Geographia?qsrc=3044

1535 printed edition, title page

The Geography (also known as Geographia, Cosmographia, or Geographike Hyphegesis) is Ptolemy's main work besides the Almagest. It is a treatise on cartography ^[1] and a compilation of what was known about the world's geography in the Roman Empire of the 2nd century. Ptolemy relied mainly on the work of an earlier geographer, Marinos of Tyre, and on gazetteers of the Roman and ancient Persian empire, but most of his sources beyond the perimeter of the Empire were unreliable.

Table of Contents

1	The books
2	Principles of mapping
3	Reception in the Renaissance
4	Christopher Columbus and the Geography
5	References
6	See also
7	External links
	7.1	Primary sources
	7.2	Secondary material

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 monk Maximus 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 to Palla Strozzi in Florence by Emanuel Chrysoloras. The first Latin translation – Geographia Claudii Ptolemaei – was made in 1406 by Florentine Giacomo 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 coordinates to all the places and geographic features he knew, in a grid that spanned the globe. Latitude was measured from the equator, 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 the midsummer day increases from 12h to 24h as one goes from the equator to the polar circle). He put the meridian of 0 longitude at the most western land he knew, the Canary Islands.

Principles of mapping

The Ptolemy world map, reconstituted from Ptolemy's Geographia (circa 150), indicating the countries of "Serica" and "Sinae" (Cattigara) (Southeast Asian peninsula) at the extreme right, beyond the island of "Taprobane" (Sri Lanka, oversized) and the "Aurea Chersonesus" (Malay peninsula).

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 necessary topographic lists, and captions for the maps. His oikoumenè spanned 180 degrees of longitude from the Canary islands in the Atlantic Ocean to China, and about 80 degrees of latitude from the Arctic to the East Indies and deep into Africa; 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 of Eratosthenes (3rd century BC), but Ptolemy improved projections. It is known that a world map based on the Geographia was on display in Autun, Gaul in late Roman times.

Scandinavia in the Zamoyski codex of Ptolemy's Geographia, ca 1467 (National Library, Warsaw)

Reception in the Renaissance

Ptolemy's text reached Italy from Constantinople about 1400. The first printed edition, probably in 1477 in Bologna, was also the first printed book with engraved illustrations. Many editions followed (more often using woodcut in the early days), some following traditional versions of the maps, and others updating them.^[2] An edition printed at Ulm in 1482 was the first one printed north of the Alps. 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: while Eratosthenes 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 of marine chronometers 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 the history of cartography.

In the latter years of the fifteenth century Ptolemy’s Geography became the geographical Bible to the peoples of Western Europe. Ptolemy had mapped the whole world from the Fortunatae Insulae (Canary Islands) eastward to the eastern shore of the Magnus Sinus. This known portion of the world was comprised within 180 degrees. In his extreme east Ptolemy placed Serica (the Land of Silk), the Sinarum Situs (the Port of the Sinae), and the emporium of Cattigara.^[3] On the 1489 map of the world by Henricus Martellus, which was based on Ptolemy’s work, Asia terminated in its southeastern point in a cape, the Cape of Cattigara. Cattigara was understood by Ptolemy to be a port on the Sinus Magnus, or Great Gulf, the actual Gulf of Thailand, at eight and a half degrees north of the Equator, on the coast of Cambodia, which is where he located it in his Canon of Famous Cities. It was the easternmost port reached by shipping trading from the Graeco-Roman world to the lands of the Far East. The promontory or cape on which it was situated, the Cape of Cattigara, formed the southeastern point of Asia.^[4] In Ptolemy’s later and more well-known Geography, a scribal error was made and Cattigara was located at eight and a half degrees South of the Equator. On Ptolemaic maps, such as that of Martellus, Catigara was located on the easternmost shore of the Mare Indicum, 180 degrees East of the Cape St Vincent at, due to the scribal error, eight and a half degrees South of the Equator. ^[5] Catigara is also shown at this location on Martin Waldseemueller’s 1507 world map, which avowedly followed the tradition of Ptolemy.^[6] Ptolemy’s information was thereby misinterpreted so that the coast of China, which should have been represented as part of the coast of eastern Asia, was falsely made to represent an eastern shore of the Indian Ocean. As a result, Ptolemy implied more land east of the 180th meridian and an ocean beyond. Marco Polo’s account of his travels in eastern Asia described lands and seaports on an eastern ocean apparently unknown to Ptolemy. Marco Polo’s narrative authorized the extensive additions to the Ptolemaic map shown on the 1492 globe of Martin Behaim. The fact that Ptolemy did not represent an eastern coast of Asia made it admissible for Behaim to extend that continent far to the east. Behaim’s globe placed Marco Polo’s Mangi and Cathay east of Ptolemy’s 180th meridian, and the Great Khan’s capital, Cambaluc (near Beijing), on the 41st parallel of latitude at approximately 233 degrees East. Behaim allowed 60 degrees beyond Ptolemy’s 180 degrees for the mainland of Asia and 30 degrees more to the east coast of Cipangu (Japan). Cipangu and the mainland of Asia were thus placed only 90 and 120 degrees, respectively, west of the Canary Islands.

