Becquerel, a French physicist, was the son and grandson of physicists.Becquerel was familiar with the work of Wilhelm Conrad Roentgen on December22 1895, "photographed" his wife's hand, revealing the unmistakable imageof her skeleton, complete with wedding ring. Roentgen's wife had placedher hand in the path of X-rays which Roentgen created by beaming an electronray energy source onto a cathode tube. Roentgen's discovery of these "mysterious"rays capable of producing an image on a photographic plate excited scientistsof his day, including Becquerel. Becquerel chose to study the related phenomenaof fluorescence and phosphorescence. In March of 1896, quite by accident,he made a remarkable discovery. Becquerel found that, while the phenomena of fluorescence and phosphorescencehad many similarities to each other and to X-rays, they also had importantdifferences. While fluorescence and X-rays stopped when the initiatingenergy source was halted, phosphorescence continued to emit rays some timeafter the initiating energy source was removed. However, in all three cases,the energy was derived initially from an outside source. In March of 1896, during a time of overcast weather, Becquerel foundhe couldn't use the sun as an initiating energy source for his experiments.He put his wrapped photographic plates away in a darkened drawer, alongwith some crystals containing uranium. Much to his Becquerel's surprise,the plates were exposed during storage by invisible emanations from theuranium. The emanations did not require the presence of an initiating energysource--the crystals emitted rays on their own! Although Becquerel didnot pursue his discovery of radioactivity, others did and, in so doing,changed the face of both modern medicine and modern science.
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