Wilhelm Röntgen


Wilhelm Conrad Röntgen († February 10, 1923 in Munich) was a German physicist. He discovered “X-rays” (the X-rays named after him) on November 8, 1895, at the Physics Institute of the University of Würzburg. For this he received the first Nobel Prize in Physics in 1901 when the first Nobel Prizes were awarded. His discovery revolutionized medical diagnostics, among other things, and led to other important discoveries of the 20th century, such as the discovery and research of radioactivity.

Childhood and study

Wilhelm Conrad Röntgen was born on March 27, 1845 in Lennep, which today belongs to Remscheid. He was the only child of the upper middle-class cloth manufacturer and cloth merchant Friedrich Conrad Röntgen and his wife Charlotte Constanze, née Frowein, who came from Amsterdam. For economic reasons, the family moved to Apeldoorn in the Netherlands in 1848. Another reason for the move was probably that the mother of the later Nobel Prize winner was Dutch.

A curriculum vitae written by Röntgen in 1869 shows that he attended primary and secondary schools in Apeldoorn until 1861. Until 1862, he attended the Martinus Herman van Doorn “Kostschule” institute, a private elementary school. In December 1862, Wilhelm Conrad Röntgen moved to Utrecht, and in 1863 he attended a smaller private school that admitted boys between the ages of 14 and 18 to prepare them for a technical profession. There he had mostly good grades, but his diligence was considered too moderate in the report cards. For disciplinary reasons, because he was mistaken for the author of a caricature of his class teacher, he was expelled from school without graduating.

Although he subsequently made up for language skills, he then failed to pass the “examen admissionis” entrance examination for a university, which was possible in the Netherlands, but in 1865 he took courses in biology (botany, zoology), mathematics, physics and chemistry as a guest student at the University of Utrecht.

Röntgen, who related his kinship with the engineer of the first steamboat on the Rhine to his fondness for mechanical skills and design, began studying at the Swiss Federal Institute of Technology in Zurich (ETH Zurich) as a regular student on November 23, 1865. This was possible because at the Polytechnic there an entrance examination was decisive, not proof of a degree. There he received his diploma as a mechanical engineer on August 6, 1868. In the time that followed, he completed postgraduate studies in physics with August Kundt, who was six years his senior, and became his assistant. In June 1869, he received his doctorate in physics from the University of Zurich, the title of his thesis being Studien über Gase.

Scientific career and life

Afterwards, in 1870, he accompanied August Kundt, on whose advice Röntgen had decided to study physics, to Würzburg as an assistant to the “Physical Cabinet” in the building of the old university in Domerschulstraße. In Würzburg he published his first paper as a scientist in the Annalen der Physik und Chemie. In July 1870, he joined the Physikalisch-Medizinische Gesellschaft in Würzburg. On January 19, 1872, he married Anna Bertha Ludwig (1839-1919), the daughter of an innkeeper from Zurich, in Apeldoorn.

On April 1, 1872, he moved to the Kaiser Wilhelm University in Strasbourg together with Kundt. Röntgen habilitated in Strasbourg in 1874 and initially settled there as a private lecturer on March 13, 1874. Previously, he had been refused a habilitation by the University of Würzburg because he had not passed his Abitur. From April 1, 1875, he worked as an associate professor of physics and mathematics at the Hohenheim Agricultural Academy near Stuttgart. At the request of his former academic teacher and patron Kundt, Röntgen was then offered a position as associate professor of physics in Strasbourg from October 1, 1876.

His appointment to a full professorship in Giessen on April 1, 1879, gave Röntgen a fixed salary for the first time in his scientific career. In 1887 the Röntgens took into their household the six-year-old Josephine Berta (1881-1972), the daughter of Anna Röntgen”s brother Hans Ludwig, born in Zurich on December 21, 1881. They later adopted the child, who was named Josephine Berta Donges-Röntgen after his marriage in Munich on March 6, 1909.

