


Concave Rowland diffraction grating on speculum metal
1894

Concave Rowland diffraction grating on speculum metal
1898

Plane Rowland diffraction grating on speculum metal
1895-1909 (estimated)

Concave Rowland diffraction grating on speculum metal
1899

Concave Rowland diffraction grating on speculum metal
1894

Concave Rowland-type diffraction grating on speculum metal
1882-1899

Concave Rowland-type diffraction grating on speculum metal
1882-1909 (estimated)

Concave Rowland-type diffraction grating on speculum metal
1926, April

Concave Rowland diffraction grating on speculum metal
1882, Nov 6
Plane diffraction grating with 14
1890