"Röntgen was an experimental physicist of the old school and built most of his own equipment. ...It was Rontgen's custom, when beginning new investigations, to repeat important experiments made previously by others in the same field. Since he was repeating Hertz' and Lenard's experiments with cathode rays, he used an armamentarium employed by those workers... he extended his experiments to include a Hittorf-Crookes' tube... when he discovered the new rays. The whole room was darkened... Röntgen suddenly saw a few brightly fluorescent crystals which lay on the table at some distance from the tube."