Prince Regent Luitpold appointed Röntgen to succeed Friedrich Kohlrausch in Würzburg on August 31, 1888. Röntgen took up this post as full professor at the University of Würzburg on October 1, 1888.

Röntgen turned down calls to Jena and Utrecht. In 1893 and 1894 he was elected rector of the University of Würzburg. He also turned down a call to the University of Freiburg in 1895, even before his famous discovery, as well as a call four years later to succeed Gustav Heinrich Wiedemann in Leipzig.

In Würzburg, Röntgen achieved his greatest scientific feat on November 8, 1895: the discovery of what he called “X-rays,” which were given the name “Röntgenstrahlen” in German, while they continue to be called x-rays in English. On December 22, 1895, he used them to take an image of his wife”s hand in which the bones and wedding ring are clearly visible.

At a lecture before Kaiser Wilhelm II on January 12, 1896, Röntgen publicly presented his discovery, and on January 23 he gave a lecture to a packed lecture hall of the Physics Institute on the occasion of a meeting of the Würzburg Physical-Medical Society before an enthusiastic audience from all circles of science and society. Following the lecture, the anatomist Albert Kölliker proposed renaming the “X-rays” to “Röntgen”sche Strahlen” (or “X-rays”), which was promptly adopted by the meeting chaired by Karl Bernhard Lehmann.

From April 1, 1900, Röntgen was a full professor of physics at the University of Munich. There he became head of the Physics Institute of the university city as well as conservator of the Physical-Metronomical Institute of the state. Among his academic students from the Munich period was Peter Pringsheim, later professor of physics in Berlin.

Wilhelm Conrad Röntgen was awarded the Barnard Medal in 1900. In 1901, he was the first Nobel Prize winner in physics “in recognition of the extraordinary merit he has acquired by the discovery of the rays named after him”.

In September 1914, Geheimrat Röntgen was a co-signer of the Manifesto of 93 Intellectuals To the Cultural World! which he later regretted. He also donated the English Rumford Medal, which had been awarded to him, as support for the German war effort.

In 1919, Röntgen”s wife died after a long and serious illness. In the same year he was made an honorary member of the German Physical Society. He retired from his position as professor at the University of Munich on April 1, 1920.

End of life

Due to inflation in the post-war years, Röntgen lost large parts of his considerable fortune. As a retired civil servant, however, he received regular pension payments and therefore did not suffer any hardship.

In Munich in 1923, Röntgen was a patient of the surgeon Ferdinand Sauerbruch, who removed a small benign tumor from the patient”s face, which Röntgen assumed could be cancer (the Munich pathologist Borst later described the tumor as harmless). Sauerbruch complained to Röntgen that his invention had led doctors to stop examining their patients closely and to rely too much on the new procedure; Röntgen is said to have said to Sauerbruch “Where there is a lot of X-ray light, there must also be X-ray shadow”.

On February 10, 1923, Wilhelm Conrad Röntgen died of intestinal cancer in Munich at the age of 77. Based on his testamentary wishes, he is buried in the Old Cemetery in Giessen (opposite the gravesite of the pioneer of hemodialysis, Georg Haas), where Röntgen”s parents had already found their final resting place. Contrary to the usual spelling Conrad, his middle name appears in the inscription on the gravestone as Konrad. The remains of his fortune went to charitable institutions, including the care of the poor in Weilheim, where he owned a country house.

In his will, he further stipulated that all his scientific records were to be destroyed. His friends complied with this wish, so that only a few documents of Wilhelm Conrad Röntgen still exist.


Conrad Röntgen is described as an introvert to whom few found deeper access. Prominent traits were his modesty and sense of justice. When Röntgen was absorbed in his scientific work, he found it difficult to relate to other people. This is probably how his wife often found herself facing her taciturn husband, who did not even respond to questions. He worked out his scientific results with perseverance and diligence. He did not publish anything that was not backed up on all sides. His lectures always remained factual even after his great discovery. Even the first public demonstration of the newly discovered rays in Würzburg in January 1896 was marked by Röntgen”s simplicity and modesty.

