Exploring various aspects of the science of optics, these illustrations were all featured in the French science writer Amédée Guillemin’s popular textbook Les phénomènes de la physique (1868) and later reprinted in his five-volume magnum opus, Le monde physique (1882) (of which you can see a condensed 1877 English version here).

Many of the prints are the work of the Parisian intaglio printer and engraver René Henri Digeon. Some of the more psychedelic-looking illustrations by Digeon are based on images made by the physicist J. Silbermann showing how light waves look when they pass through various objects, ranging from a bird’s feather (plate VI in Les phénomènes de la physique) to crystals mounted and turned in tourmaline tongs (plate VIII in Les phénomènes de la physique and plate VII in Le monde physique).

These images — along with one executed by M. Rapine (based on a painting by Alexandre-Blaise Desgoffe), showing the effects of light on a soap bubble — were used to explain the phenomenon of birefringence, or double refraction: the colourful results of light waves moving through material at unequal speeds. And their subjects were not chosen haphazardly. Newton was famously interested in the iridescence of soap bubbles. His observations of their refractive capacities helped him develop the undulatory theory of light. But he was no stranger to feathers either. In the Opticks (1704), he noted with wonder that, “by looking on the Sun through a Feather or black Ribband held close to the Eye, several Rain-bows will appear.”