Alpha particles impinging on a screen coated with zinc sulphide will produce tiny flashes or scintillations of light. William Crooks (1832-1819) was one of the discoverers of the effect in 1903, along with Julius Elster and Hans Geitel.

   The spinthariscope (from the Greek word for scintillation)is a brass tube with a magnifying eyepiece at one end and a screen of zinc sulphide at the other. A small thumb-wheel allows the alpha particle stream from a uranium compound to be directed toward the scintillator. When used in a dark room, bright flashes may be seen with a dark-adapted eye. 

   This instrument, only 3.3 cm in length, is marked "Spinthariscope / W. Crookes / 1903 / R. & J. Beck, Ltd London". It is in the Greenslade Collection.

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