The rudiments of colours and of colouring : with the nature of pigments for the use of decorative artists, painters, etc.
A colour theory treatise by George Field and Robert Mallet, published in London by Strahan in 1870 for decorative artists and painters. The pictures are simple line diagrams: a colour wheel with letter labels, a geometric construction with lines of sight, a prism refracting light into red, yellow and green, and a graph of overlapping spectral curves labelled R, Y and B, useful for designers wanting schematic, scientific-looking figures.
