Polarising apparatus

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This polarising apparatus (pictured here with its box) was made around 1860, probably by James Bryson (1824-94) of Edinburgh.

The apparatus consists of black reflecting glass inside the lid, a Nicol prism on an adjustable pillar and a glass stand. The stand tilts to allow objects to be illuminated by light partially polarised by inclined reflection from the black glass surface.

The apparatus is used to show the lines of strain in unannealed glass shapes through the Nicol prism analyser. This photo-elastic effect was discovered by David Brewster (1781-1868) in 1816, but not widely investigated until the 20th century.

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• Online ID: 000-100-102-649-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  T.1860.525
• Date: Around 1860
  c. 1860
  
• Material: Glass / selenite designs
  Light polarizing apparatus / design
  
• Dimensions:
• What: Light polarizing apparatus / design
  
• Subject: 22. PHYSICS, Light (Departmental Classification)
  
• Who: Bryson, Edinburgh (Maker)
  
• Where: Scotland, Midlothian, Edinburgh
  
• Event:
• Description: Apparatus for polarizing light, with seventeen pieces of unannealed glass and three selenite designs for the polarizer, probably by James Bryson, Edinburgh, c. 1860
  
• References:
  • Brewster, D., 'On the Communication of the structure of Doubly-refracting Crystals to Glass, Muriate of Soda, Fluor Spar and Other substances by mechanised compression and dilatation' in Philosophical Transactions of the Royal Society of London 106 (1816) 
  • Clarke, T.N., Morrison-Low, A.D. & Simpson, A.D.C., Brass & glass scientific instrument making workshops in Scotland as illustrated by instruments from the Arthur Frank Collection at the Royal Museum of Scotland. Edinburgh: NMS, 1989, pp 112-20 
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