Bell, AlexanderGraham

 Inventor and educator. Born March 3, 1847, in Edinburgh, Scotland. Bell is best known for perfecting the telephone to transmit vocal messages by electricity. The telephone inaugurated a new age in communication technology.
Bell’s father, Alexander Melville Bell, was an expert in vocal physiology and elocution; his grandfather, Alexander Bell, was an elocution professor. After studying at the University of Edinburgh and University College, London, Bell became his father's assistant. He taught the deaf to talk by adopting his father's system of visible speech (illustrations of speaking positions of the lips and tongue). In London he studied Hermann Ludwig von Helmholtz's experiments with tuning forks and magnets to produce complex sounds. In 1865, Bell made scientific studies of the resonance of the mouth while speaking.

In 1870, the Bells moved to Brantford, Ontario, Canada, to preserve Alexander's health. He went to Boston in 1871 to teach at Sarah Fuller's School for the Deaf, the first such school in the world. He also tutored private students, including Helen Keller. As professor of vocal physiology and speech at Boston University in 1873, he initiated conventions for teachers of the deaf. Throughout his life he continued to educate the deaf, and he founded the American Association to Promote the Teaching of Speech to the Deaf.

From 1873 to 1876, Bell experimented with a phonautograph, a multiple telegraph, and an electric speaking telegraph (the telephone). Funds came from the fathers of two of his pupils; one of these men, Gardiner Hubbard, had a deaf daughter, Mabel, who later became Bell's wife.
To help deaf children, Bell experimented in the summer of 1874 with a human ear and attached bones, a tympanum, magnets, and smoked glass. He conceived the theory of the telephone: an electric current can be made to change intensity precisely as air density varies during sound production. Unlike the telegraph's use of intermittent current, the telephone requires continuous current with varying intensity. That same year, Bell invented a harmonic telegraph, to transmit several messages simultaneously over one wire, and a telephonic-telegraphic receiver. Trying to reproduce the human voice electrically, he became expert with electric wave transmission. Bell supplied the ideas; Thomas Watson made and assembled the equipment. Working with tuned reeds and magnets to synchronize a receiving instrument with a sender, they transmitted a musical note on June 2, 1875. Bell's telephone receiver and transmitter were identical: a thin disk in front of an electromagnet.

On February 14, 1876, Bell's attorney filed for a patent. The exact hour was not recorded, but on that same day Elisha Gray filed his caveat (intention to invent) for a telephone. The U.S. Patent Office granted Bell the patent for the "electric speaking telephone" on March 7. It was the most valuable single patent ever issued, and it opened a new age in communication technology. Bell continued his experiments to improve the telephone's quality. By accident, Bell sent the first sentence, "Watson, come here; I want you," on March 10, 1876. The first demonstration occurred at the American Academy of Arts and Sciences convention in Boston two months later.