Meanings of quadruplex telegraphy in English

It further notes that the term is "said to have originated in quadruplex telegraphy and have been transferred to all electric apparatus."

Then there are the stock printer, the automatic repeating telegraph, quadruplex telegraphy, the phono-plex, the ore-milling process, the railway telegraph, the electric engine, the phonograph.

He experimented with submarine cables and worked out a system of quadruplex telegraphy by which one wire was made to do the work of four.

Quadruplex telegraphy, 104, 265.