invent a new mould which he called polyamatype (1819), because it founded one hundred letters at a time. Henri Didot engraved the assignats, the paper money used during the French Revolution. Saint-Léger Didot Saint-Léger Didot (son of Pierre-François Didot) was born in 1767 and died in 1829. Saint-Léger Didot devoted his attention to papermaking in the famous factory of Essonne, where one of his workers, Louis-Nicolas Robert invented a machine to make "endless" paper, and eventually sold the patent to Didot. Fourth generation Jules Didot Jules Didot (son of Pierre Didot) was born in 1794 and died in 1871. Jules Didot is famous for his invention of round-edged initials, to take the place of the sharp-edged ones. In 1825 he took his printing plant to Brussels and founded the Royal Printing House. Ambroise-Firmin Didot Ambroise-Firmin Didot (son of Firmin Didot) was born 1790 and died in 1876. Ambroise-Firmin Didot first followed a diplomatic career and was for a time attache of the French Embassy at Constantinople. He took advantage of his position to visit the East and Greece, being the first to discover the location of Pergamacum. When his father retired in 1827, he, together with his brother Hyacinthe, took the management of the publishing business. They published the three book series Bibliothèque des auteurs grecs (Scriptorum graecorum bibliotheca), Collection des auteurs latins, and Bibliothèque des auteurs français, which comprised 200 volumes in all. Their greatest work was a new edition of the Thesaurus Graecae Linguae, of Henry Stephens, edited by Jean François Boissonade de Fontarabie, Dindorf, and Hase (9 vols., 1855–59). Ambroise-Firmin Didot was also involved with the 4th edition of L'Encyclopedie Moderne, 30 vols in total, published in the years 1846–1861. A part was also published as: "Essay sur la Typographie, Extrait du Tome XXVI de l'Encyclopédie moderne, Typographie de Firmin Didot Frères, Imprimereurs de l'Institut de France, Paris, Rue Jacob 56, 1851" Edouard Didot Edouard Didot (son of Saint-Léger Didot) was born in 1797 and died in 1825. Edouard Didot made a translation of Johnson's "Lives of the Poets", which was printed by Jules Didot. References Further reading Eugène Piton (pseud. de Dupériel Sainte-Marie), Famille Firmin-Didot : imprimeurs, libraires, fondeurs, graveurs, papetiers, inventeurs et littérateurs, Paris, 1856, 16 p. Edmond Werdet, Etudes bibliographiques sur la famille des Didot : imprimeurs, libraires, graveurs, fondeurs de caracteres, fabricants de papiers, etc. (1713-1864), Paris: E. Dentu, 1864. Edmond Werdet, Histoire