Experimental transmitting ‘jigger’ used by the Marconi Company, 1899
1899
1899
1899
1900-1950
1898
1892
1900-1950
1923
1915
1954-1983
1930-1950
1924
circa 1925
1910-1930
1924
1904
1940-1945
1948
1950
unknown
1890-1910
1950s
1940-1969
1930-1950
1926
circa 1991
1903
1920-1950
1920-1930
circa 1900
1962
1950-1969