Missionary Cartography of the Amazon after the Treaty of Madrid (1750): The Jesuit Contribution to the Demarcation of Imperial Frontiers

Abstract

The Spanish-Portuguese treaty signed in Madrid in 1750 was a turning point not only in the colonial history of Brazil, but also in the history of Jesuit cartography of that area. In 1753, the Spanish-Portuguese demarcation in the Amazon region was entrusted to a group of military engineering officers who, under the king’s orders, were joined by a royal mathematician and astronomer from Croatia, the Jesuit Ignatius Szentmártonyi (1718–1793). Based on Szentmártonyi’s astronomical and geodetic survey along the river courses of the Amazon and Negro Rivers, the first detailed, mathematically-based map of the area was created in 1755. In addition to being the first accurate map of the Amazon and Negro Rivers, this map is significant because it represents a rare case of cooperation between the Jesuit and military cartographers in their joint service to imperial authorities. This service would, however, have disastrous consequences for the Jesuit order.