The revival of interest in earth-measurement and survey led directly to the furthering of the study of theoretical geography. We have happened already upon the names of Peter Apianus and Gemma Frisius in the history of the mathematical branch of geography; these two--Apianus by publishing in 1524 his _Cosmographicus Liber_, and Frisius by editing and expanding that work under the title of _Cosmographia_--re-founded the science on a mathematical basis, though they remained bound to the Ptolemaic view of a sharp distinction between geography, the general description of the world, and chorography, the particular description of a region. There is, perhaps, something characteristic in the insistence on this curiously arbitrary distinction; there has been sometimes a tendency to narrow the view of the field of “pure” geography on the part of workers labouring in one corner of it and turning their backs upon the rest. Indeed, at this very period is found another _Cosmographia_, to which its author added the epithet “universalis,” wherein the now familiar view of geography as a human and political field of study appeared, to the no less familiar exclusion of the mathematical aspect; for Sebastian Münster, in his work published in 1544, neglected the mathematical side entirely, modelling his work on that of Strabo. Philip Cluverius, again, in his _Introduction to Universal Geography_ (1624), preserves the distinction between geography and chorography, albeit but one out of his six books deals with the earth at large, while in the rest countries are treated in detail, the human aspect being closely studied. Nathanael Carpenter of Oxford, however, threw over the distinction in so far as he recognized that neither geography, as distinguished by earlier writers from chorography, nor chorography itself, nor topography (under which term were classified the closer descriptions of smaller areas than those which belonged to chorography), was anything more than a part of a whole. Therefore, he divided his _Geography_ (1625) into “spherical” and “topical” parts, the first dealing with the mathematical side, the second with different divisions of the earth according to physical, not political, considerations; his work is thus notable as indicating his realization of the function of geographical study which follows from those of measurement and description--namely, that of the correlation of phenomena. In 1650 appeared the _Geographia Generalis_ of Bernhard Varenius, who died, still a young man, in that year. He laid down a broad division of the subject into general and special parts. His general part was sub-divided so as to include, firstly, the shape, size, and general physical characteristics of the earth, the distribution of land and water, land forms and hydrography; secondly, the astronomical and mathematical aspects, such as zones, latitude and longitude, the investigation of which was carried further