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Communication between nations and at great distances was not always as available, and certainly not as fast, as it is in many places today. The site of the first transatlantic communication via cable is Valentia Island, Ireland, where over 160 years ago the first telegram was sent between the United States and Great Britain. Sent on Aug. 16, 1858, it read:
“The queen is convinced that the president will join with her in fervently hoping that the electric cable, which now connects Great Britain with the United States, will prove an additional link between the two places whose friendship is founded upon their common interests and reciprocal esteem .”
This telegram came a year after the failure of the first transatlantic cable and several attempts to successfully install it. The telegram was sent at about 0.1 words per minute through 1,686 nautical miles of cable laid through the Atlantic Ocean from Valentia Island to Newfoundland. Despite the hopefulness of that first message, the cable stopped working three weeks later. It would take another eight years to lay a working transatlantic cable that provided reliable communication.
In 1858, telegraphic messages were still a new technology. Samuel Morse, who also co-developed Morse code, had sent the world’s first telegraphic message from Washington, DC, to Baltimore — “What hath God wrought?” — in 1844, a little less than 15 years prior. After that first message, the US and Britain began transmitting messages over land and small bodies of water. But the question arose: What about large bodies of water? Sending a message over the Atlantic could take ten days by ship, so what could be accomplished by laying cable to speed communication?
Communications spanning the globe
The Atlantic Telegraph Company was formed in 1856 by an American investor named Cyrus Field and two British engineers, John Watkins Brett and Charles Tilston Bright. The cable that sent the first message was overseen primarily by chief electrician EOW Whitehouse, who was dismissed after it failed.
Funding for and interest in the project was stymied by the American Civil War, but a second cable was later proposed under the supervision of physicist William Thomson, who would later become Lord Kelvin. The British Admiralty lent the HMS Amethyst and the HMS Iris to assist in carrying and laying cable beginning in 1864. It took until 1866 to successfully complete the project.
On its first day, the new telegraph service generated about $1200 in revenue; the cost to send a telegram was about $0.0003809 for one word transmitted over one mile. The Atlantic Telegraph Company operated two trans–Atlantic cables — the second laid in 1868 — without competition until 1869 when a French cable was laid. Soon after the French company established itself, an agreement was made coordinating the pricing of telegraph services and share revenues, combining French and Anglo–American interests into one.
With the Atlantic successfully bridged, attention turned to other routes. An all–sea route to India was completed in 1870 with the help of the SS Great Eastern. The network was then extended to other parts of the British Empire: Madras, Penang, Singapore, Hong Kong, and eventually Australia. Florida and Cuba were connected in 1866, and Portugal to Brazil in 1874. In 1904, a globe–circling path connecting the Empire was completed, called the All–Red Route.
The technology also slowly improved. A major technical advance was the application of Oliver Heaviside’s theoretical work on the benefits of inductive loading. This led to improved loading using Permalloy, which, along with improved insulation and automatic transmitting and receiving equipment, enabled a speed of 400 words per minute, attained in 1928.
These submarine telegraph cables, laid along common ship routes and following the global structures of colonization, remained in operation until 1965. Discussion of telephone cables began in the 1920s, but the technology was not advanced enough to be practical until the 1940s.
The first transatlantic telephone cable system, TAT–1, was laid in 1955 and 1956 by the cable ship Monarch. It ran between Gallanach Bay in the UK and Clarenville, Newfoundland, initially carrying 36 telephone channels. In the first 24 hours of public service, 588 calls were placed between London and the US and 119 between London and Canada.
TAT–1 was retired in 1978 and replaced with coaxial cables installed throughout the 1970s. These used transistors and had higher bandwidth. All cables presently in service employ fiber optic technology, which succeeded the coaxial cables of the seventeens. Many still terminate in Newfoundland and Ireland, continuing to follow the great circle route from London to New York City.
Late in the 20th century, most North Atlantic telephone traffic moved from communication satellites to these low-cost, high-capacity, low-latency cables. These advantages only increased as tighter cables provided higher bandwidth, with the 2012 generation of cables lowering the transatlantic latency to under sixty milliseconds.
A few new routes have been announced in recent years, such as the South Atlantic Cable System (SACS), which finished in 2018, and the South Atlantic Express (SAEx), which is still in progress. SACS links Luanda, Angola, with Fortaleza, Brazil, while SAEx is intended to connect Virginia Beach to Cape Town and Amanzimtoti to India and Singapore.
Currently, 99% of the data traffic that is crossing oceans is carried by submarine cables, which are highly reliable — especially when multiple paths are available. Their modern carrying capacity is in the range of terabits per second, while satellites offer 1,000 megabits per second and display higher latency. However, the typical construction cost of a transatlantic system is several hundred million dollars.
This intersection of cost and usefulness means that, as at their inception, they are valuable both to corporations building and operating them for profit and to national governments. Submarine cables remain important to modern militaries, which use them for data transfer from conflict zones to command centers in the US
Most cables still run through the Atlantic, although there has been some expansion into the Pacific, and they connect every continent except for Antarctica. What began in years of failure to maintain a connection between the US and the UK has become a huge influence on modern life.