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 Julius Foerster Wilhelm Julius Foerster Wilhelm Julius Foerster (December 16, 1832 – January 18, 1921) was a German astronomer. His name can also be written Förster, but is usually written "Foerster" even in most German sources where 'ö' is otherwise used in the text. A native of Grünberg, Silesia, he studied at the University of Berlin and Rheinische Friedrich-Wilhelms-Universität Bonn, and worked as Johann Franz Encke's assistant. In 1860, he co-discovered asteroid 62 Erato with Oskar Lesser, the first co-discovery on record. He became professor of astronomy at the University of Berlin in 1863. After Encke's death in 1865, he became director