Book Lucien Cayeux (1864 - 1944) was one of the leading sedimentary petrographers of the late 1800's and early 1900's. Cayeux was born in Semousies in the north of France, and became a teacher of science in Lille. His interest in fossils led to his career in geology. Cayeux is regarded as one of the early innovators in sedimentary petrography, creating new methods for petrographic determination of sedimentary components and genesis. He is particularly noted for his pioneering studies of sediments with the polarizing microscope. He published six books over the course of his career, most notably "Introduction à l'étude Pétrographique des Roches Sédimentaires" (Introduction to the Petrographic Study of Sedimentary Rocks) in 1916 and "Les Roches Sédimentaires de France" (The Sedimentary Rocks of France) in 1929. Cayeux was a professor of geology at the Ecole des Mines and the Collège of France, and was admitted to the French Académie des Sciences in 1928. He was immortalized in science when the Dorsum Cayeux wrinkle-ridge on the moon was named after him.

Lucien Cayeux
Photograph from
http://www.annales.com/archives/x/cayeux.html

Book Plate (right) from Les Roches Sédimentaires de France showing radial calcite ooids with sparry cement. To fully appreciate these images it's important for the modern reader to consider the technical challenges that Cayeux faced as he captured these beautiful images on film using a microscope that probably did not come up to current standards for optics and illumination. The clarity of these images fully rivals and in many cases exceeds that produced today by digital photomicrography. Look closely at the crispness of the cement crystal boundaries in the two right-side images on the plate. The key difference in photomicrography then and now, of course, is in the amount of effort required: then one had to load the film, determine the exposure time, get the image focused onto the film plane, keep detailed notes linking image to content (no immediate file names!), develop the film, print each individual frame, and ultimately compose the plates for the printer. Working in this manner the microscopist wouldn't know if the image succeeded in capturing the desired information until the film-development or even the printing stage. Going back to try again was not unusual. Composing an atlas today is a lot of work; at the time of Lucien Cayeux it was an immense undertaking.