What prompted Becquerel to develop the plates?
But why had Becquerel bothered to develop those plates, which he thought were faintly exposed at best? His behavior has been explained as thoroughness: Jean Becquerel has suggested that his father planned to resume his experiments and wished to use fresh plates, so why to develop the old ones anyway? The explanation (proffered by G.E.M. Jauncey in a 1946 paper in the American Journal of Physics) is “impatience after awaiting four days for the sun to shine”. Yet other reasons, suggested, are “simple thrift or an overriding curiosity”. We can dismiss the belief that Becquerel planned to resume his experiments on that Sunday: Meteorological records indicate that the day was less sunny than the average of the ceding four days A better explanation for Becquerel’s activity is that he wanted to have sufficient material to report at the next day’s session of the academy. In previous experiments he had already found, or so he believed, that weak illumination triggered his crystals somewhat. Per
