Henri Becquerel received the Royal Society’s Rumford Medal in 1900 for his discoveries concerning radiation proceeding from uranium. The award recognized his pioneering investigation of what became known as radioactivity.
In 1896, Becquerel discovered that uranium salts could expose photographic plates even when protected from sunlight. He initially investigated whether uranium fluorescence was connected with X-rays, which Wilhelm Röntgen had announced the previous year. The unexpected penetrating emissions from uranium proved to be a different phenomenon.
Becquerel’s work inspired Marie and Pierre Curie, whose research identified the far more strongly radioactive elements polonium and radium. Becquerel shared the 1903 Nobel Prize in Physics with the Curies for their work on spontaneous radioactivity.
The Rumford Medal is not the same as the Copley, Davy or Hughes Medals, all important Royal Society awards with different histories and criteria. Becquerel later received other honors, but the 1900 Royal Society medal specifically associated with his uranium-radiation discoveries was the Rumford Medal.