After many experiments, Wilhelm Röntgen found that many materials were transparent or translucent when interposed in the path of the rays. These materials included paper, wood, aluminum, and very importantly, skin and flesh.
A few weeks later, he took the first picture - a radiograph of his wife's hand. Röntgen published a paper on December 28, 1895, detailing his discovery titled “On a New Kind of Rays.” The news spread over the next two years. His discovery of the x-ray fundamentally changed medial practices forever.