Cartographie

1750 · ABC_46337 — France 1750. Folio. Sewn in quires and stored loose in a portfolio covered with grey paper grey cloth ties paper label on the front board. Manuscript in French on thick paper written in a neat 18th-century cursive hand. With 5 manuscript plates showing 14 geometrical figures. 2 blank 1 1 blank 61 3 blank pp. Cartographic manuscript intended to teach engineer-geographers how to in the author’s words “centrer les angles ” bisect angles and to triangulate to calculate locations on a map as precisely as possible. The author remains unidentified but probably taught cartography. He the field was hardly open to women gives many examples to explain his methods all richly illustrated in the manuscript’s geometric figures and with tables. He quotes the methods of the important French mathematician physician and hydrographer Pierre Bouguer 1698-1758 who was also geometer at the Académie des Sciences in Paris for the means to “centrer les angles” though we have not found Bouguer using that phrase and those of the French astronomer and cartographer César-François Cassini de Thury 1714-1784 also member of the Académie for triangulation. Altogether the work is a practical guideline for engineer-geographers in which the author not only describes methods for bisecting angles and for triangulation but for example also how to use his own tables on pp. 29-44. A highly interesting cartographic manuscript with a strong geometrical focus quoting two of the foremost French cartographers of the 18th century.With the library stamp of the Danish national library Det Kongelige Bibliothek in Copenhagen. Portfolio a little worn dust-soiled and somewhat stained but the leaves are still in good condition.l Katalog der Bibliothek und Kartensammlung der Königlichen Allgemeinen Kriegsschule 1851 56. hardcover