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Concave Rowland-type diffraction grating on speculum metal

Concave Rowland-type diffraction grating on speculum metal

1926, April
Concave Rowland diffraction grating on speculum metal

Concave Rowland diffraction grating on speculum metal

1898
Six Barton's buttons

Six Barton's buttons

1825-1835
Concave Rowland diffraction grating on speculum metal

Concave Rowland diffraction grating on speculum metal

1899
Concave Rowland-type diffraction grating on speculum metal

Concave Rowland-type diffraction grating on speculum metal

1882-1899
Concave Rowland diffraction grating on speculum metal

Concave Rowland diffraction grating on speculum metal

1882, Nov 6
Replica concave diffraction grating

Replica concave diffraction grating

1913, 14 November
Photograph of spectroscope

Photograph of spectroscope

1876
Concave diffraction grating on speculum metal

Concave diffraction grating on speculum metal

1926, May
diffraction grating on speculum metal, gra

diffraction grating on speculum metal, gra

1881
Thorp replica gratings on glass

Thorp replica gratings on glass

1907-05
reflection diffraction grating on speculum metal

reflection diffraction grating on speculum metal

1879
Two different gratings used in pioneering work on the infra-red spectrum, 1920-1940

Two different gratings used in pioneering work on the infra-red spectrum, 1920-1940

circa 1930
Plane Rowland diffraction grating on speculum metal

Plane Rowland diffraction grating on speculum metal

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

Concave Rowland diffraction grating on speculum metal

1894
Concave diffraction grating on speculum metal

Concave diffraction grating on speculum metal

1910-1948 (estimated)
Circular diffraction grating ruled on glass

Circular diffraction grating ruled on glass

1910-1920
Concave Rowland diffraction grating on speculum metal

Concave Rowland diffraction grating on speculum metal

1894
Coarse plane diffraction grating for infrared radiation

Coarse plane diffraction grating for infrared radiation

1960-1969 (estimated)
Rectangular replica reflection grating (8 x 6 inches) on glass substrate (135 x 265 mm) with wooden case

Rectangular replica reflection grating (8 x 6 inches) on glass substrate (135 x 265 mm) with wooden case

1957
Concave Rowland-type diffraction grating on speculum metal

Concave Rowland-type diffraction grating on speculum metal

1882-1909 (estimated)
Diffraction Grating

Diffraction Grating

Concave reflection-type diffraction grating with 528 lines per mm approx.

Concave reflection-type diffraction grating with 528 lines per mm approx.

1975-1979
Concave diffraction grating

Concave diffraction grating

1950-1974 (estimated)
Circular diffraction grating ruled on silvered glass

Circular diffraction grating ruled on silvered glass

1910-1915
Glass replica reflection grating (55mm square) in aluminium mount for use with optical bench

Glass replica reflection grating (55mm square) in aluminium mount for use with optical bench

1960-1970
Concave Thorp grating for diffraction

Concave Thorp grating for diffraction

Coarse plane diffraction grating for infrared radiation

Coarse plane diffraction grating for infrared radiation

1960-1969 (estimated)
Diffraction grating area 5 cm by 4.5 cm on 8 cm by 7.5 cm (approx) block of speculum metal

Diffraction grating area 5 cm by 4.5 cm on 8 cm by 7.5 cm (approx) block of speculum metal

1905-05-26
Spectroscope from Norman Lockyer Observatory for solar work by John Browning with diffraction reflection grating ruled on speculum metal by D.C. Chapman with engine of Lewis Morris Rutherfurd, 24 April 1878, 17296 lines per inch.

Spectroscope from Norman Lockyer Observatory for solar work

1878
Square replica reflection grating (52 x 52mm) on glass substrate (he 25 x 60 x 60mm), 150 lines per mm, 5000 Angstrom blaze wavelength and 2º 09' blaze angle. Made by Bausch & Lomb, Rochester, New York State, USA in 1984, Cat. No. 35-53-06-201, Serial No. 1055-33-2-2. Supplied to the University Observatory, Oxford through Glen Creston, 16 Dalston Gardens, London. Separate note indicates the grating was used with a spectroscope at the La Palma Observatory in the Canary Isles.

