Returning home to Brantford after six months abroad, Bell continued his experiments with his "harmonic telegraph".[N 12] The basic concept behind his device was that messages could be sent through a single wire if each message was transmitted at a different pitch, but work on both the transmitter and receiver was needed.
ఎన్ని వైర్లు బెల్ ద్వారా ఒక సిగ్నల్ పంపారు?
1