After Edison had established himself, a rival of his, JB Stearns, beat him to creating the
duplex telegraph, but Edison was still working away at a better model and ''never tired of working on the telegraph''. This improved version would be able to send four
messages at a time on a single wire. The way Edison thought to achieve this was by combining the duplex telegraph (
sending and
receiving a message simultaneously on the same wire) and the diplex telegraph (sending or receiving two messages in the same direction on the same line). It was a ''combination of sounders, circuits, condensers, batteries, and relays that only a truly scientific and ingenious mind could construct''.
At the time that Edison was completing this project, he had been working for two different
companies: Western Union and the Automatic Telegraph Company. Since both companies knew that whoever owned this invention would dominate the industry, they went to court for seven years over the matter of ownership of this product.
Although Edison never received payment for this invention he made a successful demonstration of it on 9 July, 1874, and a press conference was held to announce this accomplishment.
This invention of Edison''s was later useful when the invention of the
telephone came around. Many of the ideas used in this invention were also applicable to the telephone.
More summaries about the Thomas Edison - The Multiplex Telegraph (1874)