from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An early gas discharge tube used to demonstrate the principles of electrical glow discharge.
from the GNU version of the Collaborative International Dictionary of English
- 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 who devised it.
After Heinrich Geissler, who invented it in 1857. (Wiktionary)