Gautier's color-printed picture accompanied one of his many anti-Newtonian publications about color theories. The band of color at the center imitates an illustration in Newton's Opticks but "proves" Gautier's assertion that all colors cannot be found in Newton's spectrum of light. Source: Planche A. de Physique. From Jacques-Fabien Gautier, "Observations sur les Couleurs Newtonienne," in Observations sur l'histoire naturelle sur la physique et sur la peinture 1, pt. 2 (1752), after page 106.

From The creation of color in eighteenth-century Europe by Sarah Lowengard