Interesting 19th Century example of Samuel Fritz's highly important map of the Marañon River and the Basin of the Amazon River, which was first printed in Quito in 1707 and later appeared in In Lettres édifiantes et curieuses. Écrites des missions etrangères, par quelques missionaries de la compagnie de Jesus. (Paris, N. Le Clerc, 1717. Recueil v. 12, p. 212 ) and thereafter in subsequent editions of the reports of the Jesuit Missionaries.
The map provides a remarkably detailed depiction of the course of the river, with particular importance in its treatment of the Marañon River, where Fritz worked for most of his life and produced a map of the highest importance, which was subsequently copied by other map makers for many years thereafter.
Samuel Fritz (1654-1728) joined the Society of Jesus in 1673. In 1684 he was sent to Quito as a missionary, where he worked with the Indians of the Upper Marañon for 42 years. He succeeded in converting among others the powerful tribe of Omaguas (Omayas) and in concentrating into settlements indigenous peoples from forty different localities, in the country between the River Napo and River Negro.
In 1687, at the request of the Spanish Colonial Government in the Audiencia of Quito, he undertook the mapping of the disputed missionary territory on the Upper Marañon between Peru and Quito. In 1689 he undertook, in a pirogue, an expedition down the Amazon to Pará, where he was captured and imprisoned for two years on the suspicion of being a Spanish spy.
Despite his lack of proper equipment, Fritz completed a comparatively accurate chart of the river's course. This was the first approximately correct chart of the Marañon territory. Fritz was also the first to follow the Tunguragua instead of the Gran Pará (Ucayali) and prove it the real source of the Marañon. Johann Eduard Wappaeus (1813-1879) writes of him in his Handbuch der Geographie und Statistik (Leipzig, 1863-70, I, pt. III, 595) :
The great respect justly shown at that time by European scientists for the geographical work of the Jesuits led to the admission into their ranks of Father Fritz by acclamation.
In 1707, Fritz's map was printed at Quito and thereafter appeared in several examples of the Jesuit "Lettres Edifiantes" over the next century.