Conrad Röntgen – Biography
Wilhelm Conrad Röntgen was born on March 27, 1845, at Lennep in
the Lower Rhine Province of Germany, as the only child of a merchant
in, and manufacturer of, cloth. His mother was Charlotte Constanze Frowein
of Amsterdam, a member of an old Lennep family which had settled in
When he was three
years old, his family moved to Apeldoorn in The Netherlands, where he
went to the Institute of Martinus Herman van Doorn, a boarding school.
He did not show any special aptitude, but showed a love of nature and
was fond of roaming in the open country and forests. He was especially
apt at making mechanical contrivances, a characteristic which remained
with him also in later life. In 1862 he entered a technical school at
Utrecht, where he was however unfairly expelled, accused of having produced
a caricature of one of the teachers, which was in fact done by someone
He then entered
the University of Utrecht in 1865 to study physics. Not having attained
the credentials required for a regular student, and hearing that he
could enter the Polytechnic at Zurich by passing its examination, he
passed this and began studies there as a student of mechanical engineering.
He attended the lectures given by Clausius and also worked in the laboratory
of Kundt. Both Kundt and Clausius exerted great influence on his development.
In 1869 he graduated Ph.D. at the University of Zurich, was appointed
assistant to Kundt and went with him to Würzburg in the same year,
and three years later to Strasbourg.
In 1874 he qualified
as Lecturer at Strasbourg University and in 1875 he was appointed Professor
in the Academy of Agriculture at Hohenheim in Wurtemberg. In 1876 he
returned to Strasbourg as Professor of Physics, but three years later
he accepted the invitation to the Chair of Physics in the University
After having declined
invitations to similar positions in the Universities of Jena (1886)
and Utrecht (1888), he accepted it from the University of Würzburg
(1888), where he succeeded Kohlrausch und found among his colleagues
Helmholtz and Lorenz. In 1899 he declined an offer to the Chair of Physics
in the University of Leipzig, but in 1900 he accepted it in the University
of Munich, by special request of the Bavarian government, as successor
of E. Lommel. Here he remained for the rest of his life, although he
was offered, but declined, the Presidency of the Physikalisch-Technische
Reichsanstalt at Berlin and the Chair of Physics of the Berlin Academy.
work was published in 1870, dealing with the specific heats of gases,
followed a few years later by a paper on the thermal conductivity of
crystals. Among other problems he studied were the electrical and other
characteristics of quartz; the influence of pressure on the refractive
indices of various fluids; the modification of the planes of polarised
light by electromagnetic influences; the variations in the functions
of the temperature and the compressibility of water and other fluids;
the phenomena accompanying the spreading of oil drops on water.
however, is chiefly associated with his discovery of the rays that he
called X-rays. In 1895 he was studying the phenomena accompanying the
passage of an electric current through a gas of extremely low pressure.
Previous work in this field had already been carried out by J. Plucker
(1801-1868), J. W. Hittorf (1824-1914), C. F. Varley (1828-1883), E.
Goldstein (1850-1931), Sir William Crookes (1832-1919), H. Hertz (1857-1894)
and Ph. von Lenard (1862-1947), and by the work of these scientists
the properties of cathode rays - the name given by Goldstein to the
electric current established in highly rarefied gases by the very high
tension electricity generated by Ruhmkorff's induction coil-had become
well known. Röntgen's work on cathode rays led him, however, to
the discovery of a new and different kind of rays.
On the evening of
November 8, 1895, he found that, if the discharge tube is enclosed in
a sealed, thick black carton to exclude all light, and if he worked
in a dark room, a paper plate covered on one side with barium platinocyanide
placed in the path of the rays became fluorescent even when it was as
far as two metres from the discharge tube. During subsequent experiments
he found that objects of different thicknesses interposed in the path
of the rays showed variable transparency to them when recorded on a
photographic plate. When he immobilised for some moments the hand of
his wife in the path of the rays over a photographic plate, he observed
after development of the plate an image of his wife's hand which showed
the shadows thrown by the bones of her hand and that of a ring she was
wearing, surrounded by the penumbra of the flesh, which was more permeable
to the rays and therefore threw a fainter shadow. This was the first
"röntgenogram" ever taken. In further experiments, Röntgen
showed that the new rays are produced by the impact of cathode rays
on a material object. Because their nature was then unknown, he gave
them the name X-rays. Later, Max von Laue and his pupils showed that
they are of the same electromagnetic nature as light, but differ from
it only in the higher frequency of their vibration.
were showered upon him. In several cities, streets were named after
him, and a complete list of Prizes, Medals, honorary doctorates, honorary
and corresponding memberships of learned societies in Germany as well
as abroad, and other honours would fill a whole page of this book. In
spite of all this, Röntgen retained the characteristic of a strikingly
modest and reticent man. Throughout his life he retained his love of
nature and outdoor occupations. Many vacations were spent at his summer
home at Weilheim, at the foot of the Bavarian Alps, where he entertained
his friends and went on many expeditions into the mountains. He was
a great mountaineer and more than once got into dangerous situations.
Amiable and courteous by nature, he was always understanding the views
and difficulties of others. He was always shy of having an assistant,
and preferred to work alone. Much of the apparatus he used was built
by himself with great ingenuity and experimental skill.
Anna Bertha Ludwig of Zürich, whom he had met in the café
run by her father. She was a niece of the poet Otto Ludwig. They married
in 1872 in Apeldoorn, The Netherlands. They had no children, but in
1887 adopted Josephine Bertha Ludwig, then aged 6, daughter of Mrs.
