The Size of the Ecumene of the Mediterranean in Ancient Times
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Journal of Geographical Research | Volume 03 | Issue 04 | October 2020 Journal of Geographical Research https://ojs.bilpublishing.com/index.php/jgr ARTICLE The Size of the Ecumene of the Mediterranean in Ancient Times Aleksandar Valjarević* University of Belgrade, Faculty of Geography, Studentski Trg 3/III, Belgrade, Serbia ARTICLE INFO ABSTRACT Article history For the purpose of this manuscript, we used the old maps of Europe and of Received: 22 June 2020 the ecumene, as it was known at the time, in order to establish the ecumene properties, as well as the size of the Mediterranean in the time of Ptolemy. Accepted: 31 July 2020 We obtained the coordinates (geographic longitude and latitude) from Pto- Published Online: 30 September 2020 lemy’s map of ecumene of ancient Mediterranean settlements. According to the historical data the coordinates of the Mediterranean ecumene were Keywords: studied in the 7th century, since the Mediterranean was the centre connect- Ptolemy’s ecumene map ing the civilizations of Europe, Asia and Africa. Although longitudinal and latitudinal errors are large, these coordinates are of great importance for the Density of settlements studies of the past settlements. Today, these settlements are the symbol of Coordinates civilisation and of human existence. Using the data from 501 settlements The Mediterranean overall, we obtained two principal maps of the Mediterranean ecumene with the average density of settlements on the area of 2000 km2. All Ptole- Ptolemy my’s maps, which were used, were of great significance from the scientific Modern and Ptolemy’s coordinates point of view, since they made the description of 2000 years old civilization possible. Historically, part of these civilizations, and those formed after- wards, belonged to the Mediterranean. 1. Introduction year. The complexity of the equinox lines, in the further context of parallels, begins from the equator. These lines tolemy (Claudius Ptolemy) is considered to be one extend in durations of the diurnal light reckoning from of the founders of geography, which was formed in the summer solstice. The durations increase by a quarter P100 AD in Alexandria, today’s Egypt. According to from 12 to 18 equinox hours by the geographic latitude of historical resources, Ptolemy lived in the first century AD. (58°φ), i. e. by 24 equinox hours on the Arctic Circle (66° Together with Eratosthenes (Eratosthenes), Ptolemy is re- 8ʹ 40ʺ φ). The major problem in establishing the total area garded as the best father of geography because he was the of the ancient ecumene is the northernmost point situated first to introduce the concept of geographic coordinates at the place of Thule (coordinates: 30° 30ʹ λ, 63° 00ʹφ). (longitude and latitude) and the idea of creating some The most probable position of that point has still not been maps using geographical projections. Most of the coordi- completely confirmed, but most scientists think that this nates of the ecumene, set at that time can be found in the settlement belongs either to Iceland or Greenland. The epochal book of Almagest. Ptolemy was the first to present southernmost point according to Ptolemy’s ecumene map the relation between the geographic longitude and gno- had the following coordinates: 60° 00ʹλ, -20°00ʹ φ, near monic projection of the solar declination throughout the Cartum (in present time Assuan) (Orbis Ptolemai, the map *Corresponding Author: Aleksandar Valjarević, University of Belgrade, Faculty of Geography, Studentski Trg 3/III, Belgrade, Serbia; Email: [email protected] Distributed under creative commons license 4.0 DOI: https://doi.org/10.30564/jgr.v3i4.2030 1 Journal of Geographical Research | Volume 03 | Issue 04 | October 2020 of ecumene). The majority of coordinates we used for smaller in latitude, larger in longitude). Ptolemy obtained the present purpose are from Ptolemy’s Geography (III, the coordinates as a part of degree measured from the IV). In order to georeference this old map successfully, equator which was then relatively precisely determined. we compared it to modern, as for construction and defor- The longitude was most likely determined from the prime mations, the most similar projections. The ecumene back meridian, then located at ~30°.60 from the Greenwich. It then, as well as the whole world, was divided into three is also known that the settlement positions (their coordi- continents. To the east, it reached Asia Major, India today, nates) have higher precision in the internal Mediterranean; to the south, Ethiopia, south of Libya (part of Ethiopia its value being 5 arc minutes. Finally, the total number of presented on Ptolemy’s ecumene map was called Agisym- Ptolemy’s coordinates is 8000, 233 of which were taken ba), to the west, the bay bordering the Ethiopian Bay in for the purpose of this manuscript from the regions of the Western Atlantic Ocean [1]. All the countries, as