A millionaire twice over since his father”s death, he donated the prize money of 50,000 crowns associated with the award of the Nobel Prize to the University of Würzburg. Likewise, Röntgen refrained from patenting, which enabled his X-ray apparatus to spread more quickly. When asked, he told AEG that he was of the opinion that “his inventions and discoveries belong to the general public and should not be reserved for individual companies by means of patents, license agreements and the like”. He also rejected the title of nobility that had been offered to him.

Since his student days, Conrad Röntgen preferred to relax in the Alps and, since his time in Würzburg, also by hunting. From Würzburg, he went hunting in the forest of Rimpar. He often spent his summer vacations in Pontresina in the Engadine. After moving to Munich, he bought a country house in 1904 on the southern outskirts of Weilheim in Upper Bavaria, which was popularly known as the “Röntgen Villa”. Röntgen liked to retreat there to relax, hunt and invite other hunters and friends. In Munich, he missed the intellectual stimulation he had received from his friends in Würzburg. These friends included Theodor Boveri and Margret Boveri, with whom he was in correspondence. Shortly before his death, he went hiking in the Swiss mountains.

Emil von Behring chose Wilhelm Conrad Röntgen as godfather to one of his sons.

Wilhelm Conrad Röntgen published 60 scientific papers during his career.

He wrote his first scientific paper at the age of 20. It was a chemistry revision of a standard work by the chemistry professor Jan Willem Gunning. This work already shows Röntgen”s ability to clearly arrange a wide variety of facts and to schematize them well in order to rule out confusion.

In many of his works, Röntgen dealt with the fields of thermodynamics and electrodynamics, in which he especially investigated electrical discharges under various conditions. Crystal physics, however, was his greatest interest because its aesthetics and beauty fascinated him.

In 1876, during his time in Strasbourg, he worked out together with Kundt the proof of the rotation of the plane of polarization of light in gases. This proof had already been sought in vain by Michael Faraday and others, whereas Röntgen not only provided the proof but was also able to present precise measurements for this.

As a professor at the University of Würzburg, Röntgen discovered X-rays in 1895, which were later renamed X-rays in German-speaking countries and in Poland in defiance of the will. This discovery happened by chance. Röntgen had previously followed with great interest investigations on cathode rays generated in vacuum tubes, as explored by Heinrich Hertz and Philipp Lenard as well as other physicists, and (mainly stimulated by Lenard) had started to perform independent experiments with them from the end of October 1895. In 1894, Röntgen had studied Philipp Lenard”s widely acclaimed paper published in Poggendorf”s Annalen der Physik (Annals of Physics) on cathode rays emerging from a window on the generating tube and still detectable far into the room behind it, and obtained one of these tubes from Lenard. On the evening of November 8, 1895, during an experiment with a Hittorf tube, a paper specially coated (with barium platinum cyanur, which is barium platinum(II) cyanide) began to glow. However, this glow was still visible and even at greater distances from the tube when the discharge tube was enclosed in thick black cardboard. However, it is unclear whether it was really the blackened paper that led Röntgen to the X-rays, or whether there was a luminescent screen nearby on which the radiation became visible. Roentgen said about this “I worked with a Hittorf-Crookes tube, which was completely wrapped in black paper. A piece of barium platinum cyanide paper lay next to it on the table. I sent a current through the tube and noticed a peculiar black line across the paper! Soon all doubt was eliminated. There were ”rays” coming from the tube, which had a luminescent effect on the screen. “In the period that followed until January 1896, Röntgen wrote three scientific research reports on this discovery. The first report, which Röntgen had already submitted as a manuscript for printing to the secretary of the Physikalisch-Medizinische Gesellschaft in Würzburg on December 28, 1895, was entitled Über eine neue Art von Strahlen (On a new type of rays), was printed immediately without a prior meeting of the society, and appeared shortly thereafter in English (January 23, 1896), French (February 8), Italian, and Russian. On January 1, 1896, Röntgen had already sent some of the ten-page separate prints of his first report, which were also immediately prepared by Stahel”sche Kgl. Hof- und Universitäts-Buch- und Kunsthandlung, to colleagues (such as Jonathan Zenneck and Otto Lummer). On January 1, Röntgen also sent some copies of his first X-rays to the Viennese physicist Franz Exner. At a collegial discussion evening at Exner”s, Ernst Lecher from Prague borrowed the photographs and showed them to his father, Zacharius Konrad Lecher, who was then editor of the old “Presse” in Vienna and commissioned his son to write an account of the sensational discovery for the Sunday paper of the “Presse”.

