268 GEOGRAPHICAL SCIENCE. 



the Mediterranean ; and his treatise, which formed a luminous and rapid sum- 

 mary, was one of the handbooks of geographical study in the Middle Ages. 



A Greek geometer, named Claudius Ptolemaeus, born at Pelusa, in Lower 

 Egypt, who was at the famous school of Alexandria in the middle of the 

 second century, formed an idea of writing a general treatise upon Mathema- 

 tical Geography after the plan traced by Hipparchus in the year 125 H.C. 

 He had prepared himself for this task by a long series of astronomical 

 observations and calculations. In the second book of his " Almagest " he 

 wrote, " I intend to mark the longitude and latitude of the principal towns 

 of each country, to facilitate the calculation of the celestial phenomena 

 which occur there. I shall mark by how many degrees, counting from the 

 meridian, each of these towns is distant from the equator, and I shall 

 also compute, in degrees counted from the equator, the eastern and western 

 distance of each meridian compared with that which passes at Alexandria, for 

 it is after the meridian of that city that I intend to reckon those of the 

 other places on the earth's surface." Ptolemaeus was more of an astronomer 

 and a geometer than a geographer; he had not travelled at all, and had, 

 therefore, no personal experience, while, excepting the astronomical part of 

 his book, he merely borrowed from his predecessors and contemporaries cos- 

 mographic materials which he loosely arranged without sequence or comment. 

 The best features in his work are what he borrowed from the treatise of 

 Marinus of Tyre, and he says, " I resolved to preserve so much of his book as 

 does not require correction, and to throw light, by means of the most recent 

 information, and by a better arrangement of the places on the maps, upon 

 the obscure points of his treatise." Ptolemaeus unfortunately, while preparing 

 his list of all the places in the known world, making eight thousand names, 

 committed the most glaring errors, owing to his having sought to fix the 

 latitude and longitude of the localities by means of astronomical observations. 



The Geography of Ptolemaeus, written in Greek (Fig. 193), and doubtless 

 translated simultaneously into Latin for the use of persons travelling through 

 the Roman empire, was, in spite of his faults of omission and commission, 

 consulted as being the most useful guide-book during a long journey. The 

 coloured maps appended to it were, perhaps, rectified soon afterwards, upon 

 new itinerary measurements being taken ; for, previously to Ptolemasus, there 

 existed not only road maps, to which Vegetius refers in his treatise on the 

 Art of "War, under the name of itincra picta (coloured itineraries), but 



