Crookes' spinthariscope (1903)

Crookes'; of Crookes' cathode ray tube and Crookes' radimeter fame, made a scintillation counter that he called a spinthariscope.

A small screen coated with ZnS was placed at one end of a microscope eyepiece. As a tiny alpha particle source was brought very close (~1 mm) on the end of a pin the dark adapted eye saw a flood of tiny green scintillations; single alpha particle interactions with the ZnS. In his own words "On bringing the radium nearer the screen the scintillations become more numerous and brighter, until when close together, the flashes followed each other so quickly that the surface looked like a turbulent, luminous sea." The device became a high-tech toy. Everyone wanted one for a Christmas present.

This one came from Millikan's lab. Marsden counted ZnS flashes and discovered the nucleus. Check the web at...

http://www.orau.org/