Although Wilhelm Röntgen is credited with the discovery of X-rays, he was almost certainly not the first to observe them, since they were readily produced using cathode ray devices. Many earlier scientists may have noticed but ignored such strange effects around their laboratories as glowing lights and foggy or overdeveloped photographic plates while experimenting with cathode rays, but probably dismissed or ignored them. It was Röntgen who recognized X-rays as a new type of radiation.

Born in a small German village, Röntgen decided at an early age to study science, rather than follow his father as a cloth merchant. As a student, however, he preferred the outdoors to a classroom, and he was expelled from high school for assisting in a prank which had offended one of the instructors. Reputed to be insubordinate, Röntgen found the doors to the universities...