The Geissler tube is an electrical demonstration device that was invented in 1857 by Heinrich Geissler. Starting in the 1880s, Geissler tubes were mass-produced as functionally useless decorative devices, designed to provide entertainment to wealthy Victorians, and such tubes could arguably considered to be the world's first electronic entertainment product. Technically, a Geissler tube is simply an evacuated glass tube with two electrodes, which has been filled with a noble gas or other substance to produce a demonstrational glow discharge. In practice however, Geissler tubes are usually highly decorated, formed into complex shapes and encrusted with whorls of uranium glass and liquid filled cavities.
This example is a fairly representative of the typical form of a Geissler tube; it is constructed of two glass spirals connected to glass bubbles at each end which contain the electrodes. The center 'grape' bubble of the tube is made out of uranium glass, and fluoresces green when the tube is under high tension.
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