spinthariscope
nounA 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.
nounAn 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.
nounA 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.
nounan early