The Transatlantic Cable – A story of engineering, ingenuity, and perseverance!

Today, in the age where Zoom is now a verb! Ever wonder how communications and information was shared between one continent and another?


At a glance it may appear that most modern communication is done wirelessly though mobile phones & satellites however in reality 99% of the traffic that crosses oceans is done via underwater cables. Believe it or believe it not - Valentia was at the epicentre of a Global Communications strategy and to this day remains a vibrant hub of news and stories. Hon Valentia.

Many of us are well aware of the Transatlantic cable story and how historic an accomplishment it was but perhaps less of us know how close the project came to being abandoned. This blog only skims the surface of how Valentia Island became a central player in one of the most daring projects ever attempted at the time. We happened upon a copy of a book called – “The Story of the Atlantic Cable" – by Charles Bright, Engineer in Chief and much of below is from this book.


The story starts around the early 1800’s with the invention of the electric telegraph, which sparked a revolution in communication. It allowed messages to be sent across wires as electric pulses which could be translated into letters and words. In 1854, an American named Cyrus West Field was presented with a business opportunity to connect New York to Newfoundland and then pushed things further by suggesting that the line could be extended across the North Atlantic, firstly to Ireland and then across to London, which at the time was the hub of the global economy.


[Fig 1 - Early map of Transatlantic cable routes, circa 1900s]

Field then set about the arduous task of raising funds. At the time, he had a network of contacts and managed to secure initial investment from a wide series of investors including the British and American Governments. Field also persuaded both Governments to loan their finest ships to work on the mammoth effort ahead. Both Governments would benefit from faster communications between both sides of the Atlantic and invested in the project from the early stages.

The First Cable

After much debate, the the route between both continents had been decided upon - Valentia Island on the European side and Trinity Bay, Newfoundland on the American side. The distance between the two sides, being 1,640 nautical miles, equal to 3,037km. It was estimated that a length of 2,500 nautical miles (4,630km) would be sufficient for the cable length, allowing for various ocean depths along the route. The seabed for the chosen route was known to be one which would drop to thousands of fathoms deep.

[Fig 2 - Submarine Atlantic Telegraph Chart - showing Cyrus W Field in the center]

20,500 miles of copper were needed – allowing for the strands of the 2,500 mile cable to be created. The shore ends of the cable would be much heavier as were strengthened to cope with wave forces and sharp rocks near the coastline. The contract price of the cable was £225,000, the core costing £40/mile with the armour costing £50/mile.

[Fig 3 - an enlarged view of the Atlantic cable]

No single vessel existed at the time to carry all of the cable so two ships were required and hence the cable would need to be spliced (joined) to allow a continuous cable between both sides. The British provided one of their finest warships, HSM Agamemnon, a screw propelled line of Battleship while the Americans provided their finest ship of the time, a frigate, USS Niagara. Smaller ships were also used to pilot the larger cable laying vessels, from the US came The Gorgon whilst the British provided, The Valorous.

[Fig 4 - early print of both ships and the first message between both Governments of the time]

The two main ships were adapted from their previous uses as Navy vessels to allow for the cable storage and paying out equipment. It would take 3 weeks to load the cable onto both ships.

The initial landing point chosen was Ballycarberry, Over the Water, just outside Caherciveen. On the Monday,  3rd August, 1857 - Valentia Harbour was alive with activity welcoming the ships and the other convoy of vessels which accompanied the larger ships. Something akin to Valentia winning the South Kerry Championship after years in the doldrums. On Wednesday, 5th August, 1857 – The cable was hauled ashore at Ballycarberry Strand.

On Friday, 7th August 1857 - both ships left Valentia harbour and headed West for Newfoundland. Bar a few small hiccups in the first few calm days, all was going well until 3:45pm on Tuesday, 11th August, 1857, the cable snapped after 380miles had been laid, due to mismanagement of the braking system as the USS Niagara mounted a large wave. Efforts would be eventually abandoned and both ships headed back Eastwards towards land.

The project would be paused, improvements to the ships paying out systems and in particular the self releasing braking system to avoid a similar incident in the future.

The revised second attempt would take place, the following summer on 10th June 1858. This time it was decided that both ships would sail to the mid-Atlantic, splice the cable out at sea and then head for their respective landing points at either sides of the Atlantic. 25th June 1858 – HMS Agamenmon would sail East to Valentia Harbour and the USS Niagara would sail West to Newfoundland. Both ships encountered a fierce storm and feared that the masts might shear off, which could have been catastrophic for the project and crew but alas both managed to weather the high seas and steamed on Westwards. On the 25th June 1858 – the ships reached the mid-Atlantic point, the sea was eerily calm –the cables were spliced and a “bent sixpence” put in for luck. After just 40miles had been payed out the cable again snapped and both ships would need to rendezvous at the mid-point to form another splice, which was determined to be a final attempt given that the crew were weary and tired following the exhausting storm encountered just days beforehand. Sadly, after another successful cable spice between the two ships, the cable again mysteriously snapped when the two ships were just 112 miles apart. This spelled the end of the expedition and both ships headed Eastwards to Cobh (Queenstown). HMS Agamemnon reached Cobh on 12th July 1858 with the USS Niagara having reached Cobh over a week earlier.  The team and its investors were on the verge of aborting the project, but persuasive voices prevailed and they decided that the mission should be given one last chance.

Third Attempt – the ships left Cobh on the 17th July 1858 with a much more subdued atmosphere in the air. On the 28th July 1858, both ships reached their mid-Atlantic point. The cables once again were spliced and the cable dropped to the murky depths with both ships setting off in their respective directions. Not long after both ships had set for their respective coastlines, a large whale was spotted at the starboard bow of the Agamemnon heading for the stern, directly in line with the cable being payed out but luckily for all involved, it dived below the cable and a gasp of relief reverberated around the deck.

