Horseshoe magnet and keep used with experimental form of magnetic detector, 1900-1910
1900-1910
1900-1910
1750-1795
1950-1980
1750-1780
1954-1955
1700-1850
1876
1750-1800
1876
1822-1856
1980-1982
1828-1857
circa 1997
1996-1997
1966
circa 1997
1900-1974
1903-1970
1957
1903-1970
circa 1997
1957
1750
1870
1980-1989
1900
1972
1876