Radio Electroscope
   The new experimental science of radioactivity soon  spawned its own technology. The favored detector was the electroscope and the electrometer; Cajorie, writing in A History of Physics (1929) about Marie Curie's work, noted that she was "working with the electrometer as the chemist works with the spectroscope" in her research.

   The Radio Electroscope at the right appears in the flyer "Improved Physical Apparatus for Advanced Laboratory Work",  published by the Gaertner Scientific Corporation of Chicago, ca. 1930. The electroscope leaves in the cylindrical metal case are observed with a [missing] microscope by the light scattered from the ground glass window. A shallow tray placed on a platform inside the cylinder holds the radioactive material.

   This apparatus, which cost $95.00, is in the Greenslade Collection.

   During a visit to Franklin and Marshall College in Lancaster, Pennsylvania in September 2002 I discovered another copy of the Gaertner Radio Electroscope. In this case the microscope used to examine the leaves is still in place.
   The 1921 catalogue of E. Leybold's Nachfolger of Cologne shows electroscopes like the one at the left, specially outfitted for radioactivity work. The insulation of the vertical rod holding the gold leaf is amber, similar to the Gaertner instrument above. The lens is used to focus light from an external source onto the gold leaf.

   The original cost of this piece of apparatus, in the Greenslade Collection, was about $30.00.

    Zeleny's Electroscope is a piece of apparatus designed to make quantitative measurements of ionizing radiation. 

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