Remarks on the examination and classification of cases of colour-blindness
A medical treatise of 1879 by George Andreas Berry on examining and classifying colour-blindness, published in Edinburgh by Oliver and Boyd for ophthalmic practitioners and students. Its diagrams are plain geometric line drawings: a circle with perpendicular axes, rotated chords and dashed projection lines, and a set of hatched spectral curves labelled R, O, Y, G, B, V with vertical guides, which a designer might borrow as clean schematic devices for showing angle, rotation, or spectrum bands.
