spinthariscope

n. [ Gr. spinqari`s spark + -scope. ] 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. -- Spin*thar`i*scop"ic a. [Webster 1913 Suppl.]