wire and insulation to allow for an increase in transmission intensity. The cable was designed under careful research and many experiments were carried out. The cable design was improved thanks to those experiments. The core consisted of seven strands of very pure copper stranded, weighing 300 pounds per nautical mile (73 kg/km), coated with a Chatterton compound. It was then covered with four layers of gutta-percha, alternating with four thin layers of the cementing compound of the set, and bringing the weight of the insulator up to 400 pounds/NMI (98 kg/km). This core was covered with hemp saturated in a preservative solution, and on the hemp were spirally wound eighteen single chains of high tension steel produced by Webster & Horsfall Ltd of Hay Mills of Birmingham, each covered with fine manila threads also impregnated in the preservative. The weight of the new cable increased to 35.75 quintals (4,000 pounds) per nautical mile (980 kg/km), almost double the weight of the old one. The Haymills site successfully manufactured wire (1600 tonnes), employing 250 workers for over eleven months.

Cable repair

The broken cables required an elaborate repair procedure. The approximate distance where the break had occurred was determined by measuring the resistance of the broken cable. Repair ships sailed to that location. The cable was hooked with a grappling hook and hoisted on board to check electrical continuity. Buoys were deployed to mark the ends of the good cable and a new splice was made between the two ends.[14]​[15]​.

The ship Great Eastern under the command of Captain Sir James Anderson laid a new cable.[16] Her immense hull was equipped with three iron warehouses for the reception of 2,300 nautical miles (4,300 km) of cable, and her decks were filled with tools. At noon on July 15, 1865, the Great Eastern left the Nore of Foilhommerum Bay, on Valentia Island, the Caroline bringing the end to shore. This attempt failed on 31 July when, after extending 1,062 miles (1,968 km), the cable snapped near the stern of the ship, and the end was lost.[17]

The steamer Great Eastern returned to England, where she published another Field pamphlet, and formed the Anglo-American Telegraph Company, to lay a new cable and complete the broken one. On July 13, 1866, the Great Eastern began sailing once again. Despite the problems with the weather, on the night of Friday, July 27, the expedition arrived at the port in thick fog. The next morning at 9 a.m. a message from England quoted these words from the leader of The Times: "It is a great work, a glory of our time and nation, and the men who have accomplished it deserve to be honored among the benefactors of their race." "Peace treaty signed between Prussia and Austria." The end of the shore was laid during the day by the Medway. Congratulations, and friendly telegrams were again exchanged between Queen Victoria and the United States.

On August 9, the Great Eastern put to sea again, in order to recover the lost cable of 1865, and complete it to Newfoundland.[18]​ They were determined to find it. Some thought it was a futile task, stating that locating a cable a mile deep and after two years, would be like searching for a small needle in a large haystack. Robert Halpin managed to navigate the ship to the correct location.[19] For days, the Great Eastern moved slowly back and forth, attempting to "fish" the missing cable with a grappling hook at the end of a rope. Suddenly, the cable was "captured" and hoisted to the surface, but as the men cheered it slipped from their hook and disappeared again. Two weeks later it was found again, it took 26 hours to get the cable safely aboard the Great Eastern. The cable was taken to the electrical shop, where it was determined that the cable had continuity. Everyone on the ship became animated, rockets were launched to illuminate the sea. The recovered cable was spliced ​​to a new cable in the warehouse, and was grounded at Heart's Content, Newfoundland, where it arrived on Saturday, September 7. There were now two operational telegraph lines.

Inicialmente, los mensajes eran enviados por un operador en código Morse. La recepción era de muy mala calidad en el cable de 1858, y se necesitaban dos minutos para transmitir un solo carácter (una letra o un dígito), una tasa de alrededor de 0,1 palabras por minuto. Esto era a pesar del uso de la alta sensibilidad del galvanómetro de espejo, una nueva invención de la época.

