"Jean-François Gerbillon (1654-1707), a French Jesuit, reached China in 1687 with Joachim Bouvet and others, and the Kangxi Emperor kept him at court for his scientific learning. In 1689 he and Thomas Pereira served as interpreters in the negotiations for the Treaty of Nerchinsk; afterwards he often travelled with the emperor beyond the Great Wall, fixing the latitude and longitude of many places, and wrote works on geometry. In 1692 he obtained an edict granting the free exercise of the Christian religion; after Gerbillon and Bouvet attended the emperor through a fever, Kangxi gave them a site for a chapel and residence. He died in Beijing in 1707."
— Wikipedia
Source: Wikipedia, "Jean-François Gerbillon" (after the Catholic Encyclopedia, 1913)