Wilhelm Conrad Röntgen

Imaging

“Röntgen must have gone mad”

The discovery of X-rays

4min

Ingo Zenger

Published on November 8, 2022

The 19th century was a golden era for sensational scientific discoveries. Never before in history had so much been discovered, invented, measured, and mapped – and newspapers were reporting astonishing findings and innovative electrical devices on an almost daily basis. Toward the end of the century, the first motorized streetcars were operating in cities; streets and alleyways were lit with electric lamps; and people were using elevators, sending telegrams, having their photos taken. In an era such as this, you would be forgiven for thinking that new discoveries ought not to come as a great surprise.

Der Ort der Entdeckung der X-Strahlen: Röntgens Labor an der Universität Würzburg Quelle: Deutsches Röntgen-Museum

In 1895, at his lab at the University of Würzburg, the physics professor Wilhelm Conrad Röntgen discovered a phenomenon so peculiar that, at first, no one could quite believe it.

The London Standard printed one of the first reports of Röntgen’s discovery and ended its article with the following words: “The Presse assures its readers that there is no joke or humbug in the matter. It is a serious discovery by a serious German Professor.” News of Röntgen’s discovery spread around the world from early January 1896 and must have been hard to believe back in those days. Newspapers reported that the professor in Würzburg had successfully used a new type of “light” to take “a photograph of a set of weights without opening the wooden box in which the weights were kept” and of a human hand, showing the bones “without the flesh. Many scientists responded with bewilderment, while others dismissed the reports as the trick of a practical joker. Even Röntgen’s good friend, the Berlin-based physics professor Otto Lummer, appeared doubtful of his colleague at first:

Röntgen has otherwise always been a sensible fellow, and it’s not carnival season yet.”
Otto Lummer about Wilhelm Conrad Röntgen

When Wilhelm Conrad Röntgen first observed what he called “X-rays,” on November 8, 1895, even he initially believed he was a “victim of deception.” Crystals that happened to be lying nearby during one of his experiments involving gas discharge tubes began to glow green in the darkened laboratory. Light could not have been responsible for this, because the tube was wrapped in black paper. Röntgen placed wood, paper notebooks, and a book of around 1,000 pages between the crystals and the tube, but none of them could stop the mysterious rays in their tracks. When he ultimately held his hand in the path of the rays, he made probably the most exciting discovery of his lifetime: On the screen, he could see the shadows of the bones in his hand!

Das „Schattenbild“ eines Gewichtssatzes im Inneren eines Kästchens Quelle: Röntgen-Gedächtnisstätte Würzburg

The “shadow-image” of a set of weights inside a box

Röntgen initially kept the discovery to himself. He withdrew into his work and was barely seen for the next seven weeks. No one knew what was going on in the professor’s laboratory – his assistants found the doors locked, and his wife, Bertha, went through what she would later describe as a “dreadful time.” Röntgen came home late and in a foul mood, barely spoke as he ate, and raced back to his lab immediately afterwards. Soon, he even had his bed taken into his laboratory, and his wife sometimes didn’t see him for days on end. When Bertha asked what the matter was, she initially received no answer. It was only when she pressed him that Röntgen said if people knew what he was doing, “they would say ‘Röntgen must have gone mad.’”

It must have been difficult for Röntgen to convince his contemporaries of what had been going on behind the closed laboratory doors for all those weeks: As well as “X-raying” a wooden spool to produce a photograph of the wire inside it, Röntgen was able to read the direction on a compass enclosed in a metal case and – in one particularly noteworthy example of his many experiments – to look through a closed door by setting up a fluorescent screen in the room next to his lab. Take a glance at Röntgen´s laboratory und learn more about his experiments in our video “Wilhelm Conrad Röntgen“ from 1968.

In late 1895, after seven weeks of tireless work and without telling another soul about the X-rays, Röntgen decided to make his discovery public. He wrote a paper entitled On a New Kind of Rays and included a number of “shadow-pictures” – as Röntgen called the images, taking his inspiration from the world of photography – as visible proof of his discovery.

Röntgens handgeschriebene erste Seite des Manuskripts zur Abhandlung „Über eine neue Art von Strahlen“. Quelle: Deutsches Röntgen-Museum

The most sensational of these images was taken on December 22, 1895. By asking Bertha to place her hand on a photographic plate and “X-raying” it for 15 minutes, Röntgen took one of the most famous photos in the world: the bones of Bertha Röntgen’s hand, showing a wedding ring that appeared to be floating around her finger.

The scientific community’s initial skepticism quickly subsided – for one simple reason: In those days, virtually every physics laboratory was equipped with apparatus similar to that used by Röntgen, and his experiments could therefore be reproduced and confirmed with little effort. By mid-January 1896, the world was in the grips of “X-ray mania.” Everything imaginable was X-rayed: purses, mummies, furniture – and above all the human body.

Das aufsehenerregendste der ersten Röntgenbilder: Bertha Röntgens Handknochen mit Ehering Quelle: Deutsches Röntgen-Museum

The most sensational example of the early X-ray images: the bones of Bertha Röntgen’s hand with wedding ring
Source: German Röntgen Museum

X-ray technology developed rapidly within a few years, and in 1905 the delegates at the first German Radiology Congress remarked that it was “an indispensable tool in all specialties of human medicine.” Even Wilhelm Conrad Röntgen was excited about the developments of the previous few years. In a telegram, he told those attending the Radiology Congress: “I am filled with joy and admiration for what the work of others has made of the discovery of X-rays.” The wealth of advances and potential applications of the first ten years had indeed been astonishing – but the technology’s development was just getting started…

By Ingo Zenger

Technology journalist and author at the Siemens Healthineers Historical Institute