
Horseshoe magnet and keep used with experimental form of magnetic detector, 1900-1910
1900-1910
1900-1910
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1899
1901
1901
1899
1900-1910
1937-1960
1922-1924
1950-1955
1922-1925
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1898
1900-1950
1900-1950
1900-1950
1900-1950
1900-1950
1901
1923
1923
1922
1954-05-29
1929
circa 1878-1927
circa 1882
1961
1943-1980
1943-1980
1900-1902
1898
1898
1926
1951-1988