![](https://coimages.sciencemuseumgroup.org.uk/501/930/large_thumbnail_smg00280757.jpg)
Protection electrometer
1958
1958
1942-1948
1964-11-18
1949-04
1993
1993
1942-1948
1942-1948
1942-1948
1942-1948
1950-1960
1993
1993
1947-06-30
1964-11-18
1947-06-30
1964-11-18
1960-1979
1838
1970-1979
1947-07-05
1965
1955-1960
1996
1965
1965
1965
1965
1962
1906