The first 50 years of International radio communication
Haraden Pratt · Transactions of the American Institute of Electrical Engineers Part I Communication and Electronics · 1952
ONE hundred and sixty-four years ago Galvani discovered the existence of current electricity, previous knowledge having been confined to static electricity and the spark discharges associated with it. Significant additional fundamental discoveries made by Volta, Oersted, and Faraday provided the knowledge that enabled Morse to develop the practical instrumentality of the wire telegraph which used direct current interrupted in accordance with the code which he devised. Later Bell developed the telephone using the same basic technical information but employing alternating currents having acoustic frequencies.