From Wikipedia

Transatlantic Cable

The transatlantic telegraph cable was the first cable used for telegraph communications laid across the floor of the Atlantic Ocean. It crossed from the Telegraph Field, Foilhommerum Bay, Valentia Island, in western Ireland to Heart's Content in eastern Newfoundland. The transatlantic cable bridged North America and Europe, and expedited communication between the two. Whereas it would normally take at least ten days to deliver a message by ship, it now took a matter of minutes by telegraph.

Five attempts to lay it were made over a nine-year period—in 1857, two in 1858, in 1865, and in 1866—before lasting connections were finally achieved by the ship SS Great Eastern, captained by Sir James Anderson, with the 1866 cable and the repaired 1865 cable.

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.

Cyrus West Field was the force behind the first transatlantic telegraph cable, attempted unsuccessfully in 1857 and completed on August 5, 1858. Although not considered particularly successful or long-lasting, it was the first transatlantic cable project to yield practical results. The first official telegram to pass between two continents was a letter of congratulation from Queen Victoria of the United Kingdom to the President of the United States James Buchanan on August 16. The cable was destroyed the following month when Wildman Whitehouse applied excessive voltage to it while trying to achieve faster telegraph operation. The shortness of the period of use undermined public and investor confidence in the project, and delayed efforts to restore a connection. A next 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 time the connection was more durable, and increased public confidence resulted when the 1865 cable was repaired and put into service shortly afterwards.

Whereas, previously, communication between Europe and the Americas could only happen by ship, the transatlantic cable sped up communication to within minutes, allowing an inquiry and a response within the same day. In the 1870s, duplex and quadruplex transmission and receiving systems were set up that could relay multiple messages over the cable. In cross-Atlantic currency trading, the pound sterling to US dollar exchange rate came to be referred as "cable" and this term is still in common usage today. The great utility of the cable built on itself, and multiple cables were established soon afterward.