What a find, this absolute beauty of a Crookes vacuum tube, in an excellent condition. A Crookes tube (also Crookes–Hittorf tube) is an early experimental discharge tube with partial vacuum invented by English physicist William Crookes and others around 1869–1875, in which cathode rays, streams of electrons, were discovered. Wilhelm Röntgen discovered X-rays using the Crookes tube in 1895. This model of tube was used until around 1920. During the last quarter of the 19th century Crookes tubes were used in dozens of historic experiments to try to find out what cathode rays were. There were two theories: British scientists Crookes and Cromwell Varley believed they were particles of 'radiant matter', that is, electrically charged atoms. German researchers E. Wiedemann, Heinrich Hertz, and Eugen Goldstein believed they were 'aether vibrations', some new form of electromagnetic waves, and were separate from what carried the current through the tube. The debate continued until J. J. Thomson measured cathode ray’s mass, proving they were a previously unknown negatively charged particle in an atom, the first subatomic particle, which he called a 'corpuscle' but was later renamed the 'electron'. A piece of history and a must-have for collectors. Will be packaged carefully and shipped with track&trace. The pictures are part of the description, please take a good look at them. You buy this product at your own expense and risk. Shipments are usually on Mondays and Wednesdays.