TAT-1

node · earth · North Atlantic

The first transatlantic telephone cable, and the object that turned the ocean floor from a telegraph medium into a communications system carrying live human conversation. Laid between 1955 and 1956 between Gallanach Bay near Oban in Argyll and Clarenville in Newfoundland, with an onward link to Nova Scotia, it was inaugurated on 25 September 1956 and carried 36 telephone circuits. The engineering was coaxial rather than optical: a pair of cables, one for each direction, with vacuum-tube repeaters spliced into the line at intervals along the seabed, powered from shore. Thirty-six circuits is the number to hold on to. It is a number of simultaneous conversations that a modern office switchboard would find unremarkable, and it was the entire telephone capacity between two continents; calls had to be booked, and the system was so heavily used that its capacity was a matter of national policy. TAT-1 also established the pattern that everything since has followed — a consortium of national carriers, a shared cable, a design life measured in decades and a landing point inherited from the telegraph era. It was retired in 1978.