when did alexander graham bell invented the photophone
February 19, 1880
title: Photophone text: the Smithsonian Institution. Footnotes Photophone The photophone is a telecommunications device that allows 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 title: Photophone text: Photophone The photophone is a telecommunications device that allows 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 title: Alexander Graham Bell text: in the Volta Laboratory Association. On June 21, 1880, Bell's assistant transmitted a wireless voice telephone message a considerable distance, from the roof of the Franklin School in Washington, D.C., to Bell at the window of his laboratory, some away, 19 years before the first voice radio transmissions. Bell believed the photophone's principles were his life's "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 which achieved popular worldwide usage in the 1980s. Its master title: Photophone text: 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 ( "Apparatus for Signalling and Communicating, called Photophone") was issued in December 1880, many decades before its principles came to title: Photophone text: the window of his laboratory. The marker did not acknowledge Tainter's scientific and engineering contributions. On February 19, 1980, exactly 100 years to the day after Bell and Tainter's first photophone transmission in their laboratory, staff from the Smithsonian Institution, the National Geographic Society and AT&T's Bell Labs gathered at the location of Bell's former 1325 'L' Street Volta Laboratory in Washington, D.C. for a commemoration of the event. The Photophone Centenary commemoration had first been proposed by electronics researcher and writer Forrest M. Mims, who suggested it to Dr. Melville Bell Grosvenor, the inventor's grandson, during a visit to