Chalk: Materials and Concepts in Mathematics Research

Chalk in hand, his formulas expressed themselves, it seems, more easily on the board than they were able to with pen in his notebooks, for in his listeners’ presence his fecund genius found again a new zeal, and a ray of joy illuminated the lines of his face when the proof he sought to render understandable struck his audience as obvious.¹ So recounts an admiring biographer the pedagogical exploits of Augustin-Louis Cauchy, a towering figure of early nineteenth-century mathematics. Cauchy was trained and then became professor of analysis at the prestigious Ecole Polytechnique, a school for military engineers that not