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book; instructions
Stearman Optical Co Ltd; Stearman, S.R.
Europe: United Kingdom
Late 1930s
paper, cardboard
overall: 227 x 146 mm
Booklet outlining the construction and use of the British Refracting Unit (BRU) including preliminary questioning, retinoscopy, subjective testing, measuring phorias by Maddox test or Duplicating Prism method, measurement of ductions, use of crossed-cylinders. Black and white illustrations of the unit, its accessories (including various drum charts and the F-L chart), the Pulzone hydraulic chair and the operation of controls (including p.d. adjustment, rotating the spherical lenses, the cylindrical batteries, crossed-cylinders, Stevens' phorometer, Risley rotary prisms and use of the +1.50 D lens in retinoscopy. Also instructions for cleaning the lenses. 19 pages. Stiff cover.
2004.622
Gift of A. H. Rivron & Son Ltd, 2004