In 1842 Alexander Keith Johnston (1804–1871) visited Gotha to discuss several projects with Perthes. These negotiation first resulted in the publication of the "National Atlas of General Geography", which contained 4 maps by Berghaus. Though Berghaus deemed the commercial and scientific climate in England not ready for scientific maps Johnston persisted in wanting to publish a translation of the Physikalischer Atlas, on which he requested aid from Berghaus. With a letter of recommendation by von Humboldt in October 1844 Heinrich 'Henry' Lange joined Johnston in Edinburgh for this purpose. Petermann stayed behind in Gotha and became teacher in the 2nd course of Berghaus' school. In April 1845 he followed Lange, who received him in his house in Edinburgh and acquainted him with the friends he had made. Together they made a tour through the Grampians, applying what they had learned by using barometers for height measurements and taking geological and botanical samples. Meanwhile, they also worked on the Johnston's Physical atlas ("Physical geography, illustrating in a series of original designs, the elementary facts of geology, hydrology, meteorology and natural history etc.") and several other cartographic publications.