Caption:
Historical artwork of Alexander Graham Bell's first telephone transmitter (left) and receiver (right). Patented in 1876, it used existing telegraph lines to transmit and receive sound. The mouthpiece (far left) doubled as the earpiece for the call's receiver, but this two way system was later improved as it was not practical to speak and listen concurrently. Bell was born in Scotland in 1847, emigrating to Massachusetts, USA, where he worked on a system to teach deaf mutes to speak. He also patented a system to send more than one message at a time along existing telegraphic systems. It was this improvement that lead him to invent the telephone.