All-in-one galvonometer by Pifco Ltd
circa 1932
circa 1932
circa 1920
1955
1930
1920
1910
1930
1896
1904
1901
1935
1910
1905
1905
1890
1895
1940
1905
1940
1941
1920
1915
1900
1930
1905
1945
1907
1940
1940
1920
1955
1955
1904
1883
1885
1905
1925
1910
1910
1890
1930
1950
1945
1920
1945
1930
1910