TIME

November 3, 1947 12:00 AM GMT-5

One thing a radioactive world needs is a good “atom-sized” Geiger counter. Last week the University of Chicago proudly displayed a handy, hip-pocket model. The new gadget is so easy to read that anybody can tell when his surroundings become dangerously radioactive.

The pocket model was developed by Dr. O. G. Landsverk and two aids as a wartime device (e.g., to protect troops in such hazardous spots as blasted Hiroshima). The military now thinks it is all right for civilians to know about it. The instrument’s chief working parts are a small chamber, a bronze wire (charged by a battery) and a fine, platinum-coated quartz fiber one-thirtieth the thickness of a human hair. When X rays or gamma rays enter the chamber, they leave a trail of ions which collect on the wire, neutralize its charge and move the quartz fiber.

Unlike the standard Geiger counter, which may record radiation by a series of clicks, the pocket model does its recording on a lighted scale. The user just presses a button; if the fiber moves across the scale, he can be pretty sure that he is being bombarded by unhealthy radiation.

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