Wilhelm Conrad Roentgen was born on March 27, 1845, at Lennep in Germany.
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.
After that he 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. In 1869 he graduated Ph.D. at the University of Zurich. 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 of Giessen.
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. Here he remained for the rest of his life. although.
Roentgen’s name, 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. Roentgen’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 ‘roentgenogram’ ever taken. In further experiments, Rontgen 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.
Numerous honours were showered upon him. In several cities, streets were named after him. In spite of all this, Roentgen retained the characteristic of a strikingly modest and reticent man. Throughout his life he retained his love of nature and outdoor occupations. 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.
Roentgen died at Munich on February 10, 1923.
