from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A device for observing individual scintillations produced by ionizing radiation, as one consisting of a tube with a magnifying lens at one end and a phosphorescent screen and speck of radioactive salt at the other.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. an early device used for observing individual nuclear disintegrations
from the GNU version of the Collaborative International Dictionary of English
- n. A small instrument containing a minute particle of a radium compound mounted in front of a fluorescent screen and viewed with magnifying lenses. The tiny flashes produced by the continual bombardment of the screen by the α rays are thus rendered visible.
from The Century Dictionary and Cyclopedia
- n. An instrument, invented by Sir William Crookes, exhibiting the fluorescence produced by radium, containing a screen of fluorescent material, usually willemite (zinc silicate), on which a trace of radium is mounted, and a magnifying-glass in front of the screen. In darkness the screen shows a number of scintillating sparks caused by the impact of the radium rays on the willemite.
Greek spintharis, spark + -scope.(American Heritage® Dictionary of the English Language, Fourth Edition)