Hand-held apparatus for crystal examination

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This hand-held apparatus was used for crystal examination in the 19th century. Certain crystals show particular characteristics when they are examined through a pair of Nicol prisms. The light entering the first prism, called the polarise, passes on to the second, called the analyser: if these are at right angles to each other, no light will pass out of the second. If strained glass, or certain mineral crystals are placed between the crossed Nicol prisms, patterns or colours, or both, may be observed.

This demonstration device has an eyepiece containing a pair of Nicol prisms: a rotating wheel of mineral samples can be revolved past these, and observed. This has an ivory centre, which is stamped with the names of each: 'QUARTZ / CALC: SPAR / NITRE / ARRAGONITE / TOPAZ / BORAX'. The instrument is unsigned.

Possibly this piece was designed to be passed round a classroom, or for evening entertainment. It appears to be more for instruction than for serious intentions.

Record details

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• Online ID: 000-180-000-925-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland Part 2
  Project description   View all records in project
• Ref: National Museums Scotland  T.1925.64
• Date: 19th century
  
• Material: Apparatus, hand / mineral / light, polarised
  
• Dimensions:
• What: Apparatus, hand / mineral / light, polarised
  
• Subject: 22. PHYSICS, Light (Departmental Classification)
  
• Who:
• Where: England
  
• Event:
• Description: Hand apparatus for examining quartz, calcspar, nitre, arragonite, topaz and borax by polarised light
  
• References:
  • Turner, G.L'E. Nineteenth-Century Scientific Instruments. London, 1983, pp 154-6. 
• Translations:
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