well as Hispania, Italia and large islands near Greece, Asia Minor, the settlement coordinates in the past, belong to the Med- Levant and Egypt. The missing coordinates were obtained iterranean of today in a broader geographic sense; histor- by means of specially created algorithm wherein the ically and geographically, countries forming the Mediter- relative error in (longitude) within ~1*4 was taken into ranean are: Gibraltar, Spain, France, Monaco, Italy, Malta, account. We also used special tools in GIS in order to de- Slovenia, Croatia, Bosnia and Hezegovina, Montenegro, termine the coordinates today. Albania, Greece, Turkey, Cyprus, Syria, Lebanon, Israel, Egypt, Libya, Tunisia, Algeria, Morocco [2]. The rest of 2. Ptolemy’s Simple Conic Projection the data were taken from (Tabula of Europe) with the set- One of the first projections made with precision belongs tlements in the internal and external parts of the Mediter- to Ptolemy. In Ptolemy’s conic projection the parallels ranean. Ptolemy’s first ecumene map was done in simple are given as concentric circles (circle outsides). The me- conic projection. This projection might also be referred to ridians are given as straight lines. However, the historical as gnomonic one or shadow projection because its coordi- importance of this projection is that it was the first to indi- nates were determined by using the declination of the Sun. cate a given point with the help of a coordinate (longitude, Ancient geographers determined geographic positions us- latitude). In constructing the cartographic grid, the prime ing some astronomical phenomena, such as, for instance: meridian belonged to the Rhodes parallel ( φ0 ). From the star places in the sky, the ratio of the height to the length Rhodes parallel all other radii of other coordinates from of the shadow during a year, the longest daytime dura- the map are drawn (see Eq.2). tion within a year for the same terrestrial position. To the ancient geographers, the most useful star was, certainly, ρ00 = Rctgφ (2) the one observed from the Rhodes and Alexandria. It was [3] Canopus in the Carina constellation . Almost all of these where R is the radius of the terrestrial sphere reduced coordinates were investigated and the analysis of latitude according to the map scale. Arc (arcsecant) of the other and longitude was performed by means of GIS analysis parallels starts from the common centre. The radius is [4] and the method of geospace dispersion . Between the equal to that of the standard parallel (see Eq.3). caps occupied by circumpolar and anticircumpolar con- stellations, there is a zone defined in the following way ρ = ρ0 + RΔφ (3) φ-9000≤≤ δ 90 -φ (1) The angle (δ) obtained from the meridian grid, as well as the meridian approaching angle, is found by applying Then for a star attaining the zenith in its upper culmi- the formula for chord length within equilateral triangle. nation it is valid δ=φ. The chord length, as well as the angle between meridians, is calculated by using the following equations (see, Eq.4, So the coordinates of a point on the Eath’s surface Eq.5). (latitude) could also be determined from a lunar eclipse. Two towns where the measuring took place were Arabela d δ Δλ = Rctgφ sin = Rcosφ sin (4) and Catagena. The major measuring error between the 2200 2 two towns exceeded 110 in longitude [5]. For the further analysis of data, we used Ptolemy’s coordinates, and those δ = Δλsinφ which were missing were obtained directly from the map 0 (5) after its georeferencing. Most of the coordinates contained errors, so we minimised them using the equation (error is In Ptolemy’s conic projection the direction and the 2 Distributed under creative commons license 4.0 DOI: https://doi.org/10.30564/jgr.v3i4.2030 Journal of Geographical Research | Volume 03 | Issue 04 | October 2020 shape of the prime meridian depends on the direction of insight of its present state, but also of its future. Follow- its extension. The standard parallel of this projection has ing some theoreticians who minimalise the frontiers, preserved the zero deformation only. As the standard par- the Mediterranean is bordered by olive dispersion to the allel becomes more distant, the deformations of lengths, north and the south. Following the maximalist definitions, angles, as well as of the areas, enormously increase. At the the Mediterranean is given through historical transition poles the deformations are infinite. The basic formula for zones. In the present paper, the authors are focussed on construction of Ptolemy’s projection is given in Equation the Mediterranean within the Roman Empire presented in (6). [7]. In the 1st and the 2nd century, the population was partly assimilated by the Roman Empire so that the frontiers of δ = Δλ*sinφ0 , ρ00 = R * ctgφ , ρ = R *ctgφ00 + R(φ - φ) , the ancient Mediterranean states were removed, since the Mediterranean economically and culturologically merged ρE = R *ctgφ 00 + Rφ , x = q - ρ *cosδ , y = ρ *sinδ , n=1, into the Roman Empire.