This 115-year-old picture of fingers is one of the first images ever made with x-rays, whose discovery is being feted Monday with an anniversary Google doodle. (See "X-Rays on Google: Surprising Ways the Rays Are Used Today.")
The hand belonged to Anna Bertha, wife of German physicist Wilhelm Röntgen, the discover of x-rays. The black glob on the fourth finger is a ring made of gold, which absorbs x-rays.
Röntgen stumbled across x-rays on November 8, 1895, while experimenting with an early vacuum tube known as a Crooke's radiometer. He noticed that, when the cathode rays from the tube struck the end of a discharge tube, a previously unknown type of radiation that could penetrate matter was emitted.
Röntgen created the picture of his wife's hand using the unknown, or x, rays a few days later.
"She apparently was not impressed by his photography," said Martin Richardson, a professor of optics at the University of Central Florida, whose group has been helping to pioneer the use of x-ray microscopy for biological studies since the early 1990s.
According to some accounts, Anna exclaimed "I have seen my death!" after seeing the now famous image.
(Related: "Iceman Bled Out From Arrow Wound, X-Rays Reveal.")