He Put the “X” in X-Rays
November 8, 1895: Röntgen Stumbles Upon X-Rays
On this day in 1895 German Physics Professor Wilhelm Röntgen stumbles upon what he would later describe as “X-rays” while experimenting with electrical discharge tubes.
In early November, Röntgen was repeating an experiment with one of Lenard’s tubes when he observed that the invisible cathode rays caused a fluorescent effect on a small cardboard screen painted with barium platinocyanide.
In the late afternoon of November 8th he carefully constructed a black cardboard covering and 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 he noticed a faint shimmering from a bench a few feet away from the tube. 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. November 8 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 the many properties of the new rays he temporarily termed “X-rays”.
Nearly two weeks after his discovery, he took the very first picture using X-rays of his wife Anna Bertha’s hand. When she saw her skeleton she exclaimed “I have seen my death!”
He later reported that it was at this point that he determined to continue his experiments in secrecy, because he feared for his professional reputation if his observations were in error.
Röntgen’s original paper, “On A New Kind Of Rays” (Über eine neue Art von Strahlen), was published on 28 December 1895. On 5 January 1896, an Austrian newspaper reported Röntgen’s discovery of a new type of radiation. Röntgen was awarded an honorary Doctor of Medicine degree from the University of Würzburg after his discovery.
Today, Röntgen is considered the father of diagnostic radiology, the medical specialty which uses imaging to diagnose disease. He referred to the rays as “X”, indicating that they were an unknown form of radiation at the time. The name has stuck, although in several languages, X-rays are referred to as Röntgen rays, in tribute to his discovery.
Incidentally, Röntgen was awarded the very first Nobel Prize in Physics in 1901 for his work on X-rays.