Photography in colours
Photography in Colours is a 1917 New York technical manual by George Lindsay Johnson, published by E. P. Dutton, explaining colour photography to amateur and professional photographers. Its pictures are plain line diagrams: a lens focusing light onto a plate, wavefronts spreading from a source, a darkroom-style apparatus layout, and a sectioned eye with iris, lens and retina labelled. A designer could take from them a clean, schematic vocabulary of rays, arcs and labelled cross-sections suited to scientific infographics.
