Image of the Maltese Cross.
One of Henri Becquerel photographic plates - developed on 1 March 1896 - shows the image of a Maltese cross. The copper cross was interposed on February 26, 1896 between the photographic plate wrapped in paper and a thin glass slide supporting salts of uranium. All ended up in a dark drawer. The appearance of the cross is due to the fact that the copper has absorbed the radiation emitted from uranium salts.