Square replica reflection grating (52 x 52mm) on glass substrate (he 25 x 60 x 60mm)

1984
Concave Thorp grating (prepared by T. Thorp himself), with box and accessories

Concave Thorp grating (prepared by T. Thorp himself)

Plane diffraction grating with 14,438 lines per inch ruled on Rowland's engine at Johns Hopkins University on a plate prepared at the Astronomical and Physical Instrument Works of J.A. Brashear at Allegheny in 1890, on oxidised brass mount with circular rack and pinion for rotating grating, and three levelling screws

Plane diffraction grating with 14

1890
Concave Rowland-type diffraction grating on speculum metal, grating area 139 x 57 mm, with scratched markings reading 'Ruled at J. H. U. 1934 / R. W. Wood & W. H. Perry / 30,000 lines per inch / 21' radius of curvature'. (J. H. U. = Johns Hopkins University.)

Concave Rowland-type diffraction grating on speculum metal

1934
Rectangular echelle reflection grating (10 x 5 inches) on glass substrate (135 x 265 mm) with cardboard box, 300 lines per mm, and 63º 26' ' blaze angle. Made by Bausch & Lomb, Rochester, New York State, USA in 1964, Cat. No. 35-53-32-45, Serial No. 0177-4. . Used at the University Observatory, Oxford.

Rectangular echelle reflection grating (10 x 5 inches) on glass substrate (135 x 265 mm) with cardboard box

1964
Rectangular reflection grating (8 x 6 inches) on glass substrate (220 x 170 mm) with cardboard box , 600 lines per mm, and 28º 41' ' blaze angle. Made by Bausch & Lomb, Rochester, New York State, USA in 1964, Cat. No. 35-53-28-55, Serial No. 921-5. Used at the University Observatory, Oxford.

Rectangular reflection grating (8 x 6 inches) on glass substrate (220 x 170 mm) with cardboard box

1964
Square replica reflection grating (52 x 52mm) on glass substrate (he 25 x 60 x 60mm), 600 lines per mm, 5000 Angstrom blaze wavelength and 8º 38' blaze angle. Made by Bausch & Lomb, Rochester, New York State, USA in 1984, Cat. No. 35-53-09-260, Serial No. 2538-13-2.

Square replica reflection grating (52 x 52mm) on glass substrate (he 25 x 60 x 60mm)

1984
Rectangular echelle reflection grating (10 x 5 inches) on glass substrate (135 x 265 mm) with cardboard box, 300 lines per mm, and 63º 26' ' blaze angle. Made by Bausch & Lomb, Rochester, New York State, USA in 1964, Cat. No. 35-53-32-45. Used at the University Observatory, Oxford.

Rectangular echelle reflection grating (10 x 5 inches) on glass substrate (135 x 265 mm) with cardboard box

1964
Spectrometer, fitted with replica of Rowlands grating (has fitted leather case), by W. Watson and Sons, London, England, 1905-7. Fitted with 5-inch circle, reading by Vernier to minutes, rack focus to telescope etc.

Spectrometer, fitted with replica of Rowlands grating (has fitted leather case)

1905-1907
Replica reflection grating on glass base 4 x 3 x 1/2-inches (3600 lines/inch). Made from a ruled cylinder using Merton's method, vacuum-coated with aluminium, from National Physics Laboratory, Teddington, London, c. 1950

Replica reflection grating on glass base 4 x 3 x 1/2-inches (3600 lines/inch)

Large reflection grating (8 x 5 inches) on a flat circular aluminised glass plate (11-inch) mounted in a brass stand for a optical bench spectrograph. Used with the original 12 1/2-inch aperture solar telescope at the University Observatory, Oxford, unsigned, 1945-1955.

Large reflection grating (8 x 5 inches) on a flat circular aluminised glass plate (11-inch)

1945-1955
Exhibit to show the effect of "blazing" a grating, comprising: (a) one replica reflecting grating on glass base 4" x 3" x 1/2", [P. 1027, Hy.10, approx, 3000 lines/ inch], (b) one "blazed" replica reflection grating on glass base 4" x 3" x 1/2", [P.1025, Cyl. 351A approx 3000 lines/inch], (c) glass block (4" x 3" x 1/2") front- aluminished to form plane mirror

Exhibit to show the effect of "blazing" a grating