In addition, Röntgen gave lectures in experimental physics in the fields of mechanics, acoustics and optics every working day in Würzburg. He was supported in this and in his research by assistants such as Zehnder, Heydweiller, Cohen, Wierusz-Kowalski, Geigel, Wien, Stern and Hanauer. From 1890 to 1891 Röntgen was Dean of the Faculty of Physics at the University of Würzburg.

Pioneers of glass apparatus engineering proved to be irreplaceable pioneers of Röntgen”s discovery and its subsequent further development to use and market maturity. Able engineers and glassblowers, with a long tradition in the production of art and utility glass, and since the first half of the 19th century also experienced in the manufacture of technical glass and apparatus, Röntgen found in the Thuringian Forest, close by from Würzburg. Here he met with interest and willing support. The first X-ray tubes were produced in glassworks in Stützerbach (Greiner & Friedrichs glassworks) and Gehlberg (Emil Gundelach and Franz Schilling hollow glassworks) not far from the Rennsteig. In his 3rd publication on the subject in the Annalen der Physik of 1897, Röntgen expressed his gratitude for this emphatically in a footnote: “… I received a large part of it from the company Greiner & Friedrichs in Stützerbach i. T., to whom I publicly express my gratitude for the material provided to me in the richest measure and free of charge.” Together with the local glassmakers and mouth glass blowers, the discharge tubes were developed here according to Röntgen”s ideas. These were subsequently mass-produced in numerous models for many years. The companies Gundelach and Schilling in Gehlberg were among the world”s leading manufacturers until about the beginning of the 1920s. However, the introduction of the incandescent cathode by Coolidge in 1913 put the brakes on this development. Other manufacturers asserted themselves by using the new, more advantageous technology more quickly. After a failed attempt to keep up, the production of X-ray tubes was discontinued in Gehlberg in 1925.

Until then, functional tests of the prototypes on humans also took place here. Since the health hazards of the newly discovered type of radiation were not yet known at the time, and the radiation dose used was still many times that of today”s X-ray machines, many of the workers involved contracted cancer and died at an early age. A memorial stone erected in the cemetery in Gehlberg is a reminder of this. The local history and glass museum in Stützerbach bears witness to the technical development of the early days.

Never before had news of a scientific discovery spread so quickly as in the case of X-rays. On January 5, 1896, the first public news about it appeared in the morning edition of “Die Presse” in Vienna under the headline A sensational discovery. Now the usefulness of “X-rays” in medicine was immediately understandable even for laymen. Röntgen submitted his second communication on X-rays to the Physikalisch-Medizinische Gesellschaft in Würzburg on March 9, 1896, which, like the first, was immediately printed with the society”s meeting reports. Soon thereafter, Albert Hoffa, a private lecturer in Würzburg, introduced clinical examination with X-rays in his private orthopedic clinic founded with Ernst Bumm in 1887, where he also set up an X-ray station. As early as March 1896, Hermann Gocht set up an X-ray institute at Hermann Kümmell”s clinic in Hamburg-Eppendorf. Three years after Röntgen”s discovery, the Radiation Cabinet at St. Joseph-Stift in Bremen was one of the first German clinics to have an X-ray institute.Röntgen”s discovery not only revolutionized medical diagnostics, however, but also made possible other groundbreaking scientific achievements of the 20th century.

