Experimenting one November evening with a discharge tube, Röntgen noticed a screen across the room glowing where no light should reach it. He had stumbled upon a new and penetrating ray, which he called, for its unknown nature, X.
When he placed his wife's hand before it, the bones appeared in shadow upon the plate, her ring floating about the finger. Medicine had been given, for the first time, an eye that could see within the living body.