![](https://coimages.sciencemuseumgroup.org.uk/18/108/medium_thumbnail_2010_0003__0004_.jpg)
![Wehnelt radiometer, for use in diagnostic work](https://coimages.sciencemuseumgroup.org.uk/502/502/medium_smg00292504.jpg)
Wehnelt radiometer, for use in diagnostic work, used with a fluorescent screen, by Schall and Son, 75 New Cavendish Street, London, England, 1909-1925.
Wehnelt radiometer, for use in diagnostic work, used with a fluorescent screen, by Schall and Son, 75 New Cavendish Street, London, England, 1909-1925.