[Fig 5 - A close call with a large whale]
"By Daylight on the morning of Thursday the 5th August, 1858, the bold rocky mountains which entirely surround the wild and picturesque neighbourhood of Valentia rose right before us at a few miles distance. Never, probably was the sight of land more welcome, as it brought to a successful termination one of the greatest, but at the same time most difficult, schemes which was ever undertaken"
"No one on shore was apparently conscious of our approach, so the Valorous went ahead to the mouth of the harbour and fired a gun. Both ships made straight for Doulas Bay, the Agamemnon steaming into the harbour with a feeling she had done something and about 6am came to anchor at the side of Beginish Island, opposite to Valentia"

Every man, woman and child in Valentia soon heard the commotion and came to join in the celebrations. The toughened shore end of the cable was safely brought to shore at White Strand Bay, near Knighstown Valentia. The cable end was soon pulled to the Electrical Room in the cable station. Meanwhile the cable also reached Trinity Bay, Newfoundland on the 5th August 1858. The jubilant scenes lasted a few days and transatlantic telegraph messages were now possible for the first time. On the 16th August 1858 the first message was sent from Europe to the United States of America and read:

"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, goodwill towards men"

Later a message from Queen Victoria to US President James Buchanan.  It took approx. 2mins 5secs to send one character. Queen Vic’s message was just 98 words long but took over 17Hrs to transmit! Sadly after only a few weeks of operation the high currents being transmitted through the new cable in a bid to speed up the transmission times became too much for the cable and after only 732 messages in total had been transmitted over the course of just 3 months, the cable ultimately sent it’s last message on 20th October 1858.  

"Summing up the cause of the untimely ending to the ill used cable, perhaps the most apt verdict would be, in mechanical parlance high pressure steam had been got up in a low-pressure boiler" 


Several years passed with insufficient appetite to tackle replacing the 1858 cable with an improved version, until 1865 when with renewed vigor and a new sense of hope, it was decided that with an improved cable design, the Translantic cable crossing would be possible. As part of this, a new and improved cable protection system was now in production with the copper core surrounded with a substance called Chattertons compound. This new cable weighed approx. twice as much as the initial cable in 1858 and offered much more benefits than its predecessor. 4,000 lbs per nautical mile (980kgs per km) This time around, a single ship – The SS Great Eastern would be used, a wooden hulled paddle steamer, which was capable of carrying the entire 2,400 miles of cable. The SS Great Eastern was the largest ship in the World at the time by a considerable margin and wad designed by the renowned English Engineer, Isambard Kingdom Brunel.  

[Fig 6 - The mighty SS Great Eastern]

On the 23rd July 1865 – The Great Eastern headed for Foilhommerun Bay, Valentia Island and shortly after steamed clear of the Irish coast, but on the 29th July, 1865, disaster struck again and a cable fault was noticed after a regular electrical current reading was being taken. 1,186 miles of cable had been laid at this stage. The crew tried in vain to haul in the damaged section and repair onboard however after several failed attempts,  the expedition was abandoned on the 11thAugust 1865 and the previously high hopes were now as low as the ropes used to try haul the damaged cable back up  from the murky depths of over 2,000 fathoms. The interested parties and stakeholders decided to pause and mull over what should be done next. They eventually decided that they would reconvene the following summer in 1866.


On the 30th June of the following year, 1866 – The Great Eastern set sail from the river Thames in London and arrived shortly at Valentia Harbour, where the HMS Terrible and Racoon would accompany her. On the 7th July 1866, The William Cory (also known as The Dirty Billy) landed the shore end of the new cable at Foilhommerum Bay, then afterward laid 27 miles of the intermediate cable, where the Great Eastern took the end on board, spliced it with the main cable and started paying out the cable once more. Finally -14 days after starting the voyage of 1866 – The SS Great Eastern arrived off Heart’s Content, Trinity Bay. The total length of cable laid was 1,852 nautical miles at an average depth of 1,400 fathoms. Shortly after this, the cable between Newfoundland and New York City was repaired and once more ensured that transatlantic telegraph communication across the Atlantic was possible following its brief introduction in 1858.

[Fig 7 - Map of Trinity Bay, Newfoundland]

Rescue Mission!

Shortly after successfully laying that new cable, the Great Eastern set about Eastwards once again to try and find the cable that had been lost the year before. A task that seemed highly unlikely even to the most optimistic optimist, given they had only approx. coordinates to work from. However, incredibly they did manage to find the elusive cable, 2.5 miles below the surface of the Atlantic by using grappling hooks at the end of long ropes.

The engineers then amazingly managed to relay communications back across the Atlantic to Valentia Island via the 1865 cable. The long speechless cable began to talk, and the welcome assurance arrived, “Ship to Shore; I have much pleasure in speaking to you through the1865 cable ” The Great Eastern then laden with cable headed Westwards once more towards Trinity Bay. There now were two cables in operation between both cable stations on the East and West sides of the Atlantic.

The new cable could transmit 8 words per minute which was an order of magnitude faster than its earlier cousin.

Mission Complete!

Telephones eventually replaced telegraphs and digital data replaced analogue signals. Today’s fibre optic cables can transfer hundreds of Terrabytes of data per sec. Today there are approx. 750,000 miles of fibre optic cables along the sea floors across the world’s oceans allowing communications to be shared and received at lightning speeds but once upon a time, Valentia Island was the center of global communications and Cyrus West Field became a Hero of Enterprise after masterminding the project. Valentia Island remains a place of fortitude and an outpost on the Western seaboard.