Studien über angeborene Farbenblindheit
A German medical study of congenital colour blindness by Hermann Ludwig Cohn, published in Breslau in 1879 for ophthalmologists and physicians. Its pictures are numbered diagrams of the visual field, with concentric rings, clock-style meridian labels and irregular toothed outlines plotting where colours are seen, which a designer might borrow for scientific charts, radial grids or geometric technical linework.
