 In 1677 the city of Toruń (Thorn) invited Hartknoch to become director at its gymnasium, where he worked for ten years.Wearied by poverty, Hartknoch died and was buried there in 1687 at the age of 43.Hartknoch's extensive scientific body of works contributed greatly to knowledge of Prussia, Pomerania, Samogitia, Courland, and Poland.