Concave Rowland diffraction grating on speculum metal

Concave Rowland diffraction grating on speculum metal, grating area 53 x 23 mm, with scratched markings reading 'Plate prepared at the Astronomical / and Physical Instrument Works / of J A Brashear Allegheny, PA USA / 1894' and 'Ruled on Rowlands first [?] Engine / Johns Hopkins University / Baltimore Md USA / 1894', in wooden case marked 'V.210.' A paper label on the box marked in German indicates (according to the donor) that the grating came from Paschen's laboratory.