English: A modern electrical artwork that is an imitation of a Geissler tube, a gas discharge tube invented by Heinrich Geissler in 1857. It consists of a series of glass tubes filled with various gases at low pressure, with metal electrodes at each end. A high voltage of several thousand volts is applied between the electrodes. The high voltage ionizes the gas causing it to give off light by fluorescence in a glow discharge. The color of the light depends on the gas used. Geissler tubes like this of many elaborate shapes and colors were made for entertainment starting around 1860 until the turn of the 20th century. By the 1920s this technology was commercialized in neon signs.