SERVICE GEOGRAPHIQUE DE L'ARMEE - Nankin [Nanjing, Jiangsu]

Very detailed (1:1.000.000) map showing the area north of Nanjing, Jiangsu. The French Service géographique des armées was founded in 1887 and provided the French military and administrative forces with maps, their publications usually do not appear on the market. In 1940 the division became L'Institut géographique national (IGN).
The helio engraving was initially cited by J. N. Niépce (1829) to describe his photo-etching process (1826), which used a pewter plate coated with a bitumen resist that hardened on prolonged exposure to light.