Bell�s liquid transmitter, 1876.

UNITED STATES - MARCH 03: Replica of a liquid transmitter made by Scottish-born telephony pioneer Alexander Graham Bell (1847-1922). Bell was born in Edinburgh, Scotland but emigrated to the United States, settling in Boston where began his career as an inventor. On 7th March 1876, he secured a patent for an electrical speech machine, which he called the telephone, defending the patent against the claims of Elisha Gray (1835-1901), whose patent for the �liquid transmitter� was filed on the same day as Bell�s - 14 February 1876. Later that year, Bell went on to give a public demonstration at the centenary festival of Phildelphia, and in 1877 installed the first telephone exchange in Connecticut. (Photo by SSPL/Getty Images)