Christopher Columbus and the Geography

Christopher Columbus modified this geography further by using 53⅔ Italian nautical miles as the length of a degree instead of the longer degree of Ptolemy, and by adopting Marinus of Tyre’s longitude of 225 degrees for the east coast of the Magnus Sinus. This resulted in a considerable eastward advancement of the longitudes given by Behaim and other contemporaries of Columbus. By some process Columbus reasoned that the longitudes of eastern Asia and Cipangu respectively were about 270 and 300 degrees east, or 90 and 60 degrees west of the Canary Islands. He said that he had sailed 1100 leagues from the Canaries when he found Cuba in 1492. This was approximately where he thought the coast of eastern Asia would be found. On this basis of calculation he identified Hispaniola with Cipangu, which he had expected to find on the outward voyage at a distance of about 700 leagues from the Canaries. His later voyages resulted in further exploration of Cuba and in the discovery of South and Central America. At first South America, the Mundus Novus (New World) was considered to be a great island of continental proportions; but as a result of his fourth voyage, it was apparently considered to be identical with the great Upper India peninsula (India Superior) represented by Behaim—the Cape of Cattigara. This seems to be the best interpretation of the sketch map made by Alessandro Zorzi on the advice of Bartholomew Columbus (Christopher’s brother) around 1506, which bears an inscription saying that according to the ancient geographer Marinus of Tyre and Christopher Columbus the distance from Cape St Vincent on the coast of Portugal to Cattigara on the peninsula of India Superior was 225 degrees, while according to Ptolemy the same distance was 180 degrees. ^[7]

References

^ J. L. Berggren, Alexander Jones; Ptolemy's Geography By Ptolemy, Princeton University Press, 2001 ISBN 0691092591
^ David Landau & Peter Parshall, The Renaissance Print, pp 241-2, Yale, 1996, ISBN 0300068832
^ See Oc Eo.
^ J.W. McCrindle, Ancient India as described by Ptolemy, London, Trubner, 1885, revised edition by Ramachandra Jain, New Delhi, Today & Tomorrow’s Printers & Publishers, 1974, p.204: “By the Great Gulf is meant the Gulf of Siam, together with the sea that stretches beyond it toward China”; Albert Herrmann, “Der Magnus Sinus und Cattigara nach Ptolemaeus”, Comptes Rendus du 15me Congrès International de Géographie, Amsterdam, 1938, Leiden, Brill, 1938, tome II, sect. IV, Géographie Historique et Histoire de la Géographie, pp.123-8.
^ Paul Schnabel, „Die Entstehungsgeschichte des kartographischen Erdbildes des Klaudios Ptolemaios“, Sitzungsberichte der Preussischen Akademie der Wissenschaften: Philosophisch-Historische Klasse, Verlag der Akademie der Wissenschaften, Bd.XIV, 1930, S.214-250, n.b. 239-243; cited in Albert Herrmann, “South-Eastern Asia on Ptolemy’s Map”, Research and Progress: Quarterly Review of German Science, vol.V, no.2, March-April 1939, pp.121-127, p.123.
^ See Waldseemuller Map
^ “Alberico”, vol.IV, c.169, Florence, Biblioteca Nazionale Centrale, Banco Rari 234; Sebastian Crino, "Schizzi cartografici inediti dei primi anni della scoperta dell' America", Rivista marittima, vol. LXIV, no.9, Supplemento, Novembre 1930, p.48, fig.18. Downloadable at: www.henry-davis.com/MAPS/Ren/Ren1/304.1.html

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.
Diller, Aubrey (February 1935). "Review of Stevenson's translation". Isis 22 (2): 533–539. http://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/journals/ISIS/22/2/reviews/Stevensons_Ptolemy*.html. Retrieved 2007-07-15.