
1) German invention 2) Vacuum tube display
Found on
https://www.crosswordclues.com/clue/geissler-tube

A Geissler tube is an early gas discharge tube used to demonstrate the principles of electrical glow discharge. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. It consists of a sealed, partially evacuated glass cylinder of various shapes with a metal electrode at each end, containing rarefied gasses such as...
Found on
http://en.wikipedia.org/wiki/Geissler_tube

• A glass tube provided with platinum electrodes, and containing some gas under very low tension, which becomes luminous when an electrical discharge is passed through it; -- so called from the name of a noted maker in germany. It is called also Plucker tube, from the German physicist who devised it.
Found on
http://thinkexist.com/dictionary/meaning/geissler_tube/
Geis'sler tube` (Electricity) A glass tube provided with platinum electrodes, and containing some gas under very low tension, which becomes luminous when an electrical discharge is passed through it; -- so called from the name of a noted maker in germany. It is called also
Plücker tube , from the German physicist w...
Found on
http://www.encyclo.co.uk/webster/G/16

The Geissler Tube is a discharge tube made of very hard glass, often of ornamental shape, and exhausted to a pressure of a few millimetres of mercury. Each end of the tube has a platinum wire sealed into it to serve as electrodes. When a discharge of electricity is caused to take place in these tubes by connecting the electrodes to the terminals of...
Found on
http://www.probertencyclopaedia.com/browse/GG.HTM
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