September 25

1956: TAT-1 opens for use. TAT-1 or Transatlantic No. 1, was the first submarine transatlantic telephone cable system. The cable ran from Oban, Scotland, to Clarenville, Newfoundland. Between 1955 and 1956, two cables were laid down, one for each direction. Each line could carry 35 simultaneous telephone calls and a 36^th line was able to carry up to 22 telegraph lines. The first transatlantic telegraph cable had been laid nearly a century earlier. Finished in 1858, it ran for only a month, but was replaced by a new and improved line in 1866. Radio based transatlantic phone service began in 1927. It was a bit expensive, coasting £9 for three minutes. In the US, it was about $45 for those three minutes or about $615 today. Even at that price, they handled about 300,000 calls per year.

A telephone cable was discussed during that time, but the technology was not yet developed. It would take until the 1940s for the needed components to be available. Coaxial cable had been invented back in 1880 by English engineer Oliver Heaviside. The gutta-percha insulation, a latex based product, was used for the underwater telegraph cables and led to the collapse of the supply through unsustainable harvesting. A new product was needed and it came in the form of polyethylene insulation. This is, today, the most commonly used plastic in the world and was prepared by accident in 1898. It wasn’t industrially practically produced until 1933 and was greatly improved upon by 1939.

While the cable itself was important, more was needed. Reliable vacuum tubes were needed for the submerged repeaters. Transistors were not used in this cable as they were of relatively new construction and their efficacy was uncertain. It was also needed to have a general improvement in the carrier equipment overall. The project got underway when an agreement was struck between the General Post Office of the United Kingdom and the American Telephone and Telegraph company along with the Canadian Overseas Telecommunications Corporation. The share split was for the British to have 40%, the Americans have 50%, and the Canadians to have 10%. The total cost was about £120 million or about £2.35 billion today.

The cables were laid mostly by HMS Monarch and at each end, there had to be systems built to carry messages to and from the transatlantic cables. On this day, 588 London-US calls and 119 London-Canada calls were placed. The original 36 channels were 4 kHz and they were able to increase to 48 channels by narrowing the bandwidth to 3 kHz. Later, three more channels were added by using C Carrier equipment. By 1960, using newer technology, they were up to 72 speech circuits. The cable was so successful that more of cables were laid and TAT-1 was retired in 1978. In 2006, it was recognized as an IEEE Milestone.

Communication – the human connection – is the key to personal and career success. – Paul J. Meyer

The most important thing in communication is hearing what isn’t said. – Peter Drucker

Whatever words we utter should be chosen with care for people will hear them and be influenced by them for good or ill. – Buddha

Of all of our inventions for mass communication, pictures still speak the most universally understood language. – Walt Disney