In 1874 the essential idea of the telephone formed in his mind. As he later explained it, “If I could make a current of electricity vary in intensity precisely as the air varies in density during the production of sound, I should be able to transmit speech telegraphically.” Two years later he applied for a patent, which was granted on March 7, 1876. On March 10, the first coherent complete sentence—the famous “Mr. Watson, come here; I want you”—was transmitted in his laboratory.
In later years Bell experimented with a means to detect metal in wounds and with a vacuum-jacket respirator that led to the development of the iron lung. He helped bring Thomas A. Edison’s phonograph to commercial practicality and experimented with hydrofoil boats and with airplanes as early as the 1890s.
With the wealth derived from the telephone, Bell was able to assist the careers of other scientists. He also founded and helped finance the journal Science, today the premier American scientific journal, and the National Geographic Society.
While constantly engaged in scientific experiments, Bell crusaded tirelessly on behalf of the deaf, encouraging their integration into society with the help of lip-reading and other techniques. In 1890 he founded the Alexander Graham Bell Association for the Deaf.
He died in 1922 at his summer home on Cape Breton Island, Nova Scotia. People throughout North America were urged to refrain from making phone calls during his burial so that telephones would remain silent as a tribute.