The
Geography (also known as
Geographia,
Cosmographia, or
Geographike Hyphegesis) is
PtolemyClaudius Ptolemaeus , known in English as Ptolemy , was a Roman citizen of Greek ancestry. He was a mathematician, astronomer, geographer, astrologer and a poet of a single epigram in the Greek Anthology. He lived in Egypt under the Roman Empire, and is believed to have been born in the town of...
's main work besides the
AlmagestAlmagest is the Latin form of the Arabic name of a mathematical and astronomical treatise proposing the complex motions of the stars and planetary paths, originally written in Greek as by Ptolemy of Alexandria, Egypt, written in the 2nd century...
. It is a
treatiseA treatise is a formal and systematic exposition in writing of the principles of a subject, generally longer and more detailed than an essay...
on
cartographyCartography is the study and practice of making geographical maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively.The fundamental problems of cartography are to:*Set the map's...
and a compilation of what was known about the world's
geographyGeography is the study of the Earth and its lands, features, inhabitants, and phenomena. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...
in the
Roman EmpireThe Roman Empire was the post-Republican phase of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean. The term is used to describe the Roman state during and after the time of the first emperor,...
of the 2nd century. Ptolemy relied mainly on the work of an earlier geographer, Marinos of Tyre, and on
gazetteerA gazetteer is a geographical dictionary or directory, an important reference for information about places and place names , used in conjunction with a map or a full atlas. It typically contains information concerning the geographical makeup of a country, region, or continent as well as the social...
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 monk
Maximus PlanudesMaximos Planoudes, latinized as Maximus Planudes , was a Byzantine Greek grammarian and theologian who lived and worked during the reigns of Michael VIII Palaiologos and Andronikos II Palaiologos.-Life & Work:...
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 StrozziPalla di Onorio Strozzi was an Italian banker, politician, writer, philosopher and philologist.-Biography:He was born in Florence into the rich family of the Strozzi...
in
FlorenceFlorence is the capital city of the Italian region of Tuscany and of the province of Florence...
by Emanuel Chrysoloras. The first Latin translation –
Geographia Claudii Ptolemaei – was made in 1406 by Florentine
Giacomo da ScarperiaGiacomo d'Angelo da Scarperia or Scarparia was a Renaissance humanist, born in Florence. He hastened to Venice, when Manuel Chrysoloras had arrived as an envoy of Manuel Paleologus in 1393 and had stayed to teach Greek in Italy for the first time in seven centuries...
(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
gridGrid or The Grid may refer to:In entertainment and media:* The Grid, an electronic dance group* The Grid , a 2001 third person shooter* The Grid * Mobil 1 The Grid, a motorsport magazine TV show...
that spanned the globe.
LatitudeLatitude, usually denoted by the Greek letter phi gives the location of a place on Earth north or south of the equator. Lines of Latitude are the imaginary horizontal lines shown running east-to-west on maps that run either north or south of the equator...
was measured from the
equatorThe equator is the intersection of the Earth's surface with the plane perpendicular to the Earth's axis of rotation and containing the Earth's center of mass. In simpler language, it is an imaginary line on the Earth's surface equidistant from the North Pole and South Pole that divides the Earth...
, as it is today, but Ptolemy preferred to express it as the length of the longest day rather than
degrees of arcA degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...
(the length of the
midsummerMidsummer may simply refer to the period of time centered upon the summer solstice, but more often refers to specific European celebrations that accompany the actual solstice, or that take place around the 24th of June and the preceding evening. The exact dates vary between cultures...
day increases from 12h to 24h as one goes from the equator to the
polar circleA polar circle is either the Arctic Circle or the Antarctic Circle. On Earth, the Arctic Circle is located at a latitude of 66˚ 33' 38" N, and the Antarctic Circle is located at a latitude of 66˚ 33' 38" S...
). He put the
meridianA meridian is an imaginary arc on the Earth's surface from the North Pole to the South Pole that connects all locations running along it with a given longitude. The position of a point on the meridian is given by the latitude. Each meridian is perpendicular to all circles of latitude at the...
of 0
longitudeLongitude , identified by the Greek letter lambda , is the geographic coordinate most commonly used in cartography and global navigation for east-west measurement...
at the most western land he knew, the
Canary IslandsThe Canary Islands are a Spanish archipelago which, in turn, forms one of the Spanish Autonomous Communities and an Outermost Region of the European Union. The archipelago is located just off the northwest coast of mainland Africa, 100 km west of the disputed border between Morocco and the...
.
