2,800 atlases. In the 1990s the estimate was 1,000 m of archive, some 400,000 maps (including manuscripts), and some 120,000 geographical works. All collections (currently estimated at 185,000 sheets of maps, 120,000 geographical works, and 800 m of archives) were acquired in 2003 by the Free State of Thüringen and deposited with the library of the University of Erfurt in its research center in Gotha. But the maps went beyond a simple presentation of the itinerary by also describing the area explored with all knowledge available and pointing out gaps that remained to be filled in the current knowledge. So the impact was reciprocal. Moreover, Petermann gave directions to explorers in exchange for which he was allowed to publish their results as soon as possible. Richardson's African expedition The influence Petermann tried to wield, even as a young man, can best be illustrated by his interference, together with Bunsen and Ritter, on behalf of Heinrich Barth, who wished to take part in the Richardson expedition. He later also persuaded the English government to send Eduard Vogel after them for scientific research and astronomical observations. Petermann published the results under the title Account of the expedition to Central-Africa. When first Barth and later Vogel failed to return at the expected time Germany frantically tried to discover their fate, much as Britain had with Franklin in the Arctic area. This led to many new German expeditions to Africa (by Theodor von Heuglin, Hermann Steudner, Theodor Kinzelbach, Karl Moritz von Beurmann, Gerhard Rohlfs, Karl Mauch and others), most financed by gifts due largely to Petermann's agitating actions and publications. Many found their death in Africa as shown in the map with the subtitle Four martyrs of German science in Inner-Africa shows, i.c. Overweg, Vogel, Beurmann and Steudner. Petermann first drafted maps of Barth & Overweg's routes for the journal of the German Geographical Society and followed these up with maps in PGM in 1855, 1857, and 1859. These were later worked into the maps for Barth's voluminous work on his African voyage of 1850–55. The route maps were used in new maps up to 1893. When we compare the maps in Barth's work and in PGM we may get an idea of how the information was turned into images. The first map in Barth's work gives an overview of his routes. The routes of Livingstone have already been engraved, but have not been