As with many of mankind's monumental
discoveries, X-ray technology 
was invented completely 
by accident. In
1895, a German physicist named Wilhelm Roentgen 
made the discovery
while 
experimenting with electron beams in a gas discharge tube.
Roentgen noticed that a fluorescent screen in his lab 
started to glow
when the electron beam was turned on. This response in itself wasn't so
surprising -- fluorescent material normally 
glows in reaction to
electromagnetic radiation -- but Roentgen's tube was surrounded by
heavy black cardboard. Roentgen assumed this would have blocked 
most of
the radiation.
Roentgen placed various objects 
between the tube and the screen, and
the screen still glowed. Finally, he 
put his hand in front of the tube,
and 
saw the silhouette of his bones projected onto the fluorescent
screen. Immediately after 
discovering X-rays themselves, he had
discovered their most beneficial application.
Roentgen's remarkable discovery precipitated one of the most important
medical advancements in human history. X-ray technology 
lets doctors
see straight 
through human tissue to examine broken bones, cavities and
swallowed objects with extraordinary ease. Modified X-ray procedures
can 
be used to examine softer tissue, 
such as the lungs, blood vessels
or the intestines. 
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