In his laboratory in the Institute for Physical Sciences
at the University of Würzburg,
he had set up a conventional apparatus
to investigate cathode rays.
During an experiment with
vacuum tubes and a Ruhmkorff coil,
Röntgen made his ingenious discovery.
For the next seven weeks,
he shut himself up in his laboratory
day and night, to delve into every aspect
of the mysterious rays.
He described the results of these investigations
in his famous report “On a New Type of Rays”
When the induction current was passed through the
vacuum tube, the cathode rays caused
the vacuum tube to fluoresce.
In the following tests,
the tubes were covered with black paper.
Röntgen then noticed that several crystals
lying on the table began to fluoresce as soon as
the induction current was switched on.
He observed the same mysterious green light
on a screen made of barium platinum cyanide.
By holding a book and various metals between
the tube and the screen, Röntgen was able to
investigate the permeability of various materials.
Finally, he replaced the screen by a photographic plate.
The publication of the silhouettes and the first exposure
of a hand had a sensational effect on the general public.
