On this day November 8, 1895
German physicist Wilhelm Conrad Röntgen produced and detected electromagnetic radiation in a wavelength range that is known today as X-rays.
In the late afternoon of 8 November 1895, Röntgen determined to test his idea. He carefully constructed a black cardboard covering similar to the one he had used on the Lenard tube.
He covered the Hittorf-Crookes tube with the cardboard and attached electrodes to a Ruhmkorff coil to generate an electrostatic charge.
Before setting up the barium platinocyanide screen to test his idea, Röntgen darkened the room to test the opacity of his cardboard cover.
As he passed the Ruhmkorff coil charge through the tube, he determined that the cover was light-tight and turned to prepare the next step of the experiment. It was at this point that Röntgen noticed a faint shimmering from a bench a meter away from the tube.
To be sure, he tried several more discharges and saw the same shimmering each time. Striking a match, he discovered the shimmering had come from the location of the barium platinocyanide screen he had been intending to use next.
Röntgen speculated that a new kind of ray might be responsible. 8 November was a Friday, so he took advantage of the weekend to repeat his experiments and make his first notes. In the following weeks he ate and slept in his laboratory as he investigated many properties of the new rays he temporarily termed X-rays, using the mathematical designation for something unknown.
Although the new rays would eventually come to bear his name in many languages where they became known as Röntgen Rays, he always preferred the term X-rays. Nearly two weeks after his discovery, he took the very first picture using x-rays of his wife’s hand, Anna Bertha. When she saw her skeleton she exclaimed “I have seen my death!”
The idea that Röntgen happened to notice the barium platinocyanide screen misrepresents his investigative powers; he had planned to use the screen in the next step of his experiment and would therefore have made the discovery a few moments later.