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