In 1807, accompanied by his pupils, he started on the first of a series of journeys undertaken for purposes of study and investigation. This time he visited Italy and Switzerland, In Switzerland he formed the acquaintance of Pestalozzi, Pictet, and De Candolle, living in Geneva a year. In Italy he enlisted Thorwaldsen, Overbeck, and Cornelius among his friends. In 1813 he went with his pupils to the University of Göttingen, where he had an opportunity to make use of the treasures of the library for his great geographical work. He still regularly visited the lecture-rooms of the professors and attended the different colleges. After two years at Göttingen he went to Berlin, and there, in 1817, published the first part of his "Erdkunde im Verhältnisse zur Natur und Geschichte des Menschen, oder allgemeine Vergleichende Geographie als sichere Grundlage des Studiums und des Unterrichts in physikalischen und historischen Wissenschaften (Geography in Relation to Nature and the History of Men, or General Comparative Geography as the Secure Basis of Study and Instruction in Physical and Historical Knowledge), a work in which the treatment of geography was completely transformed, and the study was raised to the rank of a true science. This part included Africa and a portion of Asia. A year afterward appeared the second part, in which Asia was concluded. In this work he delineated the form and surface of the earth, in its horizontal and vertical features, with great accuracy. Taking a comprehensive view, he considered the peculiarities of the different parts of the earth's surface in their relations to each other and to the earth as a whole, and regarded them as the underlying basis of all living existence, and the foundation and condition of the development of single peoples and of the whole human race in its manifold changes of relation.
In 1819 Hitter was appointed Professor of History in the gymnasium at Frankfort; but he soon exchanged this position for a higher one, for in the next year he accepted an invitation to Berlin, where he was appointed to the chair of geography in the military school and the university. Here begins the second great division of his life, in which he could enjoy both in the department of scientific research and as a teacher the ripe fruits of his earlier activity. Berlin, where a new, fresh life was then beginning to beat, where he was associated with Alexander von Humboldt as his hearty friend, was the right place for him to work, and he was fully conscious of it. After Prince Albert became enrolled among his scholars, he was introduced to the circle of the Crown-Princes, and afterward to King Frederick William IV., before whom he gave lectures on geography. In 1825 he became director of studies to the Cadet corps, and in 1828 founder and first President of the Berlin Geographical Society.
Ritter was accustomed, during his autumn vacations, to take considerable journeys, which not only gave him mental and bodily recreation, but also assisted in the advancement of his geographical studies.
