November 8, 1895: While experimenting with electricity, Wilhelm Röntgen discovers the X-ray. (In German we call them "Röntgenstrahlen".)

Wikipedia
http://en.wikipedia.org/wiki/X-ray
http://en.wikipedia.org/wiki/Wilhelm_Röntgen

Wikipedia
http://en.wikipedia.org/wiki/X-ray
http://en.wikipedia.org/wiki/Wilhelm_Röntgen