More than 100 years "new kind of rays" has been discovered, which occupy most of the electromagnetic spectrum. On 8 November 1895 at the University of Würzburg, professor of physics Wilhelm Conrad Röntgen (Fig. 2.1) paid attention to a remarkable phenomenon. When he was studying the vacuum (cathode) tube and noticed that when the high voltage was applied to the electrodes of the tube, the barium cyanoplatinite which was beside it began to emit a greenish glow. Such a luminescent glow under the influence of cathode beams emitting from the vacuum tube has been already discovered by that time. However, when Röntgen conducted this experiment, the tube on his table was tightly wrapped in black paper, and, though the barium cyanoplatinite was at a considerable distance from the tube, its glow resumed with each current lead.
Fig. 2.1. Wilhelm Conrad Röntgen (1845-1923)
Röntgen concluded that some unknown to the science rays appeared in the tube. He decided that these rays could penetrate solid objects and spread in the air at a distance, which can be several meters. The first X-ray image in the history of humanity was the image of the hand of the wife of Röntgen (Fig. 2.2).
Fig. 2.2. X-ray image of Berta?s hand (wife of W.C. Röntgen)
The first preliminary statement of Röntgen on "New kind of rays" was published in January 1896. In further publications in 1896-1897, he described all properties of new rays that he had discovered and the technique of their appearance.
Several days after publishing of the Röntgen's article on his discovery, it was translated into many foreign languages, including Russian. St. Petersburg University and Imperial Military Medical Academy managed to obtain an X-ray image of human limbs by 1896, and images of other organs later on. Soon A.S. Popov, the inventor of the radio, managed to create the first X-ray machine in Russia, which operated in the Kronstadt hospital.