This letter was written by Félicien de Saulcy and sent to correspondents in 1869. He requests copies of all milestones (i.e. the inscriptions on the ancestors of our modern-day road signs) and recommends using estampage in order to accurately reproduce them. This technique, which involves placing damp sheets of paper on the surface of stone, was one of the new techniques used by the Commission de Topographie des Gaules, and allowed them to obtain highly accurate imprints of inscriptions.

Archives nationales, F17/2906