Marie van Goethem
Between 1878 and 1881, Degas drew, painted and sculpted Marie in artworks including "Dancer with Fan", "Dancing Lesson", "Dancer Resting", numerous preparatory sketches, and most famously in "Little Dancer of Fourteen Years". He frequently attended ballet performances at the Paris Opera and often observed classes at the dance school. By posing for Degas, Marie likely earned five to six francs per four-hour sitting.
Ludovic-Napoléon Lepic
During the next few years, he took up archaeology and between 1869–76 was a member of the "Société d’anthropologie de Paris". In 1872, he founded a museum at Aix-les-Bains and published a ground-breaking illustrated work on prehistoric tools, "Les armes et les outils préhistoriques reconstitués". His experiments with etching during this time were equally innovative, and he developed the technique of ‘variable etching’ ("eau-forte mobile") where, by varying the ink on the plate, he was able to produce individual results at each printing. He was to teach this technique to his old friend Edgar Degas and the two co-operated on, and duly signed, Degas' large monotype "The ballet master" of 1874, now in the National Gallery of Art, Washington.