Telegraph receiver. Historical artwork of a Breguet telegraph receiver. Messages arrived at the receiver in wires as a series of long and short electric pulses. Electromagnets converted the pulses into dashes and dots printed on ticker tape (running from the spool at top through the mechanism at centre). In Morse code, each letter and number is represented by a combination of dots and dashes. Electrical telegraphs were an important application of the newly-discovered electromagnetic force. The first practical telegraph was invented by Samuel Morse in 1837. Published in La Telegraphie Historique (History of Telegraphy) by Alexis Belloc in 1888.