<P> 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 . </P>
<P> 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 . </P>
when did alexander graham bell invented the photophone
when did alexander graham bell invented the photophone
February 19 , 1880
February 19 , 1880