Accession No

6610

Brief Description

diffraction grating, reflecting, Rowland-type, by John A. Brashear, U.S.A., c. 1900

Origin

U.S.A.; Massachussetts; Baltimore; and U.S.A.; Pennsylvania; Allegheny

Maker

Brashear, John A. [polished and figured] Theodore C. Schneider [ruled using Rowland's engine]

Class

astronomy; optical

Earliest Date

1881

Latest Date

1919

Inscription Date

Material

wood; metal (brass, speculum, other); cloth (velvet); rope (cotton string); plastic

Dimensions

222mm (width) x 210mm (depth) x 130mm (height)

Special Collection

Provenance

Transferred via an individual at the Institute of Astronomy, Madingley Road, Cambridge, University of Cambridge, on or before 27/05/2014.

Inscription

Plate polished and figured by J. A. Brashear Allegheny PA U. S. A.
Ruled by Schneider on Rowland Engine
Johns Hopkins University, Baltimore MD, U.S.A.

Description Notes

Diffraction grating, reflecting, Rowland-type, by J. A. Brashear, U.S.A., c. 1900.

Concave diffraction grating in speculum, made by J.A. Brashear and ruled using Henry Rowland’s engine in Baltimore. Comes in blue velvet-lined box, with key that is currently attached to the handle by string. Paper label, sellotaped to the lid of the box reads:
‘Concave grating
Prof. Redman’.
Newer label reads ‘HIN 523’. Scratched into the surface of the box is
‘S.P.O.
133’

Manuscript inscription on the grating reads:

'Plate polished and figured by J. A. Brashear Allegheny PA U. S. A.
Ruled by Schneider on Rowland Engine
Johns Hopkins University, Baltimore MD, U.S.A.'

For many years Brashear was the sole supplier of the finished plane and concave gratings, which were figured in Brashear's workshop in Allegheny, PA and then ruled by Theodore C. Schneider using Rowland's engine at Johns Hopkins University in Baltimore, MA. This grating was previously owned by Professor Roderick Redman FRS, who was Director of the University of Cambridge Observatories and President of the Royal Astronomical Society.

Grating in good condition: some scratches and fingerprints. Box in quite good condition; velvet is coming away from the interior and glue is visible. Complete.

References

Events