Existing comment:
From the top floor of this building was sent on June 3, 1880 over a beam of light to 1325 L Street the first wireless telephone message in the history of the world.
The apparatus used in sending the message was the photophone invented by Alexander Graham Bell, inventor of the telephone.
This plaque was placed here by Alexander Graham Bell chapter Telephone Pioneers of America March 3, 1947 the centennial of Dr. Bell's birth.
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Photophone
From Wikipedia, the free encyclopedia
The photophone (later given the alternate name radiophone) is a telecommunications device that allowed for the transmission of speech on a beam of light. It was invented jointly by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880, at Bell's laboratory at 1325 L Street in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.
On June 3, 1880, Bell's assistant transmitted a wireless voice telephone message from the roof of the Franklin School to the window of Bell's laboratory, some 213 meters (about 700 ft.) away.
Bell believed the photophone was his most important invention. Of the 18 patents granted in Bell's name alone, and the 12 he shared with his collaborators, four were for the photophone, which Bell referred to as his "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone".
The photophone was a precursor to the fiber-optic communication systems that achieved worldwide popular usage starting in the 1980s. The master patent for the photophone (U.S. Patent 235,199 Apparatus for Signalling and Communicating, called Photophone) was issued in December 1880, many decades before its principles came to have practical applications. |