to the subject by Alexander von Humboldt. In 1848 Johnston published Physical Atlas of Natural Phenomena, followed by a second and enlarged edition in 1856. The atlas contained maps and descriptive letterpress to illustrate the geology, hydrography, meteorology, botany, zoology, and ethnology of the globe. The Physical Atlas was partly based on Heinrich Berghaus's German language Physikalischer Atlas and reflected the increased interest in the mapping of zoological and biological distributions. 18th century thinkers such as Montesquieu had stressed the importance of geography and climate as determining factors in history, and the concept of natural frontiers. The atlas was a visual representation of Humboldtian science, which became popular in the 19th century and was preoccupied with the measurement of environmental parameters on a global scale. Berghaus and Johnston effectively illustrated the text of Humboldt's Kosmos and both atlases were subsequently plagiarized and abridged for school editions. Johnston published a Dictionary of Geography in 1850, with many later editions. The Royal Atlas of Modern Geography was first published in 1855 and served as an atlas of military geography to accompany Alison's History of Europe published in 1848. A variety of other atlases and maps for educational or scientific purposes. In 1856 Johnston published the "School Atlas of Astronomy". In 1861 Johnston published the first edition of the Royal Atlas of Modern Geography with 48 maps. By 1914 the atlas had gone through 12 editions and morphed into the Johnston's Handy Royal Atlas of Modern Geography with 61 colour lithographed maps and an index of 84 pages. While the Bartholomew's Citizen's Atlas sold more copies, being half the price, the Royal Altlasbecame the standard library atlas throughout the British Empire. In 1867 Johnston produced a new edition of his School Atlas of Classical Geography. It contained a series of new maps that reflected the results of the most recent research into the classical antiquity. The Map of the Outer Geography of the Odyssey and two maps of ancient Greece were based on the scholarly work of William Ewart Gladstone, who had also revised the map plates and text of the atlas. In 1871 Johnston published the Half-Crown Atlas of British History for the price sensitive educational market. It was designed as a connected series of maps for teachers and students and illustrated leading events of history. Family He married Margaret Gray in 1837. She was thereafter known as Margaret Keith Johnston. His