Hysteresis magnetometer by Griffin and George Ltd.
1954-1980
1954-1980
1968-1972
1837-1843
1870-1900
1890-1920
1966-1968
1924
1913
1931
1914
1951
1951
1968-1972
1851-1859
1850
1883
1951
1930-1940
1883
circa 1959
1913
1914
1850
1883
1850
1951
1850
1944-1954