El primer mensaje en el cable de 1858 necesitó 17 horas para transmitirse.[20]​ En el cable de 1866, los métodos de fabricación de cable, así como el envío de mensajes, habían mejorado sensiblemente. El cable de 1866 podría transmitir ocho palabras por minuto,[21]​ unas 80 veces más rápido que el cable de 1858. Oliver Heaviside y Michael Pupin en las décadas posteriores descubrieron que el problema era un desequilibrio entre la inductancia y la reactancia capacitiva, y podía ser resuelto mediante una cinta de hierro o mediante la carga de bobinas. No fue sino hasta el siglo que la velocidad de transmisión de mensajes a través de cables transatlánticos llegó hasta 120 palabras por minuto. A pesar de las limitaciones, Londres se había convertido en el centro mundial de las telecomunicaciones. Con el tiempo, no menos de once cables irradiaban desde Cable Station de Porthcurno cerca de Land's End y formaban con sus vínculos con la Commonwealth "en vivo" faja alrededor del mundo.

Repeaters

The original cables were not equipped with repeaters (which would have amplified the signal along the way) because there was no practical way to position the relays. When technology advanced it was possible to install intermediate relays.

• - The cable is one of many underwater landmarks observed by Jules Verne's Nautilus from Twenty Thousand Leagues Under the Sea.

• - The 2003 novel "The Signal and the Noise" by John Griesemer tells a fictional story about the project, including many real incidents.

• - In the novel «Open the door!» (1918) by Catherine Carswell, the Bannermans visit the Great Eastern, which was in Liverpool Harbor as a demonstration ship before it was broken up, Bannerman's linnet imagination having been captured by the cable.

• - Hans Christian Andersen's novel "The Great Sea Serpent" describes the chaos and confusion among the inhabitants of the sea caused by the laying of the cable.

William Fothergill Cooke and Charles Wheatstone presented their work on the telegraph in 1839. Already in 1840 Samuel F.B. Morse developed the idea of ​​a submarine line across the Atlantic Ocean. In 1850 Great Britain and France were joined by cable. That same year, Bishop John T. Mullock, head of the Catholic Church in Newfoundland, proposed establishing a telegraph line from St. John's, Newfoundland to Cape Ray, and through the mouth of the St. Lawrence, from Cape Ray to Nova Scotia via Cabot Strait.

About the same time a similar plan occurred to Frederick Newton Gisborne, a telegraph engineer in Nova Scotia. In the spring of 1851, Gisborne obtained a grant from the Newfoundland legislature and, having created a company, began construction of the landline. In 1853 his company went bankrupt, he was arrested for debt and lost everything. The following year he introduced himself to businessman Cyrus West Field. Field invited Gisborne to his home to discuss the project. After the visit, Field considered the idea that the cable to Newfoundland could be extended across the Atlantic Ocean. Field adopted Gisborne's idea and created the New York, Newfoundland & London Telegraph Company, later the Atlantic Telegraph Company), to establish a telegraph line between America and Europe.

However, the viability of this business was difficult to predict. The longest submarine cable, at that time, was the Black Sea cable, 574 km, while it was needed to cross the Atlantic. In addition, the cable had to rest on the ocean floor more than 3 km deep. Since this would be the first attempt, there was a good chance that the placement of the cable would not be without problems.

Field lacked knowledge of submarine cables and the deep sea. He consulted Morse on telegraphy matters. And with Lieutenant Matthew Maury"), an authority on oceanography, seafloor issues. Maury was familiar with the work of John Mercer Brooke") on a topographical map of the North Atlantic. This is how he achieved the topography and lack of currents on the ocean floor. Cable routing seemed like it wouldn't be a problem. Funds were raised from both American and British sources through the sale of shares in the Atlantic Telegraph Company. Field would provide a quarter of the necessary capital.

Cyrus West Field and the Atlantic Telegraph Company made the first transatlantic telegraph cable. The project began in 1857 and was completed on August 5, 1858. The cable operated for only three weeks, but it was the first of the projects to achieve practical results. The first official telegram sent between the two continents was a congratulatory letter from Queen Victoria of the United Kingdom to President of the United States James Buchanan on August 16, 1858. The quality of the signal deteriorated rapidly, slowing the transmission speed until it was practically unusable. The cable deteriorated quickly due to excessive voltage being applied in an attempt to achieve faster operation. (It has been argued that manufacturing, storage and handling defects in the 1858 cable would have led to premature failure in any case.)[5]​.

