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thumb|alt=An image of darkened brass historical plaque with a streak of green corrosion running down it, mounted on the exterior side of a brick building. |A historical plaque on the side of the Franklin School in Washington, D.C. which marks one of the points from which the photophone was demonstrated thumb|A diagram from one of Bell's 1880 papers
thumb|alt=An image of darkened brass historical plaque with a streak of green corrosion running down it, mounted on the exterior side of a brick building. |A historical plaque on the side of the Franklin School in Washington, D.C. which marks one of the points from which the photophone was demonstrated thumb|A diagram from one of Bell's 1880 papers
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 NW in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).