
Plane Rowland diffraction grating on speculum metal
1895-1909 (estimated)
1895-1909 (estimated)
1960-1970
1875-1885
1851-1900
1894
1898
1944
1941
1899
1894
1882-1909 (estimated)
1926, April
1882, Nov 6
2003-2006
1939
1941
1941
1939
1998
1985
1890
1939
1934