 Puzzled, he turned off the lights, but it continued to glow. He realized the cathode tube was emitting something other than light. When he went to move the barium board, he noticed a lead plate cast a shadow on it. He began to try to create images, placing objects between the tube and the cardboard. He realized the mysterious rays were penetrating soft objects, but not hard. He was shocked to see in one image what looked like the bones of his hand.