What was the relationship between mathematics and ornament in the nineteenth century? At the crossroads of technical drawing and artistic drawing, education in ornamental drawing was thus placed under the auspices of the mathematical culture of architects and engineers. This geometric approach to line drawing, which largely dominated the training of designers, may have obscured other kinds of affinities between mathematics and ornament. Jules Bourgoin proposed a detailed investigation into the relations between mathematics and ornament in the numerous books written between the middle of the nineteenth century and the beginning of the twentieth. He opened up a whole field of reflection, between geometry of situation and composition methods.