Five more attempts to lay the cable were made over the next nine years—one in 1857, two in 1858, one in 1865, by the ship SS Great Eastern (built by John Scott Russell and Isambard Kingdom Brunel, captained by Sir James Anderson),[6]​ and another in 1866—before lasting connections were finally made with the 1866 cable also laid by the Great Eastern and The 1865 cable was recovered.

The first step was to complete the line between St. John and Nova Scotia, and in 1855 an attempt was made to lay a cable across Cabot Strait in the Gulf of St. Lawrence. It was established from a boat on the trailer of a steamship. When the cable became entangled due to a gale, the line was cut to prevent the ship from sinking. The following summer a new steamboat was fitted out and the link from Cape Ray, Newfoundland, to Aspy Bay, Nova Scotia, was successfully laid.

Contenido

El cable se componía de siete alambres de cobre, cada uno pesaba 26 kg/km (107 libras por milla náutica), cubierto con tres capas de gutapercha, con un peso de 64 kg/km (261 libras por milla náutica), y terminó con el asfaltado de cáñamo, sobre el cual una vaina de 18 hilos, cada uno de siete alambres de hierro, se colocó en forma de espiral. Pesaba cerca de 550 kg/km (1.1 toneladas por milla náutica), era relativamente flexible y capaz de soportar una fuerza de varias decenas de kN (varias toneladas). Fue realizado conjuntamente por dos empresas inglesas: Glass, Elliot & Co., de Greenwich, y RS Newall & Co., de Birkenhead. Al final de la fabricación se descubrió que las secciones respectivas se habían realizado con los filamentos retorcidos en direcciones opuestas. Aunque resultó una simple cuestión de unir las dos secciones, la opinión pública magnificó posteriormente este error.[7]​.

El Gobierno británico concedió a Field un subsidio de 1400 £ al año y prestó los barcos necesarios. Field solicitó la ayuda del Congreso de los Estados Unidos. La votación fue muy ajustada, con una serie de senadores anglófobos oponiéndose a cualquier concesión, y el proyecto de ley se aprobó por un solo voto de diferencia. En la Cámara de Representantes se encontró con una hostilidad similar, pero en última instancia, fue firmado por el presidente Franklin Pierce.

The first attempt

The first attempt, in 1857, was a failure. The ships chosen for the installation of the cable were converted warships: HMS Agamemnon&action=edit&redlink=1 "HMS Agamemnon (1852) (not yet drafted)") and USS Niagara&action=edit&redlink=1 "USS Niagara (1855) (not yet drafted)"). The cable began near Ballycarbery Castle, County Kerry, on the south-west coast of Ireland, on 5 August 1857.[8] The cable broke on the first day at almost 3.2 km depth, and the operation was abandoned that year.

Second attempt

The following summer, the Agamemnon and the Niagara, after several trials in the Bay of Biscay, tried again. The ships were to meet in the middle of the Atlantic, where the two halves of the cable were to be spliced ​​together, and while the Agamemnon would unwind eastward to the island of Valentia, the Niagara would unwind west toward Newfoundland. On June 26, the center splice was made and the cable sank. Once again the cable broke, first after less than 5.5 km (three nautical miles), again after about 100 km (54 nautical miles), and for the third time when about 370 km (200 nautical miles) of cable had been left outside each vessel.

Third attempt

The expedition returned to Queenstown to depart again on 17 July with little enthusiasm among the crews. The center splice was completed on July 29, 1858. The cable ran easy this time. The Niagara reached Trinity Bay, Newfoundland, on August 4, and the next morning the end of the shore came ashore. The Agamemnon had an equally successful career. On 5 August, she reached Valentia Island, with the shore end coming ashore at Knightstown and then connecting with the nearby local cable.[9]​.

First message

On August 16, 1858, the first message sent over the cable was a congratulatory telegram that Queen Victoria sent to American President James Buchanan and expressed her hope that there would result "an additional bond between nations whose friendship is based on their common interest and mutual esteem." The president responded that “it is the most glorious triumph, because it is much more useful to humanity, than was ever won by the conqueror on the battlefield. That the Atlantic telegraph, under the blessing of heaven, will become a link of perpetual peace and friendship between sister nations, and an instrument destined by Divine Providence to spread religion, civilization, liberty and law throughout the world.

