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. COUNT 4
QSN1 How many wires did Bell send a signal through? ANS1 1 QSN2 For  his system to work, Bell had to change what about each code? ANS2 pitch QSN3 Bell needed to fix both the transmitter and what? ANS3 receiver QSN4 Where was Bell's home? ANS4 Brantford