Alexander Bell was born in Edinburgh, Scotland, in 1847 in a family interested in the problems of speech. Both his father and his grandfather had studied the mechanics of a sound. Bell's father had been one of the pioneer teachers of speech to the deaf. He was a world-famous inventor of "Visible Speech", which helped deaf people to pronounce words they could not hear. Between 1868 and 1870 Alexander worked with his father and studied speech and taught deaf children in Edinburgh. In 1870 he moved to Canada and the next year he went to the USA. In 1866 the nineteen-year-old Bell started thinking about sending tones by telegraph, and it was then that there came to his mind the idea of the "harmonic telegraph", which would send musical tones electrically from one place to another. In 1873 he was appointed a professor at Boston University. He became interested in the mechanical production of a sound, basing his work on the theories of Helmholtz. It seemed to Bell that it was possible to convert the sound wave vibrations into a fluctuating electric current. Then the current, in its turn, can be converted into sound waves identical with the original at the end of the circuit. In this way, sound could be carried across wires at the speed of light. It was through his famous experiments that in 1876 he was able to develop the telephone, which enables people to talk to each other over long distances. One day, while working with an instrument designed to carry sound, Bell automatically cried to his assistant, "Watson, please, come here." Watson, at the other end of the circuit on the other floor, heard the instrument speak and ran downstairs with joy. It was the first telephone communication. In 1915 the first transcontinental telephone was opened. Bell died on August 2, 1922.