Those messages generated an explosion of enthusiasm. The next morning a celebration of 100 guns resounded through New York City, the streets were decorated with flags, church bells rang, and at night the city was illuminated.[12] The Atlantic cable was a subject of countless sermons and a prodigious amount of storytelling.

First cable failure

Operation of the new cable was problematic because the company's two senior electrical engineers had very different ideas about how the cable should be operated.[13] Additionally, Lord Kelvin and Dr. Whitehouse were at opposite ends of the cable and could only communicate over the cable itself.

Lord Kelvin, who was at the western end, believed that it was only necessary to generate a low voltage to detect the peak rise of the current coming out of the wire, and once this had been done, nothing would be gained by further monitoring (Morse code uses a positive current for a dot and a negative current for a dash). Lord Kelvin invented the mirror galvanometer, precisely to quickly observe the change of current.

At the eastern end of the cable stood Dr. Whitehouse. He was the company's chief electrician and a medical doctor, but his knowledge of electricity was self-taught. Whitehouse believed that, in order to obtain a change in current at the receiving end as quickly as possible, the cable must be connected to a high voltage source (several thousand volts via induction coils). The situation was made worse because whenever intelligible Morse code was received on the mirror galvanometer at the eastern end, Whitehouse insisted that the galvanometer be disconnected and replaced with his own patent recording telegraph, which was much less sensitive.

The effects of poor handling and design of the cable, along with Whitehouse's repeated attempts to operate the cable at high voltages, led to deterioration of the cable's insulation. It took more and more time to send messages. Towards the end, sending a half-page text message took a day.

In September, the isolation continued to deteriorate. On October 20, the cable stopped working. In total 732 telegrams had been transmitted.

The reaction to this news was tremendous. Some writers even suggested that the telegraph cable was a hoax, and others thought it was stock market speculation. In the subsequent investigation, Dr Whitehouse was held responsible for the failure, but the company did not escape criticism for employing an electrical engineer without recognized qualifications. Although the handling and conservation of the cable also had its influence: the part of the cable that was not used in the first attempt was left outdoors while the remaining section was built. This deteriorated the gutta-percha insulation.

Reconsideration of the plan

Because of repeated failures, shareholders stopped investing. Furthermore, the following year the Red Sea cable also ended in failure. Submarine cable companies were forced into a fundamental review. In 1859, the British government established a special committee which issued a report that believed that the Atlantic cable was possible.

Cyrus Field was not discouraged by the failure. He was eager to return to work, but the public had lost confidence in the system and his efforts to revive the company were futile. Field received the report: "we decided to try the cable operators again across the Atlantic." Until 1864, with the help of Thomas Brassey and John Pender, he was unable to raise the necessary capital. A start-up company Telcon, later part of BICC, was engaged to manufacture and lay the new cable.

In addition, Field fired Whitehouse as chief electrician and replaced him with Thomson. Thomson took the above observations into account and increased the cross-sectional area of ​​the copper wire and insulation to allow for an increase in transmission intensity. The cable was designed under careful research and many experiments were carried out. The cable design was improved thanks to those experiments. The core consisted of seven strands of very pure copper stranded, weighing 300 pounds per nautical mile (73 kg/km), coated with a Chatterton compound. It was then covered with four layers of gutta-percha, alternating with four thin layers of the cementing compound of the set, and bringing the weight of the insulator up to 400 pounds/NMI (98 kg/km). This core was covered with hemp saturated in a preservative solution, and on the hemp were spirally wound eighteen single chains of high tension steel produced by Webster & Horsfall Ltd of Hay Mills of Birmingham, each covered with fine manila threads also impregnated in the preservative. The weight of the new cable increased to 35.75 quintals (4,000 pounds) per nautical mile (980 kg/km), almost double the weight of the old one. The Haymills site successfully manufactured wire (1600 tonnes), employing 250 workers for over eleven months.

Cable repair

The broken cables required an elaborate repair procedure. The approximate distance where the break had occurred was determined by measuring the resistance of the broken cable. Repair ships sailed to that location. The cable was hooked with a grappling hook and hoisted on board to check electrical continuity. Buoys were deployed to mark the ends of the good cable and a new splice was made between the two ends.[14]​[15]​.

