Shown next to General Ferrié, one of the great names in wireless telegraphy, is this model of a radio telegraphy device widely used in the 20th century for long-distance communication.

Notably the work of the Italian Guglielmo Marconi, wireless telegraphy uses the radio waves discovered by the German physicist Heinrich Hertz to carry telegraph messages: these are sent in the form of electrical signals, as in conventional telegraphy, but are then converted into radio waves by the transmitters; receivers pick up the radio signal, which is then changed back into an electrical signal, readable by telegraph devices.

This technology was used extensively from the First World War onwards, replacing the obsolete carrier pigeon system. The number of radiotelegraphy stations increased during the 20th century, before giving way to the new telephone technology.