An optical prism, this rare antique scientific measurement instrument is Rowlands Diffraction Grating by Thorp, an original Diffraction Grating identical to that held by the Science Museum in the UK, thought to be made between 1900-15. Complete with it's original small leather case. Size: 50 mm x 37 mm x 3 mm, case: 17 mm x 64 mm x 56 mm, Worldwide insured delivery with tracking £2.99.
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