
Filings coherer, glass tube curved into near U-shape at one end with coil winding at other end, 1894-1904
1894-1904
1894-1904
1894-1904
1902-1907
1894-1904
1900-1910
1898
1894-1904
1892
1921-1926
1925
1936
1904
1902-1923
1901-1911
1880-1940
1901
1901
1880-1920
1885-1895
1897
1935
1893
1894
1933
1901
1904
1892-1902
1900
1920
1915-1925
1880
1911
1935
1910
1897
1940
1920
1902
1930-1940
1897
1899
1896
1880
1930
circa 1927
circa 1913
circa 1880
1929
1925-1930
1938