Noch einmal die Farbensysteme
A German-language scientific paper on colour perception by the Dutch physiologist F. C. Donders, published in Leipzig in 1884 and held by the Royal College of Surgeons of England. Its single picture is a dense chart of a grid with a rising and falling line graph marked with spectral wavelength values and letters, useful to a designer as a study in plotting data on a squared ground with labelled peaks.
