Brother-in-law to Pierre Du Val. He helped Du Val's widow and daughters continue the business after Du Val's death in 1683, assuming the title Geographer to the King.
Decorative map of Portugal by Le Père Placide de Sainte-Hélène, the brother-in-law of the famous French mapmaker Pierre Duval. The map provides a large detailed treatment of Portugal, with an inset of the area around Porto on the Douro River.
