FIG. 116.—AN ELECTRIC DISCHARGE SIXTY-FIVE FEET IN LENGTH
X-Rays and Radium
A strange light which passes through the human body as readily as sunlight through a window was discovered by Prof. Wilhelm Konrad Roentgen, of the University of Würzburg. This light, which Professor Roentgen named X-rays, is given out when an electric discharge at high pressure passes through a certain kind of glass tube from which the air has been pumped out until there is a nearly perfect vacuum.
X-rays were discovered by accident. Professor Roentgen was working at his desk with one of the glass tubes when he was called to lunch. He laid the tube with the electric discharge passing through it on a book. Returning from lunch he took a photographic plate-holder which was under the book and made some outdoor exposures with his camera. On developing the plates a picture of a key appeared on one of them. He was greatly puzzled at first, but after a search for the key found it between the leaves of the book. The strange light from the electric discharge in the glass tube had passed through the book and the hard-rubber slide of the plate-holder and made a shadow-picture of the key on the photographic plate. He tried the strange light in many ways, and found that it would go through many objects. It would even go through the human body, so that shadow-pictures of the bones and organs of the body could be obtained. In Fig. 117 is shown a physician using X-rays. Fig. 118 is an X-ray photograph of the eye.
FIG. 117–A PHYSICIAN EXAMINING THE BONES OF THE ARM BY MEANS OF X-RAYS
FIG. 118–X-RAY PHOTOGRAPH OF THE EYE