As early as February 1896, Henri Becquerel, inspired by X-rays, experimented with luminescent materials and accidentally came across the penetrating effect of a new type of radiation. Thus, the discovery of X-rays indirectly led to the discovery of radioactivity, for which Becquerel, together with Marie and Pierre Curie, was awarded the Nobel Prize in 1903.

Medical diagnostics is still the most important field of application for X-rays today. Over the course of time, it has been possible to reduce the radiation exposure more and more, while at the same time the images have become increasingly detailed. By using mathematical methods, new imaging techniques such as computed tomography can now produce three-dimensional images of the inside of the body.

However, X-rays also help in the exploration of the microcosm (X-ray microscope) and in the exploration of the universe (X-ray astronomy). Other important areas of application are in materials testing, where, for example, flaws in metals or defective weld seams can be detected with the aid of X-ray technology (radiographic testing).

Orders and other awards (selection)

Röntgen as name giver

In honor of Röntgen, the following were named after him:

Also, various scientific prizes:

Schools, streets and squares in Germany also bear his name. For example, there is a Röntgen high school in Würzburg and a Röntgen grammar school in Remscheid-Lennep, as well as a Wilhelm Conrad Röntgen secondary school in Weilheim. The Röntgental residential area also bears his name. He is also commemorated on medals, coins, stamps, banknotes, pewter plates, beer mats and Bocksbeuteln. In Antarctica, Röntgen Peak is named after him.

Museum and memorials

In Lennep, where Röntgen received a memorial after his death, the German Röntgen Museum has also been located since 1930.Within walking distance of the German Röntgen Museum, the house where Wilhelm Conrad Röntgen was born still stands today. It was acquired by the German Röntgen Society in 2011 in order to renovate it professionally and make it accessible to the public.

The Röntgen Memorial was established in 1985 at the site of the discovery of X-rays, in the former Physics Institute of the University of Würzburg on Pleicher Ring (later Röntgenring). It provides an insight into the experimental physics of the late 19th century and shows, in addition to the discovery apparatus, a cathode ray experiment – which was the basis for the discovery of X-rays – as well as a fluoroscopy experiment with X-rays and Röntgen”s historic lecture hall. The memorial is run by the Röntgen-Kuratorium Würzburg e. V.

In the spring of 1905, a commemorative plaque with the inscription “In this house W. C. Röntgen discovered the rays named after him in 1895” was affixed to the Institute of Physics. The plaque was commissioned by his renowned colleagues Ludwig Boltzmann, Ferdinand Braun, Paul Drude, Hermann Ebert, Leo Graetz, Friedrich Kohlrausch, Hendrik Antoon Lorentz, Max Planck, Eduard Riecke, Emil Warburg, Wilhelm Wien, Otto Wiener and Ludwig Zehnder.

On July 27, 1928, a bust created by Georgii was unveiled in the atrium of the University of Munich. A bust of Röntgen has been erected in the Valhalla near Regensburg since 1959. Commemorative plaques have been erected at the Röntgenweg in Pontresina and at Röntgen”s country house in Weilheim, among other places.

From 1898 to 1942, an X-ray monument created by Reinhold Felderhoff stood on the Potsdamer Bridge in Berlin. In 1962, an X-ray monument depicting stylized X-rays was erected in Giessen. Other X-ray monuments are located in Berlin and Remscheid-Lennep.

Information on the early technical development history of the first X-ray tubes and their involvement by Röntgen himself is provided by the Stützerbach Museum of Local History and Glass and the Gehlberg Glass Museum.


Four emergency money issues (20, 50, 100 and 200 billion marks) from Weilheim show X-rays.

To mark the 100th anniversary of the awarding of the Nobel Prize, the Röntgen Run has been held annually in Remscheid on the last Sunday in October since 2001 with the support of the city administration. This is a marathon run in many variations and with an international echo that leads around Remscheid.

Magazine articles


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