Principles of mapping
Ptolemy also devised and provided instructions on how to create maps both of the whole inhabited world (
oikoumenèEcumene a term originally used in the Greco-Roman world to refer to the inhabited earth . The term derives from the Greek , short for "inhabited world"...
) 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 OceanThe Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about 106.4 million square kilometres , it covers approximately one-fifth of the Earth's surface and about one-quarter of its water surface area. The first part of its name refers to the Atlas of Greek...
to
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
, and about 80 degrees of latitude from the Arctic to the East Indies and deep into
AfricaAfrica is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area. With a billion people in 61 territories, it accounts for about 14.8% of the...
; Ptolemy was well aware that he knew about only a quarter of the globe.
MapsMaps is the plural of map, a visual representation of an area.As an acronym, MAPS may refer to:* Mail Abuse Prevention System* Manx Aviation Preservation Society...
based on scientific principles had been made since the time of
EratosthenesEratosthenes of Cyrene was a Greek mathematician, elegiac poet, athlete, geographer, and astronomer. He made several discoveries and inventions including a system of latitude and longitude...
(3rd century BC), but Ptolemy improved
projectionA map projection is any method of representing the surface of a sphere or other shape on a plane. Map projections are necessary for creating maps. All map projections distort the surface in some fashion...
s. It is known that a world map based on the
Geographia was on display in
AutunAutun is a commune in the Saône-et-Loire department in Burgundy in eastern France.The history of Autun dates back to Roman times.Autun marks the easternmost extent of the Umayyad campaign in Europe.-History:...
,
GaulFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
in late Roman times.
Reception in the Renaissance
Ptolemy's text reached Italy from Constantinople about 1400. The first printed edition, probably in 1477 in
BolognaBologna is the capital city of Emilia-Romagna, in the Po Valley of northern Italy...
, was also the first printed book with
engravedEngraving is the practice of incising a design on to a hard, usually flat surface, by cutting grooves into it. The result may be a decorated object in itself, as when silver, gold, steel, or glass are engraved, or may provide an intaglio printing plate, of copper or another metal, for printing...
illustrations. Many editions followed (more often using
woodcutWoodcut — formally known as xylography — is a relief printing artistic technique in printmaking in which an image is carved into the surface of a block of wood, with the printing parts remaining level with the surface while the non-printing parts are removed, typically with gouges...
in the early days), some following traditional versions of the maps, and others updating them. An edition printed at
UlmUlm is a city in the German Bundesland of Baden-Württemberg, situated on the River Danube. The city, whose population is estimated at 120,000 , forms an urban district of its own and is the administrative seat of the Alb-Donau district. Ulm, founded around 850, is rich in history and traditions...
in 1482 was the first one printed north of the
AlpsThe Alps are one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east; through Italy, Switzerland, Liechtenstein and Germany; to France in the west....
. Also in 1482,
Francesco BerlinghieriFrancesco Berlinghieri was an Italian scholar and humanist who lived during the fifteenth century. He promoted the value of classical Greek learning and was one of the first to print a text based on Ptolemy's Geographica...
printed the first edition in vernacular
ItalianItalian is a Romance language spoken by about 60 million people in Italy, and by a total of around 70 million in the world. In Switzerland, Italian is one of four official languages. It is also the official language of San Marino, as well as the primary language of Vatican City...
. 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
EratosthenesEratosthenes of Cyrene was a Greek mathematician, elegiac poet, athlete, geographer, and astronomer. He made several discoveries and inventions including a system of latitude and longitude...
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 chronometerA marine chronometer is a timekeeper precise enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation. When first developed in the eighteenth century it was a major technical achievement, as accurate knowledge of the time over a...
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 the
history of cartographyCartography , or mapmaking, has been an integral part of the human story for a long time, possibly up to 8,000 years...
.
See also
- Bibliotheca historica
Bibliotheca historica , is a work of Universal history by Diodorus Siculus. It consisted of forty books, which were divided into three sections. The first six books are geographical in theme, and describe the history and culture of Egypt , of Mesopotamia, India, Scythia, and Arabia , of North...
- Diodorus Siculus
Diodorus Siculus , was a Greek historian who flourished in the 1st century BC. According to Diodorus' own work, he was born at Agyrium in Sicily . With one exception, antiquity affords no further information about Diodorus' life and doing than is to be found in his own work, Bibliotheca historica...
- Geography in medieval Islam
- Strabo
Strabo was a Greek historian, geographer and philosopher.-Life:Strabo was born in a wealthy family from Amaseia in Pontus , which had recently become part of the Roman Empire.. He studied under various geographers and philosophers; first in Nysa, later in Rome...
Primary sources
Secondary material