The ship Great Eastern under the command of Captain Sir James Anderson laid a new cable.[16] Her immense hull was equipped with three iron warehouses for the reception of 2,300 nautical miles (4,300 km) of cable, and her decks were filled with tools. At noon on July 15, 1865, the Great Eastern left the Nore of Foilhommerum Bay, on Valentia Island, the Caroline bringing the end to shore. This attempt failed on 31 July when, after extending 1,062 miles (1,968 km), the cable snapped near the stern of the ship, and the end was lost.[17]

The steamer Great Eastern returned to England, where she published another Field pamphlet, and formed the Anglo-American Telegraph Company, to lay a new cable and complete the broken one. On July 13, 1866, the Great Eastern began sailing once again. Despite the problems with the weather, on the night of Friday, July 27, the expedition arrived at the port in thick fog. The next morning at 9 a.m. a message from England quoted these words from the leader of The Times: "It is a great work, a glory of our time and nation, and the men who have accomplished it deserve to be honored among the benefactors of their race." "Peace treaty signed between Prussia and Austria." The end of the shore was laid during the day by the Medway. Congratulations, and friendly telegrams were again exchanged between Queen Victoria and the United States.

On August 9, the Great Eastern put to sea again, in order to recover the lost cable of 1865, and complete it to Newfoundland.[18]​ They were determined to find it. Some thought it was a futile task, stating that locating a cable a mile deep and after two years, would be like searching for a small needle in a large haystack. Robert Halpin managed to navigate the ship to the correct location.[19] For days, the Great Eastern moved slowly back and forth, attempting to "fish" the missing cable with a grappling hook at the end of a rope. Suddenly, the cable was "captured" and hoisted to the surface, but as the men cheered it slipped from their hook and disappeared again. Two weeks later it was found again, it took 26 hours to get the cable safely aboard the Great Eastern. The cable was taken to the electrical shop, where it was determined that the cable had continuity. Everyone on the ship became animated, rockets were launched to illuminate the sea. The recovered cable was spliced ​​to a new cable in the warehouse, and was grounded at Heart's Content, Newfoundland, where it arrived on Saturday, September 7. There were now two operational telegraph lines.

Inicialmente, los mensajes eran enviados por un operador en código Morse. La recepción era de muy mala calidad en el cable de 1858, y se necesitaban dos minutos para transmitir un solo carácter (una letra o un dígito), una tasa de alrededor de 0,1 palabras por minuto. Esto era a pesar del uso de la alta sensibilidad del galvanómetro de espejo, una nueva invención de la época.

El primer mensaje en el cable de 1858 necesitó 17 horas para transmitirse.[20]​ En el cable de 1866, los métodos de fabricación de cable, así como el envío de mensajes, habían mejorado sensiblemente. El cable de 1866 podría transmitir ocho palabras por minuto,[21]​ unas 80 veces más rápido que el cable de 1858. Oliver Heaviside y Michael Pupin en las décadas posteriores descubrieron que el problema era un desequilibrio entre la inductancia y la reactancia capacitiva, y podía ser resuelto mediante una cinta de hierro o mediante la carga de bobinas. No fue sino hasta el siglo que la velocidad de transmisión de mensajes a través de cables transatlánticos llegó hasta 120 palabras por minuto. A pesar de las limitaciones, Londres se había convertido en el centro mundial de las telecomunicaciones. Con el tiempo, no menos de once cables irradiaban desde Cable Station de Porthcurno cerca de Land's End y formaban con sus vínculos con la Commonwealth "en vivo" faja alrededor del mundo.

Repeaters

The original cables were not equipped with repeaters (which would have amplified the signal along the way) because there was no practical way to position the relays. When technology advanced it was possible to install intermediate relays.

• - The cable is one of many underwater landmarks observed by Jules Verne's Nautilus from Twenty Thousand Leagues Under the Sea.

• - The 2003 novel "The Signal and the Noise" by John Griesemer tells a fictional story about the project, including many real incidents.

• - In the novel «Open the door!» (1918) by Catherine Carswell, the Bannermans visit the Great Eastern, which was in Liverpool Harbor as a demonstration ship before it was broken up, Bannerman's linnet imagination having been captured by the cable.

• - Hans Christian Andersen's novel "The Great Sea Serpent" describes the chaos and confusion among the inhabitants of the sea caused by the laying of the cable.