Concave Rowland diffraction grating on speculum metal

1894

Plane Rowland diffraction grating on speculum metal

1895-1909 (estimated)

Concave Rowland diffraction grating on speculum metal

1898

Langley's 'Great' Bolometer, 1880-1890

1880-1890

Concave Rowland-type diffraction grating on speculum metal

1882-1909 (estimated)

Concave Rowland diffraction grating on speculum metal

1894

Concave Rowland diffraction grating on speculum metal

1899

Concave Rowland diffraction grating on speculum metal

1882, Nov 6

Langley's Bolometer, 1880-1890

1880-1890