Fluorescent lamp began with the Geissler tube continued as even better vacuums were produced. The most famous was the evacuated tube used for scientific research by William Crookes. That tube was evacuated by the highly effective mercury vacuum pump created by Hermann Sprengel. Research conducted by Crookes and others ultimately led to the discovery of the electron in 1897 by J. J. Thomson and X-rays in 1895 by Wilhelm Roentgen. But the Crookes tube, as it came to be known, produced little light because the vacuum in it was too good and thus lacked the trace amounts of gas that are needed
Wilhelm Filehne at the medical polyclinic. In 1876 he became an associate professor of pharmacology at Erlangen, and ten years later, was appointed a full professor of the same subject at the University of Breslau. In 1911 he was succeeded at Breslau by Julius Pohl. In addition to work in the field of pharmacology, he made contributions in his research of optical illusions, being known for his experimentation with a phenomenon known as a Zöllner illusion. The so-called "Filehne illusion" is the illusory motion of a stationary background when smooth pursuit eye movements are made across the stationary background. Wilhelm Filehne Wilhelm