- Geographia
The "Geographia" or "Geography" is
Ptolemy 's main work besides the "Almagest ". It is a compilation of what was known about the world'sgeography in theRoman Empire of the2nd century . Ptolemy relied mainly on the work of an earlier geographer,Marinos of Tyre , and ongazetteer s of the Roman and ancient Persian empire, but most of his sources beyond the perimeter of the Empire were unreliable.The books
The "Geographia" comprises two parts: Book 1, a discussion of the data and of the methods used; and Books 2–5, an atlas. The original work included maps, but due to the difficulties involved in copying them by hand, they have fallen out of the manuscript transmission. The work has been discovered and used through the ages by several noted people around the world. Arabic writer
al-Mas'udi , while writing around 956, mentioned a colored map of the Geography which had 4530 cities and over 200 mountains. Byzantine monkMaximus Planudes found a copy of the Geography in 1295, and since there were no maps in his copy, he drew his own based on the coordinates found in the text. In 1397 a copy was given toPalla Strozzi inFlorence byEmanuel Chrysoloras . The first Latin translation – "Geographia Claudii Ptolemaei" – was made in 1406 by FlorentineGiacomo da Scarperia (latinsed name Jacobus Angelus), and since this, various translations in other languages have been made available to people all over the world.As with the model of the solar system in the "Almagest", Ptolemy put all this information into a grand scheme. He assigned
coordinate s to all the places and geographic features he knew, in agrid that spanned the globe.Latitude was measured from theequator , as it is today, but Ptolemy preferred to express it as the length of the longest day rather than degrees of arc (the length of themidsummer day increases from 12h to 24h as one goes from the equator to thepolar circle ). He put the meridian of 0longitude at the most western land he knew, theCanary Islands .Principles of mapping
Ptolemy also devised and provided instructions on how to create maps both of the whole inhabited world ("
oikoumenè ") and of the Roman provinces. In the second part of the "Geographia" he provided the necessarytopographic lists, and captions for the maps. His "oikoumenè" spanned 180 degrees of longitude from the Canary islands in theAtlantic Ocean toChina , and about 80 degrees of latitude from the Arctic to theEast Indies and deep intoAfrica ; Ptolemy was well aware that he knew about only a quarter of the globe.Maps based on scientific principles had been made since the time ofEratosthenes (3rd century BC), but Ptolemy improved projections. It is known that a world map based on the "Geographia" was on display inAutun , Gaul in late Roman times.Reception in the Renaissance
Ptolemy's text reached Italy from
Byzantium about 1400. The first printed edition, probably in 1477 inBologna , was also the first printed book with engraved illustrations. Many editions followed (more often usingwoodcut in the early days), some following traditional versions of the maps, and others updating them. [David Landau & Peter Parshall, The Renaissance Print, pp 241-2, Yale, 1996, ISBN 0300068832 ] An edition printed atUlm in 1482 was the first one printed north of theAlps . Also in 1482,Francesco Berlinghieri printed the first edition in vernacular Italian. The maps look distorted as compared to modern maps, because Ptolemy's data was inaccurate. One reason is that Ptolemy estimated the size of the Earth as too small: whileEratosthenes found 700 "stadia" for a degree on the globe, in the "Geographia" Ptolemy uses 500 "stadia". It is not certain if these geographers used the same "stadion", but if we assume that they both stuck to the traditional Attic "stadion" of about 185 meters, then the older estimate is 1/6 too large, and Ptolemy's value is 1/6 too small. Because Ptolemy derived most of his topographic coordinates by converting measured distances to angles, his maps get distorted. So his values for the latitude were in error by up to 2 degrees. For longitude this was even worse, because there was no reliable method to determine geographic longitude; Ptolemy was well aware of this. It remained a problem in geography until the invention ofmarine chronometer s at the end of the 18th century. It must be added that his original topographic list cannot be reconstructed: the long tables with numbers were transmitted to posterity through copies containing many scribal errors, and people have always been adding or improving the topographic data: this is a testimony to the persistent popularity of this influential work in thehistory of cartography .References
*Berggren, J. Lennart and Jones, Alexander. 2000. "Ptolemy's" Geography: "An Annotated Translation of the Theoretical Chapters". Princeton University Press. Princeton and Oxford. ISBN 0-691-01042-0.
*Cosgrove, Dennis. 2003. "Apollo's Eye: A Cartographic Genealogy of the Earth in the Western Imagination". Johns Hopkins University Press. Baltimore and London.
*Stevenson, Edward Luther. Trans. and ed. 1932. "Claudius Ptolemy: The Geography". New York Public Library. Reprint: Dover, 1991. This is the only complete English translation of Ptolemy's most famous work. Unfortunately, it is marred by numerous mistakes (see Diller) and the place names are given in Latinised forms, rather than in the original Greek.
*cite journal |last=Diller |first=Aubrey |year=1935 |month=February |title=Review of Stevenson's translation |quotes=no |journal=Isis |volume=22 |issue=2 |pages=533–539 |url=http://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/journals/ISIS/22/2/reviews/Stevensons_Ptolemy*.html |accessdate= 2007-07-15ee also
*
Bibliotheca historica
*Diodorus Siculus
*Strabo External links
Primary sources
* [http://penelope.uchicago.edu/Thayer/E/Gazetteer/Periods/Roman/_Texts/Ptolemy/home.html Ptolemy's Geography at LacusCurtius] (English translation, incomplete)
* [http://dsr.nii.ac.jp/toyobunko/III-2-F-b-2/V-1/page/0162.html.ja Extracts of Ptolemy on the country of the Seres (China)] (English translation)
* [http://www.dioi.org/diller8/diller8.htm 1st critical edition of Geography Book 8, by Aubrey Diller]econdary material
* [http://www.abila.org/html/ptolemy.html Ptolemy the Geographer]
* [http://www.chass.utoronto.ca/~ajones/ptolgeog/ Alexander Jones, "Ptolemy and his "Geography"]
* [http://wwwuser.gwdg.de/~fhasele/ptolemaeus/index.html Ptolemy's Geography of Asia] - Selected problems of Ptolemy's Geography of Asia (in German)
* [http://www.fiks.de/rom/index.htm?rom10.htm Ptolemy's Geography of Northwestern Europe] (in German)
* [http://www.newberry.org/smith/slidesets/ss08.html History of Cartography] including a discussion of the Geographia
* [http://www.dioi.org/gad.htm#nlgd Dennis Rawlins, Investigations of the Geographical Directory 1979-2007]
Wikimedia Foundation. 2010.