Röntgen's only brother. Four years after his wife, Röntgen
died at Munich on February 10, 1923, from carcinoma of the intestine.
From Nobel Lectures, Physics 1901-1921, Elsevier Publishing Company,
This autobiography/biography was written at the time of the award and
later published in the book series Les Prix Nobel/Nobel Lectures. The
information is sometimes updated with an addendum submitted by the Laureate.
To cite this document, always state the source as shown above.
Conrad Röntgen (March 27, 1845 – February 10, 1923) was a
German physicist, of the University of Würzburg, who, on November
8, 1895, produced wavelengths of electromagnetic radiation that are
now known as x-rays or Röntgen Rays. The machine which Röntgen
built to emit these rays, was the x-ray machine. Röntgen's name
is usually given as Roentgen in English, therefore most scientific and
medical references to him are found under this spelling.
During 1895 Röntgen
was using equipment developed by his colleagues Hertz, Hifforf, Crookes,
and Lenard to explore the effects of high tension electrical discharges
in evacuated glass tubes. By late 1895 these investigators were beginning
to explore the properties of cathode rays outside the tubes. In early
November Röntgen was repeating an experiment with one of Lenard's
tubes in which a thin aluminum window had been added to permit the cathode
rays to exit the tube but a cardboard covering was added to protect
the aluminum from damage by the strong electrostatic field that is necessary
to produce the cathode rays. He knew the cardboard covering prevented
light from escaping, yet Röntgen observed that the invisible cathode
rays caused a fluorescent effect on a small cardboard screen painted
with barium platinocyanide when it was placed close to the aluminum
window. It occured to Röntgen that the Hifforf-Crookes tube, which
had a much thicker glass wall than the Lenard tube, might also cause
this fluorescent effect.
In the late afternoon
of November 8, 1895 he 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 Hifforf-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 he 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.
the next several hours repeating the experiment again and again. He
quickly determined that the screen would fluoresce at a distance from
the tube much greater than his previous tests. He speculated that a
new kind of ray might be responsible. Novermber 8 was a Friday and Röntgen
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 nearly all the 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 when they
became known as Röntgen Rays, he always preferred the term x-rays.
of x-rays was no accident and he was not working alone. With the investigations
he and his colleagues in various countries were pursuing, the discovery
was imminent. In fact, x-rays were produced and a film image recorded
at the University of Pennsylvania two years earlier. However, the investigators
did not realize the significance of their discovery, filed their film
for further reference, and thereby lost the opportunity for recognition
of one of the greatest physics discoveries of all time. The idea that
he just happened to notice the barium platinocyanide screen totally
misrepresents his investigative powers. He had planned to use the screen
in the next step of his experiment and would have made the discovery
at that point a few moments later.
At one point while
he was investigating the ability of various materials to stop the rays,
he brought a small piece of lead into position while a discharge was
occurring. Imagine Röntgen's astonishment as he saw the first radiographic
image, his own flickering ghostly skeleton on the barium platinocyanide
screen. 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.
paper, "On A New Kind Of X-Rays," was published 50 days later
on December 28, 1895. On January 5, 1896, an Austrian newspaper reported
Röntgen's discovery of a new type of radiation. Röntgen was
awarded an honorary degree of Doctor of Medicine from University of
Würzburg after his discovery. He published a total of 3 papers
on x-rays between 1895 and 1897. His investigative powers were so phenomenal
that none of his conclusions have yet been proven false.
In 1901 Röntgen
was awarded the very first Nobel Prize in Physics. The award was officially,
in recognition of the extraordinary services he has rendered by the
discovery of the remarkable rays subsequently named after him. Röntgen
donated the monetary reward from the prize to his university. Like Pierre
Curie would do several years later he refused to take out any patents
related to his discovery on moral grounds. He did not even want the
rays to be named after him. (On November 2004 IUPAC named the element
Roentgenium after him as well.)
He was born in Lennep (now a part of Remscheid), Germany, to a clothmaker.
His family moved to Apeldoorn in the Netherlands when he was three years
old. He received his early education at the Institute of Martinus Herman
van Doorn. He later attended Utrecht Technical School, from which he
was expelled for producing a caricature of one of the teachers, a "crime"
he claimed not to have committed.
In 1865, he attended
the University of Utrecht. He then began to attend the Polytechnic at
Zurich to study mechanical engineering. In 1869, he graduated with a
Ph.D. from the University of Zurich.
In 1867 he became a lecturer at Strasbourg University and in 1871 became
a professor at the Academy of Agriculture at Hohenheim, Württemberg.
In 1876, he returned to Strasbourg as a professor of Physics and in
1879, he became the Chair of the physics department at the University
of Giessen. In 1888, he became the physics chair at the University of
Würzburg and in 1900 he became the physics chair at the University
of Munich, by special request of the Bavarian government. Röntgen
had family in the United States (in Iowa) and at one time he planned
to emmigrate. Although he accepted an appointment at Columbia University
in New York City and had actually purchased transatlantic tickets, the
outbreak of World War I changed his plans and he remained in Munich
for the rest of his career. Röntgen died in 1923 of carcinoma of
the bowel. It is not believed his carcinoma was a result of his work
with ionizing radiation because his investigations were only for a short
time and he was one of the few pioneers in the field who used protective
lead shields routinely.