Dolezalek quadrant electrometer
1913
1913
1876
1890
1902
1895
1801-1825
1895
1946
1886
1857
1924
1912
1929
1900
1890
1924
1867
1886
1900
1891
1891
1945-1954
1902
1960-1979
1979
1880-1890
1975-1980
1876
1855
1929
1867-1896
1870-1889
1867
1901
1900-1926
1861