Henley needle galvanometer, 1855-1860
1855-1860
1855-1860
1858
1865-1866
1843-1897
1858
1854
1830-1870
1858
1959-1961
1910-1920
1943-1970
1920-1930
1890-1930
1955
1900
1910
1900
1864-1886
1881-1926
1906
1937
1960
circa 1910
1890-1891
1906
1935
1963
1890
1852-1870
1859
1900
1921
1903
1908
1888
circa 1902-1925
1926
1926
1878-1900
1898-1913
1901-1908
1920