Petermann's father, August Rudolf Petermann, who was registrar at Bleicherode, could not pay for the further education of his son. When he read the advertisement for Berghaus' school he send his son's maps and other work for evaluation. One of the maps, drawn when he was 16, shows South America, and was later published in the journal which was to carry his name. Berghaus must have recognized the quality of his work, and therewith his potential and soon took him in as a foster-son. As he had already a large family to feed, however, he requested an annual subsidy of 60 thaler from the king to support Petermann, which request was granted. During the 3rd course Berghaus treated his nephew Hermann Berghaus the same way. Only Lange really paid for the courses, the rest following them at Berghaus's own expense.