Thomas Edison dictating instructions to an employee on his Telescribe machine / Getty Images

The machine designed to record telephone conversations was unveiled 100 years ago today

* "It makes the telephone more useful, the phonograph more valuable and both more necessary," said Thomas Edison, with an uncharacteristic lack of foresight. The Telescribe, a machine designed to record telephone conversations, was unveiled 100 years ago today, with praise heaped upon it by journalists who hadn't actually seen it working. "Telescribing will become a custom," predicted The Rotarian, incorrectly.

* Edison had long been convinced that the telephone could only reach its full potential by being twinned with his own invention, the phonograph. Our inability to record conversations for posterity restricted the telephone, he said, to "simple conversational chit-chat", and was thus useless for conducting business. He set about inventing such a machine, and in 1878 produced a prototype for what he called a "carbon telephone" – but it was another 37 years before he proudly announced the Telescribe.

* The truth was that there was widespread suspicion, then as now, about the recording of telephone conversations. In 1900, the Danish inventor Valdemar Poulsen had come up with a machine that recorded calls on huge spools of thin copper wire, but it never worked very well, and the business selling them in the US went bankrupt at around the time that the Telescribe was announced.

* Edison's invention had two telephone receivers, one of which you plugged into the phonograph when a call came in, and a smaller one which you talked through. Edison envisaged that, once completed, the wax cylinders would be replayed and transcribed by a stenographer, before sending paper copies to both parties for confirmation. He regarded the commercial possibilities as "almost unlimited", but in the event only a handful of Telescribes were produced before it was quietly withdrawn from the market.