Colour measurement and mixture
A technical manual on colour measurement and mixture by Sir William de Wiveleslie Abney, published in London and New York in 1891 by the Society for Promoting Christian Knowledge for students and practitioners of colour science. Its pictures are plain line graphs of spectral absorption and transmission curves plotted against wavelength scales, plus a geometric diagram for constructing a colour template, which a designer might use as a reference for how colour pigments and filters behave.
